Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1992-01-01

ATTAP activities during the past year included test-bed engine design and development, ceramic component design, materials and component characterization, ceramic component process development and fabrication, ceramic component rig testing, and test-bed engine fabrication and testing. Significant technical challenges remain, but all areas exhibited progress. Test-bed engine design and development included engine mechanical design, combustion system design, alternate aerodynamic designs of gasifier scrolls, and engine system integration aimed at upgrading the AGT-5 from a 1038 C (1900 F) metal engine to a durable 1372 C (2500 F) structural ceramic component test-bed engine. ATTAP-defined ceramic and associated ceramic/metal component design activities completed include the ceramic gasifier turbine static structure, the ceramic gasifier turbine rotor, ceramic combustors, the ceramic regenerator disk, the ceramic power turbine rotors, and the ceramic/metal power turbine static structure. The material and component characterization efforts included the testing and evaluation of seven candidate materials and three development components. Ceramic component process development and fabrication proceeded for the gasifier turbine rotor, gasifier turbine scroll, gasifier turbine vanes and vane platform, extruded regenerator disks, and thermal insulation. Component rig activities included the development of both rigs and the necessary test procedures, and conduct of rig testing of the ceramic components and assemblies. Test-bed engine fabrication, testing, and development supported improvements in ceramic component technology that permit the achievement of both program performance and durability goals. Total test time in 1991 amounted to 847 hours, of which 128 hours were engine testing, and 719 were hot rig testing.

Lunar Dust Simulant in Mechanical Component Testing - Paradigm and Practicality

NASA Technical Reports Server (NTRS)

Jett, T.; Street, K.; Abel, P.; Richmond, R.

2008-01-01

Due to the uniquely harsh lunar surface environment, terrestrial test activities may not adequately represent abrasive wear by lunar dust likely to be experienced in mechanical systems used in lunar exploration. Testing to identify potential moving mechanism problems has recently begun within the NASA Engineering and Safety Center Mechanical Systems Lunar Dust Assessment activity in coordination with the Exploration Technology and Development Program Dust Management Project, and these complimentary efforts will be described. Specific concerns about differences between simulant and lunar dust, and procedures for mechanical component testing with lunar simulant will be considered. In preparing for long term operations within a dusty lunar environment, the three fundamental approaches to keeping mechanical equipment functioning are dust avoidance, dust removal, and dust tolerance, with some combination of the three likely to be found in most engineering designs. Methods to exclude dust from contact with mechanical components would constitute mitigation by dust avoidance, so testing seals for dust exclusion efficacy as a function of particle size provides useful information for mechanism design. Dust of particle size less than a micron is not well documented for impact on lunar mechanical components. Therefore, creating a standardized lunar dust simulant in the particulate size range of ca. 0.1 to 1.0 micrometer is useful for testing effects on mechanical components such as bearings, gears, seals, bushings, and other moving mechanical assemblies. Approaching actual wear testing of mechanical components, it is beneficial to first establish relative wear rates caused by dust on commonly used mechanical component materials. The wear mode due to dust within mechanical components, such as abrasion caused by dust in grease(s), needs to be considered, as well as the effects of vacuum, lunar thermal cycle, and electrostatics on wear rate.

46 CFR 50.25-10 - Acceptance of piping components by specific letter or approved plan.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) MARINE ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-10 Acceptance... approved plan must do the following: (1) Submit an engineering type catalog or representative drawings of... specifications by comparing details of the materials' chemical composition, mechanical properties, method of...

46 CFR 50.25-10 - Acceptance of piping components by specific letter or approved plan.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) MARINE ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-10 Acceptance... approved plan must do the following: (1) Submit an engineering type catalog or representative drawings of... specifications by comparing details of the materials' chemical composition, mechanical properties, method of...

46 CFR 50.25-10 - Acceptance of piping components by specific letter or approved plan.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) MARINE ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-10 Acceptance... approved plan must do the following: (1) Submit an engineering type catalog or representative drawings of... specifications by comparing details of the materials' chemical composition, mechanical properties, method of...

46 CFR 50.25-10 - Acceptance of piping components by specific letter or approved plan.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) MARINE ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-10 Acceptance... approved plan must do the following: (1) Submit an engineering type catalog or representative drawings of... specifications by comparing details of the materials' chemical composition, mechanical properties, method of...

46 CFR 50.25-10 - Acceptance of piping components by specific letter or approved plan.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) MARINE ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-10 Acceptance... approved plan must do the following: (1) Submit an engineering type catalog or representative drawings of... specifications by comparing details of the materials' chemical composition, mechanical properties, method of...

Valves and other mechanical components and equipment: A compilation

NASA Technical Reports Server (NTRS)

1976-01-01

The articles in this Compilation will be of interest to mechanical engineers, users and designers of machinery, and to those engineers and manufacturers specializing in fluid handling systems. Section 1 describes a number of valves and valve systems. Section 2 contains articles on machinery and mechanical devices that may have applications in a number of different areas.

Investigation of performance deterioration of the CF6/JT9D, high-bypass ratio turbofan engines

NASA Technical Reports Server (NTRS)

Ziemianski, J. A.; Mehalic, C. M.

1980-01-01

The aircraft energy efficiency program within NASA is developing technology required to improve the fuel efficiency of commercial subsonic transport aricraft. One segment of this program includes engine diagnostics which is directed toward determining the sources and causes of performance deterioration in the Pratt and Whitney Aircraft JT9D and General Electric CF6 high-bypass ratio turbofan engines and developing technology for minimizing the performance losses. Results of engine performance deterioration investigations based on historical data, special engine tests, and specific tests to define the influence of flight loads and component clearances on performance are presented. The results of analysis of several damage mechanisms that contribute to performance deterioration such as blade tip rubs, airfoil surface roughness and erosion, and thermal distortion are also included. The significance of these damage mechanisms on component and overall engine performance is discussed.

Summary of engine design and analytical studies to mature the 1137400E engine baseline

NASA Technical Reports Server (NTRS)

Kleinert, D. E.; Lester, W. A.

1972-01-01

Activities in packaging components into integral module arrangements compatible with engine design requirements for the 1137400E flight engine baseline are summarized along with the applied mechanics and thermal analysis. Revisions to drawings, configurations, and support structures are discussed.

Development of structural ceramic components for automobile applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawamoto, H.

1995-12-01

Development efforts have been made in automobile technologies on heat engines to improve the power performance, the fuel economy, and so on. It is well recognized that ceramic applications are keys to succeed in such advanced heat engines, because of their good mechanical and thermal properties. This paper discusses present automobile applications of structural ceramic components and the expectations in automobile uses. The strength and reliability of mass-produced components for the engines are described with the manufacturing processes. The future R&D directions are recommended for structural ceramics.

Space transportation booster engine configuration study. Addendum: Design definition document

NASA Technical Reports Server (NTRS)

1989-01-01

Gas generator engine characteristics and results of engine configuration refinements are discussed. Updated component mechanical design, performance, and manufacturing information is provided. The results are also provided of ocean recovery studies and various engine integration tasks. The details are provided of the maintenance plan for the Space Transportation Booster Engine.

Quiet Clean Short-haul Experimental Engine (QCSEE). Under-The-Wing (UTW) engine boilerplate nacelle test report. Volume 3: Mechanical performance

NASA Technical Reports Server (NTRS)

1977-01-01

Results of initial tests of the under the wing experimental engine and boilerplate nacelle are presented. The mechanical performance of the engine is reported with emphasis on the advanced technology components. Technology elements of the propulsion system covered include: system dynamics, composite fan blades, reduction gear, lube and accessory drive system, fan frame, inlet, core cowl cooling, fan exhaust nozzle, and digital control system.

Orbit Transfer Vehicle (OTV) advanced expander cycle engine point design study. Volume 2: Study results

NASA Technical Reports Server (NTRS)

1980-01-01

Detailed computer models of the engine were developed to predict both the steady state and transient operation of the engine system. Mechanical design layout drawings were prepared for the following components: thrust chamber and nozzle; extendible nozzle actuating mechanism and seal; LOX turbopump and boost pump; hydrogen turbopump and boost pump; and the propellant control valves. The necessary heat transfer, stress, fluid flow, dynamic, and performance analyses were performed to support the mechanical design.

Energy efficient engine low-pressure compressor component test hardware detailed design report

NASA Technical Reports Server (NTRS)

Michael, C. J.; Halle, J. E.

1981-01-01

The aerodynamic and mechanical design description of the low pressure compressor component of the Energy Efficient Engine were used. The component was designed to meet the requirements of the Flight Propulsion System while maintaining a low cost approach in providing a low pressure compressor design for the Integrated Core/Low Spool test required in the Energy Efficient Engine Program. The resulting low pressure compressor component design meets or exceeds all design goals with the exception of surge margin. In addition, the expense of hardware fabrication for the Integrated Core/Low Spool test has been minimized through the use of existing minor part hardware.

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1993-01-01

The Advanced Turbine Technologies Application Project (ATTAP) is in the fifth year of a multiyear development program to bring the automotive gas turbine engine to a state at which industry can make commercialization decisions. Activities during the past year included reference powertrain design updates, test-bed engine design and development, ceramic component design, materials and component characterization, ceramic component process development and fabrication, ceramic component rig testing, and test-bed engine fabrication and testing. Engine design and development included mechanical design, combustion system development, alternate aerodynamic flow testing, and controls development. Design activities included development of the ceramic gasifier turbine static structure, the ceramic gasifier rotor, and the ceramic power turbine rotor. Material characterization efforts included the testing and evaluation of five candidate high temperature ceramic materials. Ceramic component process development and fabrication, with the objective of approaching automotive volumes and costs, continued for the gasifier turbine rotor, gasifier turbine scroll, extruded regenerator disks, and thermal insulation. Engine and rig fabrication, testing, and development supported improvements in ceramic component technology. Total test time in 1992 amounted to 599 hours, of which 147 hours were engine testing and 452 were hot rig testing.

Diesel Engine Mechanics.

ERIC Educational Resources Information Center

Foutes, William A.

Written in student performance terms, this curriculum guide on diesel engine repair is divided into the following eight sections: an orientation to the occupational field and instructional program; instruction in operating principles; instruction in engine components; instruction in auxiliary systems; instruction in fuel systems; instruction in…

Enhancements to the Engine Data Interpretation System (EDIS)

NASA Technical Reports Server (NTRS)

Hofmann, Martin O.

1993-01-01

The Engine Data Interpretation System (EDIS) expert system project assists the data review personnel at NASA/MSFC in performing post-test data analysis and engine diagnosis of the Space Shuttle Main Engine (SSME). EDIS uses knowledge of the engine, its components, and simple thermodynamic principles instead of, and in addition to, heuristic rules gathered from the engine experts. EDIS reasons in cooperation with human experts, following roughly the pattern of logic exhibited by human experts. EDIS concentrates on steady-state static faults, such as small leaks, and component degradations, such as pump efficiencies. The objective of this contract was to complete the set of engine component models, integrate heuristic rules into EDIS, integrate the Power Balance Model into EDIS, and investigate modification of the qualitative reasoning mechanisms to allow 'fuzzy' value classification. The results of this contract is an operational version of EDIS. EDIS will become a module of the Post-Test Diagnostic System (PTDS) and will, in this context, provide system-level diagnostic capabilities which integrate component-specific findings provided by other modules.

Towards an Automated Full-Turbofan Engine Numerical Simulation

NASA Technical Reports Server (NTRS)

Reed, John A.; Turner, Mark G.; Norris, Andrew; Veres, Joseph P.

2003-01-01

The objective of this study was to demonstrate the high-fidelity numerical simulation of a modern high-bypass turbofan engine. The simulation utilizes the Numerical Propulsion System Simulation (NPSS) thermodynamic cycle modeling system coupled to a high-fidelity full-engine model represented by a set of coupled three-dimensional computational fluid dynamic (CFD) component models. Boundary conditions from the balanced, steady-state cycle model are used to define component boundary conditions in the full-engine model. Operating characteristics of the three-dimensional component models are integrated into the cycle model via partial performance maps generated automatically from the CFD flow solutions using one-dimensional meanline turbomachinery programs. This paper reports on the progress made towards the full-engine simulation of the GE90-94B engine, highlighting the generation of the high-pressure compressor partial performance map. The ongoing work will provide a system to evaluate the steady and unsteady aerodynamic and mechanical interactions between engine components at design and off-design operating conditions.

Enhancements to the Engine Data Interpretation System (EDIS)

NASA Technical Reports Server (NTRS)

Hofmann, Martin O.

1993-01-01

The Engine Data Interpretation System (EDIS) expert system project assists the data review personnel at NASA/MSFC in performing post-test data analysis and engine diagnosis of the Space Shuttle Main Engine (SSME). EDIS uses knowledge of the engine, its components, and simple thermodynamic principles instead of, and in addition to, heuristic rules gathered from the engine experts. EDIS reasons in cooperation with human experts, following roughly the pattern of logic exhibited by human experts. EDIS concentrates on steady-state static faults, such as small leaks, and component degradations, such as pump efficiencies. The objective of this contract was to complete the set of engine component models, integrate heuristic rules into EDIS, integrate the Power Balance Model into EDIS, and investigate modification of the qualitative reasoning mechanisms to allow 'fuzzy' value classification. The result of this contract is an operational version of EDIS. EDIS will become a module of the Post-Test Diagnostic System (PTDS) and will, in this context, provide system-level diagnostic capabilities which integrate component-specific findings provided by other modules.

Durability and CMAS Resistance of Advanced Environmental Barrier Coatings Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2015-01-01

Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. This paper will emphasize advanced environmental barrier coating developments for SiCSiC turbine airfoil components, by using advanced coating compositions and processing, in conjunction with mechanical and environment testing and durability validations. The coating-CMC degradations and durability in the laboratory simulated engine fatigue-creep and complex operating environments are being addressed. The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will be discussed. The results help understand the advanced EBC-CMC system performance, aiming at the durability improvements of more robust, prime-reliant environmental barrier coatings for successful applications of the component technologies and lifing methodologies.

Investigation of Exoskeletal Engine Propulsion System Concept

NASA Technical Reports Server (NTRS)

Roche, Joseph M.; Palac, Donald T.; Hunter, James E.; Myers, David E.; Snyder, Christopher A.; Kosareo, Daniel N.; McCurdy, David R.; Dougherty, Kevin T.

2005-01-01

An innovative approach to gas turbine design involves mounting compressor and turbine blades to an outer rotating shell. Designated the exoskeletal engine, compression (preferable to tension for high-temperature ceramic materials, generally) becomes the dominant blade force. Exoskeletal engine feasibility lies in the structural and mechanical design (as opposed to cycle or aerothermodynamic design), so this study focused on the development and assessment of a structural-mechanical exoskeletal concept using the Rolls-Royce AE3007 regional airliner all-axial turbofan as a baseline. The effort was further limited to the definition of an exoskeletal high-pressure spool concept, where the major structural and thermal challenges are represented. The mass of the high-pressure spool was calculated and compared with the mass of AE3007 engine components. It was found that the exoskeletal engine rotating components can be significantly lighter than the rotating components of a conventional engine. However, bearing technology development is required, since the mass of existing bearing systems would exceed rotating machinery mass savings. It is recommended that once bearing technology is sufficiently advanced, a "clean sheet" preliminary design of an exoskeletal system be accomplished to better quantify the potential for the exoskeletal concept to deliver benefits in mass, structural efficiency, and cycle design flexibility.

Overview of thermal barrier coatings in diesel engines

NASA Technical Reports Server (NTRS)

Yonushonis, T. M.

1995-01-01

An understanding of delamination mechanisms in thermal barrier coatings has been developed for diesel applications through nondestructive evaluation, structural analysis modeling and engine evaluation of various thermal barrier coatings. This knowledge has resulted in improved thermal barrier coatings which survive abusive cyclic fatigue tests in high output diesel engines. Significant efforts are still required to improve the plasma spray processing capability and the economics for complex geometry diesel engine components. Data obtained from advanced diesel engines on the effect of thermal barrier coatings on engine fuel economy and emission has not been encouraging. Although the underlying metal component temperatures have been reduced through the use of thermal barrier coating, engine efficiency and emission trends have not been promising.

A Robust Damage Reporting Strategy for Polymeric Materials Enabled by Aggregation Induced Emission

DTIC Science & Technology

2016-08-17

and Technology, ‡Department of Chemistry, ∥Department of Materials Science and Engineering, ⊥Department of Mechanical Science and Engineering, and...enabled by aggregation-induced emission (AIE). This simple, yet powerful system relies on a single active component, and the general mechanism ...delivers outstanding performance in a wide variety of materials with diverse chemical and mechanical properties. Small (micrometer) scale damage in

The Effect of Weld Metal Strength Mismatch on the Deformation and Fracture Behavior of Steel Butt Weldments

DTIC Science & Technology

1991-01-01

Society 6 of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code [ 1980]. Their results are similar to those of Satoh and Toyoda, and are...E813-89. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code , Section III, Nuclear Power Plant Components, 1980. American

The role of mechanical loading in ligament tissue engineering.

PubMed

Benhardt, Hugh A; Cosgriff-Hernandez, Elizabeth M

2009-12-01

Tissue-engineered ligaments have received growing interest as a promising alternative for ligament reconstruction when traditional transplants are unavailable or fail. Mechanical stimulation was recently identified as a critical component in engineering load-bearing tissues. It is well established that living tissue responds to altered loads through endogenous changes in cellular behavior, tissue organization, and bulk mechanical properties. Without the appropriate biomechanical cues, new tissue formation lacks the necessary collagenous organization and alignment for sufficient load-bearing capacity. Therefore, tissue engineers utilize mechanical conditioning to guide tissue remodeling and improve the performance of ligament grafts. This review provides a comparative analysis of the response of ligament and tendon fibroblasts to mechanical loading in current bioreactor studies. The differential effect of mechanical stimulation on cellular processes such as protease production, matrix protein synthesis, and cell proliferation is examined in the context of tissue engineering design.

Microstructural indicators of transition mechanisms in time-dependent fatigue crack growth in nickel base superalloys

NASA Astrophysics Data System (ADS)

Heeter, Ann E.

Gas turbine engines are an important part of power generation in modern society, especially in the field of aerospace. Aerospace engines are design to last approximately 30 years and the engine components must be designed to survive for the life of the engine or to be replaced at regular intervals to ensure consumer safety. Fatigue crack growth analysis is a vital component of design for an aerospace component. Crack growth modeling and design methods date back to an origin around 1950 with a high rate of accuracy. The new generation of aerospace engines is designed to be efficient as possible and require higher operating temperatures than ever seen before in previous generations. These higher temperatures place more stringent requirements on the material crack growth performance under creep and time dependent conditions. Typically the types of components which are subject to these requirements are rotating disk components which are made from advanced materials such as nickel base superalloys. Traditionally crack growth models have looked at high temperature crack growth purely as a function of temperature and assumed that all crack growth was either controlled by a cycle dependent or time dependent mechanism. This new analysis is trying to evaluate the transition between cycle-dependent and time-dependent mechanism and the microstructural markers that characterize this transitional behavior. The physical indications include both the fracture surface morphology as well as the shape of the crack front. The research will evaluate whether crack tunneling occurs and whether it consistently predicts a transition from cycle-dependent crack growth to time-dependent crack growth. The study is part of a larger research program trying to include the effects of geometry, mission profile and environmental effects, in addition to temperature effects, as a part of the overall crack growth system. The outcome will provide evidence for various transition types and correlate those physical attributes back to the material mechanisms to improve predictive modeling capability.

An investigation of crankshaft oscillations for cylinder health diagnostics

NASA Astrophysics Data System (ADS)

Geveci, Mert; Osburn, Andrew W.; Franchek, Matthew A.

2005-09-01

The vibrational characteristics of an internal combustion engine crankshaft are investigated from a cylinder health diagnostics point of view. Experimental results from a six-cylinder industrial diesel engine are presented to demonstrate the effects of cylinder imbalance on the individual harmonic components of the engine speed signal. A crank-angle domain numerical model of the crankshaft dynamics for a six-cylinder industrial diesel engine is also adopted to establish the effects of continuous low-power production in individual cylinders of a multi-cylinder engine. Outline of a diagnostics algorithm that makes use of the properties of crankshaft vibration behaviour is provided. In particular, crank-angle domain notch filters are employed to extact the harmonic components of engine speed. The outlined method can be implemented for individual cylinder health diagnostics across a family of multi-cylinder engines and can be formulated to handle changes in crankshaft characteristics due to replacement of mechanical components and/or wear.

Forensic engineering: applying materials and mechanics principles to the investigation of product failures.

PubMed

Hainsworth, S V; Fitzpatrick, M E

2007-06-01

Forensic engineering is the application of engineering principles or techniques to the investigation of materials, products, structures or components that fail or do not perform as intended. In particular, forensic engineering can involve providing solutions to forensic problems by the application of engineering science. A criminal aspect may be involved in the investigation but often the problems are related to negligence, breach of contract, or providing information needed in the redesign of a product to eliminate future failures. Forensic engineering may include the investigation of the physical causes of accidents or other sources of claims and litigation (for example, patent disputes). It involves the preparation of technical engineering reports, and may require giving testimony and providing advice to assist in the resolution of disputes affecting life or property.This paper reviews the principal methods available for the analysis of failed components and then gives examples of different component failure modes through selected case studies.

Lewis Structures Technology, 1988. Volume 2: Structural Mechanics

NASA Technical Reports Server (NTRS)

1988-01-01

Lewis Structures Div. performs and disseminates results of research conducted in support of aerospace engine structures. These results have a wide range of applicability to practitioners of structural engineering mechanics beyond the aerospace arena. The engineering community was familiarized with the depth and range of research performed by the division and its academic and industrial partners. Sessions covered vibration control, fracture mechanics, ceramic component reliability, parallel computing, nondestructive evaluation, constitutive models and experimental capabilities, dynamic systems, fatigue and damage, wind turbines, hot section technology (HOST), aeroelasticity, structural mechanics codes, computational methods for dynamics, structural optimization, and applications of structural dynamics, and structural mechanics computer codes.

The Use of Mini-projects in the Teaching of Geotechnics to Civil Engineering Undergraduates.

ERIC Educational Resources Information Center

Anderson, W. F.; And Others

1985-01-01

Geotechnics (which encompasses soil and rock mechanics, engineering geology, foundation design, and ground engineering methods) is a major component of virtually all civil engineering courses. Show how mini-projects are used to teach this subject. Format of projects, development of presentation skills, and assessment considerations are discussed.…

High-Heat-Flux Cyclic Durability of Thermal and Environmental Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Ghosn, Louis L.; Miller, Robert A.

2007-01-01

Advanced ceramic thermal and environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect the engine components and further raise engine temperatures. For the supersonic vehicles currently envisioned in the NASA fundamental aeronautics program, advanced gas turbine engines will be used to provide high power density thrust during the extended supersonic flight of the aircraft, while meeting stringent low emission requirements. Advanced ceramic coating systems are critical to the performance, life and durability of the hot-section components of the engine systems. In this work, the laser and burner rig based high-heat-flux testing approaches were developed to investigate the coating cyclic response and failure mechanisms under simulated supersonic long-duration cruise mission. The accelerated coating cracking and delamination mechanism under the engine high-heat-flux, and extended supersonic cruise time conditions will be addressed. A coating life prediction framework may be realized by examining the crack initiation and propagation in conjunction with environmental degradation under high-heat-flux test conditions.

Thermal and Environmental Barrier Coatings for Advanced Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Miller, Robert A.

2005-01-01

Ceramic thermal and environmental barrier coatings (T/EBCs) will play a crucial role in advanced gas turbine engine systems because of their ability to significantly increase engine operating temperatures and reduce cooling requirements, thus help achieve engine low emission and high efficiency goals. Advanced T/EBCs are being developed for the low emission SiC/SiC ceramic matrix composite (CMC) combustor applications by extending the CMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water vapor containing combustion environments. Low conductivity thermal barrier coatings (TBCs) are also being developed for metallic turbine airfoil and combustor applications, providing the component temperature capability up to 1650 C (3000 F). In this paper, ceramic coating development considerations and requirements for both the ceramic and metallic components will be described for engine high temperature and high-heat-flux applications. The underlying coating failure mechanisms and life prediction approaches will be discussed based on the simulated engine tests and fracture mechanics modeling results.

Assessment of potential asbestos exposures from jet engine overhaul work.

PubMed

Mlynarek, S P; Van Orden, D R

2012-06-01

Asbestos fibers have been used in a wide variety of products and numerous studies have shown that exposures from the use or manipulation of these products can vary widely. Jet engines contained various components (gaskets, clamps, o-rings and insulation) that contained asbestos that potentially could release airborne fibers during routine maintenance or during an engine overhaul. To evaluate the potential exposures to aircraft mechanics, a Pratt & Whitney JT3D jet engine was obtained and overhauled by experienced mechanics using tools and work practices similar to those used since the time this engine was manufactured. This study has demonstrated that the disturbance of asbestos-containing gaskets, o-rings, and other types of asbestos-containing components, while performing overhaul work to a jet engine produces very few airborne fibers, and that virtually none of these aerosolized fibers is asbestos. The overhaul work was observed to be dirty and oily. The exposures to the mechanics and bystanders were several orders of magnitude below OSHA exposure regulations, both current and historic. The data presented underscore the lack of risk to the health of persons conducting this work and to other persons in proximity to it from airborne asbestos. Copyright © 2012 Elsevier Inc. All rights reserved.

Energy Efficient Engine Low Pressure Subsystem Flow Analysis

NASA Technical Reports Server (NTRS)

Hall, Edward J.; Lynn, Sean R.; Heidegger, Nathan J.; Delaney, Robert A.

1998-01-01

The objective of this project is to provide the capability to analyze the aerodynamic performance of the complete low pressure subsystem (LPS) of the Energy Efficient Engine (EEE). The analyses were performed using three-dimensional Navier-Stokes numerical models employing advanced clustered processor computing platforms. The analysis evaluates the impact of steady aerodynamic interaction effects between the components of the LPS at design and off-design operating conditions. Mechanical coupling is provided by adjusting the rotational speed of common shaft-mounted components until a power balance is achieved. The Navier-Stokes modeling of the complete low pressure subsystem provides critical knowledge of component aero/mechanical interactions that previously were unknown to the designer until after hardware testing.

Energy Efficient Engine Low Pressure Subsystem Aerodynamic Analysis

NASA Technical Reports Server (NTRS)

Hall, Edward J.; Delaney, Robert A.; Lynn, Sean R.; Veres, Joseph P.

1998-01-01

The objective of this study was to demonstrate the capability to analyze the aerodynamic performance of the complete low pressure subsystem (LPS) of the Energy Efficient Engine (EEE). Detailed analyses were performed using three- dimensional Navier-Stokes numerical models employing advanced clustered processor computing platforms. The analysis evaluates the impact of steady aerodynamic interaction effects between the components of the LPS at design and off- design operating conditions. Mechanical coupling is provided by adjusting the rotational speed of common shaft-mounted components until a power balance is achieved. The Navier-Stokes modeling of the complete low pressure subsystem provides critical knowledge of component acro/mechanical interactions that previously were unknown to the designer until after hardware testing.

Intelligent Life-Extending Controls for Aircraft Engines

NASA Technical Reports Server (NTRS)

Guo, Ten-Huei; Chen, Philip; Jaw, Link

2005-01-01

Aircraft engine controllers are designed and operated to provide desired performance and stability margins. The purpose of life-extending-control (LEC) is to study the relationship between control action and engine component life usage, and to design an intelligent control algorithm to provide proper trade-offs between performance and engine life usage. The benefit of this approach is that it is expected to maintain safety while minimizing the overall operating costs. With the advances of computer technology, engine operation models, and damage physics, it is necessary to reevaluate the control strategy fro overall operating cost consideration. This paper uses the thermo-mechanical fatigue (TMF) of a critical component to demonstrate how an intelligent engine control algorithm can drastically reduce the engine life usage with minimum sacrifice in performance. A Monte Carlo simulation is also performed to evaluate the likely engine damage accumulation under various operating conditions. The simulation results show that an optimized acceleration schedule can provide a significant life saving in selected engine components.

Mechanisms for Robust Cognition

ERIC Educational Resources Information Center

Walsh, Matthew M.; Gluck, Kevin A.

2015-01-01

To function well in an unpredictable environment using unreliable components, a system must have a high degree of robustness. Robustness is fundamental to biological systems and is an objective in the design of engineered systems such as airplane engines and buildings. Cognitive systems, like biological and engineered systems, exist within…

Effect of Surface Impulsive Thermal Loads on Fatigue Behavior of Constant Volume Propulsion Engine Combustor Materials

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Miller, Robert A.; Ghosn, Louis J.; Kalluri, Sreeramesh

2004-01-01

The development of advanced high performance constant-volume-combustion-cycle engines (CVCCE) requires robust design of the engine components that are capable of enduring harsh combustion environments under high frequency thermal and mechanical fatigue conditions. In this study, a simulated engine test rig has been established to evaluate thermal fatigue behavior of a candidate engine combustor material, Haynes 188, under superimposed CO2 laser surface impulsive thermal loads (30 to 100 Hz) in conjunction with the mechanical fatigue loads (10 Hz). The mechanical high cycle fatigue (HCF) testing of some laser pre-exposed specimens has also been conducted under a frequency of 100 Hz to determine the laser surface damage effect. The test results have indicated that material surface oxidation and creep-enhanced fatigue is an important mechanism for the surface crack initiation and propagation under the simulated CVCCE engine conditions.

Energy efficient engine fan component detailed design report

NASA Technical Reports Server (NTRS)

Halle, J. E.; Michael, C. J.

1981-01-01

The fan component which was designed for the energy efficient engine is an advanced high performance, single stage system and is based on technology advancements in aerodynamics and structure mechanics. Two fan components were designed, both meeting the integrated core/low spool engine efficiency goal of 84.5%. The primary configuration, envisioned for a future flight propulsion system, features a shroudless, hollow blade and offers a predicted efficiency of 87.3%. A more conventional blade was designed, as a back up, for the integrated core/low spool demonstrator engine. The alternate blade configuration has a predicted efficiency of 86.3% for the future flight propulsion system. Both fan configurations meet goals established for efficiency surge margin, structural integrity and durability.

Health care professional workstation: software system construction using DSSA scenario-based engineering process.

PubMed

Hufnagel, S; Harbison, K; Silva, J; Mettala, E

1994-01-01

This paper describes a new method for the evolutionary determination of user requirements and system specifications called scenario-based engineering process (SEP). Health care professional workstations are critical components of large scale health care system architectures. We suggest that domain-specific software architectures (DSSAs) be used to specify standard interfaces and protocols for reusable software components throughout those architectures, including workstations. We encourage the use of engineering principles and abstraction mechanisms. Engineering principles are flexible guidelines, adaptable to particular situations. Abstraction mechanisms are simplifications for management of complexity. We recommend object-oriented design principles, graphical structural specifications, and formal components' behavioral specifications. We give an ambulatory care scenario and associated models to demonstrate SEP. The scenario uses health care terminology and gives patients' and health care providers' system views. Our goal is to have a threefold benefit. (i) Scenario view abstractions provide consistent interdisciplinary communications. (ii) Hierarchical object-oriented structures provide useful abstractions for reuse, understandability, and long term evolution. (iii) SEP and health care DSSA integration into computer aided software engineering (CASE) environments. These environments should support rapid construction and certification of individualized systems, from reuse libraries.

40 CFR Appendix Vi to Part 86 - Vehicle and Engine Components

Code of Federal Regulations, 2014 CFR

2014-07-01

.... (2) Drive belts. (3) Manifold and cylinder head bolts. (4) Engine oil and filter. (5) Engine coolant...) Carburetor-idle RPM, mixture ratio. (3) Choke mechanism. (4) Fuel system filter and fuel system lines and... filter breather cap. (4) Manifold inlet (carburetor spacer, etc.). V. External Exhaust Emission Control...

Modular Engine Noise Component Prediction System (MCP) Technical Description and Assessment Document

NASA Technical Reports Server (NTRS)

Herkes, William H.; Reed, David H.

2005-01-01

This report describes an empirical prediction procedure for turbofan engine noise. The procedure generates predicted noise levels for several noise components, including inlet- and aft-radiated fan noise, and jet-mixing noise. This report discusses the noise source mechanisms, the development of the prediction procedures, and the assessment of the accuracy of these predictions. Finally, some recommendations for future work are presented.

Creep Behavior of Hafnia and Ytterbium Silicate Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis J.; Harder, Bryan

2011-01-01

Environmental barrier coatings will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability and stability of SiC/SiC ceramic matrix composite (CMC) engine components, thus improving the engine performance. In order to develop high performance, robust coating systems for engine components, appropriate test approaches simulating operating temperature gradient and stress environments for evaluating the critical coating properties must be established. In this paper, thermal gradient mechanical testing approaches for evaluating creep and fatigue behavior of environmental barrier coated SiC/SiC CMC systems will be described. The creep and fatigue behavior of Hafnia and ytterbium silicate environmental barrier coatings on SiC/SiC CMC systems will be reported in simulated environmental exposure conditions. The coating failure mechanisms will also be discussed under the heat flux and stress conditions.

Engine balance apparatus and accessory drive device

NASA Technical Reports Server (NTRS)

Brogdon, James William (Inventor); Gill, David Keith (Inventor)

2000-01-01

A balancing mechanism for an engine that has a rotating crankshaft and reciprocating pistons such as those engines used in automobiles, aircrafts, boats, piston-driven compressors, piston-driven slider crank mechanisms, etc. The present balancing mechanism may comprise a first balance mass non-rotatably affixed to the crankshaft and a second balance mass rotatably supported on the crankshaft. A driver assembly is affixed to crankshaft to cause the second balance mass to rotate in a direction that is opposite to the direction in which the crank shaft is rotating. The driver assembly may include auxiliary gears configured to transport rotary power to auxiliary components.

Piston Ring Pressure Distribution

NASA Technical Reports Server (NTRS)

Kuhn, M.

1943-01-01

The discovery and introduction of the internal combustion engine has resulted in a very rapid development in machines utilizing the action of a piston. Design has been limited by the internal components of the engine, which has been subjected to ever increasing thermal and mechanical stresses, Of these internal engine components, the piston and piston rings are of particular importance and the momentary position of engine development is not seldom dependent upon the development of both of the components, The piston ring is a well-known component and has been used in its present shape in the steam engine of the last century, Corresponding to its importance, the piston ring has been a rich field for creative activity and it is noteworthy that in spite of this the ring has maintained its shape through the many years. From the many and complicated designs which have been suggested as a packing between piston and cylinder wall hardly one suggestion has remained which does not resemble the original design of cast iron rectangular ring.

Environmental Barrier Coating Fracture, Fatigue and High-Heat-Flux Durability Modeling and Stochastic Progressive Damage Simulation

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Nemeth, Noel N.

2017-01-01

Advanced environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect emerging light-weight SiC/SiC ceramic matrix composite (CMC) engine components, further raising engine operating temperatures and performance. Because the environmental barrier coating systems are critical to the performance, reliability and durability of these hot-section ceramic engine components, a prime-reliant coating system along with established life design methodology are required for the hot-section ceramic component insertion into engine service. In this paper, we have first summarized some observations of high temperature, high-heat-flux environmental degradation and failure mechanisms of environmental barrier coating systems in laboratory simulated engine environment tests. In particular, the coating surface cracking morphologies and associated subsequent delamination mechanisms under the engine level high-heat-flux, combustion steam, and mechanical creep and fatigue loading conditions will be discussed. The EBC compostion and archtechture improvements based on advanced high heat flux environmental testing, and the modeling advances based on the integrated Finite Element Analysis Micromechanics Analysis Code/Ceramics Analysis and Reliability Evaluation of Structures (FEAMAC/CARES) program will also be highlighted. The stochastic progressive damage simulation successfully predicts mud flat damage pattern in EBCs on coated 3-D specimens, and a 2-D model of through-the-thickness cross-section. A 2-parameter Weibull distribution was assumed in characterizing the coating layer stochastic strength response and the formation of damage was therefore modeled. The damage initiation and coalescence into progressively smaller mudflat crack cells was demonstrated. A coating life prediction framework may be realized by examining the surface crack initiation and delamination propagation in conjunction with environmental degradation under high-heat-flux and environment load test conditions.

Mechanics of a two-fiber model with one nested fiber network, as applied to the collagen-fibrin system.

PubMed

Nedrelow, David S; Bankwala, Danesh; Hyypio, Jeffrey D; Lai, Victor K; Barocas, Victor H

2018-05-01

The mechanical behavior of collagen-fibrin (col-fib) co-gels is both scientifically interesting and clinically relevant. Collagen-fibrin networks are a staple of tissue engineering research, but the mechanical consequences of changes in co-gel composition have remained difficult to predict or even explain. We previously observed fundamental differences in failure behavior between collagen-rich and fibrin-rich co-gels, suggesting an essential change in how the two components interact as the co-gel's composition changes. In this work, we explored the hypothesis that the co-gel behavior is due to a lack of percolation by the dilute component. We generated a series of computational models based on interpenetrating fiber networks. In these models, the major network component percolated the model space but the minor component did not, instead occupying a small island embedded within the larger network. Each component was assigned properties based on a fit of single-component gel data. Island size was varied to match the relative concentrations of the two components. The model predicted that networks rich in collagen, the stiffer component, would roughly match pure-collagen gel behavior with little additional stress due to the fibrin, as seen experimentally. For fibrin-rich gels, however, the model predicted a smooth increase in the overall network strength with added collagen, as seen experimentally but not consistent with an additive parallel model. We thus conclude that incomplete percolation by the low-concentration component of a co-gel is a major determinant of its macroscopic properties, especially if the low-concentration component is the stiffer component. Models for the behavior of fibrous networks have useful applications in many different fields, including polymer science, textiles, and tissue engineering. In addition to being important structural components in soft tissues and blood clots, these protein networks can serve as scaffolds for bioartificial tissues. Thus, their mechanical behavior, especially in co-gels, is both interesting from a materials science standpoint and significant with regard to tissue engineering. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Preassembled Building Components. Proceedings of a Program Conducted as Part of the Conferences of the Building Research Institute Division of Engineering and Industrial Research (Fall 1960).

ERIC Educational Resources Information Center

National Academy of Sciences - National Research Council, Washington, DC.

Four aspects of preassembled building components are discussed--(1) attitudes on preassembled components, (2) principles of preassembled components construction, (3) structural component case studies, and (4) mechanical component case studies. In section 1, various views on preassembled components are discussed including--(1) the architect's view,…

A comprehensive combustion model for biodiesel-fueled engine simulations

NASA Astrophysics Data System (ADS)

Brakora, Jessica L.

Engine models for alternative fuels are available, but few are comprehensive, well-validated models that include accurate physical property data as well as a detailed description of the fuel chemistry. In this work, a comprehensive biodiesel combustion model was created for use in multi-dimensional engine simulations, specifically the KIVA3v R2 code. The model incorporates realistic physical properties in a vaporization model developed for multi-component fuel sprays and applies an improved mechanism for biodiesel combustion chemistry. A reduced mechanism was generated from the methyl decanoate (MD) and methyl-9-decenoate (MD9D) mechanism developed at Lawrence Livermore National Laboratory. It was combined with a multi-component mechanism to include n-heptane in the fuel chemistry. The biodiesel chemistry was represented using a combination of MD, MD9D and n-heptane, which varied for a given fuel source. The reduced mechanism, which contained 63 species, accurately predicted ignition delay times of the detailed mechanism over a range of engine-specific operating conditions. Physical property data for the five methyl ester components of biodiesel were added to the KIVA library. Spray simulations were performed to ensure that the models adequately reproduce liquid penetration observed in biodiesel spray experiments. Fuel composition impacted liquid length as expected, with saturated species vaporizing more and penetrating less. Distillation curves were created to ensure the fuel vaporization process was comparable to available data. Engine validation was performed against a low-speed, high-load, conventional combustion experiments and the model was able to predict the performance and NOx formation seen in the experiment. High-speed, low-load, low-temperature combustion conditions were also modeled, and the emissions (HC, CO, NOx) and fuel consumption were well-predicted for a sweep of injection timings. Finally, comparisons were made between the results of biodiesel composition (palm vs. soy) and fuel blends (neat vs. B20). The model effectively reproduced the trends observed in the experiments.

Construction Mechanic, Engine Tune-Up II (Diesel), 8-8. Military Curriculum Materials for Vocational and Technical Education.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This course, adapted from military curriculum materials for vocational and technical education, teaches students to restore diesel engine performance to the manufacturer's specifications through troubleshooting and analyzing diesel engine fuel systems and to make minor and major adjustments to those components that directly affect engine…

Arctic communications techniques: Remote unattended power systems

NASA Astrophysics Data System (ADS)

Walker, G.

1986-02-01

The purpose of this report is to describe the accomplishments during the reporting period, 16 December 1985 through 1 February 1986, on the project entitled Arctic Communications Techniques: Remote Unattended Power Systems. All of the fabricated component parts for the first Ross-Stirling engine were completed. During the assembly process several interferences between some of the parts in the rotating mechanism were discovered causing drawing changes and subsequent rework to a few of the components. Assembly of the first engine was then completed. On the first attempt the engine ran successfully at approximately 3500 rpm.

In vitro physical stimulation of tissue-engineered and native cartilage.

PubMed

Li, Kelvin W; Klein, Travis J; Chawla, Kanika; Nugent, Gayle E; Bae, Won C; Sah, Robert L

2004-01-01

Because of the limited availability of donor cartilage for resurfacing defects in articular surfaces, there is tremendous interest in the in vitro bioengineering of cartilage replacements for clinical applications. However, attaining mechanical properties in engineered cartilaginous constructs that approach those of native cartilage has not been previously achieved when constructs are cultured under free-swelling conditions. One approach toward stimulating the development of constructs that are mechanically more robust is to expose them to physical environments that are similar, in certain ways, to those encountered by native cartilage. This is a strategy motivated by observations in numerous short-term experiments that certain mechanical signals are potent stimulators of cartilage metabolism. On the other hand, excess mechanical loading can have a deleterious effect on cartilage. Culture conditions that include a physical stimulation component are made possible by the use of specialized bioreactors. This chapter addresses some of the issues involved in using bioreactors as integral components of cartilage tissue engineering and in studying the physical regulation of cartilage. We first consider the generation of cartilaginous constructs in vitro. Next we describe the rationale and design of bioreactors that can impart either mechanical deformation or fluid-induced mechanical signals.

Performance deterioration based on existing (historical) data; JT9D jet engine diagnostics program

NASA Technical Reports Server (NTRS)

Sallee, G. P.

1978-01-01

The results of the collection and analysis of historical data pertaining to the deterioration of JT9D engine performance are presented. The results of analyses of prerepair and postrepair engine test stand performance data from a number of airlines to establish the individual as well as average losses in engine performance with respect to service use are included. Analysis of the changes in mechanical condition of parts, obtained by inspection of used gas-path parts of varying age, allowed preliminary assessments of component performance deterioration levels and identification of the causitive factors. These component performance estimates, refined by data from special engine back-to-back testing related to module performance restoration, permitted the development of preliminary models of engine component/module performance deterioration with respect to usage. The preliminary assessment of the causes of module performance deterioration and the trends with usage are explained, along with the role each module plays in overall engine performance deterioration. Preliminary recommendations with respect to operating and maintenance practices which could be adopted to control the level of performance deterioration are presented. The needs for additional component sensitivity testing as well as outstanding issues are discussed.

Programming a topologically constrained DNA nanostructure into a sensor

NASA Astrophysics Data System (ADS)

Liu, Meng; Zhang, Qiang; Li, Zhongping; Gu, Jimmy; Brennan, John D.; Li, Yingfu

2016-06-01

Many rationally engineered DNA nanostructures use mechanically interlocked topologies to connect individual DNA components, and their physical connectivity is achieved through the formation of a strong linking duplex. The existence of such a structural element also poses a significant topological constraint on functions of component rings. Herein, we hypothesize and confirm that DNA catenanes with a strong linking duplex prevent component rings from acting as the template for rolling circle amplification (RCA). However, by using an RNA-containing DNA [2] catenane with a strong linking duplex, we show that a stimuli-responsive RNA-cleaving DNAzyme can linearize one component ring, and thus enable RCA, producing an ultra-sensitive biosensing system. As an example, a DNA catenane biosensor is engineered to detect the model bacterial pathogen Escherichia coli through binding of a secreted protein, with a detection limit of 10 cells ml-1, thus establishing a new platform for further applications of mechanically interlocked DNA nanostructures.

Programming a topologically constrained DNA nanostructure into a sensor

PubMed Central

Liu, Meng; Zhang, Qiang; Li, Zhongping; Gu, Jimmy; Brennan, John D.; Li, Yingfu

2016-01-01

Many rationally engineered DNA nanostructures use mechanically interlocked topologies to connect individual DNA components, and their physical connectivity is achieved through the formation of a strong linking duplex. The existence of such a structural element also poses a significant topological constraint on functions of component rings. Herein, we hypothesize and confirm that DNA catenanes with a strong linking duplex prevent component rings from acting as the template for rolling circle amplification (RCA). However, by using an RNA-containing DNA [2] catenane with a strong linking duplex, we show that a stimuli-responsive RNA-cleaving DNAzyme can linearize one component ring, and thus enable RCA, producing an ultra-sensitive biosensing system. As an example, a DNA catenane biosensor is engineered to detect the model bacterial pathogen Escherichia coli through binding of a secreted protein, with a detection limit of 10 cells ml−1, thus establishing a new platform for further applications of mechanically interlocked DNA nanostructures. PMID:27337657

Recent developments in turbomachinery component materials and manufacturing challenges for aero engine applications

NASA Astrophysics Data System (ADS)

Srinivas, G.; Raghunandana, K.; Satish Shenoy, B.

2018-02-01

In the recent years the development of turbomachinery materials performance enhancement plays a vital role especially in aircraft air breathing engines like turbojet engine, turboprop engine, turboshaft engine and turbofan engines. Especially the transonic flow engines required highly sophisticated materials where it can sustain the entire thrust which can create by the engine. The main objective of this paper is to give an overview of the present cost-effective and technological capabilities process for turbomachinery component materials. Especially the main focus is given to study the Electro physical, Photonic additive removal process and Electro chemical process for turbomachinery parts manufacture. The aeronautical propulsion based technologies are reviewed thoroughly where in surface reliability, geometrical precession, and material removal and highly strengthened composite material deposition rates usually difficult to cut dedicated steels, Titanium and Nickel based alloys. In this paper the past aeronautical and propulsion mechanical based manufacturing technologies, current sophisticated technologies and also future challenging material processing techniques are covered. The paper also focuses on the brief description of turbomachinery components of shaping process and coating in aeromechanical applications.

Advanced Combustor in the Four Burner Area

NASA Image and Video Library

1966-03-21

Engineer Frank Kutina and a National Aeronautics and Space Administration (NASA) mechanic examine the setup of an advanced combustor rig inside one of the test cells at the Lewis Research Center’s Four Burner Area in the Engine Research Building. Kutina, of the Research Operations Branch, served as go-between for the researchers and the mechanics. He helped develop the test configurations and get the hardware installed. At the time of this photograph, Lewis Center Director Abe Silverstein had just established the Airbreathing Engine Division to address the new propulsion of the 1960s. After nearly a decade of focusing almost exclusively on space, NASA Lewis began tackling issues relating to the new turbofan engine, noise reduction, energy efficiency, supersonic transport, and the never-ending quest for higher performance levels with smaller and more lightweight engines. The Airbreathing Engine Division’s Combustion Branch was dedicated to the study and mitigation of the high temperatures and pressures found in advanced combustor designs. These high temperatures and pressures could destroy engine components. The Lewis investigation included film cooling, diffuser flow, and jet mixing. Components were tested in smaller test cells, but a full-scale augmenting burner rig, seen here, was tested extensively in the Four Burner Area test cell.

Mechanisms for Robust Cognition.

PubMed

Walsh, Matthew M; Gluck, Kevin A

2015-08-01

To function well in an unpredictable environment using unreliable components, a system must have a high degree of robustness. Robustness is fundamental to biological systems and is an objective in the design of engineered systems such as airplane engines and buildings. Cognitive systems, like biological and engineered systems, exist within variable environments. This raises the question, how do cognitive systems achieve similarly high degrees of robustness? The aim of this study was to identify a set of mechanisms that enhance robustness in cognitive systems. We identify three mechanisms that enhance robustness in biological and engineered systems: system control, redundancy, and adaptability. After surveying the psychological literature for evidence of these mechanisms, we provide simulations illustrating how each contributes to robust cognition in a different psychological domain: psychomotor vigilance, semantic memory, and strategy selection. These simulations highlight features of a mathematical approach for quantifying robustness, and they provide concrete examples of mechanisms for robust cognition. © 2014 Cognitive Science Society, Inc.

Product Design Engineering--A Global Education Trend in Multidisciplinary Training for Creative Product Design

ERIC Educational Resources Information Center

de Vere, Ian; Melles, Gavin; Kapoor, Ajay

2010-01-01

Product design is the convergence point for engineering and design thinking and practices. Until recently, product design has been taught either as a component of mechanical engineering or as a subject within design schools but increasingly there is global recognition of the need for greater synergies between industrial design and engineering…

A method to estimate weight and dimensions of small aircraft propulsion gas turbine engines: User's guide

NASA Technical Reports Server (NTRS)

Hale, P. L.

1982-01-01

The weight and major envelope dimensions of small aircraft propulsion gas turbine engines are estimated. The computerized method, called WATE-S (Weight Analysis of Turbine Engines-Small) is a derivative of the WATE-2 computer code. WATE-S determines the weight of each major component in the engine including compressors, burners, turbines, heat exchangers, nozzles, propellers, and accessories. A preliminary design approach is used where the stress levels, maximum pressures and temperatures, material properties, geometry, stage loading, hub/tip radius ratio, and mechanical overspeed are used to determine the component weights and dimensions. The accuracy of the method is generally better than + or - 10 percent as verified by analysis of four small aircraft propulsion gas turbine engines.

CF6 Jet Engine Performance Improvement Program: High Pressure Turbine Aerodynamic Performance Improvement

NASA Technical Reports Server (NTRS)

Fasching, W. A.

1980-01-01

The improved single shank high pressure turbine design was evaluated in component tests consisting of performance, heat transfer and mechanical tests, and in core engine tests. The instrumented core engine test verified the thermal, mechanical, and aeromechanical characteristics of the improved turbine design. An endurance test subjected the improved single shank turbine to 1000 simulated flight cycles, the equivalent of approximately 3000 hours of typical airline service. Initial back-to-back engine tests demonstrated an improvement in cruise sfc of 1.3% and a reduction in exhaust gas temperature of 10 C. An additional improvement of 0.3% in cruise sfc and 6 C in EGT is projected for long service engines.

Strain Compatible Oxidation and Corrosion Protection Coatings for Enhanced Thermo-Mechanical Durability of Turbine Airfoils

DTIC Science & Technology

2011-12-05

Report: Grant N00014-08-0331 Technical Objectives As critical components of advanced aircraft engines , turbine airfoils require coatings for...advanced aircrafi engines , turbine airfoils require coatings for enhancement of oxidation, corrosion and thermal capabilities . Airfoil coatings ofien...Oxidation and Corrosion Protection Coatings for Enhanced Thermo-Mechanical Durability of Turbine Airfoils 5b. GRANT NUMBER N00014-08-l-0331 5c

Modeling and Reduction of Shocks on Electronic Components Within a Projectile

DTIC Science & Technology

2008-08-01

Engineering, University of Nevada, Las Vegas, NV 89154-4027 †Department of Civil and Environmental Engineering, University of Nevada, Las Vegas, NV...Samaan Ladkanyb, Mostafiz Chowdhuryc aDepartment of Mechanical Engineering, University of Nevada, Las Vegas, Las Vegas, NV 89154-4027, USA bDepartment...of Civil and Environmental Engineering, University of Nevada, Las Vegas, Las Vegas, NV 89154-4027, USA cAMSRL-WM-MB (ALC), Ordnance Materials Branch

Processing study of injection molding of silicon nitride for engine applications

NASA Technical Reports Server (NTRS)

Rorabaugh, M. E.; Yeh, H. C.

1985-01-01

The high hardness of silicon nitride, which is currently under consideration as a structural material for such hot engine components as turbine blades, renders machining of the material prohibitively costly; the near net shape forming technique of injection molding is accordingly favored as a means for component fabrication. Attention is presently given to the relationships between injection molding processing parameters and the resulting microstructural and mechanical properties of the resulting engine parts. An experimental program has been conducted under NASA sponsorship which tests the quality of injection molded bars of silicon nitride at various stages of processing.

Lifing of Engine Components

NASA Technical Reports Server (NTRS)

2005-01-01

The successful development of advanced aerospace engines depends greatly on the capabilities of high performance materials and structures. Advanced materials, such as nickel based single crystal alloys, metal foam, advanced copper alloys, and ceramics matrix composites, have been engineered to provide higher engine temperature and stress capabilities. Thermal barrier coatings have been developed to improve component durability and fuel efficiency, by reducing the substrate hot wall metal temperature and protecting against oxidation and blanching. However, these coatings are prone to oxidation and delamination failures. In order to implement the use of these materials in advanced engines, it is necessary to understand and model the evolution of damage of the metal substrate as well as the coating under actual engine conditions. The models and the understanding of material behavior are utilized in the development of a life prediction methodology for hot section components. The research activities were focused on determining the stress and strain fields in an engine environment under combined thermo-mechanical loads to develop life prediction methodologies consistent with the observed damage formation of the coating and the substrates.

The Further Development of Heat-Resistant Materials for Aircraft Engines

NASA Technical Reports Server (NTRS)

Bollenrath, Franz

1946-01-01

The present report deals with the problems involved in the greater utilization and development of aircraft engine materials, and specifically; piston materials, cylinder heads, exhaust valves, and exhaust gas turbine blading. The blades of the exhaust gas turbine are likely to be the highest stressed components of modern power plants from a thermal-mechanical and chemical standpoint, even though the requirements on exhaust valves of engines with gasoline injection are in general no less stringent. For the fire plate in Diesel engines the specifications for mechanical strength and design are not so stringent, and the question of heat resistance, which under these circumstances is easier obtainable, predominates.

MSIAC’s M&S Journal Online: Volume 2, September 2006

DTIC Science & Technology

2006-09-01

engineering fields, such as mechanical and electrical , rely on composability and interchangeability (substitutability) of components into workable systems...Terrain Data for the Vector-in-Command and Engineer Functional Area Models”, Technical Report GL-90-9, September 1990, USAEWES, Vicksburg 8. Frankenstein

Lewis Structures Technology, 1988. Volume 3: Structural Integrity Fatigue and Fracture Wind Turbines HOST

NASA Technical Reports Server (NTRS)

1988-01-01

The charter of the Structures Division is to perform and disseminate results of research conducted in support of aerospace engine structures. These results have a wide range of applicability to practioners of structural engineering mechanics beyond the aerospace arena. The specific purpose of the symposium was to familiarize the engineering structures community with the depth and range of research performed by the division and its academic and industrial partners. Sessions covered vibration control, fracture mechanics, ceramic component reliability, parallel computing, nondestructive evaluation, constitutive models and experimental capabilities, dynamic systems, fatigue and damage, wind turbines, hot section technology (HOST), aeroelasticity, structural mechanics codes, computational methods for dynamics, structural optimization, and applications of structural dynamics, and structural mechanics computer codes.

Materials properties, loads, and stress analysis, Spartan REM: Appendix A

NASA Technical Reports Server (NTRS)

Marlowe, D. S.; West, E. J.

1984-01-01

The mechanical properties, load tests, and stress analysis of the Spartan Release Engagement Mechanism (REM) is presented. The fracture properties of the components of the unit are also discussed. Detailed engineering drawings are included.

Computer models and output, Spartan REM: Appendix B

NASA Technical Reports Server (NTRS)

Marlowe, D. S.; West, E. J.

1984-01-01

A computer model of the Spartan Release Engagement Mechanism (REM) is presented in a series of numerical charts and engineering drawings. A crack growth analysis code is used to predict the fracture mechanics of critical components.

Scott Dana | NREL

Science.gov Websites

Dana Scott Dana Mechanical and Vibrations Engineer Scott.Dana@nrel.gov | 303-384-7036 Scott focuses on field testing of wind turbines and components for mechanical loads and power performance structural health monitoring using dynamic-based sensing methods. Education B.S. and M.S. in Mechanical

The Role of Functionality in the Mental Representations of Engineering Students: Some Differences in the Early Stages of Expertise

ERIC Educational Resources Information Center

Moss, Jarrod; Kotovsky, Kenneth; Cagan, Jonathan

2006-01-01

As engineers gain experience and become experts in their domain, the structure and content of their knowledge changes. Two studies are presented that examine differences in knowledge representation among freshman and senior engineering students. The first study examines recall of mechanical devices and chunking of components, and the second…

Integrated Evaluation of Closed Loop Air Revitalization System Components

NASA Technical Reports Server (NTRS)

Murdock, K.

2010-01-01

NASA s vision and mission statements include an emphasis on human exploration of space, which requires environmental control and life support technologies. This Contractor Report (CR) describes the development and evaluation of an Air Revitalization System, modeling and simulation of the components, and integrated hardware testing with the goal of better understanding the inherent capabilities and limitations of this closed loop system. Major components integrated and tested included a 4-Bed Modular Sieve, Mechanical Compressor Engineering Development Unit, Temperature Swing Adsorption Compressor, and a Sabatier Engineering and Development Unit. The requisite methodolgy and technical results are contained in this CR.

The 11th Aerospace Mechanisms Symposium

NASA Technical Reports Server (NTRS)

1977-01-01

Various mechanisms in aerospace engineering were presented at this conference. Specifications, design, and use of spacecraft and missile components are discussed, such as tail assemblies, radiometers, magnetormeters, pins, reaction wheels, ball bearings, actuators, mirrors, nutation dampers, airfoils, solar arrays, etc.

Effect of Casting Defect on Mechanical Properties of 17-4PH Stainless Steel

NASA Astrophysics Data System (ADS)

Kim, Jong-Yup; Lee, Joon-Hyun; Nahm, Seung-Hoon

Damage and integrity evaluation techniques should be developed steadily in order to ensure the reliability and the economic efficiency of gas turbine engines. Casting defects may exist in most casting components of gas turbine engines, and the defects could give serious effect on mechanical properties and fracture toughness. Therefore, it is very important to understand the effect of casting defects on the above properties in order to predict the safety and life of components. In this study, specimens with internal casting defects, made from 17-4PH stainless steel, were prepared and evaluated and characterized based on the volume fraction of defects. The relation between mechanical properties such as tensile, low cycle fatigue and fracture toughness and volume fraction of defect has been investigated. As a result of the analysis, the mechanical properties of 17-4PH decreased as the defect volume fraction increased with very good linearity. The mechanical properties also showed an inversely proportional relationship to electrical resistivity.

Overview of Glenn Mechanical Components Branch Research

NASA Astrophysics Data System (ADS)

Zakrajsek, James

2002-09-01

Mr. James Zakrajsek, chief of the Mechanical Components Branch, gave an overview of research conducted by the branch. Branch members perform basic research on mechanical components and systems, including gears and bearings, turbine seals, structural and thermal barrier seals, and space mechanisms. The research is focused on propulsion systems for present and advanced aerospace vehicles. For rotorcraft and conventional aircraft, we conduct research to develop technology needed to enable the design of low noise, ultra safe geared drive systems. We develop and validate analytical models for gear crack propagation, gear dynamics and noise, gear diagnostics, bearing dynamics, and thermal analyses of gear systems using experimental data from various component test rigs. In seal research we develop and test advanced turbine seal concepts to increase efficiency and durability of turbine engines. We perform experimental and analytical research to develop advanced thermal barrier seals and structural seals for current and next generation space vehicles. Our space mechanisms research involves fundamental investigation of lubricants, materials, components and mechanisms for deep space and planetary environments.

HPAC Info-dex 5: Locating engineering societies, associations

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-06-01

This is the 1995/1996 listing of heating, ventilation, air conditioning and refrigeration systems engineering societies, trade associations, and government organizations that have established performance standards for mechanical systems and components. The societies and associations are listed alphabetically along with their complete addresses and telephone and FAX numbers.

16 CFR 1211.12 - Requirements for edge sensors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... edge sensor system and associated components shall withstand 30,000 cycles of mechanical operation... accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Global Engineering Documents, 15 Inverness Way East, Englewood, CO 80112, Telephone (800) 854-7179 or Global Engineering Documents...

40 CFR Appendix Vi to Part 86 - Vehicle and Engine Components

Code of Federal Regulations, 2010 CFR

2010-07-01

... exhaust valves. (2) Drive belts. (3) Manifold and cylinder head bolts. (4) Engine oil and filter. (5...) Carburetor-idle RPM, mixture ratio. (3) Choke mechanism. (4) Fuel system filter and fuel system lines and... filter breather cap. (4) Manifold inlet (carburetor spacer, etc.). V. External Exhaust Emission Control...

40 CFR Appendix Vi to Part 86 - Vehicle and Engine Components

Code of Federal Regulations, 2012 CFR

2012-07-01

... exhaust valves. (2) Drive belts. (3) Manifold and cylinder head bolts. (4) Engine oil and filter. (5...) Carburetor-idle RPM, mixture ratio. (3) Choke mechanism. (4) Fuel system filter and fuel system lines and... filter breather cap. (4) Manifold inlet (carburetor spacer, etc.). V. External Exhaust Emission Control...

40 CFR Appendix Vi to Part 86 - Vehicle and Engine Components

Code of Federal Regulations, 2013 CFR

2013-07-01

... exhaust valves. (2) Drive belts. (3) Manifold and cylinder head bolts. (4) Engine oil and filter. (5...) Carburetor-idle RPM, mixture ratio. (3) Choke mechanism. (4) Fuel system filter and fuel system lines and... filter breather cap. (4) Manifold inlet (carburetor spacer, etc.). V. External Exhaust Emission Control...

40 CFR Appendix Vi to Part 86 - Vehicle and Engine Components

Code of Federal Regulations, 2011 CFR

2011-07-01

... exhaust valves. (2) Drive belts. (3) Manifold and cylinder head bolts. (4) Engine oil and filter. (5...) Carburetor-idle RPM, mixture ratio. (3) Choke mechanism. (4) Fuel system filter and fuel system lines and... filter breather cap. (4) Manifold inlet (carburetor spacer, etc.). V. External Exhaust Emission Control...

Joining and Integration of Silicon Carbide for Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Halbig, Michael C.; Singh, Mrityunjay; Coddington, Bryan; Asthana, Rajiv

2010-01-01

The critical need for ceramic joining and integration technologies is becoming better appreciated as the maturity level increases for turbine engine components fabricated from ceramic and ceramic matrix composite materials. Ceramic components offer higher operating temperatures and reduced cooling requirements. This translates into higher efficiencies and lower emissions. For fabricating complex shapes, diffusion bonding of silicon carbide (SiC) to SiC is being developed. For the integration of ceramic parts to the surrounding metallic engine system, brazing of SiC to metals is being developed. Overcoming the chemical, thermal, and mechanical incompatibilities between dissimilar materials is very challenging. This presentation will discuss the types of ceramic components being developed by researchers and industry and the benefits of using ceramic components. Also, the development of strong, crack-free, stable bonds will be discussed. The challenges and progress in developing joining and integration approaches for a specific application, i.e. a SiC injector, will be presented.

Assuring Structural Integrity in Army Systems

DTIC Science & Technology

1985-02-28

power plants are* I. American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code , Section III - Rules for Construction of Nuclear...Power Plant Components; 2. ASNE Boiler and Pressure Vessel Code , Section XI, Rules for In-Service Inspection of Nuclear Power Plant Components; and 3

Environmental and Mechanical Stability of Environmental Barrier Coated SA Tyrannohex SiC Composites Under Simulated Turbine Engine Environments

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Halbig, Michael Charles; Sing, Mrityunjay

2014-01-01

The environmental stability and thermal gradient cyclic durability performance of SA Tyrannohex composites were investigated for turbine engine component applications. The work has been focused on investigating the combustion rig recession, cyclic thermal stress resistance and thermomechanical low cycle fatigue of uncoated and environmental barrier coated Tyrannohex SiC SA composites in simulated turbine engine combustion water vapor, thermal gradients, and mechanical loading conditions. Flexural strength degradations have been evaluated, and the upper limits of operating temperature conditions for the SA composite material systems are discussed based on the experimental results.

Fabrication of ceramic substrate-reinforced and free forms

NASA Technical Reports Server (NTRS)

Quentmeyer, R. J.; Mcdonald, G.; Hendricks, R. C.

1985-01-01

Components fabricated of, or coated with, ceramics have lower parasitic cooling requirements. Techniques are discussed for fabricating thin-shell ceramic components and ceramic coatings for applications in rocket or jet engine environments. Thin ceramic shells with complex geometric forms involving convolutions and reentrant surfaces were fabricated by mandrel removal. Mandrel removal was combined with electroplating or plasma spraying and isostatic pressing to form a metal support for the ceramic. Rocket engine thrust chambers coated with 0.08 mm (3 mil) of ZrO2-8Y2O3 had no failures and a tenfold increase in engine life. Some measured mechanical properties of the plasma-sprayed ceramic are presented.

Mechanical Engineering Department engineering research: Annual report, FY 1986

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denney, R.M.; Essary, K.L.; Genin, M.S.

1986-12-01

This report provides information on the five areas of research interest in LLNL's Mechanical Engineering Department. In Computer Code Development, a solid geometric modeling program is described. In Dynamic Systems and Control, structure control and structure dynamics are discussed. Fabrication technology involves machine cutting, interferometry, and automated optical component manufacturing. Materials engineering reports on composite material research and measurement of molten metal surface properties. In Nondestructive Evaluation, NMR, CAT, and ultrasound machines are applied to manufacturing processes. A model for underground collapse is developed. Finally, an alternative heat exchanger is investigated for use in a fusion power plant. Separate abstractsmore » were prepared for each of the 13 reports in this publication. (JDH)« less

Fabricating Superior NiAl Bronze Components through Wire Arc Additive Manufacturing.

PubMed

Ding, Donghong; Pan, Zengxi; van Duin, Stephen; Li, Huijun; Shen, Chen

2016-08-03

Cast nickel aluminum bronze (NAB) alloy is widely used for large engineering components in marine applications due to its excellent mechanical properties and corrosion resistance. Casting porosity, as well as coarse microstructure, however, are accompanied by a decrease in mechanical properties of cast NAB components. Although heat treatment, friction stir processing, and fusion welding were implemented to eliminate porosity, improve mechanical properties, and refine the microstructure of as-cast metal, their applications are limited to either surface modification or component repair. Instead of traditional casting techniques, this study focuses on developing NAB components using recently expanded wire arc additive manufacturing (WAAM). Consumable welding wire is melted and deposited layer-by-layer on substrates producing near-net shaped NAB components. Additively-manufactured NAB components without post-processing are fully dense, and exhibit fine microstructure, as well as comparable mechanical properties, to as-cast NAB alloy. The effects of heat input from the welding process and post-weld-heat-treatment (PWHT) are shown to give uniform NAB alloys with superior mechanical properties revealing potential marine applications of the WAAM technique in NAB production.

Fabricating Superior NiAl Bronze Components through Wire Arc Additive Manufacturing

PubMed Central

Ding, Donghong; Pan, Zengxi; van Duin, Stephen; Li, Huijun; Shen, Chen

2016-01-01

Cast nickel aluminum bronze (NAB) alloy is widely used for large engineering components in marine applications due to its excellent mechanical properties and corrosion resistance. Casting porosity, as well as coarse microstructure, however, are accompanied by a decrease in mechanical properties of cast NAB components. Although heat treatment, friction stir processing, and fusion welding were implemented to eliminate porosity, improve mechanical properties, and refine the microstructure of as-cast metal, their applications are limited to either surface modification or component repair. Instead of traditional casting techniques, this study focuses on developing NAB components using recently expanded wire arc additive manufacturing (WAAM). Consumable welding wire is melted and deposited layer-by-layer on substrates producing near-net shaped NAB components. Additively-manufactured NAB components without post-processing are fully dense, and exhibit fine microstructure, as well as comparable mechanical properties, to as-cast NAB alloy. The effects of heat input from the welding process and post-weld-heat-treatment (PWHT) are shown to give uniform NAB alloys with superior mechanical properties revealing potential marine applications of the WAAM technique in NAB production. PMID:28773774

Plant salt-tolerance mechanisms

DOE PAGES

Deinlein, Ulrich; Stephan, Aaron B.; Horie, Tomoaki; ...

2014-06-01

Crop performance is severely affected by high salt concentrations in soils. To engineer more salt-tolerant plants it is crucial to unravel the key components of the plant salt-tolerance network. Here we review our understanding of the core salt-tolerance mechanisms in plants. Recent studies have shown that stress sensing and signaling components can play important roles in regulating the plant salinity stress response. We also review key Na+ transport and detoxification pathways and the impact of epigenetic chromatin modifications on salinity tolerance. In addition, we discuss the progress that has been made towards engineering salt tolerance in crops, including marker-assisted selectionmore » and gene stacking techniques. We also identify key open questions that remain to be addressed in the future.« less

Novel Multidisciplinary Models Assess the Capabilities of Smart Structures to Manage Vibration, Sound, and Thermal Distortion in Aeropropulsion Components

NASA Technical Reports Server (NTRS)

Saravanos, Dimitris A.

1997-01-01

The development of aeropropulsion components that incorporate "smart" composite laminates with embedded piezoelectric actuators and sensors is expected to ameliorate critical problems in advanced aircraft engines related to vibration, noise emission, and thermal stability. To facilitate the analytical needs of this effort, the NASA Lewis Research Center has developed mechanics and multidisciplinary computational models to analyze the complicated electromechanical behavior of realistic smart-structure configurations operating in combined mechanical, thermal, and acoustic environments. The models have been developed to accommodate the particular geometries, environments, and technical challenges encountered in advanced aircraft engines, yet their unique analytical features are expected to facilitate application of this new technology in a variety of commercial applications.

Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna; Kiser, Doug; Wiesner, Valerie L.

2016-01-01

This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiCSiC Ceramic Matrix Composite (CMC) components for next generation turbine engines. The emphasis has been placed on the current design challenges of the 2700F environmental barrier coatings; coating processing and integration with SiCSiC CMCs and component systems; and performance evaluation and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements through advanced compositions and architecture designs, as shown in recent simulated engine high heat flux, combustion environment, in conjunction with mechanical creep and fatigue loading testing conditions.

An extension of fracture mechanics/technology to larger and smaller cracks/defects

PubMed Central

Abé, Hiroyuki

2009-01-01

Fracture mechanics/technology is a key science and technology for the design and integrity assessment of the engineering structures. However, the conventional fracture mechanics has mostly targeted a limited size of cracks/defects, say of from several hundred microns to several tens of centimeters. The author and his group has tried to extend that limited size and establish a new version of fracture technology for very large cracks used in geothermal energy extraction and for very small cracks/defects or damage often appearing in the combination of mechanical and electronic components of engineering structures. Those new versions are reviewed in this paper. PMID:19907123

An extension of fracture mechanics/technology to larger and smaller cracks/defects.

PubMed

Abé, Hiroyuki

2009-01-01

Fracture mechanics/technology is a key science and technology for the design and integrity assessment of the engineering structures. However, the conventional fracture mechanics has mostly targeted a limited size of cracks/defects, say of from several hundred microns to several tens of centimeters. The author and his group has tried to extend that limited size and establish a new version of fracture technology for very large cracks used in geothermal energy extraction and for very small cracks/defects or damage often appearing in the combination of mechanical and electronic components of engineering structures. Those new versions are reviewed in this paper.

Motor-Reducer Sizing through a MATLAB-Based Graphical Technique

ERIC Educational Resources Information Center

Giberti, H.; Cinquemani, S.

2012-01-01

The design of the drive system for an automatic machine and its correct sizing is a very important competence for an electrical or mechatronic engineer. This requires knowledge that crosses the fields of electrical engineering, electronics and mechanics, as well as the skill to choose commercial components based upon their technical documentation.…

Automotive Modules. Vocational Behavioral Objectives: A Guide for Individualizing Instruction.

ERIC Educational Resources Information Center

Westinghouse Learning Corp., New York, NY.

The curriculum guide deals with automotive repair skills at the secondary level of vocational education and industrial arts. It addresses the subject in behavioral terms, as prominent components of the career education concept. Presenting four skill modules, auto body repair, gas engine repair, service, and diesel engine mechanics, the objectives…

AUTOMOTIVE DIESEL MAINTENANCE 1. UNIT VIII. ENGINE COMPONENTS--PART I.

ERIC Educational Resources Information Center

Human Engineering Inst., Cleveland, OH.

THIS MODULE OF A 30-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE CONSTRUCTION AND MAINTENANCE OF DIESEL ENGINE CYLINDER HEADS AND CYLINDER ASSEMBLIES. TOPICS ARE CYLINDER ASSEMBLY (LINERS), CYLINDER HEADS, VALVES AND VALVE MECHANISMS, AND PISTON AND PISTON RINGS. THE MODULE CONSISTS OF A SELF-INSTRUCTIONAL BRANCH PROGRAMED TRAINING…

Diesel and Truck Certification Needs Assessment: Two Surveys.

ERIC Educational Resources Information Center

Broadbent, William A.

Recommendations for the improvement of the diesel engine and truck components of the Hawaii state certification examination for automobile and truck mechanics were solicited from 14 major private businesses repairing heavy tractor rigs and/or diesel engines on Oahu and a statewide sample of 21 trucking firms and other companies making extensive…

NASA Tech Briefs, May 2000. Volume 24, No. 5

NASA Technical Reports Server (NTRS)

2000-01-01

Topics include: Sensors: Test and Measurement; Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Composites and Plastics; Materials; Computer Programs; Mechanics;

Coating for prevention of titanium combustion

NASA Technical Reports Server (NTRS)

Anderson, V. G.; Funkhouser, M.; Mcdaniel, P.

1980-01-01

A limited number of coating options for titanium gas turbine engine components were explored with the objective of minimizing potential combustion initiation and propagation without adversely affecting component mechanical properties. Objectives were met by two of the coatings, ion-plated platinum plus electroplated copper plus electroplated nickel and ion vapor deposited aluminum.

A reduced mechanism for biodiesel surrogates with low temperature chemistry for compression ignition engine applications

NASA Astrophysics Data System (ADS)

Luo, Zhaoyu; Plomer, Max; Lu, Tianfeng; Som, Sibendu; Longman, Douglas E.

2012-04-01

Biodiesel is a promising alternative fuel for compression ignition (CI) engines. It is a renewable energy source that can be used in these engines without significant alteration in design. The detailed chemical kinetics of biodiesel is however highly complex. In the present study, a skeletal mechanism with 123 species and 394 reactions for a tri-component biodiesel surrogate, which consists of methyl decanoate, methyl 9-decanoate and n-heptane was developed for simulations of 3-D turbulent spray combustion under engine-like conditions. The reduction was based on an improved directed relation graph (DRG) method that is particularly suitable for mechanisms with many isomers, followed by isomer lumping and DRG-aided sensitivity analysis (DRGASA). The reduction was performed for pressures from 1 to 100 atm and equivalence ratios from 0.5 to 2 for both extinction and ignition applications. The initial temperatures for ignition were from 700 to 1800 K. The wide parameter range ensures the applicability of the skeletal mechanism under engine-like conditions. As such the skeletal mechanism is applicable for ignition at both low and high temperatures. Compared with the detailed mechanism that consists of 3299 species and 10806 reactions, the skeletal mechanism features a significant reduction in size while still retaining good accuracy and comprehensiveness. The validations of ignition delay time, flame lift-off length and important species profiles were also performed in 3-D engine simulations and compared with the experimental data from Sandia National Laboratories under CI engine conditions.

Development of Kinetic Mechanisms for Next-Generation Fuels and CFD Simulation of Advanced Combustion Engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pitz, William J.; McNenly, Matt J.; Whitesides, Russell

Predictive chemical kinetic models are needed to represent next-generation fuel components and their mixtures with conventional gasoline and diesel fuels. These kinetic models will allow the prediction of the effect of alternative fuel blends in CFD simulations of advanced spark-ignition and compression-ignition engines. Enabled by kinetic models, CFD simulations can be used to optimize fuel formulations for advanced combustion engines so that maximum engine efficiency, fossil fuel displacement goals, and low pollutant emission goals can be achieved.

Iridium/Rhenium Parts For Rocket Engines

NASA Technical Reports Server (NTRS)

Schneider, Steven J.; Harding, John T.; Wooten, John R.

1991-01-01

Oxidation/corrosion of metals at high temperatures primary life-limiting mechanism of parts in rocket engines. Combination of metals greatly increases operating temperature and longevity of these parts. Consists of two transition-element metals - iridium and rhenium - that melt at extremely high temperatures. Maximum operating temperature increased to 2,200 degrees C from 1,400 degrees C. Increases operating lifetimes of small rocket engines by more than factor of 10. Possible to make hotter-operating, longer-lasting components for turbines and other heat engines.

Turbine Engine Clearance Control Systems: Current Practices and Future Directions

NASA Astrophysics Data System (ADS)

Lattime, Scott B.; Steinetz, Bruce M.

2002-09-01

Improved blade tip sealing in the high pressure compressor (HPC) and high pressure turbine (HPT) can provide dramatic reductions in specific fuel consumption (SFC), time-on-wing, compressor stall margin, and engine efficiency as well as increased payload and mission range capabilities. Maintenance costs to overhaul large commercial gas turbine engines can easily exceed 1M. Engine removal from service is primarily due to spent exhaust gas temperature (EGT) margin caused mainly by the deterioration of HPT components. Increased blade tip clearance is a major factor in hot section component degradation. As engine designs continue to push the performance envelope with fewer parts and the market drives manufacturers to increase service life, the need for advanced sealing continues to grow. A review of aero gas turbine engine HPT performance degradation and the mechanisms that promote these losses are discussed. Benefits to the HPT due to improved clearance management are identified. Past and present sealing technologies are presented along with specifications for next generation engine clearance control systems.

Turbine Engine Clearance Control Systems: Current Practices and Future Directions

NASA Technical Reports Server (NTRS)

Lattime, Scott B.; Steinetz, Bruce M.

2002-01-01

Improved blade tip sealing in the high pressure compressor (HPC) and high pressure turbine (HPT) can provide dramatic reductions in specific fuel consumption (SFC), time-on-wing, compressor stall margin, and engine efficiency as well as increased payload and mission range capabilities. Maintenance costs to overhaul large commercial gas turbine engines can easily exceed $1M. Engine removal from service is primarily due to spent exhaust gas temperature (EGT) margin caused mainly by the deterioration of HPT components. Increased blade tip clearance is a major factor in hot section component degradation. As engine designs continue to push the performance envelope with fewer parts and the market drives manufacturers to increase service life, the need for advanced sealing continues to grow. A review of aero gas turbine engine HPT performance degradation and the mechanisms that promote these losses are discussed. Benefits to the HPT due to improved clearance management are identified. Past and present sealing technologies are presented along with specifications for next generation engine clearance control systems.

Thermal-structural analyses of Space Shuttle Main Engine (SSME) hot section components

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Ali; Thompson, Robert L.

1988-01-01

Three dimensional nonlinear finite element heat transfer and structural analyses were performed for the first stage high pressure fuel turbopump (HPFTP) blade of the space shuttle main engine (SSME). Directionally solidified (DS) MAR-M 246 and single crystal (SC) PWA-1480 material properties were used for the analyses. Analytical conditions were based on a typical test stand engine cycle. Blade temperature and stress strain histories were calculated by using the MARC finite element computer code. The structural response of an SSME turbine blade was assessed and a greater understanding of blade damage mechanisms, convective cooling effects, and thermal mechanical effects was gained.

Fabrication of ceramic substrate-reinforced and free forms by mandrel plasma spraying metal-ceramic composites

NASA Technical Reports Server (NTRS)

Quentmeyer, R. J.; Mcdonald, G.; Hendricks, R. C.

1985-01-01

Components fabricated of, or coated with, ceramics have lower parasitic cooling requirements. Techniques are discussed for fabricating thin-shell ceramic components and ceramic coatings for applications in rocket or jet engine environments. Thin ceramic shells with complex geometric forms involving convolutions and reentrant surfaces were fabricated by mandrel removal. Mandrel removal was combined with electroplating or plasma spraying and isostatic pressing to form a metal support for the ceramic. Rocket engine thrust chambers coated with 0.08 mm (3 mil) of ZrO2-8Y2O3 had no failures and a tenfold increase in engine life. Some measured mechanical properties of the plasma-sprayed ceramic are presented.

High voltage series resonant inverter ion engine screen supply. [SCR series resonant inverter for space applications

NASA Technical Reports Server (NTRS)

Biess, J. J.; Inouye, L. Y.; Shank, J. H.

1974-01-01

A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.

Space flight requirements for fiber optic components: qualification testing and lessons learned

NASA Astrophysics Data System (ADS)

Ott, Melanie N.; Jin, Xiaodan Linda; Chuska, Richard; Friedberg, Patricia; Malenab, Mary; Matuszeski, Adam

2006-04-01

"Qualification" of fiber optic components holds a very different meaning than it did ten years ago. In the past, qualification meant extensive prolonged testing and screening that led to a programmatic method of reliability assurance. For space flight programs today, the combination of using higher performance commercial technology, with shorter development schedules and tighter mission budgets makes long term testing and reliability characterization unfeasible. In many cases space flight missions will be using technology within years of its development and an example of this is fiber laser technology. Although the technology itself is not a new product the components that comprise a fiber laser system change frequently as processes and packaging changes occur. Once a process or the materials for manufacturing a component change, even the data that existed on its predecessor can no longer provide assurance on the newer version. In order to assure reliability during a space flight mission, the component engineer must understand the requirements of the space flight environment as well as the physics of failure of the components themselves. This can be incorporated into an efficient and effective testing plan that "qualifies" a component to specific criteria defined by the program given the mission requirements and the component limitations. This requires interaction at the very initial stages of design between the system design engineer, mechanical engineer, subsystem engineer and the component hardware engineer. Although this is the desired interaction what typically occurs is that the subsystem engineer asks the components or development engineers to meet difficult requirements without knowledge of the current industry situation or the lack of qualification data. This is then passed on to the vendor who can provide little help with such a harsh set of requirements due to high cost of testing for space flight environments. This presentation is designed to guide the engineers of design, development and components, and vendors of commercial components with how to make an efficient and effective qualification test plan with some basic generic information about many space flight requirements. Issues related to the physics of failure, acceptance criteria and lessons learned will also be discussed to assist with understanding how to approach a space flight mission in an ever changing commercial photonics industry.

Space Flight Requirements for Fiber Optic Components; Qualification Testing and Lessons Learned

NASA Technical Reports Server (NTRS)

Ott, Melanie N.; Jin, Xiaodan Linda; Chuska, Richard; Friedberg, Patricia; Malenab, Mary; Matuszeski, Adam

2007-01-01

"Qualification" of fiber optic components holds a very different meaning than it did ten years ago. In the past, qualification meant extensive prolonged testing and screening that led to a programmatic method of reliability assurance. For space flight programs today, the combination of using higher performance commercial technology, with shorter development schedules and tighter mission budgets makes long term testing and reliability characterization unfeasible. In many cases space flight missions will be using technology within years of its development and an example of this is fiber laser technology. Although the technology itself is not a new product the components that comprise a fiber laser system change frequently as processes and packaging changes occur. Once a process or the materials for manufacturing a component change, even the data that existed on its predecessor can no longer provide assurance on the newer version. In order to assure reliability during a space flight mission, the component engineer must understand the requirements of the space flight environment as well as the physics of failure of the components themselves. This can be incorporated into an efficient and effective testing plan that "qualifies" a component to specific criteria defined by the program given the mission requirements and the component limitations. This requires interaction at the very initial stages of design between the system design engineer, mechanical engineer, subsystem engineer and the component hardware engineer. Although this is the desired interaction what typically occurs is that the subsystem engineer asks the components or development engineers to meet difficult requirements without knowledge of the current industry situation or the lack of qualification data. This is then passed on to the vendor who can provide little help with such a harsh set of requirements due to high cost of testing for space flight environments. This presentation is designed to guide the engineers of design, development and components, and vendors of commercial components with how to make an efficient and effective qualification test plan with some basic generic information about many space flight requirements. Issues related to the physics of failure, acceptance criteria and lessons learned will also be discussed to assist with understanding how to approach a space flight mission in an ever changing commercial photonics industry.

LEADER - An integrated engine behavior and design analyses based real-time fault diagnostic expert system for Space Shuttle Main Engine (SSME)

NASA Technical Reports Server (NTRS)

Gupta, U. K.; Ali, M.

1989-01-01

The LEADER expert system has been developed for automatic learning tasks encompassing real-time detection, identification, verification, and correction of anomalous propulsion system operations, using a set of sensors to monitor engine component performance to ascertain anomalies in engine dynamics and behavior. Two diagnostic approaches are embodied in LEADER's architecture: (1) learning and identifying engine behavior patterns to generate novel hypotheses about possible abnormalities, and (2) the direction of engine sensor data processing to perform resoning based on engine design and functional knowledge, as well as the principles of the relevant mechanics and physics.

Airframe-Jet Engine Integration Noise

NASA Technical Reports Server (NTRS)

Tam, Christopher; Antcliff, Richard R. (Technical Monitor)

2003-01-01

It has been found experimentally that the noise radiated by a jet mounted under the wing of an aircraft exceeds that of the same jet in a stand-alone environment. The increase in noise is referred to as jet engine airframe integration noise. The objectives of the present investigation are, (1) To obtain a better understanding of the physical mechanisms responsible for jet engine airframe integration noise or installation noise. (2) To develop a prediction model for jet engine airframe integration noise. It is known that jet mixing noise consists of two principal components. They are the noise from the large turbulence structures of the jet flow and the noise from the fine scale turbulence. In this investigation, only the effect of jet engine airframe interaction on the fine scale turbulence noise of a jet is studied. The fine scale turbulence noise is the dominant noise component in the sideline direction. Thus we limit out consideration primarily to the sideline.

Electronic Components, Transducers, and Basic Circuits. A Study Guide of the Science and Engineering Technician Curriculum.

ERIC Educational Resources Information Center

Mowery, Donald R.

This study guide is part of a program of studies entitled the Science and Engineering Technician (SET) Curriculum developed for the purpose of training technicians in the use of electronic instruments and their applications. The program integrates elements from the disciplines of chemistry, physics, mathematics, mechanical technology, and…

The local matrix distribution and the functional development of tissue engineered cartilage, a finite element study.

PubMed

Sengers, B G; Van Donkelaar, C C; Oomens, C W J; Baaijens, F P T

2004-12-01

Assessment of the functionality of tissue engineered cartilage constructs is hampered by the lack of correlation between global measurements of extra cellular matrix constituents and the global mechanical properties. Based on patterns of matrix deposition around individual cells, it has been hypothesized previously, that mechanical functionality arises when contact occurs between zones of matrix associated with individual cells. The objective of this study is to determine whether the local distribution of newly synthesized extracellular matrix components contributes to the evolution of the mechanical properties of tissue engineered cartilage constructs. A computational homogenization approach was adopted, based on the concept of a periodic representative volume element. Local transport and immobilization of newly synthesized matrix components were described. Mechanical properties were taken dependent on the local matrix concentration and subsequently the global aggregate modulus and hydraulic permeability were derived. The transport parameters were varied to assess the effect of the evolving matrix distribution during culture. The results indicate that the overall stiffness and permeability are to a large extent insensitive to differences in local matrix distribution. This emphasizes the need for caution in the visual interpretation of tissue functionality from histology and underlines the importance of complementary measurements of the matrix's intrinsic molecular organization.

Student Autonomy and its Effects on Student Enjoyment in a Traditional Mechanics Course for First-Year Engineering Students

NASA Astrophysics Data System (ADS)

Perera, Janaki I.; Quinlivan, Brendan T.; Simonovich, Jennifer A.; Towers, Emily; Zadik, Oren H.; Zastavker, Yevgeniya V.

2012-02-01

In light of recent literature in educational psychology, this study investigates instructional support and students' autonomy at a small technical undergraduate school. Grounded theory is used to analyze twelve semi-structured open-ended interviews about engineering students' experiences in Introductory Mechanics that includes Lecture, Recitation, and Laboratory components. Using data triangulation with each course component as a unit of analysis, this study examines students' course enjoyment as a function of instructional support and autonomy. The Lecture utilizes traditional instructor-centered pedagogy with predominantly passive learning and no student autonomy. The Recitation creates an active learning environment through small group work with a moderate degree of autonomy. The Laboratory is designed around self-guided project-based activities with significant autonomy. Despite these differences, all three course components provide similar levels of instructional support. The data reveal that students enjoy the low autonomy provided by Lecture and Recitations while finding the Laboratory frustrating. Analyses indicate that the differences in autonomy contribute to students' misinterpretation of the three course components' value within the context of the entire course.

NASA Tech Briefs, March 1996. Volume 20, No. 3

NASA Technical Reports Server (NTRS)

1996-01-01

Topics: Computer-Aided Design and Engineering; Electronic Components and Cicuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information; Books and Reports.

NASA Tech Briefs, September 1999. Volume 23, No. 9

NASA Technical Reports Server (NTRS)

1999-01-01

Topics discussed include: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences;

NASA Tech Briefs, March 1993. Volume 17, No. 3

NASA Technical Reports Server (NTRS)

1993-01-01

Topics include: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences;

Small Engine Component Technology (SECT) study

NASA Technical Reports Server (NTRS)

Singh, B.

1986-01-01

Small advanced (450 to 850 pounds thrust, 2002 to 3781 N) gas turbine engines were studied for a subsonic strategic cruise missile application, using projected year 2000 technology. An aircraft, mission characteristics, and baseline (state-of-the-art) engine were defined to evaluate technology benefits. Engine performance and configuration analyses were performed for two and three spool turbofan and propfan engine concepts. Mission and Life Cycle Cost (LCC) analyses were performed in which the candidate engines were compared to the baseline engines over a prescribed mission. The advanced technology engines reduced system LCC up to 41 percent relative to the baseline engine. Critical aerodynamic, materials, and mechanical systems turbine engine technologies were identified and program plans were defined for each identified critical technology.

Hybrid propulsion system with a gyro component for economic and dynamic operation. [of motor vehicle

NASA Technical Reports Server (NTRS)

Giera, B.; Helling, J.; Schreck, J.

1977-01-01

The design of a hybrid drive with gyro components is described and its drive components for a medium class private car are discussed. The gyro component affects the short-period output of the drive by accelerating and slowing down and -- because of the mechanical transfer of kinetic energy between the gyro and the vehicle -- it affects also the energy balance in the case of intermittent operation. Energy can be taken in as desired either in the form of fuel or as fuel and current. A high energy recovery efficiency as well as the favorable operating range of the interval combustion engine makes it possible to reduce the fuel consumption per unit distance travelled to almost half that for a private car with a traditional engine.

Direct and system effects of water ingestion into jet engine compresors

NASA Technical Reports Server (NTRS)

Murthy, S. N. B.; Ehresman, C. M.; Haykin, T.

1986-01-01

Water ingestion into aircraft-installed jet engines can arise both during take-off and flight through rain storms, resulting in engine operation with nearly saturated air-water droplet mixture flow. Each of the components of the engine and the system as a whole are affected by water ingestion, aero-thermally and mechanically. The greatest effects arise probably in turbo-machinery. Experimental and model-based results (of relevance to 'immediate' aerothermal changes) in compressors have been obtained to show the effects of film formation on material surfaces, centrifugal redistribution of water droplets, and interphase heat and mass transfer. Changes in the compressor performance affect the operation of the other components including the control and hence the system. The effects on the engine as a whole are obtained through engine simulation with specified water ingestion. The interest is in thrust, specific fuel consumption, surge margin and rotational speeds. Finally two significant aspects of performance changes, scalability and controllability, are discussed in terms of characteristic scales and functional relations.

Grizzly Usage and Theory Manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, B. W.; Backman, M.; Chakraborty, P.

2016-03-01

Grizzly is a multiphysics simulation code for characterizing the behavior of nuclear power plant (NPP) structures, systems and components (SSCs) subjected to a variety of age-related aging mechanisms. Grizzly simulates both the progression of aging processes, as well as the capacity of aged components to safely perform. This initial beta release of Grizzly includes capabilities for engineering-scale thermo-mechanical analysis of reactor pressure vessels (RPVs). Grizzly will ultimately include capabilities for a wide range of components and materials. Grizzly is in a state of constant development, and future releases will broaden the capabilities of this code for RPV analysis, as wellmore » as expand it to address degradation in other critical NPP components.« less

NASA Tech Briefs, November 1999. Volume 23, No. 11

NASA Technical Reports Server (NTRS)

1999-01-01

Topics covered include: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Materials; Computer Programs; Mechanics; Machinery/Automation; Physical Sciences; Mathematics and Information Sciences; Books and Reports.

Surface Modification Concepts for Enhancement of the High-Temperature Corrosion Resistance of Gas Turbine Superalloys,

DTIC Science & Technology

1980-12-01

now developed to the point where they could be considered as true engineering materials. ** Nickel-based alloys are used for turbine blading and...Introduction Implicit in the design of modern gas turbine engines is the premise that their aerofoil components, made of nickel- and cobalt-based...the deposit. Hot corrosion is a principal process of degradation of aerofoil surface integrity in gas turbine engines . 2.2 Mechanisms of Hot Corrosion

Multi-component nanofibrous scaffolds with tunable properties for bone tissue engineering

NASA Astrophysics Data System (ADS)

Jose, Moncy V.

Bone is a highly complex tissue which is an integral part of vertebrates and hence any damage has a major negative effect on the quality of life. Tissue engineering is regarded as an ideal route to resolve the issues related to the scarcity of tissue and organ for transplantation. Apart from cell line and growth factors, the choice of materials and fabrication technique for scaffold are equally important. The goal of this work was to develop a multi-component nanofibrous scaffold based on a synthetic polymer (poly(lactic-co-glycolide) (PLGA)), a biopolymer (collagen) and a biomineral (nano-hydroxyapatite (nano-HA)) by electrospinning technique, which mimics the nanoscopic, chemical, and anisotropic features of bone. Preliminary studies involved fabrication of nanocomposite scaffolds based on PLGA and nano-HA. Morphological and mechanical characterizations revealed that at low concentrations, nano-HA acted as reinforcements, whereas at higher concentrations the presence of aggregation was detrimental to the scaffold. Hydrolytic degradation studies revealed the scaffold had a little mass loss and the mechanical property was maintained for a period of 6 weeks. This study was followed by evaluation of a blend system based on PLGA and collagen. Collagen addition provides hydrophilicity and the necessary cell binding sites in PLGA. The structural characterization revealed that the blend had limited interactions between the two components. The mechanical characterization revealed that with increasing collagen concentration, there was a decline in mechanical properties. However, crosslinking of the blend system, with carbodiimide (EDC) resulted in improving the mechanical properties of the scaffolds. A multi-component system was developed by adding different concentrations of nano-HA to a fixed PLGA/collagen blend composition (80/20). Morphological and mechanical characterizations revealed properties similar to the PLGA/HA system. Cyto-compatibility studies revealed favorable cell adhesion and proliferation. Protein adsorption studies showed the higher surface area as well as the presence of collagen resulted in higher fibronectin and vitronectin adsorption. Crosslinking by EDC resulted in enhanced mechanical property in hydrated state and enhanced degradation stability. These results suggest that such a multi-component system can take advantage of the mechanical benefit available from the individual components and also provide specific biological cues necessary for a successful scaffold.

Comparisons of Kinematics and Dynamics Simulation Software Tools

NASA Technical Reports Server (NTRS)

Shiue, Yeu-Sheng Paul

2002-01-01

Kinematic and dynamic analyses for moving bodies are essential to system engineers and designers in the process of design and validations. 3D visualization and motion simulation plus finite element analysis (FEA) give engineers a better way to present ideas and results. Marshall Space Flight Center (MSFC) system engineering researchers are currently using IGRIP from DELMIA Inc. as a kinematic simulation tool for discrete bodies motion simulations. Although IGRIP is an excellent tool for kinematic simulation with some dynamic analysis capabilities in robotic control, explorations of other alternatives with more powerful dynamic analysis and FEA capabilities are necessary. Kinematics analysis will only examine the displacement, velocity, and acceleration of the mechanism without considering effects from masses of components. With dynamic analysis and FEA, effects such as the forces or torques at the joint due to mass and inertia of components can be identified. With keen market competition, ALGOR Mechanical Event Simulation (MES), MSC visualNastran 4D, Unigraphics Motion+, and Pro/MECHANICA were chosen for explorations. In this study, comparisons between software tools were presented in terms of following categories: graphical user interface (GUI), import capability, tutorial availability, ease of use, kinematic simulation capability, dynamic simulation capability, FEA capability, graphical output, technical support, and cost. Propulsion Test Article (PTA) with Fastrac engine model exported from IGRIP and an office chair mechanism were used as examples for simulations.

NASA Tech Briefs, October 1993. Volume 17, No. 10

NASA Technical Reports Server (NTRS)

1993-01-01

Topics include: Sensors; esign and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication technology; Mathematics and Information Sciences; Life Sciences; Books and Reports.

NASA Tech Briefs, January 2000. Volume 24, No. 1

NASA Technical Reports Server (NTRS)

2000-01-01

Topics include: Data Acquisition; Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Bio-Medical; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Information Sciences; Books and reports.

NASA Tech Briefs, March 1998. Volume 22, No. 3

NASA Technical Reports Server (NTRS)

1998-01-01

Topics include: special coverage of computer aided design and engineering, electronic components and circuits, electronic systems, physical sciences, materials, computer software, special coverage on mechanical technology, machinery/automation, manufacturing/fabrication, mathematics and information sciences, book and reports, and a special section of Electronics Tech Briefs. Profiles of the exhibitors at the National Design Engineering show are also included in this issue.

Advanced supersonic propulsion system technology study, phase 2

NASA Technical Reports Server (NTRS)

Allan, R. D.

1975-01-01

Variable cycle engines were identified, based on the mixed-flow low-bypass-ratio augmented turbofan cycle, which has shown excellent range capability in the AST airplane. The best mixed-flow augmented turbofan engine was selected based on range in the AST Baseline Airplane. Selected variable cycle engine features were added to this best conventional baseline engine, and the Dual-Cycle VCE and Double-Bypass VCE were defined. The conventional mixed-flow turbofan and the Double-Bypass VCE were on the subjects of engine preliminary design studies to determine mechanical feasibility, confirm weight and dimensional estimates, and identify the necessary technology considered not yet available. Critical engine components were studied and incorporated into the variable cycle engine design.

Overview of Lightweight Structures for Rotorcraft Engines and Drivetrains

NASA Technical Reports Server (NTRS)

Roberts, Gary D.

2011-01-01

This is an overview presentation of research being performed in the Advanced Materials Task within the NASA Subsonic Rotary Wing Project. This research is focused on technology areas that address both national goals and project goals for advanced rotorcraft. Specific technology areas discussed are: (1) high temperature materials for advanced turbines in turboshaft engines; (2) polymer matrix composites for lightweight drive system components; (3) lightweight structure approaches for noise and vibration control; and (4) an advanced metal alloy for lighter weight bearings and more reliable mechanical components. An overview of the technology in each area is discussed, and recent accomplishments are presented.

Thermomechanical Multiaxial Fatigue Testing Capability Developed

NASA Technical Reports Server (NTRS)

1996-01-01

Structural components in aeronautical gas turbine engines typically experience multiaxial states of stress under nonisothermal conditions. To estimate the durability of the various components in the engine, one must characterize the cyclic deformation and fatigue behavior of the materials used under thermal and complex mechanical loading conditions. To this end, a testing protocol and associated test control software were developed at the NASA Lewis Research Center for thermomechanical axial-torsional fatigue tests. These tests are to be performed on thin-walled, tubular specimens fabricated from the cobalt-based superalloy Haynes 188. The software is written in C and runs on an MS-DOS based microcomputer.

Inference Engine in an Intelligent Ship Course-Keeping System

PubMed Central

2017-01-01

The article presents an original design of an expert system, whose function is to automatically stabilize ship's course. The focus is put on the inference engine, a mechanism that consists of two functional components. One is responsible for the construction of state space regions, implemented on the basis of properly processed signals recorded by sensors from the input and output of an object. The other component is responsible for generating a control decision based on the knowledge obtained in the first module. The computing experiments described herein prove the effective and correct operation of the proposed system. PMID:29317859

Investigation of Deposit Formation Mechanisms for Engine In-cylinder Combustion and Exhaust Systems Using Quantitative Analysis and Sustainability Study

NASA Astrophysics Data System (ADS)

Ye, Z.; Meng, Q.; Mohamadian, H. P.; Wang, J. T.; Chen, L.; Zhu, L.

2007-06-01

The formation of SI engine combustion deposits is a complex phenomenon which depends on various factors of fuel, oil, additives, and engine. The goal of this study is to examine the effects of operating conditions, gasoline, lubricating oil, and additives on deposit formation. Both an experimental investigation and theoretical analysis are conducted on a single cylinder engine. As a result, the impact of deposits on engine performance and exhaust emissions (HC, NO x ) has been indicated. Using samples from a cylinder head and exhaust pipe as well as switching gases via the dual-gas method (N2, O2), the deposit formation mechanism is thoroughly investigated via the thermogravity analysis approach, where the roles of organic, inorganic, and volatile components of fuel, additives, and oil on deposit formation are identified from thermogravity curves. Sustainable feedback control design is then proposed for potential emission control and performance optimization

Effects of Structural Deformations of the Crank-Slider Mechanism on the Estimation of the Instantaneous Engine Friction Torque

NASA Astrophysics Data System (ADS)

CHALHOUB, N. G.; NEHME, H.; HENEIN, N. A.; BRYZIK, W.

1999-07-01

The focus on the current study is to assess the effects of structural deformations of the crankshaft/connecting-rod/piston mechanism on the computation of the instantaneous engine friction torque. This study is performed in a fully controlled environment in order to isolate the effects of structural deformations from those of measurement errors or noise interference. Therefore, a detailed model, accounting for the rigid and flexible motions of the crank-slider mechanism and including engine component friction formulations, is considered in this study. The model is used as a test bed to generate the engine friction torque,Tfa, and to predict the rigid and flexible motions of the system in response to the cylinder gas pressure. The torsional vibrations and the rigid body angular velocity of the crankshaft, as predicted by the detailed model of the crank-slider mechanism, are used along with the engine load torque and the cylinder gas pressure in the (P-ω) method to estimate the engine friction torque,Tfe. This method is well suited for the purpose of this study because its formulation is based on the rigid body model of the crank-slider mechanism. The digital simulation results demonstrate that the exclusion of the structural deformations of the crank-slider mechanism from the formulation of the (P-ω) method leads to an overestimation of the engine friction torque near the top-dead-center (TDC) position of the piston under firing conditions. Moreover, for the remainder of the engine cycle, the estimated friction torque exhibits large oscillations and takes on positive numerical values as if it is inducing energy into the system. Thus, the adverse effects of structural deformations of the crank-slider mechanism on the estimation of the engine friction torque greatly differ in their nature from one phase of the engine cycle to another.

NASA Tech Briefs, February 2000. Volume 24, No. 2

NASA Technical Reports Server (NTRS)

2000-01-01

Topics covered include: Test and Measurement; Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Bio-Medical; Mathematics and Information Sciences; Computers and Peripherals.

NASA Tech Briefs, March 1994. Volume 18, No. 3

NASA Technical Reports Server (NTRS)

1994-01-01

Topics include: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports

NASA Tech Briefs, May 2002. Volume 26, No. 5

NASA Technical Reports Server (NTRS)

2002-01-01

Topics include: a technology focus on engineering materials, electronic components and circuits, software, mechanics, machinery/automation, manufacturing, physical sciences, information sciences, book and reports, and a special section of Photonics Tech Briefs.

NASA Tech Briefs, March 2000. Volume 24, No. 3

NASA Technical Reports Server (NTRS)

2000-01-01

Topics include: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports.

NASA Tech Briefs, March 1997. Volume 21, No. 3

NASA Technical Reports Server (NTRS)

1997-01-01

Topics: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports.

An application of holographic interferometry for dynamic vibration analysis of a jet engine turbine compressor rotor

NASA Astrophysics Data System (ADS)

Fein, Howard

2003-09-01

Holographic Interferometry has been successfully employed to characterize the materials and behavior of diverse types of structures under dynamic stress. Specialized variations of this technology have also been applied to define dynamic and vibration related structural behavior. Such applications of holographic technique offer some of the most effective methods of modal and dynamic analysis available. Real-time dynamic testing of the modal and mechanical behavior of jet engine turbine, rotor, vane, and compressor structures has always required advanced instrumentation for data collection in either simulated flight operation test or computer-based modeling and simulations. Advanced optical holography techniques are alternate methods which result in actual full-field behavioral data in a noninvasive, noncontact environment. These methods offer significant insight in both the development and subsequent operational test and modeling of advanced jet engine turbine and compressor rotor structures and their integration with total vehicle system dynamics. Structures and materials can be analyzed with very low amplitude excitation and the resultant data can be used to adjust the accuracy of mathematically derived structural and behavioral models. Holographic Interferometry offers a powerful tool to aid in the developmental engineering of turbine rotor and compressor structures for high stress applications. Aircraft engine applications in particular most consider operational environments where extremes in vibration and impulsive as well as continuous mechanical stress can affect both operation and structural stability. These considerations present ideal requisites for analysis using advanced holographic methods in the initial design and test of turbine rotor components. Holographic techniques are nondestructive, real-time, and definitive in allowing the identification of vibrational modes, displacements, and motion geometries. Such information can be crucial to the determination of mechanical configurations and designs as well as critical operational parameters of turbine structural components or unit turbine components fabricated from advanced and exotic new materials or using new fabrication methods. Anomalous behavioral characteristics can be directly related to hidden structural or mounting anomalies and defects.

Materials Characterization of Additively Manufactured Components for Rocket Propulsion

NASA Technical Reports Server (NTRS)

Carter, Robert; Draper, Susan; Locci, Ivan; Lerch, Bradley; Ellis, David; Senick, Paul; Meyer, Michael; Free, James; Cooper, Ken; Jones, Zachary

2015-01-01

To advance Additive Manufacturing (AM) technologies for production of rocket propulsion components the NASA Glenn Research Center (GRC) is applying state of the art characterization techniques to interrogate microstructure and mechanical properties of AM materials and components at various steps in their processing. The materials being investigated for upper stage rocket engines include titanium, copper, and nickel alloys. Additive manufacturing processes include laser powder bed, electron beam powder bed, and electron beam wire fed processes. Various post build thermal treatments, including Hot Isostatic Pressure (HIP), have been studied to understand their influence on microstructure, mechanical properties, and build density. Micro-computed tomography, electron microscopy, and mechanical testing in relevant temperature environments has been performed to develop relationships between build quality, microstructure, and mechanical performance at temperature. A summary of GRC's Additive Manufacturing roles and experimental findings will be presented.

Material Characterization of Additively Manufactured Components for Rocket Propulsion

NASA Technical Reports Server (NTRS)

Carter, Robert; Draper, Susan; Locci, Ivan; Lerch, Bradley; Ellis, David; Senick, Paul; Meyer, Michael; Free, James; Cooper, Ken; Jones, Zachary

2015-01-01

To advance Additive Manufacturing (AM) technologies for production of rocket propulsion components the NASA Glenn Research Center (GRC) is applying state of the art characterization techniques to interrogate microstructure and mechanical properties of AM materials and components at various steps in their processing. The materials being investigated for upper stage rocket engines include titanium, copper, and nickel alloys. Additive manufacturing processes include laser powder bed, electron beam powder bed, and electron beam wire fed processes. Various post build thermal treatments, including Hot Isostatic Pressure (HIP), have been studied to understand their influence on microstructure, mechanical properties, and build density. Micro-computed tomography, electron microscopy, and mechanical testing in relevant temperature environments has been performed to develop relationships between build quality, microstructure, and mechanical performance at temperature. A summary of GRCs Additive Manufacturing roles and experimental findings will be presented.

Performance-based seismic design of nonstructural building components: The next frontier of earthquake engineering

NASA Astrophysics Data System (ADS)

Filiatrault, Andre; Sullivan, Timothy

2014-08-01

With the development and implementation of performance-based earthquake engineering, harmonization of performance levels between structural and nonstructural components becomes vital. Even if the structural components of a building achieve a continuous or immediate occupancy performance level after a seismic event, failure of architectural, mechanical or electrical components can lower the performance level of the entire building system. This reduction in performance caused by the vulnerability of nonstructural components has been observed during recent earthquakes worldwide. Moreover, nonstructural damage has limited the functionality of critical facilities, such as hospitals, following major seismic events. The investment in nonstructural components and building contents is far greater than that of structural components and framing. Therefore, it is not surprising that in many past earthquakes, losses from damage to nonstructural components have exceeded losses from structural damage. Furthermore, the failure of nonstructural components can become a safety hazard or can hamper the safe movement of occupants evacuating buildings, or of rescue workers entering buildings. In comparison to structural components and systems, there is relatively limited information on the seismic design of nonstructural components. Basic research work in this area has been sparse, and the available codes and guidelines are usually, for the most part, based on past experiences, engineering judgment and intuition, rather than on objective experimental and analytical results. Often, design engineers are forced to start almost from square one after each earthquake event: to observe what went wrong and to try to prevent repetitions. This is a consequence of the empirical nature of current seismic regulations and guidelines for nonstructural components. This review paper summarizes current knowledge on the seismic design and analysis of nonstructural building components, identifying major knowledge gaps that will need to be filled by future research. Furthermore, considering recent trends in earthquake engineering, the paper explores how performance-based seismic design might be conceived for nonstructural components, drawing on recent developments made in the field of seismic design and hinting at the specific considerations required for nonstructural components.

A Fully Non-metallic Gas Turbine Engine Enabled by Additive Manufacturing

NASA Technical Reports Server (NTRS)

Grady, Joseph E.

2014-01-01

The Non-Metallic Gas Turbine Engine project, funded by NASA Aeronautics Research Institute (NARI), represents the first comprehensive evaluation of emerging materials and manufacturing technologies that will enable fully nonmetallic gas turbine engines. This will be achieved by assessing the feasibility of using additive manufacturing technologies for fabricating polymer matrix composite (PMC) and ceramic matrix composite (CMC) gas turbine engine components. The benefits of the proposed effort include: 50 weight reduction compared to metallic parts, reduced manufacturing costs due to less machining and no tooling requirements, reduced part count due to net shape single component fabrication, and rapid design change and production iterations. Two high payoff metallic components have been identified for replacement with PMCs and will be fabricated using fused deposition modeling (FDM) with high temperature capable polymer filaments. The first component is an acoustic panel treatment with a honeycomb structure with an integrated back sheet and perforated front sheet. The second component is a compressor inlet guide vane. The CMC effort, which is starting at a lower technology readiness level, will use a binder jet process to fabricate silicon carbide test coupons and demonstration articles. The polymer and ceramic additive manufacturing efforts will advance from monolithic materials toward silicon carbide and carbon fiber reinforced composites for improved properties. Microstructural analysis and mechanical testing will be conducted on the PMC and CMC materials. System studies will assess the benefits of fully nonmetallic gas turbine engine in terms of fuel burn, emissions, reduction of part count, and cost. The proposed effort will be focused on a small 7000 lbf gas turbine engine. However, the concepts are equally applicable to large gas turbine engines. The proposed effort includes a multidisciplinary, multiorganization NASA - industry team that includes experts in ceramic materials and CMCs, polymers and PMCs, structural engineering, additive manufacturing, engine design and analysis, and system analysis.

Collagenous Extracellular Matrix Biomaterials for Tissue Engineering: Lessons from the Common Sea Urchin Tissue.

PubMed

Goh, Kheng Lim; Holmes, David F

2017-04-25

Scaffolds for tissue engineering application may be made from a collagenous extracellular matrix (ECM) of connective tissues because the ECM can mimic the functions of the target tissue. The primary sources of collagenous ECM material are calf skin and bone. However, these sources are associated with the risk of having bovine spongiform encephalopathy or transmissible spongiform encephalopathy. Alternative sources for collagenous ECM materials may be derived from livestock, e.g., pigs, and from marine animals, e.g., sea urchins. Collagenous ECM of the sea urchin possesses structural features and mechanical properties that are similar to those of mammalian ones. However, even more intriguing is that some tissues such as the ligamentous catch apparatus can exhibit mutability, namely rapid reversible changes in the tissue mechanical properties. These tissues are known as mutable collagenous tissues (MCTs). The mutability of these tissues has been the subject of on-going investigations, covering the biochemistry, structural biology and mechanical properties of the collagenous components. Recent studies point to a nerve-control system for regulating the ECM macromolecules that are involved in the sliding action of collagen fibrils in the MCT. This review discusses the key attributes of the structure and function of the ECM of the sea urchin ligaments that are related to the fibril-fibril sliding action-the focus is on the respective components within the hierarchical architecture of the tissue. In this context, structure refers to size, shape and separation distance of the ECM components while function is associated with mechanical properties e.g., strength and stiffness. For simplicity, the components that address the different length scale from the largest to the smallest are as follows: collagen fibres, collagen fibrils, interfibrillar matrix and collagen molecules. Application of recent theories of stress transfer and fracture mechanisms in fibre reinforced composites to a wide variety of collagen reinforcing (non-mutable) connective tissue, has allowed us to draw general conclusions concerning the mechanical response of the MCT at specific mechanical states, namely the stiff and complaint states. The intent of this review is to provide the latest insights, as well as identify technical challenges and opportunities, that may be useful for developing methods for effective mechanical support when adapting decellularised connective tissues from the sea urchin for tissue engineering or for the design of a synthetic analogue.

Collagenous Extracellular Matrix Biomaterials for Tissue Engineering: Lessons from the Common Sea Urchin Tissue

PubMed Central

Goh, Kheng Lim; Holmes, David F.

2017-01-01

Scaffolds for tissue engineering application may be made from a collagenous extracellular matrix (ECM) of connective tissues because the ECM can mimic the functions of the target tissue. The primary sources of collagenous ECM material are calf skin and bone. However, these sources are associated with the risk of having bovine spongiform encephalopathy or transmissible spongiform encephalopathy. Alternative sources for collagenous ECM materials may be derived from livestock, e.g., pigs, and from marine animals, e.g., sea urchins. Collagenous ECM of the sea urchin possesses structural features and mechanical properties that are similar to those of mammalian ones. However, even more intriguing is that some tissues such as the ligamentous catch apparatus can exhibit mutability, namely rapid reversible changes in the tissue mechanical properties. These tissues are known as mutable collagenous tissues (MCTs). The mutability of these tissues has been the subject of on-going investigations, covering the biochemistry, structural biology and mechanical properties of the collagenous components. Recent studies point to a nerve-control system for regulating the ECM macromolecules that are involved in the sliding action of collagen fibrils in the MCT. This review discusses the key attributes of the structure and function of the ECM of the sea urchin ligaments that are related to the fibril-fibril sliding action—the focus is on the respective components within the hierarchical architecture of the tissue. In this context, structure refers to size, shape and separation distance of the ECM components while function is associated with mechanical properties e.g., strength and stiffness. For simplicity, the components that address the different length scale from the largest to the smallest are as follows: collagen fibres, collagen fibrils, interfibrillar matrix and collagen molecules. Application of recent theories of stress transfer and fracture mechanisms in fibre reinforced composites to a wide variety of collagen reinforcing (non-mutable) connective tissue, has allowed us to draw general conclusions concerning the mechanical response of the MCT at specific mechanical states, namely the stiff and complaint states. The intent of this review is to provide the latest insights, as well as identify technical challenges and opportunities, that may be useful for developing methods for effective mechanical support when adapting decellularised connective tissues from the sea urchin for tissue engineering or for the design of a synthetic analogue. PMID:28441344

NACA Mechanics in an Allison Engine Training Class

NASA Image and Video Library

1943-10-21

The Allison Engine Company's A.G. Covell instructs mechanics from various divisions at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory on the operation of the Allison Basic Engine. The military had asked that the laboratory undertake an extensive program to improve the performance of the Allison V–1710 engine. The V–1710 was the only liquid-cooled engine used during World War II, and the military counted on it to power several types of fighter aircraft. The NACA instituted an Apprentice Program during the war to educate future mechanics, technicians, and electricians. The program was suspended for a number of years due to the increasing rates of military service by its participants. The laboratory continued its in-house education during the war, however, by offering a number of classes to its employees and lectures for the research staff. The classes and lectures were usually taught by fellow members of the staff, but occasionally external experts were brought in. The students in the Allison class in the Engine Research Building were taught how to completely disassemble and reassemble the engine components and systems. From left to right are Don Vining, Ed Cudlin, Gus DiNovo, George Larsen, Charles Diggs, Martin Lipes, Harley Roberts, Martin Berwaldt and John Dempsey. A.G. Covell is standing.

Construction of combustion models for rapeseed methyl ester bio-diesel fuel for internal combustion engine applications.

PubMed

Golovitchev, Valeri I; Yang, Junfeng

2009-01-01

Bio-diesel fuels are non-petroleum-based diesel fuels consisting of long chain alkyl esters produced by the transesterification of vegetable oils, that are intended for use (neat or blended with conventional fuels) in unmodified diesel engines. There have been few reports of studies proposing theoretical models for bio-diesel combustion simulations. In this study, we developed combustion models based on ones developed previously. We compiled the liquid fuel properties, and the existing detailed mechanism of methyl butanoate ester (MB, C(5)H(10)O(2)) oxidation was supplemented by sub-mechanisms for two proposed fuel constituent components, C(7)H(16) and C(7)H(8)O (and then, by mp2d, C(4)H(6)O(2) and propyne, C(3)H(4)) to represent the combustion model for rapeseed methyl ester described by the chemical formula, C(19)H(34)O(2) (or C(19)H(36)O(2)). The main fuel vapor thermal properties were taken as those of methyl palmitate C(19)H(36)O(2) in the NASA polynomial form of the Burcat database. The special global reaction was introduced to "crack" the main fuel into its constituent components. This general reaction included 309 species and 1472 reactions, including soot and NO(x) formation processes. The detailed combustion mechanism was validated using shock-tube ignition-delay data under diesel engine conditions. For constant volume and diesel engine (Volvo D12C) combustion modeling, this mechanism could be reduced to 88 species participating in 363 reactions.

Genetically Engineered Materials for Biofuels Production

NASA Astrophysics Data System (ADS)

Raab, Michael

2012-02-01

Agrivida, Inc., is an agricultural biotechnology company developing industrial crop feedstocks for the fuel and chemical industries. Agrivida's crops have improved processing traits that enable efficient, low cost conversion of the crops' cellulosic components into fermentable sugars. Currently, pretreatment and enzymatic conversion of the major cell wall components, cellulose and hemicellulose, into fermentable sugars is the most expensive processing step that prevents widespread adoption of biomass in biofuels processes. To lower production costs we are consolidating pretreatment and enzyme production within the crop. In this strategy, transgenic plants express engineered cell wall degrading enzymes in an inactive form, which can be reactivated after harvest. We have engineered protein elements that disrupt enzyme activity during normal plant growth. Upon exposure to specific processing conditions, the engineered enzymes are converted into their active forms. This mechanism significantly lowers pretreatment costs and enzyme loadings (>75% reduction) below those currently available to the industry.

The Development of Erosion and Impact Resistant Turbine Airfoil Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2007-01-01

Thermal barrier coatings are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments and extend component lifetimes. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Advanced erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the doped thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion and impact damage mechanisms of the thermal barrier coatings will also be discussed.

NASA Tech Briefs, July 1994. Volume 18, No. 7

NASA Technical Reports Server (NTRS)

1994-01-01

Topics covered include: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports

46 CFR 50.25-5 - Products requiring manufacturer or mill certification.

Code of Federal Regulations, 2014 CFR

2014-10-01

... ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-5 Products requiring..., the application of the product does not require knowledge of the exact chemical analysis or mechanical...

NASA Tech Briefs, November 2002. Volume 26, No. 11

NASA Technical Reports Server (NTRS)

2002-01-01

Topics include: a technology focus on engineering materials, electronic components and systems, software, mechanics, machinery/automation, manufacturing, bio-medical, physical sciences, information sciences book and reports, and a special section of Photonics Tech Briefs.

46 CFR 50.25-5 - Products requiring manufacturer or mill certification.

Code of Federal Regulations, 2013 CFR

2013-10-01

... ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-5 Products requiring..., the application of the product does not require knowledge of the exact chemical analysis or mechanical...

46 CFR 50.25-5 - Products requiring manufacturer or mill certification.

Code of Federal Regulations, 2011 CFR

2011-10-01

... ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-5 Products requiring..., the application of the product does not require knowledge of the exact chemical analysis or mechanical...

46 CFR 50.25-5 - Products requiring manufacturer or mill certification.

Code of Federal Regulations, 2012 CFR

2012-10-01

... ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-5 Products requiring..., the application of the product does not require knowledge of the exact chemical analysis or mechanical...

46 CFR 50.25-5 - Products requiring manufacturer or mill certification.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ENGINEERING GENERAL PROVISIONS Acceptance of Material and Piping Components § 50.25-5 Products requiring..., the application of the product does not require knowledge of the exact chemical analysis or mechanical...

NASA Tech Briefs, November 2000. Volume 24, No. 11

NASA Technical Reports Server (NTRS)

2000-01-01

Topics covered include: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Test and Measurement; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Data Acquisition.

NASA Tech Briefs, April 1996. Volume 20, No. 4

NASA Technical Reports Server (NTRS)

1996-01-01

Topics covered include: Advanced Composites and Plastics; Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information; Books and Reports.

NASA Tech Briefs, October 1994. Volume 18, No. 10

NASA Technical Reports Server (NTRS)

1994-01-01

Topics: Data Acquisition and Analysis; Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences; Books and Reports

Reliability study of an emerging fire suppression system

DOE PAGES

Miller, David A.; Rossati, Lyric M.; Fritz, Nathan K.; ...

2015-11-01

Self-contained fire extinguishers are a robust, reliable and minimally invasive means of fire suppression for gloveboxes. Plutonium gloveboxes are known to present harsh environmental conditions for polymer materials, these include radiation damage and chemical exposure, both of which tend to degrade the lifetime of engineered polymer components. The primary component of interest in self-contained fire extinguishers is the nylon 6-6 machined tube that comprises the main body of the system.Thermo-mechanical modeling and characterization of nylon 6-6 for use in plutonium glovebox applications has been carried out. Data has been generated regarding property degradation leading to poor, or reduced, engineering performancemore » of nylon 6-6 components. In this study, nylon 6-6 tensile specimens conforming to the casing of self-contained fire extinguisher systems have been exposed to hydrochloric, nitric, and sulfuric acids. This information was used to predict the performance of a load bearing engineering component comprised of nylon 6-6 and designed to operate in a consistent manner over a specified time period. The study provides a fundamental understanding of the engineering performance of the fire suppression system and the effects of environmental degradation due to acid exposure on engineering performance. Data generated help identify the limitations of self-contained fire extinguishers. No critical areas of concern for plutonium glovebox applications of nylon 6-6 have been identified when considering exposure to mineral acid.« less

Reliability study of an emerging fire suppression system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, David A.; Rossati, Lyric M.; Fritz, Nathan K.

Self-contained fire extinguishers are a robust, reliable and minimally invasive means of fire suppression for gloveboxes. Plutonium gloveboxes are known to present harsh environmental conditions for polymer materials, these include radiation damage and chemical exposure, both of which tend to degrade the lifetime of engineered polymer components. The primary component of interest in self-contained fire extinguishers is the nylon 6-6 machined tube that comprises the main body of the system.Thermo-mechanical modeling and characterization of nylon 6-6 for use in plutonium glovebox applications has been carried out. Data has been generated regarding property degradation leading to poor, or reduced, engineering performancemore » of nylon 6-6 components. In this study, nylon 6-6 tensile specimens conforming to the casing of self-contained fire extinguisher systems have been exposed to hydrochloric, nitric, and sulfuric acids. This information was used to predict the performance of a load bearing engineering component comprised of nylon 6-6 and designed to operate in a consistent manner over a specified time period. The study provides a fundamental understanding of the engineering performance of the fire suppression system and the effects of environmental degradation due to acid exposure on engineering performance. Data generated help identify the limitations of self-contained fire extinguishers. No critical areas of concern for plutonium glovebox applications of nylon 6-6 have been identified when considering exposure to mineral acid.« less

Effect of weld line positions on the tensile deformation of two-component metal injection moulding

NASA Astrophysics Data System (ADS)

Manonukul, Anchalee; Songkuea, Sukrit; Moonchaleanporn, Pongporn; Tange, Makiko

2017-12-01

Knowledge of the mechanical properties of two-component parts is critical for engineering functionally graded components. In this study, mono- and two-component tensile test specimens were metal injection moulded. Three different weld line positions were generated in the two-component specimens. Linear shrinkage of the two-component specimens was greater than that of the mono-component specimens because the incompatibility of sintering shrinkage of both materials causes biaxial stresses and enhances sintering. The mechanical properties of 316L stainless steel were affected by the addition of a coloured pigment used to identify the weld line position after injection moulding. For the two-component specimens, the yield stress and ultimate tensile stress were similar to those of 316L stainless steel. Because 316L and 630 (also known as 17-4PH) stainless steels were well-sintered at the interface, the mechanical properties of the weaker material (316L stainless steel) were dominant. However, the elongations of the two-component specimens were lower than those of the mono-component specimens. An interfacial zone with a microstructure that differed from those of the mono-material specimens was observed; its different microstructure was attributed to the gradual diffusion of nickel and copper.

Tribological characteristics of silicon carbide whisker-reinforced alumina at elevated temperatures

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

1991-01-01

The enhanced fracture toughness of whisker reinforced ceramics makes them attractive candidates for sliding components of advanced hear engines. Examples include piston rings and valve stems for Stirling engines and other low heat rejection devices. However, the tribological behavior of whisker reinforced ceramics is largely unknown. This is especially true for the applications described where use temperatures can vary from below ambient to well over 1000 C. An experimental research program to identify the dominant wear mechanism(s) for a silicon carbide whisker reinforced alumina composite, SiCw-Al2O3 is described. In addition, a wear mechanism model is developed to explain and corroborate the experimental results and to provide insight for material improvement.

Modeling of rolling element bearing mechanics

NASA Technical Reports Server (NTRS)

Greenhill, L. M.

1991-01-01

Roller element bearings provide the primary mechanical interface between rotating and nonrotating components in the high performance turbomachinery of the Space Shuttle Main Engine (SSME). Knowledge of bearing behavior under various loading and environmental conditions is essential to predicting and understanding the overall behavior of turbopumps, including rotordynamic stability, critical speeds and bearing life. The objective is to develop mathematical models and computer programs to describe the mechanical behavior of ball and cylinder roller bearings under the loading and environmental conditions encountered in the SSME and future high performance rocket engines. This includes characteristics such as nonlinear load/motion relationships, stiffness and damping, rolling element loads for life prediction, and roller and cage stability.

Structural dynamics verification facility study

NASA Technical Reports Server (NTRS)

Kiraly, L. J.; Hirchbein, M. S.; Mcaleese, J. M.; Fleming, D. P.

1981-01-01

The need for a structural dynamics verification facility to support structures programs was studied. Most of the industry operated facilities are used for highly focused research, component development, and problem solving, and are not used for the generic understanding of the coupled dynamic response of major engine subsystems. Capabilities for the proposed facility include: the ability to both excite and measure coupled structural dynamic response of elastic blades on elastic shafting, the mechanical simulation of various dynamical loadings representative of those seen in operating engines, and the measurement of engine dynamic deflections and interface forces caused by alternative engine mounting configurations and compliances.

Ferrographic and spectrometer oil analysis from a failed gas turbine engine

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.

1982-01-01

An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. It was concluded that a severe surge may have caused interference between rotating and stationary compressor that either directly or indirectly ignited the titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph, a plasma, an atomic absorption, and an emission spectrometer to see if this information would aid in the engine failure diagnosis. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism nor a high level of wear debris was detected in the engine oil sample taken just prior to the test in which the failure occurred. However, low concentrations (0.2 to 0.5 ppm) of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations ( 2 ppm) were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure. The oil analyses eliminated a lubrication system bearing or shaft seal failure as the cause of the engine failure.

Engineering on the straight and narrow: the mechanics of nanofibrous assemblies for fiber-reinforced tissue regeneration.

PubMed

Mauck, Robert L; Baker, Brendon M; Nerurkar, Nandan L; Burdick, Jason A; Li, Wan-Ju; Tuan, Rocky S; Elliott, Dawn M

2009-06-01

Tissue engineering of fibrous tissues of the musculoskeletal system represents a considerable challenge because of the complex architecture and mechanical properties of the component structures. Natural healing processes in these dense tissues are limited as a result of the mechanically challenging environment of the damaged tissue and the hypocellularity and avascular nature of the extracellular matrix. When healing does occur, the ordered structure of the native tissue is replaced with a disorganized fibrous scar with inferior mechanical properties, engendering sites that are prone to re-injury. To address the engineering of such tissues, we and others have adopted a structurally motivated approach based on organized nanofibrous assemblies. These scaffolds are composed of ultrafine polymeric fibers that can be fabricated in such a way to recreate the structural anisotropy typical of fiber-reinforced tissues. This straight-and-narrow topography not only provides tailored mechanical properties, but also serves as a 3D biomimetic micropattern for directed tissue formation. This review describes the underlying technology of nanofiber production and focuses specifically on the mechanical evaluation and theoretical modeling of these structures as it relates to native tissue structure and function. Applying the same mechanical framework for understanding native and engineered fiber-reinforced tissues provides a functional method for evaluating the utility and maturation of these unique engineered constructs. We further describe several case examples where these principles have been put to test, and discuss the remaining challenges and opportunities in forwarding this technology toward clinical implementation.

Engineering on the Straight and Narrow: The Mechanics of Nanofibrous Assemblies for Fiber-Reinforced Tissue Regeneration

PubMed Central

Baker, Brendon M.; Nerurkar, Nandan L.; Burdick, Jason A.; Li, Wan-Ju; Tuan, Rocky S.; Elliott, Dawn M.

2009-01-01

Tissue engineering of fibrous tissues of the musculoskeletal system represents a considerable challenge because of the complex architecture and mechanical properties of the component structures. Natural healing processes in these dense tissues are limited as a result of the mechanically challenging environment of the damaged tissue and the hypocellularity and avascular nature of the extracellular matrix. When healing does occur, the ordered structure of the native tissue is replaced with a disorganized fibrous scar with inferior mechanical properties, engendering sites that are prone to re-injury. To address the engineering of such tissues, we and others have adopted a structurally motivated approach based on organized nanofibrous assemblies. These scaffolds are composed of ultrafine polymeric fibers that can be fabricated in such a way to recreate the structural anisotropy typical of fiber-reinforced tissues. This straight-and-narrow topography not only provides tailored mechanical properties, but also serves as a 3D biomimetic micropattern for directed tissue formation. This review describes the underlying technology of nanofiber production and focuses specifically on the mechanical evaluation and theoretical modeling of these structures as it relates to native tissue structure and function. Applying the same mechanical framework for understanding native and engineered fiber-reinforced tissues provides a functional method for evaluating the utility and maturation of these unique engineered constructs. We further describe several case examples where these principles have been put to test, and discuss the remaining challenges and opportunities in forwarding this technology toward clinical implementation. PMID:19207040

Superconducting Qubits as Mechanical Quantum Engines

NASA Astrophysics Data System (ADS)

Sachtleben, Kewin; Mazon, Kahio T.; Rego, Luis G. C.

2017-09-01

We propose the equivalence of superconducting qubits with a pistonlike mechanical quantum engine. The work reports a study on the nature of the nonequilibrium work exchanged with the quantum-nonadiabatic working medium, which is modeled as a multilevel coupled quantum well system subject to an external control parameter. The quantum dynamics is solved for arbitrary control protocols. It is shown that the work output has two components: one that depends instantaneously on the level populations and another that is due to the quantum coherences built in the system. The nonadiabatic coherent dynamics of the quantum engine gives rise to a resistance (friction) force that decreases the work output. We consider the functional equivalence of such a device and a rf-SQUID flux qubit.

Task 6 -- Advanced turbine systems program conceptual design and product development

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-01-10

The Allison Engine Company has completed the Task 6 Conceptual Design and Analysis of Phase 2 of the Advanced Turbine System (ATS) contract. At the heart of Allison`s system is an advanced simple cycle gas turbine engine. This engine will incorporate components that ensure the program goals are met. Allison plans to commercialize the ATS demonstrator and market a family of engines incorporating this technology. This family of engines, ranging from 4.9 MW to 12 MW, will be suitable for use in all industrial engine applications, including electric power generation, mechanical drive, and marine propulsion. In the field of electricmore » power generation, the engines will be used for base load, standby, cogeneration, and distributed generation applications.« less

Multiphysics Code Demonstrated for Propulsion Applications

NASA Technical Reports Server (NTRS)

Lawrence, Charles; Melis, Matthew E.

1998-01-01

The utility of multidisciplinary analysis tools for aeropropulsion applications is being investigated at the NASA Lewis Research Center. The goal of this project is to apply Spectrum, a multiphysics code developed by Centric Engineering Systems, Inc., to simulate multidisciplinary effects in turbomachinery components. Many engineering problems today involve detailed computer analyses to predict the thermal, aerodynamic, and structural response of a mechanical system as it undergoes service loading. Analysis of aerospace structures generally requires attention in all three disciplinary areas to adequately predict component service behavior, and in many cases, the results from one discipline substantially affect the outcome of the other two. There are numerous computer codes currently available in the engineering community to perform such analyses in each of these disciplines. Many of these codes are developed and used in-house by a given organization, and many are commercially available. However, few, if any, of these codes are designed specifically for multidisciplinary analyses. The Spectrum code has been developed for performing fully coupled fluid, thermal, and structural analyses on a mechanical system with a single simulation that accounts for all simultaneous interactions, thus eliminating the requirement for running a large number of sequential, separate, disciplinary analyses. The Spectrum code has a true multiphysics analysis capability, which improves analysis efficiency as well as accuracy. Centric Engineering, Inc., working with a team of Lewis and AlliedSignal Engines engineers, has been evaluating Spectrum for a variety of propulsion applications including disk quenching, drum cavity flow, aeromechanical simulations, and a centrifugal compressor flow simulation.

Quiet Clean Short-Haul Experimental Engine (QCSEE) ball spline pitch-change mechanism whirligig test report

NASA Technical Reports Server (NTRS)

1978-01-01

The component testing of a ball spline variable pitch mechanism is described including a whirligig test. The variable pitch actuator successfully completed all planned whirligig tests including a fifty cycle endurance test at actuation rates up to 125 deg per second at up to 102 percent fan speed (3400 rpm).

AGT (Advanced Gas Turbine) technology project

NASA Technical Reports Server (NTRS)

1988-01-01

An overall summary documentation is provided for the Advanced Gas Turbine Technology Project conducted by the Allison Gas Turbine Division of General Motors. This advanced, high risk work was initiated in October 1979 under charter from the U.S. Congress to promote an engine for transportation that would provide an alternate to reciprocating spark ignition (SI) engines for the U.S. automotive industry and simultaneously establish the feasibility of advanced ceramic materials for hot section components to be used in an automotive gas turbine. As this program evolved, dictates of available funding, Government charter, and technical developments caused program emphases to focus on the development and demonstration of the ceramic turbine hot section and away from the development of engine and powertrain technologies and subsequent vehicular demonstrations. Program technical performance concluded in June 1987. The AGT 100 program successfully achieved project objectives with significant technology advances. Specific AGT 100 program achievements are: (1) Ceramic component feasibility for use in gas turbine engines has been demonstrated; (2) A new, 100 hp engine was designed, fabricated, and tested for 572 hour at operating temperatures to 2200 F, uncooled; (3) Statistical design methodology has been applied and correlated to experimental data acquired from over 5500 hour of rig and engine testing; (4) Ceramic component processing capability has progressed from a rudimentary level able to fabricate simple parts to a sophisticated level able to provide complex geometries such as rotors and scrolls; (5) Required improvements for monolithic and composite ceramic gas turbine components to meet automotive reliability, performance, and cost goals have been identified; (6) The combustor design demonstrated lower emissions than 1986 Federal Standards on methanol, JP-5, and diesel fuel. Thus, the potential for meeting emission standards and multifuel capability has been initiated; (7) Small turbine engine aerodynamic and mechanical design capability has been initiated; and (8) An infrastructure of manpower, facilities, materials, and fabrication capabilities has been established which is available for continued development of ceramic component technology in gas turbine and other heat engines.

NASA Tech Briefs, August 2000. Volume 24, No. 8

NASA Technical Reports Server (NTRS)

2000-01-01

Topics include: Simulation/Virtual Reality; Test and Measurement; Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Medical Design.

A real time neural net estimator of fatigue life

NASA Technical Reports Server (NTRS)

Troudet, T.; Merrill, W.

1990-01-01

A neural net architecture is proposed to estimate, in real-time, the fatigue life of mechanical components, as part of the Intelligent Control System for Reusable Rocket Engines. Arbitrary component loading values were used as input to train a two hidden-layer feedforward neural net to estimate component fatigue damage. The ability of the net to learn, based on a local strain approach, the mapping between load sequence and fatigue damage has been demonstrated for a uniaxial specimen. Because of its demonstrated performance, the neural computation may be extended to complex cases where the loads are biaxial or triaxial, and the geometry of the component is complex (e.g., turbopump blades). The generality of the approach is such that load/damage mappings can be directly extracted from experimental data without requiring any knowledge of the stress/strain profile of the component. In addition, the parallel network architecture allows real-time life calculations even for high frequency vibrations. Owing to its distributed nature, the neural implementation will be robust and reliable, enabling its use in hostile environments such as rocket engines. This neural net estimator of fatigue life is seen as the enabling technology to achieve component life prognosis, and therefore would be an important part of life extending control for reusable rocket engines.

Fibrocartilage tissue engineering: the role of the stress environment on cell morphology and matrix expression.

PubMed

Thomopoulos, Stavros; Das, Rosalina; Birman, Victor; Smith, Lester; Ku, Katherine; Elson, Elliott L; Pryse, Kenneth M; Marquez, Juan Pablo; Genin, Guy M

2011-04-01

Although much is known about the effects of uniaxial mechanical loading on fibrocartilage development, the stress fields to which fibrocartilaginous regions are subjected to during development are mutiaxial. That fibrocartilage develops at tendon-to-bone attachments and in compressive regions of tendons is well established. However, the three-dimensional (3D) nature of the stresses needed for the development of fibrocartilage is not known. Here, we developed and applied an in vitro system to determine whether fibrocartilage can develop under a state of periodic hydrostatic tension in which only a single principal component of stress is compressive. This question is vital to efforts to mechanically guide morphogenesis and matrix expression in engineered tissue replacements. Mesenchymal stromal cells in a 3D culture were exposed to compressive and tensile stresses as a result of an external tensile hydrostatic stress field. The stress field was characterized through mechanical modeling. Tensile cyclic stresses promoted spindle-shaped cells, upregulation of scleraxis and type one collagen, and cell alignment with the direction of tension. Cells experiencing a single compressive stress component exhibited rounded cell morphology and random cell orientation. No difference in mRNA expression of the genes Sox9 and aggrecan was observed when comparing tensile and compressive regions unless the medium was supplemented with the chondrogenic factor transforming growth factor beta3. In that case, Sox9 was upregulated under static loading conditions and aggrecan was upregulated under cyclic loading conditions. In conclusion, the fibrous component of fibrocartilage could be generated using only mechanical cues, but generation of the cartilaginous component of fibrocartilage required biologic factors in addition to mechanical cues. These studies support the hypothesis that the 3D stress environment influences cell activity and gene expression in fibrocartilage development.

Fibrocartilage Tissue Engineering: The Role of the Stress Environment on Cell Morphology and Matrix Expression

PubMed Central

Das, Rosalina; Birman, Victor; Smith, Lester; Ku, Katherine; Elson, Elliott L.; Pryse, Kenneth M.; Marquez, Juan Pablo; Genin, Guy M.

2011-01-01

Although much is known about the effects of uniaxial mechanical loading on fibrocartilage development, the stress fields to which fibrocartilaginous regions are subjected to during development are mutiaxial. That fibrocartilage develops at tendon-to-bone attachments and in compressive regions of tendons is well established. However, the three-dimensional (3D) nature of the stresses needed for the development of fibrocartilage is not known. Here, we developed and applied an in vitro system to determine whether fibrocartilage can develop under a state of periodic hydrostatic tension in which only a single principal component of stress is compressive. This question is vital to efforts to mechanically guide morphogenesis and matrix expression in engineered tissue replacements. Mesenchymal stromal cells in a 3D culture were exposed to compressive and tensile stresses as a result of an external tensile hydrostatic stress field. The stress field was characterized through mechanical modeling. Tensile cyclic stresses promoted spindle-shaped cells, upregulation of scleraxis and type one collagen, and cell alignment with the direction of tension. Cells experiencing a single compressive stress component exhibited rounded cell morphology and random cell orientation. No difference in mRNA expression of the genes Sox9 and aggrecan was observed when comparing tensile and compressive regions unless the medium was supplemented with the chondrogenic factor transforming growth factor beta3. In that case, Sox9 was upregulated under static loading conditions and aggrecan was upregulated under cyclic loading conditions. In conclusion, the fibrous component of fibrocartilage could be generated using only mechanical cues, but generation of the cartilaginous component of fibrocartilage required biologic factors in addition to mechanical cues. These studies support the hypothesis that the 3D stress environment influences cell activity and gene expression in fibrocartilage development. PMID:21091338

Advanced Gas Turbine (AGT) technology report

NASA Technical Reports Server (NTRS)

1985-01-01

Engine testing, ceramic component fabrication and evaluation, component performance rig testing, and producibility experiments at Pontiac comprised AGT 100 activities of this period, January to December 1984. Two experimental engines were available and allowed the evaluation of eight experimental assemblies. Operating time accumulated was 115 hr of burning and 156 hr total. Total cumulative engine operating time is now 225 hr. Build number 11 and 12 of engine S/N 1 totaled 28 burning hours and constituted a single assembly of the engine core--the compressor, both turbines, and the gearbox. Build number 11 of engine S/N 1 included a 1:07 hr continuous test at 100% gasifier speed (86,000 rpm). Build number 8 of engine S/N 2 was the first engine test with a ceramic turbine rotor. A mechanical loss test of an engine assembly revealed the actual losses to be near the original design allowance. Component development activity included rig testing of the compressor, combustor, and regenerator. Compressor testing was initiated on a rig modified to control the transfer of heat between flow path, lubricating oil, and structure. Results show successful thermal decoupling of the rig and lubricating/cooling oil. Rig evaluation of a reduced-friction compressor was initiated. Combustor testing covered qualification of ceramic parts for engine use, mapping of operating range limits, and evaluation of a relocated igniter plug. Several seal refinements were tested on the hot regenerator rig. An alternate regenerator disk, extruded MAS, was examined and found to be currently inadequate for the AGT 100 application. Also, a new technique for measuring leakage was explored on the regenerator rig. Ceramic component activity has focused on the development of state-of-the-art material strength characteristics in full-scale hardware. Injection-molded sintered alpha-SiC rotors were produced at Carborundum in an extensive process and tool optimization study.

The GridEcon Platform: A Business Scenario Testbed for Commercial Cloud Services

NASA Astrophysics Data System (ADS)

Risch, Marcel; Altmann, Jörn; Guo, Li; Fleming, Alan; Courcoubetis, Costas

Within this paper, we present the GridEcon Platform, a testbed for designing and evaluating economics-aware services in a commercial Cloud computing setting. The Platform is based on the idea that the exact working of such services is difficult to predict in the context of a market and, therefore, an environment for evaluating its behavior in an emulated market is needed. To identify the components of the GridEcon Platform, a number of economics-aware services and their interactions have been envisioned. The two most important components of the platform are the Marketplace and the Workflow Engine. The Workflow Engine allows the simple composition of a market environment by describing the service interactions between economics-aware services. The Marketplace allows trading goods using different market mechanisms. The capabilities of these components of the GridEcon Platform in conjunction with the economics-aware services are described in this paper in detail. The validation of an implemented market mechanism and a capacity planning service using the GridEcon Platform also demonstrated the usefulness of the GridEcon Platform.

Exploring the Use of Model-Based Systems Engineering (MBSE) to Develop Systems Architectures in Naval Ship Design

DTIC Science & Technology

2010-06-01

data such as the NSMB B-series, or be based on hydrodynamic (lifting line) predict ions. The power including still air drag and any margin that is...Provide Fuel Function 3.6 Fuel Oil System Component REQ.1.4 Fuel Efficiency Requirement 1.1 Generate Mechanical En... Function 1.1 Prime Mover Component...3.3 Provide Lubrication Function 3.7 Lube Oil System Component 3.4 Provide Cooling Water Function 3.3 Cooling System Component 3.5 Provide Combust ion

A novel bioprinting method and system for forming hybrid tissue engineering constructs.

PubMed

Shanjani, Y; Pan, C C; Elomaa, L; Yang, Y

2015-12-18

Three dimensional (3D) bioprinting is a promising approach to form tissue engineering constructs (TECs) via positioning biomaterials, growth factors, and cells with controlled spatial distribution due to its layer-by-layer manufacturing nature. Hybrid TECs composed of relatively rigid porous scaffolds for structural and mechanical integrity and soft hydrogels for cell- and growth factor-loading have a tremendous potential to tissue regeneration under mechanical loading. However, despite excessive progress in the field, the current 3D bioprinting techniques and systems fall short in integration of such soft and rigid multifunctional components. Here we present a novel 3D hybrid bioprinting technology (Hybprinter) and its capability enabling integration of soft and rigid components for TECs. Hybprinter employs digital light processing-based stereolithography (DLP-SLA) and molten material extrusion techniques for soft and rigid materials, respectively. In this study, poly-ethylene glycol diacrylate (PEGDA) and poly-(ε-caprolactone) (PCL) were used as a model material for soft hydrogel and rigid scaffold, respectively. It was shown that geometrical accuracy, swelling ratio and mechanical properties of the hydrogel component can be tailored by DLP-SLA module. We have demonstrated the printability of variety of complex hybrid construct designs using Hybprinter technology and characterized the mechanical properties and functionality of such constructs. The compressive mechanical stiffness of a hybrid construct (90% hydrogel) was significantly higher than hydrogel itself (∼6 MPa versus 100 kPa). In addition, viability of cells incorporated within the bioprinted hybrid constructs was determined approximately 90%. Furthermore, a functionality of a hybrid construct composed of porous scaffold with an embedded hydrogel conduit was characterized for vascularized tissue engineering applications. High material diffusion and high cell viability in about 2.5 mm distance surrounding the conduit indicated that culture media effectively diffused through the conduit and fed the cells. The results suggest that the developed technology is potent to form functional TECs composed of rigid and soft biomaterials.

A Fully Non-Metallic Gas Turbine Engine Enabled by Additive Manufacturing

NASA Technical Reports Server (NTRS)

Grady, Joseph E.

2015-01-01

The Non-Metallic Gas Turbine Engine project, funded by NASA Aeronautics Research Institute, represents the first comprehensive evaluation of emerging materials and manufacturing technologies that will enable fully nonmetallic gas turbine engines. This will be achieved by assessing the feasibility of using additive manufacturing technologies to fabricate polymer matrix composite and ceramic matrix composite turbine engine components. The benefits include: 50 weight reduction compared to metallic parts, reduced manufacturing costs, reduced part count and rapid design iterations. Two high payoff metallic components have been identified for replacement with PMCs and will be fabricated using fused deposition modeling (FDM) with high temperature polymer filaments. The CMC effort uses a binder jet process to fabricate silicon carbide test coupons and demonstration articles. Microstructural analysis and mechanical testing will be conducted on the PMC and CMC materials. System studies will assess the benefits of fully nonmetallic gas turbine engine in terms of fuel burn, emissions, reduction of part count, and cost. The research project includes a multidisciplinary, multiorganization NASA - industry team that includes experts in ceramic materials and CMCs, polymers and PMCs, structural engineering, additive manufacturing, engine design and analysis, and system analysis.

Educating Tomorrow's Aerrospace Engineers by Developing and Launching Liquid-Propelled Rockets

NASA Astrophysics Data System (ADS)

Besnard, Eric; Garvey, John; Holleman, Tom; Mueller, Tom

2002-01-01

conducted at California State University, Long Beach (CSULB), in which engineering students develop and launch liquid propelled rockets. The program is articulated around two main activities, each with specific objectives. The first component of CALVEIN is a systems integration laboratory where students develop/improve vehicle subsystems and integrate them into a vehicle (Prospector-2 - P-2 - for the 2001-02 academic year - AY). This component has three main objectives: (1) Develop hands- on skills for incoming students and expose them to aerospace hardware; (2) allow for upper division students who have been involved in the program to mentor incoming students and manage small teams; and (3) provide students from various disciplines within the College of Engineering - and other universities - with the chance to develop/improve subsystems on the vehicle. Among recent student projects conducted as part of this component are: a new 1000 lbf thrust engine using pintle injector technology, which was successfully tested on Dec. 1, 2001 and flown on Prospector-2 in Feb. 2002 (developed by CSULB Mechanical and Aerospace Engineering students); a digital flight telemetry package (developed by CSULB Electrical Engineering students); a new recovery system where a mechanical system replaces pyrotechnics for parachute release (developed by CSULB Mechanical and Aerospace Engineering students); and a 1-ft payload bay to accommodate experimental payloads (e.g. "CANSATS" developed by Stanford University students). The second component of CALVEIN is a formal Aerospace System Design curriculum. In the first-semester, from top-level system requirements, the students perform functional analysis, define the various subsystems and derive their requirements. These are presented at the Systems Functional and Requirement Reviews (SFR &SRR). The methods used for validation and verification are determined. Specifications and Interface Control Documents (ICD) are generated by the student team(s). Trade studies are identified and conducted, leading to a Preliminary Design Review (PDR) at the end of the first semester. A detailed design follows, culminating in a Critical Design Review (CDR), etc. A general process suitable for a two-semester course sequence will be outlined. The project is conducted in an Integrated Product Team (IPT) environment, which includes a project manager, a systems engineer, and the various disciplines needed for the project (propulsion, aerodynamics, structures and materials, mass, CAD, thermal, fluids, etc.). Each student works with a Faculty member or industry advisor who is a specialist in his/her area. This design curriculum enhances the education of the graduates and provides future employers with engineers cognizant of and experienced in the application of Systems Engineering to a full-scale project over the entire product development cycle. For the AY01-02, the curriculum is being applied to the development of a gimbaled aerospike engine and its integration into P-3, scheduled to fly in May 2002. The paper ends with a summary of "lessons learned" from this experience. Budget issues are also addressed to demonstrate the ability to replicate such projects at other institutions with minimal costs, provided that it can be taken advantages of possible synergies between existing programs, in-house resources, and cooperation with other institutions or organizations.

NASA Tech Briefs, July 2000. Volume 24, No. 7

NASA Technical Reports Server (NTRS)

2000-01-01

Topics covered include: Data Acquisition; Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Test and Measurement; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports.

NASA's Advanced Environmental Barrier Coatings Development for SiC/SiC Ceramic Matrix Composites: Understanding Calcium Magnesium Alumino-Silicate (CMAS) Degradations and Resistance

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2014-01-01

Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is essential to the viability and reliability of the envisioned CMC engine component applications, ensuring integrated EBC-CMC system durability and designs are achievable for successful applications of the game-changing component technologies and lifing methodologies.This paper will emphasize recent NASA environmental barrier coating developments for SiCSiC turbine airfoil components, utilizing advanced coating compositions, state-of-the-art processing methods, and combined mechanical and environment testing and durability evaluations. The coating-CMC degradations in the engine fatigue-creep and operating environments are particularly complex; one of the important coating development aspects is to better understand engine environmental interactions and coating life debits, and we have particularly addressed the effect of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the durability of the environmental barrier coating systems, and how the temperature capability, stability and cyclic life of the candidate rare earth oxide and silicate coating systems will be impacted in the presence of the CMAS at high temperatures and under simulated heat flux conditions. Advanced environmental barrier coating systems, including HfO2-Si with rare earth dopant based bond coat systems, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

Elevated temperature crack growth

NASA Technical Reports Server (NTRS)

Malik, S. N.; Vanstone, R. H.; Kim, K. S.; Laflen, J. H.

1987-01-01

The objective of the Elevated Temperature Crack Growth Program is to evaluate proposed nonlinear fracture mechanics methods for application to hot section components of aircraft gas turbine engines. Progress during the past year included linear-elastic fracture mechanics data reduction on nonlinear crack growth rate data on Alloy 718. The bulk of the analytical work centered on thermal gradient problems and proposed fracture mechanics parameters. Good correlation of thermal gradient experimental displacement data and finite element prediction was obtained.

CCARES: A computer algorithm for the reliability analysis of laminated CMC components

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.; Gyekenyesi, John P.

1993-01-01

Structural components produced from laminated CMC (ceramic matrix composite) materials are being considered for a broad range of aerospace applications that include various structural components for the national aerospace plane, the space shuttle main engine, and advanced gas turbines. Specifically, these applications include segmented engine liners, small missile engine turbine rotors, and exhaust nozzles. Use of these materials allows for improvements in fuel efficiency due to increased engine temperatures and pressures, which in turn generate more power and thrust. Furthermore, this class of materials offers significant potential for raising the thrust-to-weight ratio of gas turbine engines by tailoring directions of high specific reliability. The emerging composite systems, particularly those with silicon nitride or silicon carbide matrix, can compete with metals in many demanding applications. Laminated CMC prototypes have already demonstrated functional capabilities at temperatures approaching 1400 C, which is well beyond the operational limits of most metallic materials. Laminated CMC material systems have several mechanical characteristics which must be carefully considered in the design process. Test bed software programs are needed that incorporate stochastic design concepts that are user friendly, computationally efficient, and have flexible architectures that readily incorporate changes in design philosophy. The CCARES (Composite Ceramics Analysis and Reliability Evaluation of Structures) program is representative of an effort to fill this need. CCARES is a public domain computer algorithm, coupled to a general purpose finite element program, which predicts the fast fracture reliability of a structural component under multiaxial loading conditions.

Phase-exchange thermoacoustic engine

NASA Astrophysics Data System (ADS)

Offner, Avshalom; Meir, Avishai; Ramon, Guy Z.; WET Lab Team

2017-11-01

Phase-exchange thermoacoustic engines are reliable machines holding great promise in converting heat from low grade heat sources to mechanical or electrical power. In these engines the working fluid is a gas mixture containing one condensable component, decreasing the temperature difference required for ignition and steady state operation. Our experimental setup consists of a vertical acoustic resonator containing a mixture of air-water vapor. Water evaporates near the heat source, condenses at the heat sink and is drawn back down by gravity and capillary forces where it re-evaporates, sustaining a steady state closed thermodynamic cycle. We investigated the stability limit, namely the critical point at which temperature difference in the engine enables onset of self-excited oscillations, and the steady state of the engine. A simple theoretical model was derived, describing mechanisms of irreversible entropy generation and production of acoustic power in such engines. This model captures the essence in the differences between regular and phase-exchange thermoacoustic engines, and shows good agreement with experimental results of stability limit. Steady state results reveal not only a dramatic decrease in temperature difference, but also an increase in engine performances. The authors acknowledge the support from the Nancy and Stephen Grand Technion Energy Program (GTEP).

Quiet Clean Short-haul Experimental Engine (QCSEE). Composite fan frame subsystem test report

NASA Technical Reports Server (NTRS)

Stotler, C. L., Jr.; Bowden, J. H.

1977-01-01

The element and subcomponent testing conducted to verify the composite fan frame design of two experimental high bypass geared turbofan engines and propulsion systems for short haul passenger aircraft is described. Emphasis is placed on the propulsion technology required for future externally blown flap aircraft with engines located both under the wing and over the wing, including technology in composite structures and digital engine controls. The element tests confirmed that the processes used in the frame design would produce the predicted mechanical properties. The subcomponent tests verified that the detail structural components of the frame had adequate structural integrity.

Blade loss transient dynamics analysis, volume 1. Task 1: Survey and perspective. [aircraft gas turbine engines

NASA Technical Reports Server (NTRS)

Gallardo, V. C.; Gaffney, E. F.; Bach, L. J.; Stallone, M. J.

1981-01-01

An analytical technique was developed to predict the behavior of a rotor system subjected to sudden unbalance. The technique is implemented in the Turbine Engine Transient Rotor Analysis (TETRA) computer program using the component element method. The analysis was particularly aimed toward blade-loss phenomena in gas turbine engines. A dual-rotor, casing, and pylon structure can be modeled by the computer program. Blade tip rubs, Coriolis forces, and mechanical clearances are included. The analytical system was verified by modeling and simulating actual test conditions for a rig test as well as a full-engine, blade-release demonstration.

Combined Thermomechanical and Environmental Durability of Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

2016-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in next generation turbine engines for hot-section component applications. The development of prime-reliant environmental barrier coatings is essential to the EBC-CMC system durability, ensuring the successful implementations of the high temperature and lightweight engine component technologies for engine applications.This paper will emphasize recent NASA environmental barrier coating and CMC developments for SiC/SiC turbine airfoil components, utilizing advanced coating compositions and processing methods. The emphasis has been particularly placed on thermomechanical and environment durability evaluations of EBC-CMC systems. We have also addressed the integration of the EBCs with advanced SiC/SiC CMCs, and studied the effects of combustion environments and Calcium-Magnesium-Alumino-Silicate (CMAS) deposits on the durability of the EBC-CMC systems under thermal gradient and mechanical loading conditions. Advanced environmental barrier coating systems, including multicomponent rare earth silicate EBCs and HfO2-Si based bond coats, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

Robotic Scaffolds for Tissue Engineering and Organ Growth

NASA Technical Reports Server (NTRS)

Stoica, Adrian

2011-01-01

The aim of tissue engineering (TE) is to restore tissue and organ functions with minimal host rejection. TE is seen as a future solution to solve the crisis of donor organs for transplant, which faces a shortage expected only to increase in the future. In this innovation, a flexible and configurable scaffold has been conceived that mechanically stresses cells that are seeded on it, stimulating them to increased growth. The influence of mechanical stress/ loading on cell growth has been observed on all forms of cells. For example, for cartilages, studies in animals, tissue explants, and engineered tissue scaffolds have all shown that cartilage cells (chondrocytes) modify their extracellular matrix in response to loading. The chondrocyte EMC production response to dynamics of the physical environment (in vivo cartilage development) illustrates a clear benefit (better growth) when stressed. It has been shown that static and dynamic compression regulates PRG4 biosynthesis by cartilage explants. Mechanical tissue stimulation is beneficial and (flexible) scaffolds with movable components, which are able to induce mechanical stimulation, offer advantages over the fixed, rigid scaffold design. In addition to improved cell growth from physical/mechanical stimulation, additional benefits include the ability to increase in size while preserving shape, or changing shape. By making scaffolds flexible, allowing relative movement between their components, adding sensing (e.g., for detecting response of cells to drug release and to mechanical actions), building controls for drug release and movement, and building even simple algorithms for mapping sensing to action, these structures can actually be made into biocompatible and biodegradable robots. Treating them as robots is a perspective shift that may offer advantages in the design and exploitation of these structures of the future.

Using Digital Image Correlation to Characterize Local Strains on Vascular Tissue Specimens.

PubMed

Zhou, Boran; Ravindran, Suraj; Ferdous, Jahid; Kidane, Addis; Sutton, Michael A; Shazly, Tarek

2016-01-24

Characterization of the mechanical behavior of biological and engineered soft tissues is a central component of fundamental biomedical research and product development. Stress-strain relationships are typically obtained from mechanical testing data to enable comparative assessment among samples and in some cases identification of constitutive mechanical properties. However, errors may be introduced through the use of average strain measures, as significant heterogeneity in the strain field may result from geometrical non-uniformity of the sample and stress concentrations induced by mounting/gripping of soft tissues within the test system. When strain field heterogeneity is significant, accurate assessment of the sample mechanical response requires measurement of local strains. This study demonstrates a novel biomechanical testing protocol for calculating local surface strains using a mechanical testing device coupled with a high resolution camera and a digital image correlation technique. A series of sample surface images are acquired and then analyzed to quantify the local surface strain of a vascular tissue specimen subjected to ramped uniaxial loading. This approach can improve accuracy in experimental vascular biomechanics and has potential for broader use among other native soft tissues, engineered soft tissues, and soft hydrogel/polymeric materials. In the video, we demonstrate how to set up the system components and perform a complete experiment on native vascular tissue.

Fabrication and Assembly of High-Precision Hinge and Latch Joints for Deployable Optical Instruments

NASA Technical Reports Server (NTRS)

Phelps, James E.

1999-01-01

Descriptions are presented of high-precision hinge and latch joints that have been co-developed, for application to deployable optical instruments, by NASA Langley Research Center and Nyma/ADF. Page-sized versions of engineering drawings are included in two appendices to describe all mechanical components of both joints. Procedures for assembling the mechanical components of both joints are also presented. The information herein is intended to facilitate the fabrication and assembly of the high-precision hinge and latch joints, and enable the incorporation of these joints into the design of deployable optical instrument systems.

Investigation of Mechanical, Microstructural and Corrosion behaviour of Titanium subjected to Laser Peening with and without Ablation

NASA Astrophysics Data System (ADS)

Ranjith Kumar, G.; Sowmya Joshi, K.; Rajyalakshmi, G.; Kalainathan, S.; Prabhakaran, S.

2018-02-01

Present competitive world is looking for Components with high strength and fatigue resistance finding their applications in aerospace, turbine parts and especially bio-medical devices with high bio-compatibility. Advanced surface engineering techniques are required to produce parts of higher complexities and desirable surface qualities. Laser peening stood first in a row of all various surface treatments of metallic component. This paper discusses about the mechanical properties like hardness and roughness then the surface morphology and the corrosion behaviour of the laser peened titanium samples with and without coating.

Proceedings of the Annual Mechanics of Composites Review (6th),

DTIC Science & Technology

1981-02-01

containing and resisting damage in compression-loaded composite structural components. 176( CONTRACTS INCREMENTAL ANALYSIS OF IMPACT DAMAGE NASI -15888 79...EVALUATION OF THE DURABILITY AND DAMAGE TOLERANCE OF CTOL COMPOS- ITE STRUCTURES NASI -15107 77 October 12 - 80 October 11 Project Engineer: Edward P...DEVELOPMENT OF AN ORTHOTROPIC HOLE ELEMENT NASI -15890 79 July 9 - 80 September 24 Project Engineer: Dr. John H. Crews, Jr. Mail Stop 18BE NASA Langley

Ferrographic and spectrometer oil analysis from a failed gas turbine engine

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.

1983-01-01

An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. It was concluded that a severe surge may have caused interference between rotating and stationary compressor parts that either directly or indirectly ignited the titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph, and with plasma, atomic absorption, and emission spectrometers to see if this information would aid in the engine failure diagnosis. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism nor a high level of wear debris was detected in the engine oil sample taken just prior to the test in which the failure occurred. However, low concentrations (0.2 to 0.5 ppm) of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations (2 ppm) were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure. The oil analyses eliminated a lubrication system bearing or shaft seal failure as the cause of the engine failure. Previously announced in STAR as N83-12433

Fabrication and Mechanical Characterization of Hydrogel Infused Network Silk Scaffolds

PubMed Central

Kundanati, Lakshminath; Singh, Saket K.; Mandal, Biman B.; Murthy, Tejas G.; Gundiah, Namrata; Pugno, Nicola M.

2016-01-01

Development and characterization of porous scaffolds for tissue engineering and regenerative medicine is of great importance. In recent times, silk scaffolds were developed and successfully tested in tissue engineering and drug release applications. We developed a novel composite scaffold by mechanical infusion of silk hydrogel matrix into a highly porous network silk scaffold. The mechanical behaviour of these scaffolds was thoroughly examined for their possible use in load bearing applications. Firstly, unconfined compression experiments show that the denser composite scaffolds displayed significant enhancement in the elastic modulus as compared to either of the components. This effect was examined and further explained with the help of foam mechanics principles. Secondly, results from confined compression experiments that resemble loading of cartilage in confinement, showed nonlinear material responses for all scaffolds. Finally, the confined creep experiments were performed to calculate the hydraulic permeability of the scaffolds using soil mechanics principles. Our results show that composite scaffolds with some modifications can be a potential candidate for use of cartilage like applications. We hope such approaches help in developing novel scaffolds for tissue engineering by providing an understanding of the mechanics and can further be used to develop graded scaffolds by targeted infusion in specific regions. PMID:27681725

Present State of the Art of Composite Fabric Forming: Geometrical and Mechanical Approaches

PubMed Central

Cherouat, Abel; Borouchaki, Houman

2009-01-01

Continuous fibre reinforced composites are now firmly established engineering materials for the manufacture of components in the automotive and aerospace industries. In this respect, composite fabrics provide flexibility in the design manufacture. The ability to define the ply shapes and material orientation has allowed engineers to optimize the composite properties of the parts. The formulation of new numerical models for the simulation of the composite forming processes must allow for reduction in the delay in manufacturing and an optimization of costs in an integrated design approach. We propose two approaches to simulate the deformation of woven fabrics: geometrical and mechanical approaches.

SSME fault monitoring and diagnosis expert system

NASA Technical Reports Server (NTRS)

Ali, Moonis; Norman, Arnold M.; Gupta, U. K.

1989-01-01

An expert system, called LEADER, has been designed and implemented for automatic learning, detection, identification, verification, and correction of anomalous propulsion system operations in real time. LEADER employs a set of sensors to monitor engine component performance and to detect, identify, and validate abnormalities with respect to varying engine dynamics and behavior. Two diagnostic approaches are adopted in the architecture of LEADER. In the first approach fault diagnosis is performed through learning and identifying engine behavior patterns. LEADER, utilizing this approach, generates few hypotheses about the possible abnormalities. These hypotheses are then validated based on the SSME design and functional knowledge. The second approach directs the processing of engine sensory data and performs reasoning based on the SSME design, functional knowledge, and the deep-level knowledge, i.e., the first principles (physics and mechanics) of SSME subsystems and components. This paper describes LEADER's architecture which integrates a design based reasoning approach with neural network-based fault pattern matching techniques. The fault diagnosis results obtained through the analyses of SSME ground test data are presented and discussed.

Low-Thermal-Conductivity Pyrochlore Oxide Materials Developed for Advanced Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Zhu, Dong-Ming

2005-01-01

When turbine engines operate at higher temperatures, they consume less fuel, have higher efficiencies, and have lower emissions. The upper-use temperatures of the base materials (superalloys, silicon-based ceramics, etc.) used for the hot-section components of turbine engines are limited by the physical, mechanical, and corrosion characteristics of these materials. Thermal barrier coatings (TBCs) are applied as thin layers on the surfaces of these materials to further increase the operating temperatures. The current state-of-the-art TBC material in commercial use is partially yttria-stabilized zirconia (YSZ), which is applied on engine components by plasma spraying or by electron-beam physical vapor deposition. At temperatures higher than 1000 C, YSZ layers are prone to sintering, which increases thermal conductivity and makes them less effective. The sintered and densified coatings can also reduce thermal stress and strain tolerance, which can reduce the coating s durability significantly. Alternate TBC materials with lower thermal conductivity and better sintering resistance are needed to further increase the operating temperature of turbine engines.

A Robust Method to Generate Mechanically Anisotropic Vascular Smooth Muscle Cell Sheets for Vascular Tissue Engineering.

PubMed

Backman, Daniel E; LeSavage, Bauer L; Shah, Shivem B; Wong, Joyce Y

2017-06-01

In arterial tissue engineering, mimicking native structure and mechanical properties is essential because compliance mismatch can lead to graft failure and further disease. With bottom-up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve the necessary macroscale properties in the final implant. This study develops a thermoresponsive cell culture platform for growing aligned vascular smooth muscle cell (VSMC) sheets by photografting N-isopropylacrylamide (NIPAAm) onto micropatterned poly(dimethysiloxane) (PDMS). The grafting process is experimentally and computationally optimized to produce PNIPAAm-PDMS substrates optimal for VSMC attachment. To allow long-term VSMC sheet culture and increase the rate of VSMC sheet formation, PNIPAAm-PDMS surfaces were further modified with 3-aminopropyltriethoxysilane yielding a robust, thermoresponsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermoresponsive substrates exhibit cellular and collagen alignment in the direction of the micropattern. Mechanical characterization of patterned, single-layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas nonpatterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single-layer VSMC sheets makes this platform an attractive microstructural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Artificial Symmetry-Breaking for Morphogenetic Engineering Bacterial Colonies.

PubMed

Nuñez, Isaac N; Matute, Tamara F; Del Valle, Ilenne D; Kan, Anton; Choksi, Atri; Endy, Drew; Haseloff, Jim; Rudge, Timothy J; Federici, Fernan

2017-02-17

Morphogenetic engineering is an emerging field that explores the design and implementation of self-organized patterns, morphologies, and architectures in systems composed of multiple agents such as cells and swarm robots. Synthetic biology, on the other hand, aims to develop tools and formalisms that increase reproducibility, tractability, and efficiency in the engineering of biological systems. We seek to apply synthetic biology approaches to the engineering of morphologies in multicellular systems. Here, we describe the engineering of two mechanisms, symmetry-breaking and domain-specific cell regulation, as elementary functions for the prototyping of morphogenetic instructions in bacterial colonies. The former represents an artificial patterning mechanism based on plasmid segregation while the latter plays the role of artificial cell differentiation by spatial colocalization of ubiquitous and segregated components. This separation of patterning from actuation facilitates the design-build-test-improve engineering cycle. We created computational modules for CellModeller representing these basic functions and used it to guide the design process and explore the design space in silico. We applied these tools to encode spatially structured functions such as metabolic complementation, RNAPT7 gene expression, and CRISPRi/Cas9 regulation. Finally, as a proof of concept, we used CRISPRi/Cas technology to regulate cell growth by controlling methionine synthesis. These mechanisms start from single cells enabling the study of morphogenetic principles and the engineering of novel population scale structures from the bottom up.

Contact mechanics of reverse engineered distal humeral hemiarthroplasty implants.

PubMed

Willing, Ryan; King, Graham J W; Johnson, James A

2015-11-26

Erosion of articular cartilage is a concern following distal humeral hemiarthroplasty, because native cartilage surfaces are placed in contact with stiff metallic implant components, which causes decreases in contact area and increases in contact stresses. Recently, reverse engineered implants have been proposed which are intended to promote more natural contact mechanics by reproducing the native bone or cartilage shape. In this study, finite element modeling is used in order to calculate changes in cartilage contact areas and stresses following distal humeral hemiarthroplasty with commercially available and reverse engineered implant designs. At the ulna, decreases in contact area were -34±3% (p=0.002), -27±1% (p<0.001) and -14±2% (p=0.008) using commercially available, bone reverse engineered and cartilage reverse engineered designs, respectively. Peak contact stresses increased by 461±57% (p=0.008), 387±127% (p=0.229) and 165±16% (p=0.003). At the radius, decreases in contact area were -21±3% (p=0.013), -13±2% (p<0.006) and -6±1% (p=0.020), and peak contact stresses increased by 75±52% (p>0.999), 241±32% (p=0.010) and 61±10% (p=0.021). Between the three different implant designs, the cartilage reverse engineered design yielded the largest contact areas and lowest contact stresses, but was still unable to reproduce the contact mechanics of the native joint. These findings align with a growing body of evidence indicating that although reverse engineered hemiarthroplasty implants can provide small improvements in contact mechanics when compared with commercially available designs, further optimization of shape and material properties is required in order reproduce native joint contact mechanics. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hot isostatically pressed manufacture of high strength MERL 76 disk and seal shapes

NASA Technical Reports Server (NTRS)

Eng, R. D.; Evans, D. J.

1982-01-01

The feasibility of using MERL 76, an advanced high strength direct hot isostatic pressed powder metallurgy superalloy, as a full scale component in a high technology, long life, commercial turbine engine were demonstrated. The component was a JT9D first stage turbine disk. The JT9D disk rim temperature capability was increased by at least 22 C and the weight of JT9D high pressure turbine rotating components was reduced by at least 35 pounds by replacement of forged Superwaspaloy components with hot isostatic pressed (HIP) MERL 76 components. The process control plan and acceptance criteria for manufacture of MERL 76 HIP consolidated components were generated. Disk components were manufactured for spin/burst rig test, experimental engine tests, and design data generation, which established lower design properties including tensile, stress-rupture, 0.2% creep and notched (Kt = 2.5) low cycle fatigue properties, Sonntag, fatigue crack propagation, and low cycle fatigue crack threshold data. Direct HIP MERL 76, when compared to conventionally forged Superwaspaloy, is demonstrated to be superior in mechanical properties, increased rim temperature capability, reduced component weight, and reduced material cost by at least 30% based on 1980 costs.

Interactive simulations as teaching tools for engineering mechanics courses

NASA Astrophysics Data System (ADS)

Carbonell, Victoria; Romero, Carlos; Martínez, Elvira; Flórez, Mercedes

2013-07-01

This study aimed to gauge the effect of interactive simulations in class as an active teaching strategy for a mechanics course. Engineering analysis and design often use the properties of planar sections in calculations. In the stress analysis of a beam under bending and torsional loads, cross-sectional properties are used to determine stress and displacement distributions in the beam cross section. The centroid, moments and products of inertia of an area made up of several common shapes (rectangles usually) may thus be obtained by adding the moments of inertia of the component areas (U-shape, L-shape, C-shape, etc). This procedure is used to calculate the second moments of structural shapes in engineering practice because the determination of their moments of inertia is necessary for the design of structural components. This paper presents examples of interactive simulations developed for teaching the ‘Mechanics and mechanisms’ course at the Universidad Politecnica de Madrid, Spain. The simulations focus on fundamental topics such as centroids, the properties of the moment of inertia, second moments of inertia with respect to two axes, principal moments of inertia and Mohr's Circle for plane stress, and were composed using Geogebra software. These learning tools feature animations, graphics and interactivity and were designed to encourage student participation and engagement in active learning activities, to effectively explain and illustrate course topics, and to build student problem-solving skills.

Experimental Observations for Determining the Maximum Torque Values to Apply to Composite Components Mechanically Joined With Fasteners (MSFC Center Director's Discretionary Fund Final Report, Proj. 03-13}

NASA Technical Reports Server (NTRS)

Thomas, F. P.

2006-01-01

Aerospace structures utilize innovative, lightweight composite materials for exploration activities. These structural components, due to various reasons including size limitations, manufacturing facilities, contractual obligations, or particular design requirements, will have to be joined. The common methodologies for joining composite components are the adhesively bonded and mechanically fastened joints and, in certain instances, both methods are simultaneously incorporated into the design. Guidelines and recommendations exist for engineers to develop design criteria and analyze and test composites. However, there are no guidelines or recommendations based on analysis or test data to specify a torque or torque range to apply to metallic mechanical fasteners used to join composite components. Utilizing the torque tension machine at NASA s Marshall Space Flight Center, an initial series of tests were conducted to determine the maximum torque that could be applied to a composite specimen. Acoustic emissions were used to nondestructively assess the specimens during the tests and thermographic imaging after the tests.

Coarse pointing mechanism assembly for satellite interlink experiment

NASA Technical Reports Server (NTRS)

Maeusli, P. A.; Ivorra, M. T.; Gass, V.; Berthoud, J. F.

1996-01-01

Since 1975, MECANEX S.A. has been manufacturing components for solar array drives and mechanisms used in space applications. In 1991, work was started in an early phase C (Engineering Model) on a Coarse Pointing Mechanism Assembly (CPMA) for the Semiconductor-laser Inter-satellite Link EXperiment (SILEX). This paper deals with the history, the evolution, and the lessons learned from taking over a pre-design in 1991 to the delivery of last flight models (FM 5 & 6) in 1995.

Applications of Ni3Al Based Intermetallic Alloys—Current Stage and Potential Perceptivities

PubMed Central

Jozwik, Pawel; Polkowski, Wojciech; Bojar, Zbigniew

2015-01-01

The paper presents an overview of current and prospective applications of Ni3Al based intermetallic alloys—modern engineering materials with special properties that are potentially useful for both structural and functional purposes. The bulk components manufactured from these materials are intended mainly for forging dies, furnace assembly, turbocharger components, valves, and piston head of internal combustion engines. The Ni3Al based alloys produced by a directional solidification are also considered as a material for the fabrication of jet engine turbine blades. Moreover, development of composite materials with Ni3Al based alloys as a matrix hardened by, e.g., TiC, ZrO2, WC, SiC and graphene, is also reported. Due to special physical and chemical properties; it is expected that these materials in the form of thin foils and strips should make a significant contribution to the production of high tech devices, e.g., Micro Electro-Mechanical Systems (MEMS) or Microtechnology-based Energy and Chemical Systems (MECS); as well as heat exchangers; microreactors; micro-actuators; components of combustion chambers and gasket of rocket and jet engines as well components of high specific strength systems. Additionally, their catalytic properties may find an application in catalytic converters, air purification systems from chemical and biological toxic agents or in a hydrogen “production” by a decomposition of hydrocarbons.

USSR Report, Engineering and Equipment

DTIC Science & Technology

1984-04-17

MEKHANIKA ZHIDKOSTI I GAZA, No 5, May 83). 17 Wave Drag of Elongated Astroid Bodies at Moderate Supersonic Flight Velocities (M, I. Follej...mechanical components of such a test stand include an electric drive motor with speed regulation, a Belt transmission, a worm gear for speed

Generalized simulation technique for turbojet engine system analysis

NASA Technical Reports Server (NTRS)

Seldner, K.; Mihaloew, J. R.; Blaha, R. J.

1972-01-01

A nonlinear analog simulation of a turbojet engine was developed. The purpose of the study was to establish simulation techniques applicable to propulsion system dynamics and controls research. A schematic model was derived from a physical description of a J85-13 turbojet engine. Basic conservation equations were applied to each component along with their individual performance characteristics to derive a mathematical representation. The simulation was mechanized on an analog computer. The simulation was verified in both steady-state and dynamic modes by comparing analytical results with experimental data obtained from tests performed at the Lewis Research Center with a J85-13 engine. In addition, comparison was also made with performance data obtained from the engine manufacturer. The comparisons established the validity of the simulation technique.

Application of superalloy powder metallurgy for aircraft engines

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.; Miner, R. V., Jr.

1980-01-01

In the last decade, Government/Industry programs have advanced powder metallurgy-near-net-shape technology to permit the use of hot isostatic pressed (HIP) turbine disks in the commercial aircraft fleet. These disks offer a 30% savings of input weight and an 8% savings in cost compared in cast-and-wrought disks. Similar savings were demonstrated for other rotating engine components. A compressor rotor fabricated from hot-die-forged-HIP superalloy billets revealed input weight savings of 54% and cost savings of 35% compared to cast-and-wrought parts. Engine components can be produced from compositions such as Rene 95 and Astroloy by conventional casting and forging, by forging of HIP powder billets, or by direct consolidation of powder by HIP. However, each process produces differences in microstructure or introduces different defects in the parts. As a result, their mechanical properties are not necessarily identical. Acceptance methods should be developed which recognize and account for the differences.

Hair Follicle-Derived Smooth Muscle Cells and Small Intestinal Submucosa for Engineering Mechanically Robust and Vasoreactive Vascular Media

PubMed Central

Peng, Hao-Fan; Liu, Jin Yu

2011-01-01

Our laboratory recently reported a new source of smooth muscle cells (SMCs) derived from hair follicle (HF) mesenchymal stem cells. HF-SMCs demonstrated high proliferation and clonogenic potential as well as contractile function. In this study, we aimed at engineering the vascular media using HF-SMCs and a natural biomaterial, namely small intestinal submucosa (SIS). Engineering functional vascular constructs required application of mechanical force, resulting in actin reorganization and cellular alignment. In turn, cell alignment was necessary for development of receptor- and nonreceptor-mediated contractility as soon as 24 h after cell seeding. Within 2 weeks in culture, the cells migrated into SIS and secreted collagen and elastin, the two major extracellular matrix components of the vessel wall. At 2 weeks, vascular reactivity increased significantly up to three- to fivefold and mechanical properties were similar to those of native ovine arteries. Taken together, our data demonstrate that the combination of HF-SMCs with SIS resulted in mechanically strong, biologically functional vascular media with potential for arterial implantation. PMID:21083418

Failure mode analysis to predict product reliability.

NASA Technical Reports Server (NTRS)

Zemanick, P. P.

1972-01-01

The failure mode analysis (FMA) is described as a design tool to predict and improve product reliability. The objectives of the failure mode analysis are presented as they influence component design, configuration selection, the product test program, the quality assurance plan, and engineering analysis priorities. The detailed mechanics of performing a failure mode analysis are discussed, including one suggested format. Some practical difficulties of implementation are indicated, drawn from experience with preparing FMAs on the nuclear rocket engine program.

Biomaterials for Tissue Engineering

PubMed Central

Lee, Esther J.; Kasper, F. Kurtis; Mikos, Antonios G.

2013-01-01

Biomaterials serve as an integral component of tissue engineering. They are designed to provide architectural framework reminiscent of native extracellular matrix in order to encourage cell growth and eventual tissue regeneration. Bone and cartilage represent two distinct tissues with varying compositional and mechanical properties. Despite these differences, both meet at the osteochondral interface. This article presents an overview of current biomaterials employed in bone and cartilage applications, discusses some design considerations, and alludes to future prospects within this field of research. PMID:23820768

Comparison of Performance and Component Frontal Areas of Hypothetical Two-spool and One-spool Turbojet Engines

NASA Technical Reports Server (NTRS)

Dugan, James F , Jr

1956-01-01

For constant-mechanical-speed operation, the two-spool thrust values are as great as or greater than the one-spool thrust values over the entire flight range considered, while the specific fuel consumption for the two engines agrees within 1 percent. The maximum difference in thrust occurs at Mach 2.8 in the stratosphere, where the two-spool thrust advantage is about 9 percent for operation with the after burning.

Analysis of Performance of Jet Engine from Characteristics of Components II : Interaction of Components as Determined from Engine Operation

NASA Technical Reports Server (NTRS)

Goldstein, Arthur W; Alpert, Sumner; Beede, William; Kovach, Karl

1949-01-01

In order to understand the operation and the interaction of jet-engine components during engine operation and to determine how component characteristics may be used to compute engine performance, a method to analyze and to estimate performance of such engines was devised and applied to the study of the characteristics of a research turbojet engine built for this investigation. An attempt was made to correlate turbine performance obtained from engine experiments with that obtained by the simpler procedure of separately calibrating the turbine with cold air as a driving fluid in order to investigate the applicability of component calibration. The system of analysis was also applied to prediction of the engine and component performance with assumed modifications of the burner and bearing characteristics, to prediction of component and engine operation during engine acceleration, and to estimates of the performance of the engine and the components when the exhaust gas was used to drive a power turbine.

Tissue Engineering Strategies for Myocardial Regeneration: Acellular Versus Cellular Scaffolds?

PubMed

Domenech, Maribella; Polo-Corrales, Lilliana; Ramirez-Vick, Jaime E; Freytes, Donald O

2016-12-01

Heart disease remains one of the leading causes of death in industrialized nations with myocardial infarction (MI) contributing to at least one fifth of the reported deaths. The hypoxic environment eventually leads to cellular death and scar tissue formation. The scar tissue that forms is not mechanically functional and often leads to myocardial remodeling and eventual heart failure. Tissue engineering and regenerative medicine principles provide an alternative approach to restoring myocardial function by designing constructs that will restore the mechanical function of the heart. In this review, we will describe the cellular events that take place after an MI and describe current treatments. We will also describe how biomaterials, alone or in combination with a cellular component, have been used to engineer suitable myocardium replacement constructs and how new advanced culture systems will be required to achieve clinical success.

Development of Advanced Environmental Barrier Coatings for SiC/SiC Composites at NASA GRC: Prime-Reliant Design and Durability Perspectives

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2017-01-01

Environmental barrier coatings (EBCs) are considered technologically important because of the critical needs and their ability to effectively protect the turbine hot-section SiC/SiC ceramic matrix composite (CMC) components in harsh engine combustion environments. The development of NASA's advanced environmental barrier coatings have been aimed at significantly improved the coating system temperature capability, stability, erosion-impact, and CMAS resistance for SiC/SiC turbine airfoil and combustors component applications. The NASA environmental barrier coating developments have also emphasized thermo-mechanical creep and fatigue resistance in simulated engine heat flux and environments. Experimental results and models for advanced EBC systems will be presented to help establishing advanced EBC composition design methodologies, performance modeling and life predictions, for achieving prime-reliant, durable environmental coating systems for 2700-3000 F engine component applications. Major technical barriers in developing environmental barrier coating systems and the coating integration with next generation composites having further improved temperature capability, environmental stability, EBC-CMC fatigue-environment system durability will be discussed.

Tissue engineering therapy for cardiovascular disease.

PubMed

Nugent, Helen M; Edelman, Elazer R

2003-05-30

The present treatments for the loss or failure of cardiovascular function include organ transplantation, surgical reconstruction, mechanical or synthetic devices, or the administration of metabolic products. Although routinely used, these treatments are not without constraints and complications. The emerging and interdisciplinary field of tissue engineering has evolved to provide solutions to tissue creation and repair. Tissue engineering applies the principles of engineering, material science, and biology toward the development of biological substitutes that restore, maintain, or improve tissue function. Progress has been made in engineering the various components of the cardiovascular system, including blood vessels, heart valves, and cardiac muscle. Many pivotal studies have been performed in recent years that may support the move toward the widespread application of tissue-engineered therapy for cardiovascular diseases. The studies discussed include endothelial cell seeding of vascular grafts, tissue-engineered vascular conduits, generation of heart valve leaflets, cardiomyoplasty, genetic manipulation, and in vitro conditions for optimizing tissue-engineered cardiovascular constructs.

Stirling Laboratory Research Engine: Preprototype configuration report

NASA Technical Reports Server (NTRS)

Hoehn, F. W.

1982-01-01

The concept of a simple Stirling research engine that could be used by industrial, university, and government laboratories was studied. The conceptual and final designs, hardware fabrication and the experimental validation of a preprototype stirling laboratory research engine (SLRE) were completed. Also completed was a task to identify the potential markets for research engines of this type. An analytical effort was conducted to provide a stirling cycle computer model. The versatile engine is a horizontally opposed, two piston, single acting stirling engine with a split crankshaft drive mechanism; special instrumentation is installed at all component interfaces. Results of a thermodynamic energy balance for the system are reported. Also included are the engine performance results obtained over a range of speeds, working pressures, phase angles and gas temperatures. The potential for a stirling research engine to support the laboratory requirements of educators and researchers was demonstrated.

A Multicomponent Blend as a Diesel Fuel Surrogate for Compression Ignition Engine Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pei, Yuanjiang; Mehl, Marco; Liu, Wei

A mixture of n-dodecane and m-xylene is investigated as a diesel fuel surrogate for compression ignition engine applications. Compared to neat n-dodecane, this binary mixture is more representative of diesel fuel because it contains an alkyl-benzene which represents an important chemical class present in diesel fuels. A detailed multi-component mechanism for n-dodecane and m-xylene was developed by combining a previously developed n-dodecane mechanism with a recently developed mechanism for xylenes. The xylene mechanism is shown to reproduce experimental ignition data from a rapid compression machine and shock tube, speciation data from the jet stirred reactor and flame speed data. Thismore » combined mechanism was validated by comparing predictions from the model with experimental data for ignition in shock tubes and for reactivity in a flow reactor. The combined mechanism, consisting of 2885 species and 11754 reactions, was reduced to a skeletal mechanism consisting 163 species and 887 reactions for 3D diesel engine simulations. The mechanism reduction was performed using directed relation graph (DRG) with expert knowledge (DRG-X) and DRG-aided sensitivity analysis (DRGASA) at a fixed fuel composition of 77% of n-dodecane and 23% m-xylene by volume. The sample space for the reduction covered pressure of 1 – 80 bar, equivalence ratio of 0.5 – 2.0, and initial temperature of 700 – 1600 K for ignition. The skeletal mechanism was compared with the detailed mechanism for ignition and flow reactor predictions. Finally, the skeletal mechanism was validated against a spray flame dataset under diesel engine conditions documented on the Engine Combustion Network (ECN) website. These multi-dimensional simulations were performed using a Representative Interactive Flame (RIF) turbulent combustion model. Encouraging results were obtained compared to the experiments with regards to the predictions of ignition delay and lift-off length at different ambient temperatures.« less

Computer-aided operations engineering with integrated models of systems and operations

NASA Technical Reports Server (NTRS)

Malin, Jane T.; Ryan, Dan; Fleming, Land

1994-01-01

CONFIG 3 is a prototype software tool that supports integrated conceptual design evaluation from early in the product life cycle, by supporting isolated or integrated modeling, simulation, and analysis of the function, structure, behavior, failures and operation of system designs. Integration and reuse of models is supported in an object-oriented environment providing capabilities for graph analysis and discrete event simulation. Integration is supported among diverse modeling approaches (component view, configuration or flow path view, and procedure view) and diverse simulation and analysis approaches. Support is provided for integrated engineering in diverse design domains, including mechanical and electro-mechanical systems, distributed computer systems, and chemical processing and transport systems. CONFIG supports abstracted qualitative and symbolic modeling, for early conceptual design. System models are component structure models with operating modes, with embedded time-related behavior models. CONFIG supports failure modeling and modeling of state or configuration changes that result in dynamic changes in dependencies among components. Operations and procedure models are activity structure models that interact with system models. CONFIG is designed to support evaluation of system operability, diagnosability and fault tolerance, and analysis of the development of system effects of problems over time, including faults, failures, and procedural or environmental difficulties.

Probabilistic analysis for fatigue strength degradation of materials

NASA Technical Reports Server (NTRS)

Royce, Lola

1989-01-01

This report presents the results of the first year of a research program conducted for NASA-LeRC by the University of Texas at San Antonio. The research included development of methodology that provides a probabilistic treatment of lifetime prediction of structural components of aerospace propulsion systems subjected to fatigue. Material strength degradation models, based on primitive variables, include both a fatigue strength reduction model and a fatigue crack growth model. Linear elastic fracture mechanics is utilized in the latter model. Probabilistic analysis is based on simulation, and both maximum entropy and maximum penalized likelihood methods are used for the generation of probability density functions. The resulting constitutive relationships are included in several computer programs, RANDOM2, RANDOM3, and RANDOM4. These programs determine the random lifetime of an engine component, in mechanical load cycles, to reach a critical fatigue strength or crack size. The material considered was a cast nickel base superalloy, one typical of those used in the Space Shuttle Main Engine.

Processing-Related Issues for the Design and Lifing of SiC/SiC Hot-Section Components

NASA Technical Reports Server (NTRS)

DiCarlo, J.; Bhatt, R.; Morscher, G.; Yun, H. M.

2006-01-01

For successful SiC/SiC engine components, numerous process steps related to the fiber, fiber architecture, interphase coating, and matrix need to be optimized. Under recent NASA-sponsored programs, it was determined that many of these steps in their initial approach were inadequate, resulting in less than optimum thermostructural and life properties for the as-fabricated components. This presentation will briefly review many of these process issues, the key composite properties they degrade, their underlying mechanisms, and current process remedies developed by NASA and others.

Modeling the mechanical response of PBX 9501

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ragaswamy, Partha; Lewis, Matthew W; Liu, Cheng

2010-01-01

An engineering overview of the mechanical response of Plastic-Bonded eXplosives (PBXs), specifically PBX 9501, will be provided with emphasis on observed mechanisms associated with different types of mechanical testing. Mechanical tests in the form of uniaxial tension, compression, cyclic loading, creep (compression and tension), and Hopkinson bar show strain rate and temperature dependence. A range of mechanical behavior is observed which includes small strain recoverable response in the form of viscoelasticity; change in stiffness and softening beyond peak strength due to damage in the form microcracks, debonding, void formation and the growth of existing voids; inelastic response in the formmore » of irrecoverable strain as shown in cyclic tests, and viscoelastic creep combined with plastic response as demonstrated in creep and recovery tests. The main focus of this paper is to elucidate the challenges and issues involved in modeling the mechanical behavior of PBXs for simulating thermo-mechanical responses in engineering components. Examples of validation of a constitutive material model based on a few of the observed mechanisms will be demonstrated against three point bending, split Hopkinson pressure bar and Brazilian disk geometry.« less

Shake, Rattle, and Roll: Nonlinear Dynamics in Mechanical Engineering

NASA Astrophysics Data System (ADS)

Shaw, Steven

1997-03-01

This presentation will focus on three mechanical engineering applications in which methods from nonlinear dynamics have been applied with success. Each topic will be briefly surveyed by outlining the development of a mathematical model, providing a description of the analysis tools employed, and showing the main results obtained. The applications are: vibration reduction in internal combustion engines, impact dynamics of mechanical components, and the dynamics of ship capsize. The first topic demonstrates a novel arrangement of dynamic absorbers that can be used for attenuating torsional vibrations in rotating machinery. The operation of this device takes advantage of a purely nonlinear system response that results from a period doubling bifurcation. This configuration is more effective than existing absorbers and it cannot be imagined by using naive extensions of linear vibration theory. The second topic deals with the dynamics of mechanical systems in which components make intermittent contact with each another. Such dynamics are often the source of undesirable noise and wear in machinery and can be extremely complicated. Results obtained from simple predictive models and some application areas will be presented for these impacting systems. The final topic deals with the gross motions of seagoing vessels and their stability against capsize. Existing safety regulations for ship stability are based on purely static measures, whereas capsize is an inherently nonlinear dynamic event. An overview will be given that considers some basic modeling issues, dynamic analysis techniques (based on the concept of chaotic phase-space transport), and the resulting predictive tools that have been developed for this class of problems.

Life Extending Control. [mechanical fatigue in reusable rocket engines

NASA Technical Reports Server (NTRS)

Lorenzo, Carl F.; Merrill, Walter C.

1991-01-01

The concept of Life Extending Control is defined. Life is defined in terms of mechanical fatigue life. A brief description is given of the current approach to life prediction using a local, cyclic, stress-strain approach for a critical system component. An alternative approach to life prediction based on a continuous functional relationship to component performance is proposed. Based on cyclic life prediction, an approach to life extending control, called the Life Management Approach, is proposed. A second approach, also based on cyclic life prediction, called the implicit approach, is presented. Assuming the existence of the alternative functional life prediction approach, two additional concepts for Life Extending Control are presented.

[Construction of automatic elucidation platform for mechanism of traditional Chinese medicine].

PubMed

Zhang, Bai-xia; Luo, Si-jun; Yan, Jing; Gu, Hao; Luo, Ji; Zhang, Yan-ling; Tao, Ou; Wang, Yun

2015-10-01

Aim at the two problems in the field of traditional Chinese medicine (TCM) mechanism elucidation, one is the lack of detailed biological processes information, next is the low efficient in constructing network models, we constructed an auxiliary elucidation system for the TCM mechanism and realize the automatic establishment of biological network model. This study used the Entity Grammar Systems (EGS) as the theoretical framework, integrated the data of formulae, herbs, chemical components, targets of component, biological reactions, signaling pathways and disease related proteins, established the formal models, wrote the reasoning engine, constructed the auxiliary elucidation system for the TCM mechanism elucidation. The platform provides an automatic modeling method for biological network model of TCM mechanism. It would be benefit to perform the in-depth research on TCM theory of natures and combination and provides the scientific references for R&D of TCM.

Digital Image Correlation for Performance Monitoring

NASA Technical Reports Server (NTRS)

Palaviccini, Miguel; Turner, Dan; Herzberg, Michael

2016-01-01

Evaluating the health of a mechanism requires more than just a binary evaluation of whether an operation was completed. It requires analyzing more comprehensive, full-field data. Health monitoring is a process of non-destructively identifying characteristics that indicate the fitness of an engineered component. In order to monitor unit health in a production setting, an automated test system must be created to capture the motion of mechanism parts in a real-time and non-intrusive manner. One way to accomplish this is by using high-speed video and Digital Image Correlation (DIC). In this approach, individual frames of the video are analyzed to track the motion of mechanism components. The derived performance metrics allow for state-of-health monitoring and improved fidelity of mechanism modeling. The results are in-situ state-of-health identification and performance prediction. This paper introduces basic concepts of this test method, and discusses two main themes: the use of laser marking to add fiducial patterns to mechanism components, and new software developed to track objects with complex shapes, even as they move behind obstructions. Finally, the implementation of these tests into an automated tester is discussed.

Delamination Mechanisms of Thermal and Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Choi, Sung R.; Lee, Kang N.; Miller, Robert A.

2003-01-01

Advanced ceramic thermal harrier coatings will play an increasingly important role In future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating durability issue remains a major concern with the ever-increasing temperature requirements. In this paper, thermal cyclic response and delamination failure modes of a ZrO2-8wt%Y2O3 and mullite/BSAS thermaVenvironmenta1 barrier coating system on SiC/SiC ceramic matrix composites were investigated using a laser high-heat-flux technique. The coating degradation and delamination processes were monitored in real time by measuring coating apparent conductivity changes during the cyclic tests under realistic engine temperature and stress gradients, utilizing the fact that delamination cracking causes an apparent decrease in the measured thermal conductivity. The ceramic coating crack initiation and propagation driving forces under the cyclic thermal loads, in conjunction with the mechanical testing results, will be discussed.

Delamination Mechanisms of Thermal and Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Choi, Sung R.; Lee, Kang N.; Miller, Robert A.

1990-01-01

Advanced ceramic thermal barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating durability issue remains a major concern with the ever-increasing temperature requirements. In this paper, thermal cyclic response and delamination failure modes of a ZrO2-8wt%Y2O3 and mullite/BSAS thermal/environmental barrier coating system on SiC/SiC ceramic matrix composites were investigated using a laser high-heat-flux technique. The coating degradation and delamination processes were monitored in real time by measuring coating apparent conductivity changes during the cyclic tests under realistic engine temperature and stress gradients, utilizing the fact that delamination cracking causes an apparent decrease in the measured thermal conductivity. The ceramic coating crack initiation and propagation driving forces under the cyclic thermal loads, in conjunction with the mechanical testing results, will be discussed.

Creep, Fatigue and Fracture Behavior of Environmental Barrier Coating and SiC-SiC Ceramic Matrix Composite Systems: The Role of Environment Effects

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Ghosn, Louis J.

2015-01-01

Advanced environmental barrier coating (EBC) systems for low emission SiCSiC CMC combustors and turbine airfoils have been developed to meet next generation engine emission and performance goals. This presentation will highlight the developments of NASAs current EBC system technologies for SiC-SiC ceramic matrix composite combustors and turbine airfoils, their performance evaluation and modeling progress towards improving the engine SiCSiC component temperature capability and long-term durability. Our emphasis has also been placed on the fundamental aspects of the EBC-CMC creep and fatigue behaviors, and their interactions with turbine engine oxidizing and moisture environments. The EBC-CMC environmental degradation and failure modes, under various simulated engine testing environments, in particular involving high heat flux, high pressure, high velocity combustion conditions, will be discussed aiming at quantifying the protective coating functions, performance and durability, and in conjunction with damage mechanics and fracture mechanics approaches.

Aerospace engineering educational program

NASA Technical Reports Server (NTRS)

Craft, William; Klett, David; Lai, Steven

1992-01-01

The principle goal of the educational component of NASA CORE is the creation of aerospace engineering options in the mechanical engineering program at both the undergraduate and graduate levels. To accomplish this goal, a concerted effort during the past year has resulted in detailed plans for the initiation of aerospace options in both the BSME and MSME programs in the fall of 1993. All proposed new courses and the BSME aerospace option curriculum must undergo a lengthy approval process involving two cirriculum oversight committees (School of Engineering and University level) and three levels of general faculty approval. Assuming approval is obtained from all levels, the options will officially take effect in Fall '93. In anticipation of this, certain courses in the proposed curriculum are being offered during the current academic year under special topics headings so that current junior level students may graduate in May '94 under the BSME aerospace option. The proposed undergraduate aerospace option curriculum (along with the regular mechanical engineering curriculum for reference) is attached at the end of this report, and course outlines for the new courses are included in the appendix.

Effect of Maximum Cruise-power Operation at Ultra-lean Mixture and Increased Spark Advance on the Mechanical Condition of Cylinder Components

NASA Technical Reports Server (NTRS)

Harris, Herbert B.; Duffy, Robert T.; Erwin, Robert D., Jr.

1945-01-01

A continuous 50-hour test was conducted to determine the effect of maximum cruise-power operation at ultra-lean fuel-air mixture and increased spark advance on the mechanical conditions of cylinder components. The test was conducted on a nine-cylinder air-cooled radial engine at the following conditions:brake horsepower, 750; engine speed, 1900 rpm; brake mean effective pressure, 172 pounds per square inch; fuel-air ratio, 0.052; spark advance, 30 deg B.T.C.; and maximum rear-spark-plug-bushing temperature, 400 F. In addition to the data on corrosion and wear, data are presented and briefly discussed on the effect of engine operation at the conditions of this test on economy, knock, preignition, and mixture distribution. Cylinder, piston, and piston-ring wear was small and all cylinder component were in good condition at the conclusion of the 50-hour test except that all exhaust-valve guides were bellmouthed beyond the Army's specified limit and one exhaust-valve face was lightly burned. It is improbable that the light burning in one spot of the valve face would have progressed further because the burn was filled with a hard deposit so that the valve face formed an unbroken seal and the mating seat showed no evidence of burning. The bellmouthing of the exhaust-valve guides is believed to have been a result of the heavy carbon and lead-oxide deposits, which were present on the head end of the guided length of the exhaust-valve stem. Engine operational the conditions of this test was shown to result In a fuel saving of 16.8 percent on a cooled-power basis as compared with operation at the conditions recommended for this engine by the Army Air Forces for the same power.

CONFIG: Integrated engineering of systems and their operation

NASA Technical Reports Server (NTRS)

Malin, Jane T.; Ryan, Dan; Fleming, Land

1994-01-01

This article discusses CONFIG 3, a prototype software tool that supports integrated conceptual design evaluation from early in the product life cycle, by supporting isolated or integrated modeling, simulation, and analysis of the function, structure, behavior, failures and operations of system designs. Integration and reuse of models is supported in an object-oriented environment providing capabilities for graph analysis and discrete event simulation. CONFIG supports integration among diverse modeling approaches (component view, configuration or flow path view, and procedure view) and diverse simulation and analysis approaches. CONFIG is designed to support integrated engineering in diverse design domains, including mechanical and electro-mechanical systems, distributed computer systems, and chemical processing and transport systems.

Reverse engineering of wörner type drilling machine structure.

NASA Astrophysics Data System (ADS)

Wibowo, A.; Belly, I.; llhamsyah, R.; Indrawanto; Yuwana, Y.

2018-03-01

A product design needs to be modified based on the conditions of production facilities and existing resource capabilities without reducing the functional aspects of the product itself. This paper describes the reverse engineering process of the main structure of the wörner type drilling machine to obtain a machine structure design that can be made by resources with limited ability by using simple processes. Some structural, functional and the work mechanism analyzes have been performed to understand the function and role of each basic components. The process of dismantling of the drilling machine and measuring each of the basic components was performed to obtain sets of the geometry and size data of each component. The geometric model of each structure components and the machine assembly were built to facilitate the simulation process and machine performance analysis that refers to ISO standard of drilling machine. The tolerance stackup analysis also performed to determine the type and value of geometrical and dimensional tolerances, which could affect the ease of the components to be manufactured and assembled

A real time neural net estimator of fatigue life

NASA Technical Reports Server (NTRS)

Troudet, T.; Merrill, W.

1990-01-01

A neural network architecture is proposed to estimate, in real-time, the fatigue life of mechanical components, as part of the intelligent Control System for Reusable Rocket Engines. Arbitrary component loading values were used as input to train a two hidden-layer feedforward neural net to estimate component fatigue damage. The ability of the net to learn, based on a local strain approach, the mapping between load sequence and fatigue damage has been demonstrated for a uniaxial specimen. Because of its demonstrated performance, the neural computation may be extended to complex cases where the loads are biaxial or triaxial, and the geometry of the component is complex (e.g., turbopumps blades). The generality of the approach is such that load/damage mappings can be directly extracted from experimental data without requiring any knowledge of the stress/strain profile of the component. In addition, the parallel network architecture allows real-time life calculations even for high-frequency vibrations. Owing to its distributed nature, the neural implementation will be robust and reliable, enabling its use in hostile environments such as rocket engines.

Optimized and Automated design of Plasma Diagnostics for Additive Manufacture

NASA Astrophysics Data System (ADS)

Stuber, James; Quinley, Morgan; Melnik, Paul; Sieck, Paul; Smith, Trevor; Chun, Katherine; Woodruff, Simon

2016-10-01

Despite having mature designs, diagnostics are usually custom designed for each experiment. Most of the design can be now be automated to reduce costs (engineering labor, and capital cost). We present results from scripted physics modeling and parametric engineering design for common optical and mechanical components found in many plasma diagnostics and outline the process for automated design optimization that employs scripts to communicate data from online forms through proprietary and open-source CAD and FE codes to provide a design that can be sent directly to a printer. As a demonstration of design automation, an optical beam dump, baffle and optical components are designed via an automated process and printed. Supported by DOE SBIR Grant DE-SC0011858.

Engineering aspects of the application of structural materials in the 5 MW-ESS-mercury-target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guttek, B.

1996-06-01

A main problem of the ESS-Hg-target development and the design of the components of its primary Hg-circuit is the choice of structural materials. As designing, calculations and experiments with elected materials take time and are very costy, a preview on their successful application has to be done before as detailed as possible. One aspect on this is to have the knowledge of characteristics values of the structural material candidates under the occuring mechanical and thermal loads, irradiation, corrosion and erosion. Another point is the technology of engineering concerning the manufacturing, welding, surface treatment, and quality control of such parts andmore » components under the demand to reach maximum lifetime.« less

Temporal development of near-native functional properties and correlations with qMRI in self-assembling fibrocartilage treated with exogenous lysyl oxidase homolog 2.

PubMed

Hadidi, Pasha; Cissell, Derek D; Hu, Jerry C; Athanasiou, Kyriacos A

2017-12-01

Advances in cartilage tissue engineering have led to constructs with mechanical integrity and biochemical composition increasingly resembling that of native tissues. In particular, collagen cross-linking with lysyl oxidase has been used to significantly enhance the mechanical properties of engineered neotissues. In this study, development of collagen cross-links over time, and correlations with tensile properties, were examined in self-assembling neotissues. Additionally, quantitative MRI metrics were examined in relation to construct mechanical properties as well as pyridinoline cross-link content and other engineered tissue components. Scaffold-free meniscus fibrocartilage was cultured in the presence of exogenous lysyl oxidase, and assessed at multiple time points over 8weeks starting from the first week of culture. Engineered constructs demonstrated a 9.9-fold increase in pyridinoline content, reaching 77% of native tissue values, after 8weeks of culture. Additionally, engineered tissues reached 66% of the Young's modulus in the radial direction of native tissues. Further, collagen cross-links were found to correlate with tensile properties, contributing 67% of the tensile strength of engineered neocartilages. Finally, examination of quantitative MRI metrics revealed several correlations with mechanical and biochemical properties of engineered constructs. This study displays the importance of culture duration for collagen cross-link formation, and demonstrates the potential of quantitative MRI in investigating properties of engineered cartilages. This is the first study to demonstrate near-native cross-link content in an engineered tissue, and the first study to quantify pyridinoline cross-link development over time in a self-assembling tissue. Additionally, this work shows the relative contributions of collagen and pyridinoline to the tensile properties of collagenous tissue for the first time. Furthermore, this is the first investigation to identify a relationship between qMRI metrics and the pyridinoline cross-link content of an engineered collagenous tissue. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Harmonic component detection: Optimized Spectral Kurtosis for operational modal analysis

NASA Astrophysics Data System (ADS)

Dion, J.-L.; Tawfiq, I.; Chevallier, G.

2012-01-01

This work is a contribution in the field of Operational Modal Analysis to identify the modal parameters of mechanical structures using only measured responses. The study deals with structural responses coupled with harmonic components amplitude and frequency modulated in a short range, a common combination for mechanical systems with engines and other rotating machines in operation. These harmonic components generate misleading data interpreted erroneously by the classical methods used in OMA. The present work attempts to differentiate maxima in spectra stemming from harmonic components and structural modes. The detection method proposed is based on the so-called Optimized Spectral Kurtosis and compared with others definitions of Spectral Kurtosis described in the literature. After a parametric study of the method, a critical study is performed on numerical simulations and then on an experimental structure in operation in order to assess the method's performance.

Ferrographic and spectrographic analysis of oil sampled before and after failure of a jet engine

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.

1980-01-01

An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph as well as plasma, atomic absorption, and emission spectrometers. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism, nor a high level of wear debris was detected in the oil sample from the engine just prior to the test in which the failure occurred. However, low concentrations of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure.

Reducing Uncertainty in Fatigue Life Limits of Turbine Engine Alloys

DTIC Science & Technology

2014-03-01

and components designs. 5. Conclusions This paper used electropolished specimens of the high-strength a + b titanium alloy Ti–6Al–2Sn–4Zr–6Mo to...competing mechanisms in the fatigue-life variability of a titanium and gamma-TiAl alloy. JOM 2005;57:50– 4 . [49] Jha SK, Larsen JM, Rosenberger AH. The role...February 2014 4 . TITLE AND SUBTITLE REDUCING UNCERTAINTY IN FATIGUE LIFE LIMITS OF TURBINE ENGINE ALLOYS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b

High Temperature Solid Lubricant Materials for Heavy Duty and Advanced Heat Engines

NASA Technical Reports Server (NTRS)

Dellacorte, C.; Wood, J. C.

1994-01-01

Advanced engine designs incorporate higher mechanical and thermal loading to achieve efficiency improvements. This approach often leads to higher operating temperatures of critical sliding elements (e.g. piston ring/cylinder wall contacts and valve guides) which compromise the use of conventional and even advanced synthetic liquid lubricants. For these applications solid lubricants must be considered. Several novel solid lubricant composites and coatings designated PS/PM200 have been employed to dry and marginally oil lubricated contacts in advanced heat engines. These applications include cylinder kits of heavy duty diesels, and high temperature Stirling engines, sidewall seals of rotary engines, and various exhaust valve and exhaust component applications. This paper describes the tribological and thermophysical properties of these tribomaterials and reviews the results of applying them to engine applications. Other potential tribological materials and applications are also discussed with particular emphasis on heavy duty and advanced heat engines.

Energy Efficient Engine: Flight propulsion system final design and analysis

NASA Technical Reports Server (NTRS)

Davis, Donald Y.; Stearns, E. Marshall

1985-01-01

The Energy Efficient Engine (E3) is a NASA program to create fuel saving technology for future transport engines. The Flight Propulsion System (FPS) is the engine designed to achieve E3 goals. Achieving these goals required aerodynamic, mechanical and system technologies advanced beyond that of current production engines. These technologies were successfully demonstrated in component rigs, a core engine and a turbofan ground test engine. The design and benefits of the FPS are presented. All goals for efficiency, environmental considerations, and economic payoff were met. The FPS has, at maximum cruise, 10.67 km (35,000 ft), M0.8, standard day, a 16.9 percent lower installed specific fuel consumption than a CF6-50C. It provides an 8.6 percent reduction in direct operating cost for a short haul domestic transport and a 16.2 percent reduction for an international long distance transport.

CF6 jet engine performance improvement: New fan

NASA Technical Reports Server (NTRS)

Fasching, W. A.

1980-01-01

As part of the NASA sponsored engine component improvement program, and fan package was developed to reduce fuel consumption in current CF6 turbofan aircraft engine. The new fan package consist of an improved fan blade, reduced fan tip clearance due to a fan case stiffener, and a smooth fan casing tip shroud. CF6 engine performance and acoustic tests demonstrated the predicted 1.8% improvement in cruise sfc without an increase in engine noise. Power management thrust/fan speed characteristics were defined. Mechanical and structural integrity was demonstrated in model fan rotor photoelastic stress tests, full-size fan blade bench fatigue tests, and CF6 engine bird ingestion, crosswind, and cyclic endurance tests. The fan was certified in the CF6-500c2/E2 engines and is in commerical service on the Boeing 747-200, Douglas DC-10-30, and Atrbus industrie A300B aircraft.

Molecular response of canola to salt stress: insights on tolerance mechanisms.

PubMed

Shokri-Gharelo, Reza; Noparvar, Pouya Motie

2018-01-01

Canola ( Brassica napus L. ) is widely cultivated around the world for the production of edible oils and biodiesel fuel. Despite many canola varieties being described as 'salt-tolerant', plant yield and growth decline drastically with increasing salinity. Although many studies have resulted in better understanding of the many important salt-response mechanisms that control salt signaling in plants, detoxification of ions, and synthesis of protective metabolites, the engineering of salt-tolerant crops has only progressed slowly. Genetic engineering has been considered as an efficient method for improving the salt tolerance of canola but there are many unknown or little-known aspects regarding canola response to salinity stress at the cellular and molecular level. In order to develop highly salt-tolerant canola, it is essential to improve knowledge of the salt-tolerance mechanisms, especially the key components of the plant salt-response network. In this review, we focus on studies of the molecular response of canola to salinity to unravel the different pieces of the salt response puzzle. The paper includes a comprehensive review of the latest studies, particularly of proteomic and transcriptomic analysis, including the most recently identified canola tolerance components under salt stress, and suggests what researchers should focus on in future studies.

Seals/Secondary Fluid Flows Workshop 1997; Volume I

NASA Technical Reports Server (NTRS)

Hendricks, Robert C. (Editor)

2006-01-01

The 1997 Conference provided discussions and data on (a) program overviews, (b) developments in seals and secondary air management systems, (c) interactive seals flows with secondary air or fluid flows and powerstream flows, (d) views of engine externals and limitations, (e) high speed engine research sealing needs and demands, and (f) a short course on engine design development margins. Sealing concepts discussed include, mechanical rim and cavity seals, leaf, finger, air/oil, rope, floating-brush, floating-T-buffer, and brush seals. Engine externals include all components of engine fluid systems, sensors and their support structures that lie within or project through the nacelle. The clean features of the nacelle belie the minefield of challenges and opportunities that lie within. Seals; Secondary air flows; Rotordynamics; Gas turbine; Aircraft; CFD; Testing; Turbomachinery

Thermal barrier coatings for gas-turbine engine applications.

PubMed

Padture, Nitin P; Gell, Maurice; Jordan, Eric H

2002-04-12

Hundreds of different types of coatings are used to protect a variety of structural engineering materials from corrosion, wear, and erosion, and to provide lubrication and thermal insulation. Of all these, thermal barrier coatings (TBCs) have the most complex structure and must operate in the most demanding high-temperature environment of aircraft and industrial gas-turbine engines. TBCs, which comprise metal and ceramic multilayers, insulate turbine and combustor engine components from the hot gas stream, and improve the durability and energy efficiency of these engines. Improvements in TBCs will require a better understanding of the complex changes in their structure and properties that occur under operating conditions that lead to their failure. The structure, properties, and failure mechanisms of TBCs are herein reviewed, together with a discussion of current limitations and future opportunities.

Enabling Technologies for Ceramic Hot Section Components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venkat Vedula; Tania Bhatia

Silicon-based ceramics are attractive materials for use in gas turbine engine hot sections due to their high temperature mechanical and physical properties as well as lower density than metals. The advantages of utilizing ceramic hot section components include weight reduction, and improved efficiency as well as enhanced power output and lower emissions as a result of reducing or eliminating cooling. Potential gas turbine ceramic components for industrial, commercial and/or military high temperature turbine applications include combustor liners, vanes, rotors, and shrouds. These components require materials that can withstand high temperatures and pressures for long duration under steam-rich environments. For Navymore » applications, ceramic hot section components have the potential to increase the operation range. The amount of weight reduced by utilizing a lighter gas turbine can be used to increase fuel storage capacity while a more efficient gas turbine consumes less fuel. Both improvements enable a longer operation range for Navy ships and aircraft. Ceramic hot section components will also be beneficial to the Navy's Growth Joint Strike Fighter (JSF) and VAATE (Versatile Affordable Advanced Turbine Engines) initiatives in terms of reduced weight, cooling air savings, and capability/cost index (CCI). For DOE applications, ceramic hot section components provide an avenue to achieve low emissions while improving efficiency. Combustors made of ceramic material can withstand higher wall temperatures and require less cooling air. Ability of the ceramics to withstand high temperatures enables novel combustor designs that have reduced NO{sub x}, smoke and CO levels. In the turbine section, ceramic vanes and blades do not require sophisticated cooling schemes currently used for metal components. The saved cooling air could be used to further improve efficiency and power output. The objectives of this contract were to develop technologies critical for ceramic hot section components for gas turbine engines. Significant technical progress has been made towards maturation of the EBC and CMC technologies for incorporation into gas turbine engine hot-section. Promising EBC candidates for longer life and/or higher temperature applications relative to current state of the art BSAS-based EBCs have been identified. These next generation coating systems have been scaled-up from coupons to components and are currently being field tested in Solar Centaur 50S engine. CMC combustor liners were designed, fabricated and tested in a FT8 sector rig to demonstrate the benefits of a high temperature material system. Pretest predictions made through the use of perfectly stirred reactor models showed a 2-3x benefit in CO emissions for CMC versus metallic liners. The sector-rig test validated the pretest predictions with >2x benefit in CO at the same NOx levels at various load conditions. The CMC liners also survived several trip shut downs thereby validating the CMC design methodology. Significant technical progress has been made towards incorporation of ceramic matrix composites (CMC) and environmental barrier coatings (EBC) technologies into gas turbine engine hot-section. The second phase of the program focused on the demonstration of a reverse flow annular CMC combustor. This has included overcoming the challenges of design and fabrication of CMCs into 'complex' shapes; developing processing to apply EBCs to 'engine hardware'; testing of an advanced combustor enabled by CMCs in a PW206 rig; and the validation of performance benefits against a metal baseline. The rig test validated many of the pretest predictions with a 40-50% reduction in pattern factor compared to the baseline and reductions in NOx levels at maximum power conditions. The next steps are to develop an understanding of the life limiting mechanisms in EBC and CMC materials, developing a design system for EBC coated CMCs and durability testing in an engine environment.« less

Component improvement of free-piston Stirling engine key technology for space power

NASA Technical Reports Server (NTRS)

Alger, Donald L.

1988-01-01

The successful performance of the 25 kW Space Power Demonstrator (SPD) engine during an extensive testing period has provided a baseline of free piston Stirling engine technology from which future space Stirling engines may evolve. Much of the success of the engine was due to the initial careful selection of engine materials, fabrication and joining processes, and inspection procedures. Resolution of the few SPD engine problem areas that did occur has resulted in the technological advancement of certain key free piston Stirling engine components. Derivation of two half-SPD, single piston engines from the axially opposed piston SPD engine, designated as Space Power Research (SPR) engines, has made possible the continued improvement of these engine components. The two SPR engines serve as test bed engines for testing of engine components. Some important fabrication and joining processes are reviewed. Also, some component deficiencies that were discovered during SPD engine testing are described and approaches that were taken to correct these deficiencies are discussed. Potential component design modifications, based upon the SPD and SPR engine testing, are also reported.

Probabilistic evaluation of SSME structural components

NASA Astrophysics Data System (ADS)

Rajagopal, K. R.; Newell, J. F.; Ho, H.

1991-05-01

The application is described of Composite Load Spectra (CLS) and Numerical Evaluation of Stochastic Structures Under Stress (NESSUS) family of computer codes to the probabilistic structural analysis of four Space Shuttle Main Engine (SSME) space propulsion system components. These components are subjected to environments that are influenced by many random variables. The applications consider a wide breadth of uncertainties encountered in practice, while simultaneously covering a wide area of structural mechanics. This has been done consistent with the primary design requirement for each component. The probabilistic application studies are discussed using finite element models that have been typically used in the past in deterministic analysis studies.

A Structurally and Functionally Biomimetic Biphasic Scaffold for Intervertebral Disc Tissue Engineering

PubMed Central

Choy, Andrew Tsz Hang; Chan, Barbara Pui

2015-01-01

Tissue engineering offers high hopes for the treatment of intervertebral disc (IVD) degeneration. Whereas scaffolds of the disc nucleus and annulus have been extensively studied, a truly biomimetic and mechanically functional biphasic scaffold using naturally occurring extracellular matrix is yet to be developed. Here, a biphasic scaffold was fabricated with collagen and glycosaminoglycans (GAGs), two of the most abundant extracellular matrix components in the IVD. Following fabrication, the scaffold was characterized and benchmarked against native disc. The biphasic scaffold was composed of a collagen-GAG co-precipitate making up the nucleus pulposus-like core, and this was encapsulated in multiple lamellae of photochemically crosslinked collagen membranes comprising the annulus fibrosus-like lamellae. On mechanical testing, the height of our engineered disc recovered by ~82-89% in an annulus-independent manner, when compared with the 99% recovery exhibited by native disc. The annulus-independent nature of disc height recovery suggests that the fluid replacement function of the engineered nucleus pulposus core might mimic this hitherto unique feature of native disc. Biphasic scaffolds comprised of 10 annulus fibrosus-like lamellae had the best overall mechanical performance among the various designs owing to their similarity to native disc in most aspects, including elastic compliance during creep and recovery, and viscous compliance during recovery. However, the dynamic mechanical performance (including dynamic stiffness and damping factor) of all the biphasic scaffolds was similar to that of the native discs. This study contributes to the rationalized design and development of a biomimetic and mechanically viable biphasic scaffold for IVD tissue engineering. PMID:26115332

14 CFR 33.53 - Engine system and component tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine system and component tests. 33.53... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.53 Engine system and component tests. (a) For those systems and components that cannot be adequately substantiated in accordance...

Calcium-Magnesium-Alumino-Silicates (CMAS) Reaction Mechanisms and Resistance of Advanced Turbine Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Costa, Gustavo; Harder, Bryan J.; Wiesner, Valerie L.; Hurst, Janet B.; Puleo, Bernadette J.

2017-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is an essential requirement to enable the applications of the 2700-3000 F EBC - CMC systems. This presentation primarily focuses on the reaction mechanisms of advanced NASA environmental barrier coating systems, when in contact with Calcium-Magnesium Alumino-Silicates (CMAS) at high temperatures. Advanced oxide-silicate defect cluster environmental barrier coatings are being designed for ultimate balanced controls of the EBC temperature capability and CMAS reactivity, thus improving the CMAS resistance. Further CMAS mitigation strategies are also discussed.

Interfacing modules for integrating discipline specific structural mechanics codes

NASA Technical Reports Server (NTRS)

Endres, Ned M.

1989-01-01

An outline of the organization and capabilities of the Engine Structures Computational Simulator (Simulator) at NASA Lewis Research Center is given. One of the goals of the research at Lewis is to integrate various discipline specific structural mechanics codes into a software system which can be brought to bear effectively on a wide range of engineering problems. This system must possess the qualities of being effective and efficient while still remaining user friendly. The simulator was initially designed for the finite element simulation of gas jet engine components. Currently, the simulator has been restricted to only the analysis of high pressure turbine blades and the accompanying rotor assembly, although the current installation can be expanded for other applications. The simulator presently assists the user throughout its procedures by performing information management tasks, executing external support tasks, organizing analysis modules and executing these modules in the user defined order while maintaining processing continuity.

Principle of maximum entropy for reliability analysis in the design of machine components

NASA Astrophysics Data System (ADS)

Zhang, Yimin

2018-03-01

We studied the reliability of machine components with parameters that follow an arbitrary statistical distribution using the principle of maximum entropy (PME). We used PME to select the statistical distribution that best fits the available information. We also established a probability density function (PDF) and a failure probability model for the parameters of mechanical components using the concept of entropy and the PME. We obtained the first four moments of the state function for reliability analysis and design. Furthermore, we attained an estimate of the PDF with the fewest human bias factors using the PME. This function was used to calculate the reliability of the machine components, including a connecting rod, a vehicle half-shaft, a front axle, a rear axle housing, and a leaf spring, which have parameters that typically follow a non-normal distribution. Simulations were conducted for comparison. This study provides a design methodology for the reliability of mechanical components for practical engineering projects.

Maintaining the U.S. Army Research, Development and Engineering Command Prototype Integration Facilities

DTIC Science & Technology

2014-05-01

shelters, tents and fabric covers, mechanical aerial delivery parts and components, kitchens , and combat feeding items (see Figure 4). NSRDEC’s PIF is...generic terms and refrain from revealing confidential or classified information. Research hypotheses are as follows: H1: The PIF leadership predicts

Impact-Resistant Ceramic Coating

NASA Technical Reports Server (NTRS)

Wheeler, W. H.; Creedon, J. F.; Izu, Y. D.

1986-01-01

Refractory fibers more than double strength of coating. Impact strengths of ceramic coatings increase with increasing whisker content. Silicon carbide whiskers clearly produce largest increase, and improvement grows even more with high-temperature sintering. Coating also improves thermal and mechanical properties of electromagnetic components, mirrors, furnace linings, and ceramic parts of advanced internal-combustion engines.

NASA Tech Briefs, March 1995

NASA Technical Reports Server (NTRS)

1995-01-01

This issue contains articles with a special focus on Computer-Aided design and engineering amd a research report on the Ames Research Center. Other subjects in this issue are: Electronic Components and Circuits, Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Manufacturing/Fabrication, Mathematics and Information Sciences and Life Sciences

Moire strain analysis of paper

Treesearch

R. E. Rowlands; P. K. Beasley; D. E. Gunderson

1983-01-01

Efficient use of paper products involves using modern aspects of materials science and engineering mechanics. This implies the ability to determine simultaneously different components of strain at multiple locations and under static or dynamic conditions. Although measuring strains in paper has been a topic of interest for over 40 years, present capability remains...

Hypotension and AV block after diesel exhaust exposure in heart failure-prone rats: role of gaseous and particulate components

EPA Science Inventory

Acute inhalations ofdiesel engine exhaust (DE) and fine particulate matter (PM2.5) have been demonstrated to provoke adverse cardiac events in humans with preexisting heart disease. Electrophysiologic dysfunction and autonomic imbalance are among the mechanisms widely held to und...

The 7.5K lbf thrust engine preliminary design for Orbit Transfer Vehicle

NASA Technical Reports Server (NTRS)

Hayden, Warren R.; Sabiers, Ralph; Schneider, Judy

1994-01-01

This document summarizes the preliminary design of the Aerojet version of the Orbit Transfer Vehicle main engine. The concept of a 7500 lbf thrust LO2/GH2 engine using the dual expander cycle for optimum efficiency is validated through power balance and thermal calculations. The engine is capable of 10:1 throttling from a nominal 2000 psia to a 200 psia chamber pressure. Reservations are detailed on the feasibility of a tank head start, but the design incorporates low speed turbopumps to mitigate the problem. The mechanically separate high speed turbopumps use hydrostatic bearings to meet engine life requirements, and operate at sub-critical speed for better throttling ability. All components were successfully packaged in the restricted envelope set by the clearances for the extendible/retractable nozzle. Gimbal design uses an innovative primary and engine out gimbal system to meet the +/- 20 deg gimbal requirement. The hydrogen regenerator and LOX/GH2 heat exchanger uses the Aerojet platelet structures approach for a highly compact component design. The extendible/retractable nozzle assembly uses an electric motor driven jack-screw design and a one segment carbon-carbon or silicide coated columbium nozzle with an area ratio, when extended, of 1430:1. A reliability analysis and risk assessment concludes the report.

Creep fatigue life prediction for engine hot section materials (isotropic): Fourth year progress review

NASA Technical Reports Server (NTRS)

Nelson, Richard S.; Schoendorf, John F.

1986-01-01

As gas turbine technology continues to advance, the need for advanced life prediction methods for hot section components is becoming more and more evident. The complex local strain and temperature histories at critical locations must be accurately interpreted to account for the effects of various damage mechanisms (such as fatigue, creep, and oxidation) and their possible interactions. As part of the overall NASA HOST effort, this program is designed to investigate these fundamental damage processes, identify modeling strategies, and develop practical models which can be used to guide the early design and development of new engines and to increase the durability of existing engines.

Determination of Turbine Blade Life from Engine Field Data

NASA Technical Reports Server (NTRS)

Zaretsky, Erwin V.; Litt, Jonathan S.; Hendricks, Robert C.; Soditus, Sherry M.

2012-01-01

It is probable that no two engine companies determine the life of their engines or their components in the same way or apply the same experience and safety factors to their designs. Knowing the failure mode that is most likely to occur minimizes the amount of uncertainty and simplifies failure and life analysis. Available data regarding failure mode for aircraft engine blades, while favoring low-cycle, thermal mechanical fatigue as the controlling mode of failure, are not definitive. Sixteen high-pressure turbine (HPT) T-1 blade sets were removed from commercial aircraft engines that had been commercially flown by a single airline and inspected for damage. Each set contained 82 blades. The damage was cataloged into three categories related to their mode of failure: (1) Thermal-mechanical fatigue, (2) Oxidation/Erosion, and (3) "Other." From these field data, the turbine blade life was determined as well as the lives related to individual blade failure modes using Johnson-Weibull analysis. A simplified formula for calculating turbine blade life and reliability was formulated. The L(sub 10) blade life was calculated to be 2427 cycles (11 077 hr). The resulting blade life attributed to oxidation/erosion equaled that attributed to thermal-mechanical fatigue. The category that contributed most to blade failure was Other. If there were there no blade failures attributed to oxidation/erosion and thermal-mechanical fatigue, the overall blade L(sub 10) life would increase approximately 11 to 17 percent.

Ceramic Technology For Advanced Heat Engines Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-12-01

Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. The objective of the project is to develop the industrial technology base required for reliable ceramicsmore » for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. This advanced materials technology is being developed in parallel and close coordination with the ongoing DOE and industry proof of concept engine development programs. To facilitate the rapid transfer of this technology to U.S. industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. Abstracts prepared for appropriate papers.« less

Lewis Structures Technology, 1988. Volume 1: Structural Dynamics

NASA Technical Reports Server (NTRS)

1988-01-01

The specific purpose of the symposium was to familiarize the engineering structures community with the depth and range of research performed by the Structures Division of the Lewis Research Center and its academic and industrial partners. Sessions covered vibration control, fracture mechanics, ceramic component reliability, parallel computing, nondestructive testing, dynamical systems, fatigue and damage, wind turbines, hot section technology, structural mechanics codes, computational methods for dynamics, structural optimization, and applications of structural dynamics.

Mechanical Backup For Fly-By-Wire Control System

NASA Technical Reports Server (NTRS)

Stewart, Eric C.

1992-01-01

Mechanical device eliminates need for redundant fly-by-wire subsystems. Main components are two linkages. One connected to control column in conventional, reversible control system. Other slides inside first linkage and connected to pilot's control wheel. In addition to aircraft applications, design used in control systems in which computer control desirable but safety backup systems required; for example, in boat rudders, engine controls in boats and automobiles, and controls in construction equipment.

Progress of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting Radial Growth on a Rotating Disk

NASA Technical Reports Server (NTRS)

Clem, Michelle M.; Abdul-Aziz, Ali; Woike, Mark R.; Fralick, Gustave C.

2015-01-01

The modern turbine engine operates in a harsh environment at high speeds and is repeatedly exposed to combined high mechanical and thermal loads. The cumulative effects of these external forces lead to high stresses and strains on the engine components, such as the rotating turbine disks, which may eventually lead to a catastrophic failure if left undetected. The operating environment makes it difficult to use conventional strain gauges, therefore, non-contact strain measurement techniques is of interest to NASA and the turbine engine community. This presentation describes one such approach; the use of cross correlation analysis to measure strain experienced by the engine turbine disk with the goal of assessing potential faults and damage.

Chitosan Composites for Bone Tissue Engineering—An Overview

PubMed Central

Venkatesan, Jayachandran; Kim, Se-Kwon

2010-01-01

Bone contains considerable amounts of minerals and proteins. Hydroxyapatite [Ca10(PO4)6(OH)2] is one of the most stable forms of calcium phosphate and it occurs in bones as major component (60 to 65%), along with other materials including collagen, chondroitin sulfate, keratin sulfate and lipids. In recent years, significant progress has been made in organ transplantation, surgical reconstruction and the use of artificial protheses to treat the loss or failure of an organ or bone tissue. Chitosan has played a major role in bone tissue engineering over the last two decades, being a natural polymer obtained from chitin, which forms a major component of crustacean exoskeleton. In recent years, considerable attention has been given to chitosan composite materials and their applications in the field of bone tissue engineering due to its minimal foreign body reactions, an intrinsic antibacterial nature, biocompatibility, biodegradability, and the ability to be molded into various geometries and forms such as porous structures, suitable for cell ingrowth and osteoconduction. The composite of chitosan including hydroxyapatite is very popular because of the biodegradability and biocompatibility in nature. Recently, grafted chitosan natural polymer with carbon nanotubes has been incorporated to increase the mechanical strength of these composites. Chitosan composites are thus emerging as potential materials for artificial bone and bone regeneration in tissue engineering. Herein, the preparation, mechanical properties, chemical interactions and in vitro activity of chitosan composites for bone tissue engineering will be discussed. PMID:20948907

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1989-01-01

ATTAP activities during the past year were highlighted by an extensive materials assessment, execution of a reference powertrain design, test-bed engine design and development, ceramic component design, materials and component characterization, ceramic component process development and fabrication, component rig design and fabrication, test-bed engine fabrication, and hot gasifier rig and engine testing. Materials assessment activities entailed engine environment evaluation of domestically supplied radial gasifier turbine rotors that were available at the conclusion of the Advanced Gas Turbine (AGT) Technology Development Project as well as an extensive survey of both domestic and foreign ceramic suppliers and Government laboratories performing ceramic materials research applicable to advanced heat engines. A reference powertrain design was executed to reflect the selection of the AGT-5 as the ceramic component test-bed engine for the ATTAP. Test-bed engine development activity focused on upgrading the AGT-5 from a 1038 C (1900 F) metal engine to a durable 1371 C (2500 F) structural ceramic component test-bed engine. Ceramic component design activities included the combustor, gasifier turbine static structure, and gasifier turbine rotor. The materials and component characterization efforts have included the testing and evaluation of several candidate ceramic materials and components being developed for use in the ATTAP. Ceramic component process development and fabrication activities were initiated for the gasifier turbine rotor, gasifier turbine vanes, gasifier turbine scroll, extruded regenerator disks, and thermal insulation. Component rig development activities included combustor, hot gasifier, and regenerator rigs. Test-bed engine fabrication activities consisted of the fabrication of an all-new AGT-5 durability test-bed engine and support of all engine test activities through instrumentation/build/repair. Hot gasifier rig and test-bed engine testing activities were performed.

Optimized adipose tissue engineering strategy based on a neo-mechanical processing method.

PubMed

He, Yunfan; Lin, Maohui; Wang, Xuecen; Guan, Jingyan; Dong, Ziqing; Feng, Lu; Xing, Malcolm; Feng, Chuanbo; Li, Xiaojian

2018-05-26

Decellularized adipose tissue (DAT) represents a promising scaffold for adipose tissue engineering. However, the unique and prolonged lipid removal process required for adipose tissue can damage extracellular matrix (ECM) constituents. Moreover, inadequate vascularization limits the recellularization of DAT in vivo. We proposed a neo-mechanical protocol for rapidly breaking adipocytes and removing lipid content from adipose tissue. The lipid-depleted adipose tissue was then subjected to a fast and mild decellularization to fabricate high-quality DAT (M-DAT). Adipose liquid extract (ALE) derived from this mechanical process was collected and incorporated into M-DAT to further optimize in vivo recellularization. Ordinary DAT was fabricated and served as a control. This developed strategy was evaluated based on decellularization efficiency, ECM quality, and recellularization efficiency. Angiogenic factor components and angiogenic potential of ALE were evaluated in vivo and in vitro. M-DAT achieved the same decellularization efficiency, but exhibited better retention of ECM components and recellularization, compared to those with ordinary DAT. Protein quantification revealed considerable levels of angiogenic factors (basic fibroblast growth factor, epidermal growth factor, transforming growth factor-β1, and vascular endothelial growth factor) in ALE. ALE promoted tube formation in vitro and induced intense angiogenesis in M-DAT in vivo; furthermore, higher expression of the adipogenic factor PPARγ and greater numbers of adipocytes were evident following ALE treatment, compared to those in the M-DAT group. Mechanical processing of adipose tissue led to the production of high-quality M-DAT and angiogenic factor-enriched ALE. The combination of ALE and M-DAT could be a promising strategy for engineered adipose tissue construction. This article is protected by copyright. All rights reserved. © 2018 by the Wound Healing Society.

Electrical Prototype Power Processor for the 30-cm Mercury electric propulsion engine

NASA Technical Reports Server (NTRS)

Biess, J. J.; Frye, R. J.

1978-01-01

An Electrical Prototpye Power Processor has been designed to the latest electrical and performance requirements for a flight-type 30-cm ion engine and includes all the necessary power, command, telemetry and control interfaces for a typical electric propulsion subsystem. The power processor was configured into seven separate mechanical modules that would allow subassembly fabrication, test and integration into a complete power processor unit assembly. The conceptual mechanical packaging of the electrical prototype power processor unit demonstrated the relative location of power, high voltage and control electronic components to minimize electrical interactions and to provide adequate thermal control in a vacuum environment. Thermal control was accomplished with a heat pipe simulator attached to the base of the modules.

Eddy current characterization of magnetic treatment of nickel 200

NASA Technical Reports Server (NTRS)

Chern, E. J.

1993-01-01

Eddy current methods have been applied to characterize the effect of magnetic treatments on component service-life extension. Coil impedance measurements were acquired and analyzed on nickel 200 specimens that have been subjected to many mechanical and magnetic engineering processes: annealing, applied strain, magnetic field, shot peening, and magnetic field after peening. Experimental results have demonstrated a functional relationship between coil impedance, resistance and reactance, and specimens subjected to various engineering processes. It has shown that magnetic treatment does induce changes in electromagnetic properties of nickel 200 that then exhibit evidence of stress relief. However, further fundamental studies are necessary for a thorough understanding of the exact mechanism of the magnetic field processing effect on machine-tool service life.

Engine rotor health monitoring: an experimental approach to fault detection and durability assessment

NASA Astrophysics Data System (ADS)

Abdul-Aziz, Ali; Woike, Mark R.; Clem, Michelle; Baaklini, George

2015-03-01

Efforts to update and improve turbine engine components in meeting flights safety and durability requirements are commitments that engine manufacturers try to continuously fulfill. Most of their concerns and developments energies focus on the rotating components as rotor disks. These components typically undergo rigorous operating conditions and are subject to high centrifugal loadings which subject them to various failure mechanisms. Thus, developing highly advanced health monitoring technology to screen their efficacy and performance is very essential to their prolonged service life and operational success. Nondestructive evaluation techniques are among the many screening methods that presently are being used to pre-detect hidden flaws and mini cracks prior to any appalling events occurrence. Most of these methods or procedures are confined to evaluating material's discontinuities and other defects that have mature to a point where failure is eminent. Hence, development of more robust techniques to pre-predict faults prior to any catastrophic events in these components is highly vital. This paper is focused on presenting research activities covering the ongoing research efforts at NASA Glenn Research Center (GRC) rotor dynamics laboratory in support of developing a fault detection system for key critical turbine engine components. Data obtained from spin test experiments of a rotor disk that relates to investigating behavior of blade tip clearance, tip timing and shaft displacement based on measured data acquired from sensor devices such as eddy current, capacitive and microwave are presented. Additional results linking test data with finite element modeling to characterize the structural durability of a cracked rotor as it relays to the experimental tests and findings is also presented. An obvious difference in the vibration response is shown between the notched and the baseline no notch rotor disk indicating the presence of some type of irregularity.

AMSEC Users Guide.

DTIC Science & Technology

1976-11-01

Hardware • System functional configuration characteristics • Component aging mechanisms (engineering) • Subsystem/component FMEAs • Subsystem...modified to fit the specific mission(s) under investigation. 60 — .- m. • •. mi . ui ••_!!•»•••’ i • .. ••Mil ’’•^•^••BWW^WlWi^Wi...8217 / t / / / s y / ’ / / * y hO | -;-; • / / 1, r T ", 60 / / / • f tl’Jt, s s 1 / ’ • Mode 7 B=4.0 ^ / 7 / 0 Mode 8

Propulsion System Models for Rotorcraft Conceptual Design

NASA Technical Reports Server (NTRS)

Johnson, Wayne

2014-01-01

The conceptual design code NDARC (NASA Design and Analysis of Rotorcraft) was initially implemented to model conventional rotorcraft propulsion systems, consisting of turboshaft engines burning jet fuel, connected to one or more rotors through a mechanical transmission. The NDARC propulsion system representation has been extended to cover additional propulsion concepts, including electric motors and generators, rotor reaction drive, turbojet and turbofan engines, fuel cells and solar cells, batteries, and fuel (energy) used without weight change. The paper describes these propulsion system components, the architecture of their implementation in NDARC, and the form of the models for performance and weight. Requirements are defined for improved performance and weight models of the new propulsion system components. With these new propulsion models, NDARC can be used to develop environmentally-friendly rotorcraft designs.

Foam-Metal Liner Attenuation of Low-Speed Fan Noise

NASA Technical Reports Server (NTRS)

Sutliff, Daniel L.; Jones, Michael G.

2008-01-01

A foam-metal liner for attenuation of fan noise was developed for and tested on a low speed fan. This type of liner represents a significant advance over traditional liners due to the possibility for placement in close proximity to the rotor. An advantage of placing treatment in this region is the modification of the acoustic near field, thereby inhibiting noise generation mechanisms. This can result in higher attenuation levels than can be achieved by liners located in the nacelle inlet. In addition, foam-metal liners could potentially replace the fan rub-strip and containment components, ultimately reducing engine components and thus weight, which can result in a systematic increase in noise reduction and engine performance. Foam-metal liners have the potential to reduce fan noise by 4 dB based on this study.

Low Cost Heat Treatment Process for Production of Dual Microstructure Superalloy Disks

NASA Technical Reports Server (NTRS)

Gayda, John; Gabb, Tim; Kantzos, Pete; Furrer, David

2003-01-01

There are numerous incidents where operating conditions imposed on a component mandate different and distinct mechanical property requirements from location to location within the component. Examples include a crankshaft in an internal combustion engine, gears for an automotive transmission, and disks for a gas turbine engine. Gas turbine disks are often made from nickel-base superalloys, because these disks need to withstand the temperature and stresses involved in the gas turbine cycle. In the bore of the disk where the operating temperature is somewhat lower, the limiting material properties are often tensile and fatigue strength. In the rim of the disk, where the operating temperatures are higher than those of the bore, because of the proximity to the combustion gases, resistance to creep and crack growth are often the limiting properties.

Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding.

PubMed

Mi, Hao-Yang; Salick, Max R; Jing, Xin; Jacques, Brianna R; Crone, Wendy C; Peng, Xiang-Fang; Turng, Lih-Sheng

2013-12-01

Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold's microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications. © 2013.

Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding

PubMed Central

Mi, Hao-Yang; Salick, Max R.; Jing, Xin; Jacques, Brianna R.; Crone, Wendy C.; Peng, Xiang-Fang; Turng, Lih-Sheng

2015-01-01

Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold’s microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications. PMID:24094186

Engineering stategies and implications of using higher plants for throttling gas and water exchange in a controlled ecological life support system

NASA Technical Reports Server (NTRS)

Chamberland, Dennis; Wheeler, Raymond M.; Corey, Kenneth A.

1993-01-01

Engineering stategies for advanced life support systems to be used on Lunar and Mars bases involve a wide spectrum of approaches. These range from purely physical-chemical life support strategies to purely biological approaches. Within the context of biological based systems, a bioengineered system can be devised that would utilize the metabolic mechanisms of plants to control the rates of CO2 uptake and O2 evolution (photosynthesis) and water production (transpiration). Such a mechanism of external engineering control has become known as throttling. Research conducted at the John F. Kennedy Space Center's Controlled Ecological Life Support System Breadboard Project has demonstrated the potential of throttling these fluxes by changing environmental parameters affecting the plant processes. Among the more effective environmental throttles are: light and CO2 concentration for controllingthe rate of photsynthesis and humidity and CO2 concentration for controlling transpiration. Such a bioengineered strategy implies control mechanisms that in the past have not been widely attributed to life support systems involving biological components and suggests a broad range of applications in advanced life support system design.

Thermal Cyclic Behavior of Thermal and Environmental Barrier Coatings Investigated Under High-Heat-Flux Conditions

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

2002-01-01

Environmental barrier coatings (EBC's) have been developed to protect silicon-carbide- (SiC) based ceramic components in gas turbine engines from high-temperature environmental attack. With continuously increasing demands for significantly higher engine operating temperature, future EBC systems must be designed for both thermal and environmental protection of the engine components in combustion gases. In particular, the thermal barrier functions of EBC's become a necessity for reducing the engine-component thermal loads and chemical reaction rates, thus maintaining the required mechanical properties and durability of these components. Advances in the development of thermal and environmental barrier coatings (TBC's and EBC's, respectively) will directly impact the successful use of ceramic components in advanced engines. To develop high-performance coating systems, researchers must establish advanced test approaches. In this study, a laser high-heat-flux technique was employed to investigate the thermal cyclic behavior of TBC's and EBC's on SiC-reinforced SiC ceramic matrix composite substrates (SiC/SiC) under high thermal gradient and thermal cycling conditions. Because the laser heat flux test approach can monitor the coating's real-time thermal conductivity variations at high temperature, the coating thermal insulation performance, sintering, and delamination can all be obtained during thermal cycling tests. Plasma-sprayed yttria-stabilized zirconia (ZrO2-8 wt% Y2O3) thermal barrier and barium strontium aluminosilicate-based environmental barrier coatings (BSAS/BSAS+mullite/Si) on SiC/SiC ceramic matrix composites were investigated in this study. These coatings were laser tested in air under thermal gradients (the surface and interface temperatures were approximately 1482 and 1300 C, respectively). Some coating specimens were also subject to alternating furnace cycling (in a 90-percent water vapor environment at 1300 C) and laser thermal gradient cycling tests (in air), to investigate the water vapor effect. All cyclic tests were conducted using a 60-min hot-time temperature.

Digital Image Correlation for Performance Monitoring.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palaviccini, Miguel; Turner, Daniel Z.; Herzberg, Michael

2016-02-01

Evaluating the health of a mechanism requires more than just a binary evaluation of whether an operation was completed. It requires analyzing more comprehensive, full-field data. Health monitoring is a process of nondestructively identifying characteristics that indicate the fitness of an engineered component. In order to monitor unit health in a production setting, an automated test system must be created to capture the motion of mechanism parts in a real-time and non-intrusive manner. One way to accomplish this is by using high-speed video (HSV) and Digital Image Correlation (DIC). In this approach, individual frames of the video are analyzed tomore » track the motion of mechanism components. The derived performance metrics allow for state-of-health monitoring and improved fidelity of mechanism modeling. The results are in-situ state-of-health identification and performance prediction. This paper introduces basic concepts of this test method, and discusses two main themes: the use of laser marking to add fiducial patterns to mechanism components, and new software developed to track objects with complex shapes, even as they move behind obstructions. Finally, the implementation of these tests into an automated tester is discussed.« less

Finite Element Creep-Fatigue Analysis of a Welded Furnace Roll for Identifying Failure Root Cause

NASA Astrophysics Data System (ADS)

Yang, Y. P.; Mohr, W. C.

2015-11-01

Creep-fatigue induced failures are often observed in engineering components operating under high temperature and cyclic loading. Understanding the creep-fatigue damage process and identifying failure root cause are very important for preventing such failures and improving the lifetime of engineering components. Finite element analyses including a heat transfer analysis and a creep-fatigue analysis were conducted to model the cyclic thermal and mechanical process of a furnace roll in a continuous hot-dip coating line. Typically, the roll has a short life, <1 year, which has been a problem for a long time. The failure occurred in the weld joining an end bell to a roll shell and resulted in the complete 360° separation of the end bell from the roll shell. The heat transfer analysis was conducted to predict the temperature history of the roll by modeling heat convection from hot air inside the furnace. The creep-fatigue analysis was performed by inputting the predicted temperature history and applying mechanical loads. The analysis results showed that the failure was resulted from a creep-fatigue mechanism rather than a creep mechanism. The difference of material properties between the filler metal and the base metal is the root cause for the roll failure, which induces higher creep strain and stress in the interface between the weld and the HAZ.

Applied Fluid Mechanics. Lecture Notes.

ERIC Educational Resources Information Center

Gregg, Newton D.

This set of lecture notes is used as a supplemental text for the teaching of fluid dynamics, as one component of a thermodynamics course for engineering technologists. The major text for the course covered basic fluids concepts such as pressure, mass flow, and specific weight. The objective of this document was to present additional fluids…

Teaching Computer-Aided Design of Fluid Flow and Heat Transfer Engineering Equipment.

ERIC Educational Resources Information Center

Gosman, A. D.; And Others

1979-01-01

Describes a teaching program for fluid mechanics and heat transfer which contains both computer aided learning (CAL) and computer aided design (CAD) components and argues that the understanding of the physical and numerical modeling taught in the CAL course is essential to the proper implementation of CAD. (Author/CMV)

The scope of additive manufacturing in cryogenics, component design, and applications

NASA Astrophysics Data System (ADS)

Stautner, W.; Vanapalli, S.; Weiss, K.-P.; Chen, R.; Amm, K.; Budesheim, E.; Ricci, J.

2017-12-01

Additive manufacturing techniques using composites or metals are rapidly gaining momentum in cryogenic applications. Small or large, complex structural components are now no longer limited to mere design studies but can now move into the production stream thanks to new machines on the market that allow for light-weight, cost optimized designs with short turnaround times. The potential for cost reductions from bulk materials machined to tight tolerances has become obvious. Furthermore, additive manufacturing opens doors and design space for cryogenic components that to date did not exist or were not possible in the past, using bulk materials along with elaborate and expensive machining processes, e.g. micromachining. The cryogenic engineer now faces the challenge to design toward those new additive manufacturing capabilities. Additionally, re-thinking designs toward cost optimization and fast implementation also requires detailed knowledge of mechanical and thermal properties at cryogenic temperatures. In the following we compile the information available to date and show a possible roadmap for additive manufacturing applications of parts and components typically used in cryogenic engineering designs.

Refurbishment and Automation of Thermal Vacuum Facilities at NASA/GSFC

NASA Technical Reports Server (NTRS)

Dunn, Jamie; Gomez, Carlos; Donohue, John; Johnson, Chris; Palmer, John; Sushon, Janet

1999-01-01

The thermal vacuum facilities located at the Goddard Space Flight Center (GSFC) have supported both manned and unmanned space flight since the 1960s. Of the eleven facilities, currently ten of the systems are scheduled for refurbishment or replacement as part of a five-year implementation. Expected return on investment includes the reduction in test schedules, improvements in safety of facility operations, and reduction in the personnel support required for a test. Additionally, GSFC will become a global resource renowned for expertise in thermal engineering, mechanical engineering, and for the automation of thermal vacuum facilities and tests. Automation of the thermal vacuum facilities includes the utilization of Programmable Logic Controllers (PLCs), the use of Supervisory Control and Data Acquisition (SCADA) systems, and the development of a centralized Test Data Management System. These components allow the computer control and automation of mechanical components such as valves and pumps. The project of refurbishment and automation began in 1996 and has resulted in complete computer control of one facility (Facility 281), and the integration of electronically controlled devices and PLCs in multiple others.

Refurbishment and Automation of Thermal Vacuum Facilities at NASA/GSFC

NASA Technical Reports Server (NTRS)

Dunn, Jamie; Gomez, Carlos; Donohue, John; Johnson, Chris; Palmer, John; Sushon, Janet

1998-01-01

The thermal vacuum facilities located at the Goddard Space Flight Center (GSFC) have supported both manned and unmanned space flight since the 1960s. Of the eleven facilities, currently ten of the systems are scheduled for refurbishment or replacement as part of a five-year implementation. Expected return on investment includes the reduction in test schedules, improvements in safety of facility operations, and reduction in the personnel support required for a test. Additionally, GSFC will become a global resource renowned for expertise in thermal engineering, mechanical engineering, and for the automation of thermal vacuum facilities and tests. Automation of the thermal vacuum facilities includes the utilization of Programmable Logic Controllers (PLCs), the use of Supervisory Control and Data Acquisition (SCADA) systems, and the development of a centralized Test Data Management System. These components allow the computer control and automation of mechanical components such as valves and pumps. The project of refurbishment and automation began in 1996 and has resulted in complete computer control of one facility (Facility 281), and the integration of electronically controlled devices and PLCs in multiple others.

Probabilistic framework for product design optimization and risk management

NASA Astrophysics Data System (ADS)

Keski-Rahkonen, J. K.

2018-05-01

Probabilistic methods have gradually gained ground within engineering practices but currently it is still the industry standard to use deterministic safety margin approaches to dimensioning components and qualitative methods to manage product risks. These methods are suitable for baseline design work but quantitative risk management and product reliability optimization require more advanced predictive approaches. Ample research has been published on how to predict failure probabilities for mechanical components and furthermore to optimize reliability through life cycle cost analysis. This paper reviews the literature for existing methods and tries to harness their best features and simplify the process to be applicable in practical engineering work. Recommended process applies Monte Carlo method on top of load-resistance models to estimate failure probabilities. Furthermore, it adds on existing literature by introducing a practical framework to use probabilistic models in quantitative risk management and product life cycle costs optimization. The main focus is on mechanical failure modes due to the well-developed methods used to predict these types of failures. However, the same framework can be applied on any type of failure mode as long as predictive models can be developed.

Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Halbig, Michael Charles; Puleo, Bernadette J.; Costa, Gustavo; Mccue, Terry R.

2017-01-01

This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiC-SiC Ceramic Matrix Composite (CMC) combustors particularly under the NASA Environmentally Responsible Aviation, Fundamental Aeronautics and Transformative Aeronautics Concepts Programs. The emphases have been placed on the current design challenges of the 2700-3000F capable environmental barrier coatings for low NOX emission combustors for next generation turbine engines by using advanced plasma spray based processes, and the coating processing and integration with SiC-SiC CMCs and component systems. The developments also have included candidate coating composition system designs, degradation mechanisms, performance evaluation and down-selects; the processing optimizations using TriplexPro Air Plasma Spray Low Pressure Plasma Spray (LPPS), Plasma Spray Physical Vapor Deposition and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements under the NASA development programs, as demonstrated in the simulated engine high heat flux, combustion environments, in conjunction with high heat flux, mechanical creep and fatigue loading testing conditions.

19 CFR 10.183 - Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components...

Code of Federal Regulations, 2014 CFR

2014-04-01

... engines, ground flight simulators, parts, components, and subassemblies. 10.183 Section 10.183 Customs... Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components, and... aircraft, aircraft engines, and ground flight simulators, including their parts, components, and...

19 CFR 10.183 - Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components...

Code of Federal Regulations, 2013 CFR

2013-04-01

... engines, ground flight simulators, parts, components, and subassemblies. 10.183 Section 10.183 Customs... Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components, and... aircraft, aircraft engines, and ground flight simulators, including their parts, components, and...

19 CFR 10.183 - Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components...

Code of Federal Regulations, 2012 CFR

2012-04-01

... engines, ground flight simulators, parts, components, and subassemblies. 10.183 Section 10.183 Customs... Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components, and... aircraft, aircraft engines, and ground flight simulators, including their parts, components, and...

CF60 Concrete Composition Design and Application on Fudiankou Xijiang Super Large Bridge

NASA Astrophysics Data System (ADS)

Qiu, Yi Mei; Wen, Sen Yuan; Chen, Jun Xiang

2018-06-01

Guangxi Wuzhou City Ring Road Fudiankou Xijiang super large bridge CF60 concrete is a new multi-phase composite high-performance concrete, this paper for the Fudiankou Xijiang bridge structure and characteristics of the project, in accordance with the principle of local materials and technical specification requirements, combined with the site conditions of CF60 engineering high performance concrete component materials, proportion and the technical performance, quantify the main physical and mechanical performance index. Analysis main influencing factors of the technical indicators, reasonable adjustment of concrete mix design parameters, and the use of technical means of admixture and multi-function composite admixture of concrete, obtain the optimal proportion of good work, process, mechanical properties stability and durability of engineering properties, recommend and verification of concrete mix; to explore the CF60 high performance concrete Soil in the Fudiankou Xijiang bridge application technology, detection and tracking the quality of concrete construction, concrete structure during the construction of the key technology and control points is proposed, evaluation of CF60 high performance concrete in the actual engineering application effect and benefit to ensure engineering quality of bridge structure and service life, and super long span bridge engineering construction to provide basis and reference.

Bonded foil pressure transducers

NASA Astrophysics Data System (ADS)

Daube, Bernie W.

The design of bonded-foil pressure transducers is discussed, with consideration given to individual components of both the electrical and the mechanical sections of the bonded-foil pressure transducers, as well as to the temperature control and the accuracy specification of these devices. Particular attention is given to applications of bonded foil pressure transducers, which include solid and liquid rocket engine testing for fuel and exhaust pressures, fuel and oil pressure monitoring on jet engines, and nuclear underground safety system pressure monitoring and nuclear test monitoring. A diagram of a transducer cutaway view is included.

Engine component instrumentation development facility at NASA Lewis Research Center

NASA Technical Reports Server (NTRS)

Bruckner, Robert J.; Buggele, Alvin E.; Lepicovsky, Jan

1992-01-01

The Engine Components Instrumentation Development Facility at NASA Lewis is a unique aeronautics facility dedicated to the development of innovative instrumentation for turbine engine component testing. Containing two separate wind tunnels, the facility is capable of simulating many flow conditions found in most turbine engine components. This facility's broad range of capabilities as well as its versatility provide an excellent location for the development of novel testing techniques. These capabilities thus allow a more efficient use of larger and more complex engine component test facilities.

Engineering controllable bidirectional molecular motors based on myosin

PubMed Central

Chen, Lu; Nakamura, Muneaki; Schindler, Tony D.; Parker, David; Bryant, Zev

2012-01-01

Cytoskeletal motors drive the transport of organelles and molecular cargoes within cells1, and have potential applications in molecular detection and diagnostic devices2,3. Engineering molecular motors with dynamically controllable properties will allow selective perturbation of mechanical processes in living cells, and yield optimized device components for complex tasks such as molecular sorting and directed assembly3. Biological motors have previously been modified by introducing activation/deactivation switches that respond to metal ions4,5 and other signals6. Here we show that myosin motors can be engineered to reversibly change their direction of motion in response to a calcium signal. Building on previous protein engineering studies7–11 and guided by a structural model12 for the redirected power stroke of myosin VI, we constructed bidirectional myosins through the rigid recombination of structural modules. The performance of the motors was confirmed using gliding filament assays and single fluorophore tracking. Our general strategy, in which external signals trigger changes in the geometry and mechanics of myosin lever arms, should enable spatiotemporal control over a range of motor properties including processivity, stride size13, and branchpoint turning14. PMID:22343382

Engineering controllable bidirectional molecular motors based on myosin

NASA Astrophysics Data System (ADS)

Chen, Lu; Nakamura, Muneaki; Schindler, Tony D.; Parker, David; Bryant, Zev

2012-04-01

Cytoskeletal motors drive the transport of organelles and molecular cargoes within cells and have potential applications in molecular detection and diagnostic devices. Engineering molecular motors with controllable properties will allow selective perturbation of mechanical processes in living cells and provide optimized device components for tasks such as molecular sorting and directed assembly. Biological motors have previously been modified by introducing activation/deactivation switches that respond to metal ions and other signals. Here, we show that myosin motors can be engineered to reversibly change their direction of motion in response to a calcium signal. Building on previous protein engineering studies and guided by a structural model for the redirected power stroke of myosin VI, we have constructed bidirectional myosins through the rigid recombination of structural modules. The performance of the motors was confirmed using gliding filament assays and single fluorophore tracking. Our strategy, in which external signals trigger changes in the geometry and mechanics of myosin lever arms, should make it possible to achieve spatiotemporal control over a range of motor properties including processivity, stride size and branchpoint turning.

Study on the variable cycle engine modeling techniques based on the component method

NASA Astrophysics Data System (ADS)

Zhang, Lihua; Xue, Hui; Bao, Yuhai; Li, Jijun; Yan, Lan

2016-01-01

Based on the structure platform of the gas turbine engine, the components of variable cycle engine were simulated by using the component method. The mathematical model of nonlinear equations correspondeing to each component of the gas turbine engine was established. Based on Matlab programming, the nonlinear equations were solved by using Newton-Raphson steady-state algorithm, and the performance of the components for engine was calculated. The numerical simulation results showed that the model bulit can describe the basic performance of the gas turbine engine, which verified the validity of the model.

Programmable motion of DNA origami mechanisms.

PubMed

Marras, Alexander E; Zhou, Lifeng; Su, Hai-Jun; Castro, Carlos E

2015-01-20

DNA origami enables the precise fabrication of nanoscale geometries. We demonstrate an approach to engineer complex and reversible motion of nanoscale DNA origami machine elements. We first design, fabricate, and characterize the mechanical behavior of flexible DNA origami rotational and linear joints that integrate stiff double-stranded DNA components and flexible single-stranded DNA components to constrain motion along a single degree of freedom and demonstrate the ability to tune the flexibility and range of motion. Multiple joints with simple 1D motion were then integrated into higher order mechanisms. One mechanism is a crank-slider that couples rotational and linear motion, and the other is a Bennett linkage that moves between a compacted bundle and an expanded frame configuration with a constrained 3D motion path. Finally, we demonstrate distributed actuation of the linkage using DNA input strands to achieve reversible conformational changes of the entire structure on ∼ minute timescales. Our results demonstrate programmable motion of 2D and 3D DNA origami mechanisms constructed following a macroscopic machine design approach.

Programmable motion of DNA origami mechanisms

PubMed Central

Marras, Alexander E.; Zhou, Lifeng; Su, Hai-Jun; Castro, Carlos E.

2015-01-01

DNA origami enables the precise fabrication of nanoscale geometries. We demonstrate an approach to engineer complex and reversible motion of nanoscale DNA origami machine elements. We first design, fabricate, and characterize the mechanical behavior of flexible DNA origami rotational and linear joints that integrate stiff double-stranded DNA components and flexible single-stranded DNA components to constrain motion along a single degree of freedom and demonstrate the ability to tune the flexibility and range of motion. Multiple joints with simple 1D motion were then integrated into higher order mechanisms. One mechanism is a crank–slider that couples rotational and linear motion, and the other is a Bennett linkage that moves between a compacted bundle and an expanded frame configuration with a constrained 3D motion path. Finally, we demonstrate distributed actuation of the linkage using DNA input strands to achieve reversible conformational changes of the entire structure on ∼minute timescales. Our results demonstrate programmable motion of 2D and 3D DNA origami mechanisms constructed following a macroscopic machine design approach. PMID:25561550

Simulation of Crack Propagation in Engine Rotating Components under Variable Amplitude Loading

NASA Technical Reports Server (NTRS)

Bonacuse, P. J.; Ghosn, L. J.; Telesman, J.; Calomino, A. M.; Kantzos, P.

1998-01-01

The crack propagation life of tested specimens has been repeatedly shown to strongly depend on the loading history. Overloads and extended stress holds at temperature can either retard or accelerate the crack growth rate. Therefore, to accurately predict the crack propagation life of an actual component, it is essential to approximate the true loading history. In military rotorcraft engine applications, the loading profile (stress amplitudes, temperature, and number of excursions) can vary significantly depending on the type of mission flown. To accurately assess the durability of a fleet of engines, the crack propagation life distribution of a specific component should account for the variability in the missions performed (proportion of missions flown and sequence). In this report, analytical and experimental studies are described that calibrate/validate the crack propagation prediction capability ]or a disk alloy under variable amplitude loading. A crack closure based model was adopted to analytically predict the load interaction effects. Furthermore, a methodology has been developed to realistically simulate the actual mission mix loading on a fleet of engines over their lifetime. A sequence of missions is randomly selected and the number of repeats of each mission in the sequence is determined assuming a Poisson distributed random variable with a given mean occurrence rate. Multiple realizations of random mission histories are generated in this manner and are used to produce stress, temperature, and time points for fracture mechanics calculations. The result is a cumulative distribution of crack propagation lives for a given, life limiting, component location. This information can be used to determine a safe retirement life or inspection interval for the given location.

Renovation of a mechanical engineering senior design class to an industry-tied and team-oriented course

NASA Astrophysics Data System (ADS)

Liu, Yucheng

2017-11-01

In this work, an industry-based and team-oriented education model was established based on a traditional mechanical engineering (ME) senior design class in order to better prepare future engineers and leaders so as to meet the increasing demand for high-quality engineering graduates. In the renovated curriculum, industry-sponsored projects became the most important course component and critical assessment tool, from which problem-solving skills as well as employability skills of the ME students can be fully developed. Hands-on experiences in finite element analysis (FEA) modelling and simulation were also added into the renovated curriculum to promote the application of FEA on engineering design and assessment. Evaluation of the renovated course was conducted using two instruments and the results have shown that the course made the ME senior students more prepared for their future career and a win-win model was created between the industry partner and the ME programme through it. Impact of the renovated syllabus on Accreditation Board for Engineering Technology goals was discussed. Based on the current progress, a more substantial change is being planned to further improve the effectiveness and practicability of this design course. The renovated course was started to offer to the ME senior students at Mississippi State University.

Engineering Education for a New Era

NASA Astrophysics Data System (ADS)

Ohgaki, Shinichiro

Engineering education is composed of five components, the idea what engineering education ought to be, the knowledge in engineering fields, those who learn engineering, those who teach engineering and the stakeholders in engineering issues. The characteristics of all these five components are changing with the times. When we consider the engineering education for the next era, we should analyze the changes of all five components. Especially the knowledge and tools in engineering fields has been expanding, and advanced science and technology is casting partly a dark shadow on the modern convenient life. Moral rules or ethics for developing new products and engineering systems are now regarded as most important in engineering fields. All those who take the responsibility for engineering education should understand the change of all components in engineering education and have a clear grasp of the essence of engineering for sustainable society.

Design Protocols and Analytical Strategies that Incorporate Structural Reliability Models

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.

1997-01-01

Ceramic matrix composites (CMC) and intermetallic materials (e.g., single crystal nickel aluminide) are high performance materials that exhibit attractive mechanical, thermal and chemical properties. These materials are critically important in advancing certain performance aspects of gas turbine engines. From an aerospace engineer's perspective the new generation of ceramic composites and intermetallics offers a significant potential for raising the thrust/weight ratio and reducing NO(x) emissions of gas turbine engines. These aspects have increased interest in utilizing these materials in the hot sections of turbine engines. However, as these materials evolve and their performance characteristics improve a persistent need exists for state-of-the-art analytical methods that predict the response of components fabricated from CMC and intermetallic material systems. This need provided the motivation for the technology developed under this research effort. Continuous ceramic fiber composites exhibit an increase in work of fracture, which allows for "graceful" rather than catastrophic failure. When loaded in the fiber direction, these composites retain substantial strength capacity beyond the initiation of transverse matrix cracking despite the fact that neither of its constituents would exhibit such behavior if tested alone. As additional load is applied beyond first matrix cracking, the matrix tends to break in a series of cracks bridged by the ceramic fibers. Any additional load is born increasingly by the fibers until the ultimate strength of the composite is reached. Thus modeling efforts supported under this research effort have focused on predicting this sort of behavior. For single crystal intermetallics the issues that motivated the technology development involved questions relating to material behavior and component design. Thus the research effort supported by this grant had to determine the statistical nature and source of fracture in a high strength, NiAl single crystal turbine blade material; map a simplistic failure strength envelope of the material; develop a statistically based reliability computer algorithm, verify the reliability model and computer algorithm, and model stator vanes for rig tests. Thus establishing design protocols that enable the engineer to analyze and predict the mechanical behavior of ceramic composites and intermetallics would mitigate the prototype (trial and error) approach currently used by the engineering community. The primary objective of the research effort supported by this short term grant is the continued creation of enabling technologies for the macroanalysis of components fabricated from ceramic composites and intermetallic material systems. The creation of enabling technologies aids in shortening the product development cycle of components fabricated from the new high technology materials.

Design Protocols and Analytical Strategies that Incorporate Structural Reliability Models

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.

1997-01-01

Ceramic matrix composites (CMC) and intermetallic materials (e.g., single crystal nickel aluminide) are high performance materials that exhibit attractive mechanical, thermal, and chemical properties. These materials are critically important in advancing certain performance aspects of gas turbine engines. From an aerospace engineers perspective the new generation of ceramic composites and intermetallics offers a significant potential for raising the thrust/weight ratio and reducing NO(sub x) emissions of gas turbine engines. These aspects have increased interest in utilizing these materials in the hot sections of turbine engines. However, as these materials evolve and their performance characteristics improve a persistent need exists for state-of-the-art analytical methods that predict the response of components fabricated from CMC and intermetallic material systems. This need provided the motivation for the technology developed under this research effort. Continuous ceramic fiber composites exhibit an increase in work of fracture, which allows for 'graceful' rather than catastrophic failure. When loaded in the fiber direction these composites retain substantial strength capacity beyond the initiation of transverse matrix cracking despite the fact that neither of its constituents would exhibit such behavior if tested alone. As additional load is applied beyond first matrix cracking, the matrix tends to break in a series of cracks bridged by the ceramic fibers. Any additional load is born increasingly by the fibers until the ultimate strength of the composite is reached. Thus modeling efforts supported under this research effort have focused on predicting this sort of behavior. For single crystal intermetallics the issues that motivated the technology development involved questions relating to material behavior and component design. Thus the research effort supported by this grant had to determine the statistical nature and source of fracture in a high strength, NiAl single crystal turbine blade material; map a simplistic future strength envelope of the material; develop a statistically based reliability computer algorithm; verify the reliability model and computer algorithm-, and model stator vanes for rig tests. Thus establishing design protocols that enable the engineer to analyze and predict the mechanical behavior of ceramic composites and intermetallics would mitigate the prototype (trial and error) approach currently used by the engineering community. The primary objective of the research effort supported by this short term grant is the continued creation of enabling technologies for the macro-analysis of components fabricated from ceramic composites and intermetallic material systems. The creation of enabling technologies aids in shortening the product development cycle of components fabricated from the new high technology materials.

Reflections on the mechanical structure of the base of the skull and on the face. Part 1: Classical theories, observed structures.

PubMed

Ferré, J C; Chevalier, C; Robert, R; Degrez, J; Le Cloarec, A Y; Legoux, R; Orio, E; Barbin, J Y

1989-01-01

Using thick sections of the base of the skull and face their mechanical structure is viewed from the engineering aspect and the anatomic solutions evolved are compared with those selected by Aerospatiale engineers for the concept and development of the Airbus. It is concluded that the anterior and middle cranial fossae, together with the face, constitute an inseparable mechanical assembly each of whose component units participate in the rigidity of the others. Since this mechanical assembly must provide maximal rigidity for minimal weight, this suggests that aeronautical solutions should throw much light on the detail of construction of the skull and face. Indeed, the rigidity and lightness of the latter are obtained by means of solutions familiar in aeronautics: the reliance on thin-shelled beams with a honeycomb filling, the diploe analogous to a preconstrained composite or sandwich structure, a system of frames, struts and stiffeners, and the use of fillets at the sites of junction of struts.

The technique for Simulation of Transient Combustion Processes in the Rocket Engine Operating with Gaseous Fuel “Hydrogen and Oxygen”

NASA Astrophysics Data System (ADS)

Zubanov, V. M.; Stepanov, D. V.; Shabliy, L. S.

2017-01-01

The article describes the method for simulation of transient combustion processes in the rocket engine. The engine operates on gaseous propellant: oxygen and hydrogen. Combustion simulation was performed using the ANSYS CFX software. Three reaction mechanisms for the stationary mode were considered and described in detail. Reactions mechanisms have been taken from several sources and verified. The method for converting ozone properties from the Shomate equation to the NASA-polynomial format was described in detail. The way for obtaining quick CFD-results with intermediate combustion components using an EDM model was found. Modeling difficulties with combustion model Finite Rate Chemistry, associated with a large scatter of reference data were identified and described. The way to generate the Flamelet library with CFX-RIF is described. Formulated adequate reaction mechanisms verified at a steady state have also been tested for transient simulation. The Flamelet combustion model was recognized as adequate for the transient mode. Integral parameters variation relates to the values obtained during stationary simulation. A cyclic irregularity of the temperature field, caused by precession of the vortex core, was detected in the chamber with the proposed simulation technique. Investigations of unsteady processes of rocket engines including the processes of ignition were proposed as the area for application of the described simulation technique.

Ultrasound Technologies for the Spatial Patterning of Cells and Extracellular Matrix Proteins and the Vascularization of Engineered Tissue

NASA Astrophysics Data System (ADS)

Garvin, Kelley A.

Technological advancements in the field of tissue engineering could save the lives of thousands of organ transplant patients who die each year while waiting for donor organs. Currently, two of the primary challenges preventing tissue engineers from developing functional replacement tissues and organs are the need to recreate complex cell and extracellular microenvironments and to vascularize the tissue to maintain cell viability and function. Ultrasound is a form of mechanical energy that can noninvasively and nondestructively interact with tissues at the cell and protein level. In this thesis, novel ultrasound-based technologies were developed for the spatial patterning of cells and extracellular matrix proteins and the vascularization of three-dimensional engineered tissue constructs. Acoustic radiation forces associated with ultrasound standing wave fields were utilized to noninvasively control the spatial organization of cells and cell-bound extracellular matrix proteins within collagen-based engineered tissue. Additionally, ultrasound induced thermal mechanisms were exploited to site-specifically pattern various extracellular matrix collagen microstructures within a single engineered tissue construct. Finally, ultrasound standing wave field technology was used to promote the rapid and extensive vascularization of three-dimensional tissue constructs. As such, the ultrasound technologies developed in these studies have the potential to provide the field of tissue engineering with novel strategies to spatially pattern cells and extracellular matrix components and to vascularize engineered tissue, and thus, could advance the fabrication of functional replacement tissues and organs in the field of tissue engineering.

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1991-01-01

This report summarizes work performed in support of the development and demonstration of a structural ceramic technology for automotive gas turbine engines. The AGT101 regenerated gas turbine engine developed under the previous DOE/NASA Advanced Gas Turbine (AGT) program is being utilized for verification testing of the durability of next-generation ceramic components and their suitability for service at reference powertrain design conditions. Topics covered in this report include ceramic processing definition and refinement, design improvements to the test bed engine and test rigs, and design methodologies related to ceramic impact and fracture mechanisms. Appendices include reports by ATTAP subcontractors addressing the development of silicon nitride and silicon carbide families of materials and processes.

Fuel-Efficient Descent and Landing Guidance Logic for a Safe Lunar Touchdown

NASA Technical Reports Server (NTRS)

Lee, Allan Y.

2011-01-01

The landing of a crewed lunar lander on the surface of the Moon will be the climax of any Moon mission. At touchdown, the landing mechanism must absorb the load imparted on the lander due to the vertical component of the lander's touchdown velocity. Also, a large horizontal velocity must be avoided because it could cause the lander to tip over, risking the life of the crew. To be conservative, the worst-case lander's touchdown velocity is always assumed in designing the landing mechanism, making it very heavy. Fuel-optimal guidance algorithms for soft planetary landing have been studied extensively. In most of these studies, the lander is constrained to touchdown with zero velocity. With bounds imposed on the magnitude of the engine thrust, the optimal control solutions typically have a "bang-bang" thrust profile: the thrust magnitude "bangs" instantaneously between its maximum and minimum magnitudes. But the descent engine might not be able to throttle between its extremes instantaneously. There is also a concern about the acceptability of "bang-bang" control to the crew. In our study, the optimal control of a lander is formulated with a cost function that penalizes both the touchdown velocity and the fuel cost of the descent engine. In this formulation, there is not a requirement to achieve a zero touchdown velocity. Only a touchdown velocity that is consistent with the capability of the landing gear design is required. Also, since the nominal throttle level for the terminal descent sub-phase is well below the peak engine thrust, no bound on the engine thrust is used in our formulated problem. Instead of bangbang type solution, the optimal thrust generated is a continuous function of time. With this formulation, we can easily derive analytical expressions for the optimal thrust vector, touchdown velocity components, and other system variables. These expressions provide insights into the "physics" of the optimal landing and terminal descent maneuver. These insights could help engineers to achieve a better "balance" between the conflicting needs of achieving a safe touchdown velocity, a low-weight landing mechanism, low engine fuel cost, and other design goals. In comparing the computed optimal control results with the preflight landing trajectory design of the Apollo-11 mission, we noted interesting similarities between the two missions.

The logics of metabolic regulation in bacteria challenges biosensor-based metabolic engineering.

PubMed

Jules, Matthieu

2017-12-11

Synthetic Biology (SB) aims at the rational design and engineering of novel biological functions and systems. By facilitating the engineering of living organisms, SB promises to facilitate the development of many new applications for health, biomanufacturing, and the environment. Over the last decade, SB promoted the construction of libraries of components enabling the fine-tuning of genetic circuits expression and the development of novel genome engineering methodologies for many organisms of interest. SB thus opened new perspectives in the field of metabolic engineering, which was until then mainly limited to (over)producing naturally synthesized metabolic compounds. To engineer efficient cell factories, it is key to precisely reroute cellular resources from the central carbon metabolism (CCM) to the synthetic circuitry. This task is however difficult as there is still significant lack of knowledge regarding both the function of several metabolic components and the regulation of the CCM fluxes for many industrially important bacteria. Pyruvate is a pivotal metabolite at the heart of the CCM and a key precursor for the synthesis of several commodity compounds and fine chemicals. Numerous bacterial species can also use it as a carbon source when present in the environment but bacterial, pyruvate-specific uptake systems were to be discovered. This is an issue for metabolic engineering as one can imagine to make use of pyruvate transport systems to replenish synthetic metabolic pathways towards the synthesis of chemicals of interest. Here we describe a recent study (MBio 8(5): e00976-17), which identified and characterized a pyruvate transport system in the Gram-positive (G +ve ) bacterium Bacillus subtilis , a well-established biotechnological workhorse for the production of enzymes, fine chemicals and antibiotics. This study also revealed that the activity of the two-component system (TCS) responsible for its induction is retro-inhibited by the level of pyruvate influx. Following up on the open question which is whether this retro-inhibition is a generic mechanism for TCSs, we will discuss the implications in metabolic engineering.

Microstructural and Mechanical Aspects of Reinforcement Welds for Lightweight Components Produced by Friction Hydro Pillar Processing

NASA Astrophysics Data System (ADS)

Pinheiro, Gustavo; dos Santos, Jorge; Hort, Norbert; Kainer, Karl Ulrich

The development of new creep resistant and cost effective die casting magnesium alloys such as AE, MRI, MEZ, ACM, AXJ, AJ, WE have emerged as an alternative to fulfil the actual demands in structural relevant applications as engines blocks, gear and converter boxes. However, magnesium components are in most of the cases screwed with aluminium and steel bolts, which lead the screwed joint to lose the preload force due to relaxation. This barrier limits thus the broad use of magnesium within this segment and should somehow find an adequate solution to be implemented and to help overcoming this limitation. In this context Friction Welding (FW) and particularly Friction Hydro Pillar Processing (FHPP), which can be described as a drill and fill process, appears as an alternative to widespread the use of magnesium. In this context, FHPP is intended to be used to locally reinforce mechanical fastened magnesium components.

Recent Tissue Engineering Advances for the Treatment of Temporomandibular Joint Disorders.

PubMed

Aryaei, Ashkan; Vapniarsky, Natalia; Hu, Jerry C; Athanasiou, Kyriacos A

2016-12-01

Temporomandibular disorders (TMDs) are among the most common maxillofacial complaints and a major cause of orofacial pain. Although current treatments provide short- and long-term relief, alternative tissue engineering solutions are in great demand. Particularly, the development of strategies, providing long-term resolution of TMD to help patients regain normal function, is a high priority. An absolute prerequisite of tissue engineering is to understand normal structure and function. The current knowledge of anatomical, mechanical, and biochemical characteristics of the temporomandibular joint (TMJ) and associated tissues will be discussed, followed by a brief description of current TMD treatments. The main focus is on recent tissue engineering developments for regenerating TMJ tissue components, with or without a scaffold. The expectation for effectively managing TMD is that tissue engineering will produce biomimetic TMJ tissues that recapitulate the normal structure and function of the TMJ.

Recent tissue engineering advances for the treatment of temporomandibular joint disorders

PubMed Central

Aryaei, Ashkan; Vapniarsky, Natalia; Hu, Jerry C; Athanasiou, Kyriacos A

2016-01-01

Temporomandibular disorders (TMD) are among the most common maxillofacial complaints and a major cause of orofacial pain. Although, current treatments provide short- and long-term relief, alternative tissue engineering solutions are in great demand. Particularly, the development of strategies, providing long-term resolution of TMD to help patients regain normal function is a high priority. An absolute prerequisite of tissue engineering is to understand normal structure and function. The current knowledge of anatomical, mechanical, and biochemical characteristics of the temporomandibular joint (TMJ) and associated tissues will be discussed, followed by a brief description of current TMD treatments. The main focus is on recent tissue engineering developments for regenerating TMJ tissue components, with or without a scaffold. The expectation for effectively managing TMD is that tissue engineering will produce biomimetic TMJ tissues that recapitulate the normal structure and function of the TMJ. PMID:27704395

Development Status and Performance Comparisons of Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan

2016-01-01

Environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft turbine engine systems, because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. This paper presents current NASA EBC-CMC development emphases including: the coating composition and processing improvements, laser high heat flux-thermal gradient thermo-mechanical fatigue - environmental testing methodology development, and property evaluations for next generation EBC-CMC systems. EBCs processed with various deposition techniques including Plasma Spray, Electron Beam - Physical Vapor Deposition, and Plasma Spray Physical Vapor Deposition (PS-PVD) will be particularly discussed. The testing results and demonstrations of advanced EBCs-CMCs in complex simulated engine thermal gradient cyclic fatigue, oxidizing-steam and CMAS environments will help provide insights into the coating development strategies to meet long-term engine component durability goals.

Accelerated testing of space mechanisms

NASA Technical Reports Server (NTRS)

Murray, S. Frank; Heshmat, Hooshang

1995-01-01

This report contains a review of various existing life prediction techniques used for a wide range of space mechanisms. Life prediction techniques utilized in other non-space fields such as turbine engine design are also reviewed for applicability to many space mechanism issues. The development of new concepts on how various tribological processes are involved in the life of the complex mechanisms used for space applications are examined. A 'roadmap' for the complete implementation of a tribological prediction approach for complex mechanical systems including standard procedures for test planning, analytical models for life prediction and experimental verification of the life prediction and accelerated testing techniques are discussed. A plan is presented to demonstrate a method for predicting the life and/or performance of a selected space mechanism mechanical component.

Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions (Invited paper)

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2008-01-01

Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2008-01-01

Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

A Robust Damage-Reporting Strategy for Polymeric Materials Enabled by Aggregation-Induced Emission.

PubMed

Robb, Maxwell J; Li, Wenle; Gergely, Ryan C R; Matthews, Christopher C; White, Scott R; Sottos, Nancy R; Moore, Jeffrey S

2016-09-28

Microscopic damage inevitably leads to failure in polymers and composite materials, but it is difficult to detect without the aid of specialized equipment. The ability to enhance the detection of small-scale damage prior to catastrophic material failure is important for improving the safety and reliability of critical engineering components, while simultaneously reducing life cycle costs associated with regular maintenance and inspection. Here, we demonstrate a simple, robust, and sensitive fluorescence-based approach for autonomous detection of damage in polymeric materials and composites enabled by aggregation-induced emission (AIE). This simple, yet powerful system relies on a single active component, and the general mechanism delivers outstanding performance in a wide variety of materials with diverse chemical and mechanical properties.

Integrated optical motor.

PubMed

Kelemen, Lóránd; Valkai, Sándor; Ormos, Pál

2006-04-20

A light-driven micrometer-sized mechanical motor is created by laser-light-induced two-photon photopolymerization. All necessary components of the engine are built upon a glass surface by an identical procedure and include the following: a rigid mechanical framework, a rotor freely rotating on an axis, and an integrated optical waveguide carrying the actuating light to the rotor. The resulting product is a most practical stand-alone system. The light introduced into the integrated optical waveguide input of the motor provides the driving force: neither optical tweezers or even a microscope are needed for the function. The power and efficiency of the motor are evaluated. The independent unit is expected to become an important component of more complex integrated lab-on-a-chip devices.

Supplementation of exogenous adenosine 5'-triphosphate enhances mechanical properties of 3D cell-agarose constructs for cartilage tissue engineering.

PubMed

Gadjanski, Ivana; Yodmuang, Supansa; Spiller, Kara; Bhumiratana, Sarindr; Vunjak-Novakovic, Gordana

2013-10-01

Formation of tissue-engineered cartilage is greatly enhanced by mechanical stimulation. However, direct mechanical stimulation is not always a suitable method, and the utilization of mechanisms underlying mechanotransduction might allow for a highly effective and less aggressive alternate means of stimulation. In particular, the purinergic, adenosine 5'-triphosphate (ATP)-mediated signaling pathway is strongly implicated in mechanotransduction within the articular cartilage. We investigated the effects of transient and continuous exogenous ATP supplementation on mechanical properties of cartilaginous constructs engineered using bovine chondrocytes and human mesenchymal stem cells (hMSCs) encapsulated in an agarose hydrogel. For both cell types, we have observed significant increases in equilibrium and dynamic compressive moduli after transient ATP treatment applied in the fourth week of cultivation. Continuous ATP treatment over 4 weeks of culture only slightly improved the mechanical properties of the constructs, without major changes in the total glycosaminoglycan (GAG) and collagen content. Structure-function analyses showed that transiently ATP-treated constructs, and in particular those based on hMSCs, had the highest level of correlation between compositional and mechanical properties. Transiently treated groups showed intense staining of the territorial matrix for GAGs and collagen type II. These results indicate that transient ATP treatment can improve functional mechanical properties of cartilaginous constructs based on chondrogenic cells and agarose hydrogels, possibly by improving the structural organization of the bulk phase and territorial extracellular matrix (ECM), that is, by increasing correlation slopes between the content of the ECM components (GAG, collagen) and mechanical properties of the construct.

Low-Speed Fan Noise Attenuation from a Foam-Metal Liner

NASA Technical Reports Server (NTRS)

Sutliff, Daniel L.; Jones, Michael G.

2011-01-01

A foam-metal liner for attenuation of fan noise was developed for and tested on a low-speed fan. This type of liner represents a significant advance over traditional liners, due to the possibility of placement in close proximity to the rotor. An advantage of placing treatment in this region is that the acoustic near field is modified, thereby inhibiting the noise-generation mechanism. This can result in higher attenuation levels than could be achieved by liners located in the nacelle inlet. In addition, foam-metal liners could potentially replace the fan rub strip and containment components, ultimately reducing engine components and thus weight, which can result in a systematic increase in noise reduction and engine performance. Foam-metal liners have the potential to reduce fan noise by 4 dB based on this study.

Engineered Graphene Materials: Synthesis and Applications for Polymer Electrolyte Membrane Fuel Cells.

PubMed

He, Daping; Tang, Haolin; Kou, Zongkui; Pan, Mu; Sun, Xueliang; Zhang, Jiujun; Mu, Shichun

2017-05-01

Engineered graphene materials (EGMs) with unique structures and properties have been incorporated into various components of polymer electrolyte membrane fuel cells (PEMFCs) such as electrode, membrane, and bipolar plates to achieve enhanced performances in terms of electrical conductivity, mechanical durability, corrosion resistance, and electrochemical surface area. This research news article provides an overview of the recent development in EGMs and EGM-based PEMFCs with a focus on the effects of EGMs on PEMFC performance when they are incorporated into different components of PEMFCs. The challenges of EGMs for practical PEMFC applications in terms of production scale, stability, conductivity, and coupling capability with other materials are also discussed and the corresponding measures and future research trends to overcome such challenges are proposed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method of Matching Performance of Compressor Systems with that of Aircraft Power Sections

NASA Technical Reports Server (NTRS)

Bullock, Robert O.; Keetch, Robert C.; Moses, Jason J.

1945-01-01

A method is developed of easily determining the performance of a compressor system relative to that of the power section for a given altitude. Because compressors, reciprocating engines, and turbines are essentially flow devices, the performance of each of these power-plant components is presented in terms of similar dimensionless ratios. The pressure and temperature changes resulting from restrictions of the charge-air flow and from heat transfer in the ducts connecting the components of the power plant are also expressed by the same dimensionless ratios and the losses are included in the performance of the compressor. The performance of a mechanically driven, single-stage compressor in relation to the performance of a conventional air-cooled engine operating at sea-level conditions is presented as an example of the application of the method.

Waste IPSC : Thermal-Hydrologic-Chemical-Mechanical (THCM) modeling and simulation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeze, Geoffrey A.; Wang, Yifeng; Arguello, Jose Guadalupe, Jr.

2010-10-01

Waste IPSC Objective is to develop an integrated suite of high performance computing capabilities to simulate radionuclide movement through the engineered components and geosphere of a radioactive waste storage or disposal system: (1) with robust thermal-hydrologic-chemical-mechanical (THCM) coupling; (2) for a range of disposal system alternatives (concepts, waste form types, engineered designs, geologic settings); (3) for long time scales and associated large uncertainties; (4) at multiple model fidelities (sub-continuum, high-fidelity continuum, PA); and (5) in accordance with V&V and software quality requirements. THCM Modeling collaborates with: (1) Other Waste IPSC activities: Sub-Continuum Processes (and FMM), Frameworks and Infrastructure (and VU,more » ECT, and CT); (2) Waste Form Campaign; (3) Used Fuel Disposition (UFD) Campaign; and (4) ASCEM.« less

Development of a Prototype Simulation Executive with Zooming in the Numerical Propulsion System Simulation

NASA Technical Reports Server (NTRS)

Reed, John A.; Afjeh, Abdollah A.

1995-01-01

A major difficulty in designing aeropropulsion systems is that of identifying and understanding the interactions between the separate engine components and disciplines (e.g., fluid mechanics, structural mechanics, heat transfer, material properties, etc.). The traditional analysis approach is to decompose the system into separate components with the interaction between components being evaluated by the application of each of the single disciplines in a sequential manner. Here, one discipline uses information from the calculation of another discipline to determine the effects of component coupling. This approach, however, may not properly identify the consequences of these effects during the design phase, leaving the interactions to be discovered and evaluated during engine testing. This contributes to the time and cost of developing new propulsion systems as, typically, several design-build-test cycles are needed to fully identify multidisciplinary effects and reach the desired system performance. The alternative to sequential isolated component analysis is to use multidisciplinary coupling at a more fundamental level. This approach has been made more plausible due to recent advancements in computation simulation along with application of concurrent engineering concepts. Computer simulation systems designed to provide an environment which is capable of integrating the various disciplines into a single simulation system have been proposed and are currently being developed. One such system is being developed by the Numerical Propulsion System Simulation (NPSS) project. The NPSS project, being developed at the Interdisciplinary Technology Office at the NASA Lewis Research Center is a 'numerical test cell' designed to provide for comprehensive computational design and analysis of aerospace propulsion systems. It will provide multi-disciplinary analyses on a variety of computational platforms, and a user-interface consisting of expert systems, data base management and visualization tools, to allow the designer to investigate the complex interactions inherent in these systems. An interactive programming software system, known as the Application Visualization System (AVS), was utilized for the development of the propulsion system simulation. The modularity of this system provides the ability to couple propulsion system components, as well as disciplines, and provides for the ability to integrate existing, well established analysis codes into the overall system simulation. This feature allows the user to customize the simulation model by inserting desired analysis codes. The prototypical simulation environment for multidisciplinary analysis, called Turbofan Engine System Simulation (TESS), which incorporates many of the characteristics of the simulation environment proposed herein, is detailed.

Thermal Energy Conversion Branch

NASA Technical Reports Server (NTRS)

Bielozer, Matthew C.; Schreiber, Jeffrey, G.; Wilson, Scott D.

2004-01-01

The Thermal Energy Conversion Branch (5490) leads the way in designing, conducting, and implementing research for the newest thermal systems used in space applications at the NASA Glenn Research Center. Specifically some of the most advanced technologies developed in this branch can be broken down into four main areas: Dynamic Power Systems, Primary Solar Concentrators, Secondary Solar Concentrators, and Thermal Management. Work was performed in the Dynamic Power Systems area, specifically the Stirling Engine subdivision. Today, the main focus of the 5490 branch is free-piston Stirling cycle converters, Brayton cycle nuclear reactors, and heat rejection systems for long duration mission spacecraft. All space exploring devices need electricity to operate. In most space applications, heat energy from radioisotopes is converted to electrical power. The Radioisotope Thermoelectric Generator (RTG) already supplies electricity for missions such as the Cassini Spacecraft. The focus of today's Stirling research at GRC is aimed at creating an engine that can replace the RTG. The primary appeal of the Stirling engine is its high system efficiency. Because it is so efficient, the Stirling engine will significantly reduce the plutonium fuel mission requirements compared to the RTG. Stirling is also being considered for missions such as the lunar/Mars bases and rovers. This project has focused largely on Stirling Engines of all types, particularly the fluidyne liquid piston engine. The fluidyne was developed by Colin D. West. This engine uses the same concepts found in any type of Stirling engine, with the exception of missing mechanical components. All the working components are fluid. One goal was to develop and demonstrate a working Stirling Fluidyne Engine at the 2nd Annual International Energy Conversion Engineering Conference in Providence, Rhode Island.

Recent Advances in Composite Damage Mechanics

NASA Technical Reports Server (NTRS)

Reifsnider, Ken; Case, Scott; Iyengar, Nirmal

1996-01-01

The state of the art and recent developments in the field of composite material damage mechanics are reviewed, with emphasis on damage accumulation. The kinetics of damage accumulation are considered with emphasis on the general accumulation of discrete local damage events such as single or multiple fiber fractures or microcrack formation. The issues addressed include: how to define strength in the presence of widely distributed damage, and how to combine mechanical representations in order to predict the damage tolerance and life of engineering components. It is shown that a damage mechanics approach can be related to the thermodynamics of the damage accumulation processes in composite laminates subjected to mechanical loading and environmental conditions over long periods of time.

Powder metallurgy approaches to high temperature components for gas turbine engines

NASA Technical Reports Server (NTRS)

Probst, H. B.

1974-01-01

Research is reported for the tensile strength, ductility, and heat performance characterisitics of powder metallurgy (p/m) superalloys. Oxide dispersion strengthened alloys were also evaluated for their strength during thermal processing. The mechanical attributes evident in both p/m supperalloys and dispersion strengthened alloys are discussed in terms of research into their possible combination.

Effect of stringer repair methods and repair frequency on GMA performance

Treesearch

John W. Clarke; Marshall S. White; Philip A. Araman

2005-01-01

Over 135 million wooden pallets were repaired for reuse in 1995. Notched stringers are one of the most commonly damaged components. Metal plates, half companion stringers, and full companion stringers are repair methods described in the U.S. industry standard published by the American Society of Mechanical Engineers. This study evaluated the effect of these three...

Effect of Individual Component Life Distribution on Engine Life Prediction

NASA Technical Reports Server (NTRS)

Zaretsky, Erwin V.; Hendricks, Robert C.; Soditus, Sherry M.

2003-01-01

The effect of individual engine component life distributions on engine life prediction was determined. A Weibull-based life and reliability analysis of the NASA Energy Efficient Engine was conducted. The engine s life at a 95 and 99.9 percent probability of survival was determined based upon the engine manufacturer s original life calculations and assumed values of each of the component s cumulative life distributions as represented by a Weibull slope. The lives of the high-pressure turbine (HPT) disks and blades were also evaluated individually and as a system in a similar manner. Knowing the statistical cumulative distribution of each engine component with reasonable engineering certainty is a condition precedent to predicting the life and reliability of an entire engine. The life of a system at a given reliability will be less than the lowest-lived component in the system at the same reliability (probability of survival). Where Weibull slopes of all the engine components are equal, the Weibull slope had a minimal effect on engine L(sub 0.1) life prediction. However, at a probability of survival of 95 percent (L(sub 5) life), life decreased with increasing Weibull slope.

The application of S-transformation and M-2DPCA in I.C. Engine fault diagnosis

NASA Astrophysics Data System (ADS)

Zhang, Shixiong; Cai, Yanping; Mu, Weijie

2017-04-01

According to the problem of parameter selection and feature extraction for vibration diagnosis of traditional internal combustion engine is discussed. The method based on S-transformation and Module Two Dimensional Principal Components Analysis (M-2DPCA) is proposed to carry out fault diagnosis of I.C. Engine valve mechanism. First of all, the method transfers cylinder surface vibration signals of I.C. into images through S-transform. The second, extracting the optimized projection vectors from the general distribution matrix G which is obtained by all sample sub-images, so that vibration spectrum images can be modularized using M-2DPCA. The last, these features matrix obtained from images project will served as the enters of nearest neighbor classifier, it is used to achieve fault types' division. The method is applied to the diagnosis example of the vibration signal of the valve mechanism eight operating modes, recognition rate up to 94.17 percent; the effectiveness of the proposed method is proved.

Degradation Mechanisms of an Advanced Jet Engine Service-Retired TBC Component

NASA Astrophysics Data System (ADS)

Wu, Rudder T.; Osawa, Makoto; Yokokawa, Tadaharu; Kawagishi, Kyoko; Harada, Hiroshi

Current use of TBCs is subjected to premature spallation failure mainly due to the formation of thermally grown oxides (TGOs). Although extensive research has been carried out to gain better understanding of the thermo - mechanical and -chemical characteristics of TBCs, laboratory-scale studies and simulation tests are often carried out in conditions significantly differed from the complex and extreme environment typically of a modern gas-turbine engine, thus, failed to truly model service conditions. In particular, the difference in oxygen partial pressure and the effects of contaminants present in the engine compartment have often been neglected. In this respect, an investigation is carried out to study the in-service degradation of an EB-PVD TBC coated nozzle-guide vane. Several modes of degradation were observed due to three factors: 1) presence of residual stresses induced by the thermal-expansion mismatches, 2) evolution of bond coat microstructure and subsequent formation of oxide spinels, 3) deposition of CMAS on the surface of TBC.

Improving Engine Efficiency Through Core Developments

NASA Technical Reports Server (NTRS)

Heidmann, James D.

2011-01-01

The NASA Environmentally Responsible Aviation (ERA) Project and Fundamental Aeronautics Projects are supporting compressor and turbine research with the goal of reducing aircraft engine fuel burn and greenhouse gas emissions. The primary goals of this work are to increase aircraft propulsion system fuel efficiency for a given mission by increasing the overall pressure ratio (OPR) of the engine while maintaining or improving aerodynamic efficiency of these components. An additional area of work involves reducing the amount of cooling air required to cool the turbine blades while increasing the turbine inlet temperature. This is complicated by the fact that the cooling air is becoming hotter due to the increases in OPR. Various methods are being investigated to achieve these goals, ranging from improved compressor three-dimensional blade designs to improved turbine cooling hole shapes and methods. Finally, a complementary effort in improving the accuracy, range, and speed of computational fluid mechanics (CFD) methods is proceeding to better capture the physical mechanisms underlying all these problems, for the purpose of improving understanding and future designs.

FlowGo: An Educational Kit for Fluid Dynamics and Heat Transfer

NASA Astrophysics Data System (ADS)

Guri, Dominic; Portsmore, Merredith; Kemmerling, Erica

2015-11-01

The authors have designed and prototyped an educational toolkit that will help middle-school-aged students learn fundamental fluid mechanics and heat transfer concepts in a hands-on play environment. The kit allows kids to build arbitrary flow rigs to solve fluid mechanics and heat transfer challenge problems. Similar kits for other engineering fields, such as structural and electrical engineering, have resulted in pedagogical improvements, particularly in early engineering education, where visual demonstrations have a significant impact. Using the FlowGo kit, students will be able to conduct experiments and develop new design ideas to solve challenge problems such as building plant watering systems or modeling water and sewage reticulation. The toolkit consists of components such as tubes, junctions, and reservoirs that easily snap together via a modular, universal connector. Designed with the Massachusetts K-12 science standards in mind, this kit is intended to be affordable and suitable for classroom use. Results and user feedback from students conducting preliminary tests of the kit will be presented.

Coupled multi-disciplinary simulation of composite engine structures in propulsion environment

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Singhal, Surendra N.

1992-01-01

A computational simulation procedure is described for the coupled response of multi-layered multi-material composite engine structural components which are subjected to simultaneous multi-disciplinary thermal, structural, vibration, and acoustic loadings including the effect of hostile environments. The simulation is based on a three dimensional finite element analysis technique in conjunction with structural mechanics codes and with acoustic analysis methods. The composite material behavior is assessed at the various composite scales, i.e., the laminate/ply/constituents (fiber/matrix), via a nonlinear material characterization model. Sample cases exhibiting nonlinear geometrical, material, loading, and environmental behavior of aircraft engine fan blades, are presented. Results for deformed shape, vibration frequency, mode shapes, and acoustic noise emitted from the fan blade, are discussed for their coupled effect in hot and humid environments. Results such as acoustic noise for coupled composite-mechanics/heat transfer/structural/vibration/acoustic analyses demonstrate the effectiveness of coupled multi-disciplinary computational simulation and the various advantages of composite materials compared to metals.

Mechanism reduction for multicomponent surrogates: A case study using toluene reference fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niemeyer, Kyle E.; Sung, Chih-Jen

Strategies and recommendations for performing skeletal reductions of multicomponent surrogate fuels are presented, through the generation and validation of skeletal mechanisms for a three-component toluene reference fuel. Using the directed relation graph with error propagation and sensitivity analysis method followed by a further unimportant reaction elimination stage, skeletal mechanisms valid over comprehensive and high-temperature ranges of conditions were developed at varying levels of detail. These skeletal mechanisms were generated based on autoignition simulations, and validation using ignition delay predictions showed good agreement with the detailed mechanism in the target range of conditions. When validated using phenomena other than autoignition, suchmore » as perfectly stirred reactor and laminar flame propagation, tight error control or more restrictions on the reduction during the sensitivity analysis stage were needed to ensure good agreement. In addition, tight error limits were needed for close prediction of ignition delay when varying the mixture composition away from that used for the reduction. In homogeneous compression-ignition engine simulations, the skeletal mechanisms closely matched the point of ignition and accurately predicted species profiles for lean to stoichiometric conditions. Furthermore, the efficacy of generating a multicomponent skeletal mechanism was compared to combining skeletal mechanisms produced separately for neat fuel components; using the same error limits, the latter resulted in a larger skeletal mechanism size that also lacked important cross reactions between fuel components. Based on the present results, general guidelines for reducing detailed mechanisms for multicomponent fuels are discussed.« less

Mechanism reduction for multicomponent surrogates: A case study using toluene reference fuels

DOE PAGES

Niemeyer, Kyle E.; Sung, Chih-Jen

2014-11-01

Strategies and recommendations for performing skeletal reductions of multicomponent surrogate fuels are presented, through the generation and validation of skeletal mechanisms for a three-component toluene reference fuel. Using the directed relation graph with error propagation and sensitivity analysis method followed by a further unimportant reaction elimination stage, skeletal mechanisms valid over comprehensive and high-temperature ranges of conditions were developed at varying levels of detail. These skeletal mechanisms were generated based on autoignition simulations, and validation using ignition delay predictions showed good agreement with the detailed mechanism in the target range of conditions. When validated using phenomena other than autoignition, suchmore » as perfectly stirred reactor and laminar flame propagation, tight error control or more restrictions on the reduction during the sensitivity analysis stage were needed to ensure good agreement. In addition, tight error limits were needed for close prediction of ignition delay when varying the mixture composition away from that used for the reduction. In homogeneous compression-ignition engine simulations, the skeletal mechanisms closely matched the point of ignition and accurately predicted species profiles for lean to stoichiometric conditions. Furthermore, the efficacy of generating a multicomponent skeletal mechanism was compared to combining skeletal mechanisms produced separately for neat fuel components; using the same error limits, the latter resulted in a larger skeletal mechanism size that also lacked important cross reactions between fuel components. Based on the present results, general guidelines for reducing detailed mechanisms for multicomponent fuels are discussed.« less

Fibrin gels exhibit improved biological, structural, and mechanical properties compared with collagen gels in cell-based tendon tissue-engineered constructs.

PubMed

Breidenbach, Andrew P; Dyment, Nathaniel A; Lu, Yinhui; Rao, Marepalli; Shearn, Jason T; Rowe, David W; Kadler, Karl E; Butler, David L

2015-02-01

The prevalence of tendon and ligament injuries and inadequacies of current treatments is driving the need for alternative strategies such as tissue engineering. Fibrin and collagen biopolymers have been popular materials for creating tissue-engineered constructs (TECs), as they exhibit advantages of biocompatibility and flexibility in construct design. Unfortunately, a few studies have directly compared these materials for tendon and ligament applications. Therefore, this study aims at determining how collagen versus fibrin hydrogels affect the biological, structural, and mechanical properties of TECs during formation in vitro. Our findings show that tendon and ligament progenitor cells seeded in fibrin constructs exhibit improved tenogenic gene expression patterns compared with their collagen-based counterparts for approximately 14 days in culture. Fibrin-based constructs also exhibit improved cell-derived collagen alignment, increased linear modulus (2.2-fold greater) compared with collagen-based constructs. Cyclic tensile loading, which promotes the maturation of tendon constructs in a previous work, exhibits a material-dependent effect in this study. Fibrin constructs show trending reductions in mechanical, biological, and structural properties, whereas collagen constructs only show improved tenogenic expression in the presence of mechanical stimulation. These findings highlight that components of the mechanical stimulus (e.g., strain amplitude or time of initiation) need to be tailored to the material and cell type. Given the improvements in tenogenic expression, extracellular matrix organization, and material properties during static culture, in vitro findings presented here suggest that fibrin-based constructs may be a more suitable alternative to collagen-based constructs for tissue-engineered tendon/ligament repair.

Fibrin Gels Exhibit Improved Biological, Structural, and Mechanical Properties Compared with Collagen Gels in Cell-Based Tendon Tissue-Engineered Constructs

PubMed Central

Dyment, Nathaniel A.; Lu, Yinhui; Rao, Marepalli; Shearn, Jason T.; Rowe, David W.; Kadler, Karl E.; Butler, David L.

2015-01-01

The prevalence of tendon and ligament injuries and inadequacies of current treatments is driving the need for alternative strategies such as tissue engineering. Fibrin and collagen biopolymers have been popular materials for creating tissue-engineered constructs (TECs), as they exhibit advantages of biocompatibility and flexibility in construct design. Unfortunately, a few studies have directly compared these materials for tendon and ligament applications. Therefore, this study aims at determining how collagen versus fibrin hydrogels affect the biological, structural, and mechanical properties of TECs during formation in vitro. Our findings show that tendon and ligament progenitor cells seeded in fibrin constructs exhibit improved tenogenic gene expression patterns compared with their collagen-based counterparts for approximately 14 days in culture. Fibrin-based constructs also exhibit improved cell-derived collagen alignment, increased linear modulus (2.2-fold greater) compared with collagen-based constructs. Cyclic tensile loading, which promotes the maturation of tendon constructs in a previous work, exhibits a material-dependent effect in this study. Fibrin constructs show trending reductions in mechanical, biological, and structural properties, whereas collagen constructs only show improved tenogenic expression in the presence of mechanical stimulation. These findings highlight that components of the mechanical stimulus (e.g., strain amplitude or time of initiation) need to be tailored to the material and cell type. Given the improvements in tenogenic expression, extracellular matrix organization, and material properties during static culture, in vitro findings presented here suggest that fibrin-based constructs may be a more suitable alternative to collagen-based constructs for tissue-engineered tendon/ligament repair. PMID:25266738

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1991-01-01

ATTAP activities were highlighted by test bed engine design and development activities; ceramic component design; materials and engine component characterization; ceramic component process development and fabrication; component rig testing; and test bed engine fabrication and testing. Specifically, ATTAP aims to develop and demonstrate the technology of structural ceramics that have the potential for competitive automotive engine life cycle cost and for operating for 3500 hours in a turbine engine environment at temperatures up to 1371 C (2500 F).

Multiaxial and Thermomechanical Fatigue of Materials: A Historical Perspective and Some Future Challenges

NASA Technical Reports Server (NTRS)

Kalluri, Sreeramesh

2013-01-01

Structural materials used in engineering applications routinely subjected to repetitive mechanical loads in multiple directions under non-isothermal conditions. Over past few decades, several multiaxial fatigue life estimation models (stress- and strain-based) developed for isothermal conditions. Historically, numerous fatigue life prediction models also developed for thermomechanical fatigue (TMF) life prediction, predominantly for uniaxial mechanical loading conditions. Realistic structural components encounter multiaxial loads and non-isothermal loading conditions, which increase potential for interaction of damage modes. A need exists for mechanical testing and development verification of life prediction models under such conditions.

Modulation of gene expression using electrospun scaffolds with templated architecture.

PubMed

Karchin, A; Wang, Y-N; Sanders, J E

2012-06-01

The fabrication of biomimetic scaffolds is a critical component to fulfill the promise of functional tissue-engineered materials. We describe herein a simple technique, based on printed circuit board manufacturing, to produce novel templates for electrospinning scaffolds for tissue-engineering applications. This technique facilitates fabrication of electrospun scaffolds with templated architecture, which we defined as a scaffold's bulk mechanical properties being driven by its fiber architecture. Electrospun scaffolds with templated architectures were characterized with regard to fiber alignment and mechanical properties. Fast Fourier transform analysis revealed a high degree of fiber alignment along the conducting traces of the templates. Mechanical testing showed that scaffolds demonstrated tunable mechanical properties as a function of templated architecture. Fibroblast-seeded scaffolds were subjected to a peak strain of 3 or 10% at 0.5 Hz for 1 h. Exposing seeded scaffolds to the low strain magnitude (3%) significantly increased collagen I gene expression compared to the high strain magnitude (10%) in a scaffold architecture-dependent manner. These experiments indicate that scaffolds with templated architectures can be produced, and modulation of gene expression is possible with templated architectures. This technology holds promise for the long-term goal of creating tissue-engineered replacements with the biomechanical and biochemical make-up of native tissues. Copyright © 2012 Wiley Periodicals, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, A.; Hsiung, S.M.; Chowdhury, A.H.

Long-term stability of emplacement drifts and potential near-field fluid flow resulting from coupled effects are among the concerns for safe disposal of high-level nuclear waste (HLW). A number of factors can induce drift instability or change the near-field flow patterns. Repetitive seismic loads from earthquakes and thermal loads generated by the decay of emplaced waste are two significant factors. One of two key technical uncertainties (KTU) that can potentially pose a high risk of noncompliance with the performance objectives of 10 CFR Part 60 is the prediction of thermal-mechanical (including repetitive seismic load) effects on stability of emplacement drifts andmore » the engineered barrier system. The second KTU of concern is the prediction of thermal-mechanical-hydrological (including repetitive seismic load) effects on the host rock surrounding the engineered barrier system. The Rock Mechanics research project being conducted at the Center for Nuclear Waste Regulatory Analyses (CNWRA) is intended to address certain specific technical issues associated with these two KTUs. This research project has two major components: (i) seismic response of rock joints and a jointed rock mass and (ii) coupled thermal-mechanical-hydrological (TMH) response of a jointed rock mass surrounding the engineered barrier system (EBS). This final report summarizes the research activities concerned with the repetitive seismic load aspect of both these KTUs.« less

Preparation and characterization of novel functionalized multiwalled carbon nanotubes/chitosan/β-Glycerophosphate scaffolds for bone tissue engineering.

PubMed

Gholizadeh, Shayan; Moztarzadeh, Fathollah; Haghighipour, Nooshin; Ghazizadeh, Leila; Baghbani, Fatemeh; Shokrgozar, Mohammad Ali; Allahyari, Zahra

2017-04-01

A major limitation in current tissue engineering scaffolds is that some of the most important characteristics of the intended tissue are ignored. As piezoelectricity and high mechanical strength are two of the most important characteristics of the bone tissue, carbon nanotubes are getting a lot of attention as a bone tissue scaffold component in recent years. In the present study, composite scaffolds comprised of functionalized Multiwalled Carbon Nanotubes (f-MWCNT), medium molecular weight chitosan and β-Glycerophosphate were fabricated and characterized. Biodegradability and mechanical tests indicate that while increasing f-MWCNT content can improve electrical conductivity and mechanical properties, there are some limitations for these increases, such as a decrease in mechanical properties and biodegradability in 1w/v% content of f-MWCNTs. Also, MTT cytotoxicity assay was conducted for the scaffolds and no significant cytotoxicity was observed. Increasing f-MWCNT content led to higher alkaline Phosphatase activity. The overall results show that composites with f-MWCNT content between 0.1w/v% and 0.5w/v% are the most suitable for bone tissue engineering application. Additionally, Preliminary cell electrical tests proved the efficiency of the prepared scaffolds for cell electrical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Basic Wind Tech Course - Lesson Plans and Activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swapp, Andy

2011-07-01

The funds from this project were used to purchase tools and instrumentation to help replicate actual on-the-job wind energy scenarios which provided the students with the practical or applied components of wind energy jobs. This project enhanced the educational experiences provided for the students in terms of engineering and science components of wind energy by using electronics, control systems, and electro-mechanical instrumentation to help students learn standardized wind-specific craftsman skills. In addition the tools and instrumentation helped the students learn the safety necessary to work in the wind industry.

Establishment of a National Accelerator Facility: Design and construction phase

NASA Astrophysics Data System (ADS)

1981-06-01

The main components of an accelerator facility for nuclear physics, isotope production, and radiotherapy in South Africa are in 8-MeV solid pole injector cyclotron and a separated sector cyclotron with a k-value of 200 MeV. Progress made in the development of the light ion injector and in the design of the control and beam transport systems is described. Mechanical and engineering tasks associated with component manufacture are discussed as well as the construction of the building to house the facility and the installation of necessary services.

ICME for Crashworthiness of TWIP Steels: From Ab Initio to the Crash Performance

NASA Astrophysics Data System (ADS)

Güvenç, O.; Roters, F.; Hickel, T.; Bambach, M.

2015-01-01

During the last decade, integrated computational materials engineering (ICME) emerged as a field which aims to promote synergetic usage of formerly isolated simulation models, data and knowledge in materials science and engineering, in order to solve complex engineering problems. In our work, we applied the ICME approach to a crash box, a common automobile component crucial to passenger safety. A newly developed high manganese steel was selected as the material of the component and its crashworthiness was assessed by simulated and real drop tower tests. The crashworthiness of twinning-induced plasticity (TWIP) steel is intrinsically related to the strain hardening behavior caused by the combination of dislocation glide and deformation twinning. The relative contributions of those to the overall hardening behavior depend on the stacking fault energy (SFE) of the selected material. Both the deformation twinning mechanism and the stacking fault energy are individually well-researched topics, but especially for high-manganese steels, the determination of the stacking-fault energy and the occurrence of deformation twinning as a function of the SFE are crucial to understand the strain hardening behavior. We applied ab initio methods to calculate the stacking fault energy of the selected steel composition as an input to a recently developed strain hardening model which models deformation twinning based on the SFE-dependent dislocation mechanisms. This physically based material model is then applied to simulate a drop tower test in order to calculate the energy absorption capacity of the designed component. The results are in good agreement with experiments. The model chain links the crash performance to the SFE and hence to the chemical composition, which paves the way for computational materials design for crashworthiness.

Isotopic Tracing of Fuel Components in Particulate Emissions from Diesel Engines using Accelerator Mass Spectrometry (AMS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buchholz, B A; Mueller, C J; Garbak, J.

2001-08-02

Accelerator mass spectrometry (AMS) is an isotope-ratio measurement technique developed in the late 1970s for tracing long-lived radioisotopes (e.g., {sup 14}C half life = 5760 y). The technique counts individual nuclei rather than waiting for their radioactive decay, allowing measurement of more than 100 low-level {sup 14}C samples per day (Vogel et al, 1995). The LLNL AMS system is shown in Fig.1. The contemporary quantity of {sup 14}C in living things ({sup 14}C/C = 1.2 x 10{sup -12} or 110 fmol {sup 14}C/ g C) is highly elevated compared to the quantity of {sup 14}C in petroleum-derived products. This isotopicmore » elevation is sufficient to trace the fate of bio-derived fuel components in the emissions of an engine without the use of radioactive materials. If synthesis of a fuel component from biologically-derived source material is not feasible, another approach is to purchase {sup 14}C-labeled material (e.g., dibutyl maleate (DBM)) and dilute it with petroleum-derived material to yield a contemporary level of {sup 14}C. In each case, the virtual absence of {sup 14}C in petroleum based fuels gives a very low {sup 14}C background that makes this approach to tracing fuel components practical. Regulatory pressure to significantly reduce the particulate emissions from diesel engines is driving research into understanding mechanisms of soot formation. If mechanisms are understood, then combustion modeling can be used to evaluate possible changes in fuel formulation and suggest possible fuel components that can improve combustion and reduce PM emissions. The combustion paradigm assumes that large molecules break down into small components and then build up again during soot formation. AMS allows us to label specific fuel components, including oxygenates, trace the carbon atoms, and test this combustion modeling paradigm. Volatile and non-volatile organic fractions (VOF, NVOF) in the PM can be further separated. The VOF of the PM can be oxidized with catalysts in the exhaust stream to further decrease PM. The effectiveness of exhaust stream catalysts to oxidize products from tracer fuel components can be monitored through AMS measurement of carbon in PM. The objects of this report are: (1) Determine contribution of diesel fuel components and oxygenates to soot formation; (2) Separate volatile and non-volatile fractions of soot; (3) Test combustion paradigm that all carbon and oxygen in fuel is equal; and (4) Produce data to validate combustion modeling.« less

Kinetic Monte Carlo Simulations of Oxygen Diffusion in Environmental Barrier Coating Materials

NASA Technical Reports Server (NTRS)

Good, Brian S.

2017-01-01

Ceramic Matrix Composite (CMC) materials are of interest for use in next-generation turbine engine components, offering a number of significant advantages, including reduced weight and high operating temperatures. However, in the hot environment in which such components operate, the presence of water vapor can lead to corrosion and recession, limiting the useful life of the components. Such degradation can be reduced through the use of Environmental Barrier Coatings (EBCs) that limit the amount of oxygen and water vapor reaching the component. Candidate EBC materials include Yttrium and Ytterbium silicates. In this work we present results of kinetic Monte Carlo (kMC) simulations of oxygen diffusion, via the vacancy mechanism, in Yttrium and Ytterbium disilicates, along with a brief discussion of interstitial diffusion.

Simulated Single Tooth Bending of High Temperature Alloys

NASA Technical Reports Server (NTRS)

Handschuh, Robert, F.; Burke, Christopher

2012-01-01

Future unmanned space missions will require mechanisms to operate at extreme conditions in order to be successful. In some of these mechanisms, very high gear reductions will be needed to permit very small motors to drive other components at low rotational speed with high output torque. Therefore gearing components are required that can meet the mission requirements. In mechanisms such as this, bending fatigue strength capacity of the gears is very important. The bending fatigue capacity of a high temperature, nickel-based alloy, typically used for turbine disks in gas turbine engines and two tool steel materials with high vanadium content, were compared to that of a typical aerospace alloy-AISI 9310. Test specimens were fabricated by electro-discharge machining without post machining processing. Tests were run at 24 and at 490 C. As test temperature increased from 24 to 490 C the bending fatigue strength was reduced by a factor of five.

Overview of thermal barrier coatings in diesel engines

NASA Technical Reports Server (NTRS)

Yonushonis, Thomas M.

1995-01-01

An understanding of delamination mechanisms in thermal barrier coatings has been developed for diesel engine applications through rig tests, structural analysis modeling, nondestructive evaluation, and engine evaluation of various thermal barrier coatings. This knowledge has resulted in improved thermal barrier coatings which survive abusive cyclic fatigue tests in high output diesel engines. Although much conflicting literature now exists regarding the impact of thermal barrier coatings on engine performance and fuel consumption, the changes in fuel consumption appear to be less than a few percent and can be negative for state-of-the-art diesel engines. The ability of the thermal barrier coating to improve fuel economy tends to be dependent on a number of factors including the fuel injection system, combustion chamber design, and the initial engine fuel economy. Limited investigations on state-of-the-art diesel engines have indicated that the surface connected porosity and coating surface roughness may influence engine fuel economy. Current research efforts on thermal barrier coatings are primarily directed at reducing in-cylinder heat rejection, thermal fatigue protection of underlying metal surfaces and a possible reduction in diesel engine emissions. Significant efforts are still required to improve the plasma spray processing capability and the economics for complex geometry diesel engine components.

Experience with integrally-cast compressor and turbine components for a small, low-cost, expendable-type turbojet engine

NASA Technical Reports Server (NTRS)

Dengler, R. P.

1975-01-01

Experiences with integrally-cast compressor and turbine components during fabrication and testing of four engine assemblies of a small (29 cm (11 1/2 in.) maximum diameter) experimental turbojet engine design for an expendable application are discussed. Various operations such as metal removal, welding, and re-shaping of these components were performed in preparation of full-scale engine tests. Engines with these components were operated for a total of 157 hours at engine speeds as high as 38,000 rpm and at turbine inlet temperatures as high as 1256 K (1800 F).

New Material Development for Surface Layer and Surface Technology in Tribology Science to Improve Energy Efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ismail, R., E-mail: rifky-mec@yahoo.com; Tauviqirrahman, M., E-mail: rifky-mec@yahoo.com; Laboratory for Surface Technology and Tribology, Faculty of Engineering Technology, University of Twente, Enschede

This paper reviews the development of new material and surface technology in tribology and its contribution to energy efficiency. Two examples of the economic benefits, resulted from the optimum tribology in the transportation sector and the manufacturing industry are discussed. The new materials are proposed to modify the surface property by laminating the bulk material with thin layer/coating. Under a suitable condition, the thin layer on a surface can provide a combination of good wear, a low friction and corrosion resistance for the mechanical components. The innovation in layer technology results molybdenum disulfide (MoS2), diamond like carbon (DLC), cubic boronmore » nitride (CBN) and diamond which perform satisfactory outcome. The application of the metallic coatings to carbon fibre reinforced polymer matrix composites (CFRP) has the capacity to provide considerable weight and power savings for many engineering components. The green material for lubricant and additives such as the use of sunflower oil which possesses good oxidation resistance and the use of mallee leaves as bio‐degradable solvent are used to answer the demand of the environmentally friendly material with good performance. The tribology research implementation for energy efficiency also touches the simple things around us such as: erasing the laser‐print in a paper with different abrasion techniques. For the technology in the engineering surface, the consideration for generating the suitable surface of the components in running‐in period has been discussed in order to prolong the components life and reduce the machine downtime. The conclusion, tribology can result in reducing manufacturing time, reducing the maintenance requirements, prolonging the service interval, improving durability, reliability and mechanical components life, and reducing harmful exhaust emission and waste. All of these advantages will increase the energy efficiency and the economic benefits.« less

New Material Development for Surface Layer and Surface Technology in Tribology Science to Improve Energy Efficiency

NASA Astrophysics Data System (ADS)

Ismail, R.; Tauviqirrahman, M.; Jamari, Jamari; Schipper, D. J.

2009-09-01

This paper reviews the development of new material and surface technology in tribology and its contribution to energy efficiency. Two examples of the economic benefits, resulted from the optimum tribology in the transportation sector and the manufacturing industry are discussed. The new materials are proposed to modify the surface property by laminating the bulk material with thin layer/coating. Under a suitable condition, the thin layer on a surface can provide a combination of good wear, a low friction and corrosion resistance for the mechanical components. The innovation in layer technology results molybdenum disulfide (MoS2), diamond like carbon (DLC), cubic boron nitride (CBN) and diamond which perform satisfactory outcome. The application of the metallic coatings to carbon fibre reinforced polymer matrix composites (CFRP) has the capacity to provide considerable weight and power savings for many engineering components. The green material for lubricant and additives such as the use of sunflower oil which possesses good oxidation resistance and the use of mallee leaves as bio-degradable solvent are used to answer the demand of the environmentally friendly material with good performance. The tribology research implementation for energy efficiency also touches the simple things around us such as: erasing the laser-print in a paper with different abrasion techniques. For the technology in the engineering surface, the consideration for generating the suitable surface of the components in running-in period has been discussed in order to prolong the components life and reduce the machine downtime. The conclusion, tribology can result in reducing manufacturing time, reducing the maintenance requirements, prolonging the service interval, improving durability, reliability and mechanical components life, and reducing harmful exhaust emission and waste. All of these advantages will increase the energy efficiency and the economic benefits.

Bioregenerative system

NASA Technical Reports Server (NTRS)

1987-01-01

The design course is an eight semester credit multi-disciplinary engineering design course taught primarily to Engineering Science, Aerospace, Electrical and Mechanical Engineering seniors. This year the course project involved the design of the three interrelated loops: atmospheric, liquid nutrient and solid waste management, associated with growing higher plants to support man during long-term space missions. The project is complementary to the NASA Kennedy Space Center Controlled Environmental Life Support System (CELSS) project. The first semester the class worked on a preliminary design for a complete system. This effort included means for monitoring and control of composition, temperature, flow rate, etc., for the atmosphere and liquid nutrient solution; disease and contaminant monitoring and control; plant mechanical support, propagation and harvesting; solid and liquid waste recycling; and system maintenance and refurbishing. The project has significant biological, mechanical, electrical and Al/Robotics aspects. The second semester a small number of subsystems or components, identified as important and interesting during the first semester, were selected for detail design, fabrication, and testing. The class was supported by close cooperation with The Kennedy Space Center and by two teaching assistants. The availability of a dedicated, well equipped project room greatly enhanced the communication and team spirit of the class.

Development Challenges of Utilizing a Corner Cube Mechanism Design with Successful IASI Flight Heritage for the Infrared Sounder (IRS) on MTG: Recurrent Mechanical Design not Correlated to Recurrent Development

NASA Astrophysics Data System (ADS)

Spanoudakis, Peter; Schwab, Philippe; Kiener, Lionel; Saudan, Herve; Perruchoud, Gerald

2015-09-01

The Corner Cube Mechanism (CCM) design for the Infra-Red Sounder (IRS) on MTG is based on the successful mechanism currently in orbit on the Infrared Atmospheric Sounding Interferometers (IASI) on the Metop satellites. The overall CCM performance is described with attention given to the specific design developments for the MTG project. A description is presented of the modifications introduced and challenges encountered to adapt the IASI space heritage design (which is only 15 years old) to meet the MTG specifications. A detailed account is provided regarding the tests performed on the adapted components for the new programme. The major issues encountered and solutions proposed are illustrated concerning the voice- coil actuator development, optical switch design, fatigue life of the flexure components and the adaptation of the launch locking device. Nevertheless, an Engineering Qualification Model was rapidly manufactured and now undergoing a qualification test campaign.

19 CFR 10.183 - Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components...

Code of Federal Regulations, 2011 CFR

2011-04-01

... Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components, and... aircraft, aircraft engines, and ground flight simulators, including their parts, components, and... United States (HTSUS) by meeting the following requirements: (1) The aircraft, aircraft engines, ground...

19 CFR 10.183 - Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components...

Code of Federal Regulations, 2010 CFR

2010-04-01

... Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components, and... aircraft, aircraft engines, and ground flight simulators, including their parts, components, and... United States (HTSUS) by meeting the following requirements: (1) The aircraft, aircraft engines, ground...

14 CFR 43.7 - Persons authorized to approve aircraft, airframes, aircraft engines, propellers, appliances, or...

Code of Federal Regulations, 2013 CFR

2013-01-01

..., airframes, aircraft engines, propellers, appliances, or component parts for return to service after... Administrator, may approve an aircraft, airframe, aircraft engine, propeller, appliance, or component part for..., airframe, aircraft engine, propeller, appliance, or component part for return to service as provided in...

14 CFR 43.7 - Persons authorized to approve aircraft, airframes, aircraft engines, propellers, appliances, or...

Code of Federal Regulations, 2012 CFR

2012-01-01

..., airframes, aircraft engines, propellers, appliances, or component parts for return to service after... Administrator, may approve an aircraft, airframe, aircraft engine, propeller, appliance, or component part for..., airframe, aircraft engine, propeller, appliance, or component part for return to service as provided in...

14 CFR 43.7 - Persons authorized to approve aircraft, airframes, aircraft engines, propellers, appliances, or...

Code of Federal Regulations, 2011 CFR

2011-01-01

..., airframes, aircraft engines, propellers, appliances, or component parts for return to service after... Administrator, may approve an aircraft, airframe, aircraft engine, propeller, appliance, or component part for..., airframe, aircraft engine, propeller, appliance, or component part for return to service as provided in...

14 CFR 43.7 - Persons authorized to approve aircraft, airframes, aircraft engines, propellers, appliances, or...

Code of Federal Regulations, 2014 CFR

2014-01-01

..., airframes, aircraft engines, propellers, appliances, or component parts for return to service after... Administrator, may approve an aircraft, airframe, aircraft engine, propeller, appliance, or component part for..., airframe, aircraft engine, propeller, appliance, or component part for return to service as provided in...

Observations on Rotating Cavitation and Cavitation Surge from the Development of the Fastrac Engine Turbopump

NASA Technical Reports Server (NTRS)

Zoladz, Thomas F.

2000-01-01

Observations regarding rotating cavitation and cavitation surge experienced during the development of the Fastrac engine turbopump are discussed. Detailed observations acquired from the analysis of both water flow and liquid oxygen test data are offered in this paper. Scaling and general comparison of rotating cavitation between water flow and liquid oxygen testing are discussed. Complex data features linking the localized rotating cavitation mechanism of the inducer to system surge components are described in detail. Finally a description of a lumped-parameter hydraulic system model developed to better understand observed data is given.

Overview of Rotating Cavitation and Cavitation Surge in the Fastrac Engine LOX Turbopump

NASA Technical Reports Server (NTRS)

Zoladz, Thomas; Turner, Jim (Technical Monitor)

2001-01-01

Observations regarding rotating cavitation and cavitation surge experienced during the development of the Fastrac 60 Klbf engine turbopump are discussed. Detailed observations from the analysis of both water flow and liquid oxygen test data are offered. Scaling and general comparison of rotating cavitation between water flow and liquid oxygen testing are discussed. Complex data features linking the localized rotating cavitation mechanism of the inducer to system surge components are described in detail. Finally a description of a simple lumped-parameter hydraulic system model developed to better understand observed data is given.

Coupling of Mechanical Behavior of Cell Components to Electrochemical-Thermal Models for Computer-Aided Engineering of Batteries under Abuse (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pesaran, A.; Wierzbicki, T.; Sahraei, E.

The EV Everywhere Grand Challenge aims to produce plug-in electric vehicles as affordable and convenient for the American family as gasoline-powered vehicles by 2022. Among the requirements set by the challenge, electric vehicles must be as safe as conventional vehicles, and EV batteries must not lead to unsafe situations under abuse conditions. NREL's project started in October 2013, based on a proposal in response to the January 2013 DOE VTO FOA, with the goal of developing computer aided engineering tools to accelerate the development of safer lithium ion batteries.

Follow-On Studies for Design Definition of a Lift/Cruise Fan Technology V/STOL Airplane, Volume 1

NASA Technical Reports Server (NTRS)

1977-01-01

A three engine, three fan V/STOL airplane was designed for use as a Research Technology Airplane in proof-of-concept of a candidate configuration for use as a Navy multimission airplane. Use of mechanically interconnected variable pitch fans is made to accommodate power transfer for flight control in hover and to provide flight capability in the event of a single engine failure. The airplane is a modification of a T-39A transport. Design definition is provided for high risk propulsion components and a development test program is defined.

Theoretical study of the decomposition mechanism of environmentally friendly insulating medium C3F7CN in the presence of H2O in a discharge

NASA Astrophysics Data System (ADS)

Zhang, Xiaoxing; Li, Yi; Xiao, Song; Tian, Shuangshuang; Deng, Zaitao; Tang, Ju

2017-08-01

C3F7CN has been the focus of the alternative gas research field over the past two years because of its excellent insulation properties and environmental characteristics. Experimental studies on its insulation performance have made many achievements. However, few studies on the formation mechanism of the decomposition components exist. A discussion of the decomposition characteristics of insulating media will provide guidance for scientific experimental research and the work that must be completed before further engineering application. In this study, the decomposition mechanism of C3F7CN in the presence of trace H2O under discharge was calculated based on the density functional theory and transition state theory. The reaction heat, Gibbs free energy, and activation energy of different decomposition pathways were investigated. The ionization parameters and toxicity of C3F7CN and various decomposition products were analyzed from the molecular structure perspective. The formation mechanism of the C3F7CN discharge decomposition components and the influence of trace water were evaluated. This paper confirms that C3F7CN has excellent decomposition characteristics, which provide theoretical support for later experiments and related engineering applications. However, the existence of trace water has a negative impact on C3F7CN’s insulation performance. Thus, strict trace water content standards should be developed to ensure dielectric insulation and the safety of maintenance personnel.

An integrated computational tool for precipitation simulation

NASA Astrophysics Data System (ADS)

Cao, W.; Zhang, F.; Chen, S.-L.; Zhang, C.; Chang, Y. A.

2011-07-01

Computer aided materials design is of increasing interest because the conventional approach solely relying on experimentation is no longer viable within the constraint of available resources. Modeling of microstructure and mechanical properties during precipitation plays a critical role in understanding the behavior of materials and thus accelerating the development of materials. Nevertheless, an integrated computational tool coupling reliable thermodynamic calculation, kinetic simulation, and property prediction of multi-component systems for industrial applications is rarely available. In this regard, we are developing a software package, PanPrecipitation, under the framework of integrated computational materials engineering to simulate precipitation kinetics. It is seamlessly integrated with the thermodynamic calculation engine, PanEngine, to obtain accurate thermodynamic properties and atomic mobility data necessary for precipitation simulation.

Ceramic applications in turbine engines

NASA Technical Reports Server (NTRS)

Helms, H. E.; Heitman, P. W.; Lindgren, L. C.; Thrasher, S. R.

1984-01-01

The application of ceramic components to demonstrate improved cycle efficiency by raising the operating temperature of the existing Allison IGI 404 vehicular gas turbine engine is discussed. This effort was called the Ceramic Applications in Turbine Engines (CATE) program and has successfully demonstrated ceramic components. Among these components are two design configurations featuring stationary and rotating caramic components in the IGT 404 engine. A complete discussion of all phases of the program, design, materials development, fabrication of ceramic components, and testing-including rig, engine, and vehicle demonstation test are presented. During the CATE program, a ceramic technology base was established that is now being applied to automotive and other gas turbine engine programs. This technology base is outlined and also provides a description of the CATE program accomplishments.

Mathematical modeling of control system for the experimental steam generator

NASA Astrophysics Data System (ADS)

Podlasek, Szymon; Lalik, Krzysztof; Filipowicz, Mariusz; Sornek, Krzysztof; Kupski, Robert; Raś, Anita

2016-03-01

A steam generator is an essential unit of each cogeneration system using steam machines. Currently one of the cheapest ways of the steam generation can be application of old steam generators came from army surplus store. They have relatively simple construction and in case of not so exploited units - quite good general conditions, and functionality of mechanical components. By contrast, electrical components and control systems (mostly based on relay automatics) are definitely obsolete. It is not possible to use such units with cooperation of steam bus or with steam engines. In particular, there is no possibility for automatically adjustment of the pressure and the temperature of the generated steam supplying steam engines. Such adjustment is necessary in case of variation of a generator load. The paper is devoted to description of improvement of an exemplary unit together with construction of the measurement-control system based on a PLC. The aim was to enable for communication between the steam generator and controllers of the steam bus and steam engines in order to construction of a complete, fully autonomic and maintenance-free microcogeneration system.

Furnace Cyclic Oxidation Behavior of Multi-Component Low Conductivity Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Nesbitt, James A.; Barrett, Charles A.; McCue, Terry R.; Miller, Robert A.

2004-01-01

Ceramic thermal barrier coatings will play an increasingly important role in advanced gas turbine engines because of their ability to further increase engine operating temperatures and reduce cooling, thus helping achieve future engine low emission, high efficiency and improved reliability goals. Advanced multi-component zirconia-based thermal barrier coatings are being developed using an oxide defect clustering design approach to achieve the required coating low thermal conductivity and high temperature stability. Although the new composition coatings were not yet optimized for cyclic durability, an initial durability screening of the candidate coating materials was conducted using conventional furnace cyclic oxidation tests. In this paper, furnace cyclic oxidation behavior of plasma-sprayed zirconia-based defect cluster thermal barrier coatings was investigated at 1163 C using 45 min hot cycles. The ceramic coating failure mechanisms were studied using scanning electron microscopy (SEM) combined with X-ray diffraction (XRD) phase analysis after the furnace tests. The coating cyclic lifetime is also discussed in relation to coating processing, phase structures, dopant concentration, and other thermo-physical properties.

Re-Educating Jet-Engine-Researchers to Stay Relevant

NASA Astrophysics Data System (ADS)

Gal-Or, Benjamin

2016-06-01

To stay relevantly supported, jet-engine researchers, designers and operators should follow changing uses of small and large jet engines, especially those anticipated to be used by/in the next generation, JET-ENGINE-STEERED ("JES") fleets of jet drones but fewer, JES-Stealth-Fighter/Strike Aircraft. In addition, some diminishing returns from isolated, non-integrating, jet-engine component studies, vs. relevant, supersonic, shock waves control in fluidic-JES-side-effects on compressor stall dynamics within Integrated Propulsion Flight Control ("IPFC"), and/or mechanical JES, constitute key relevant methods that currently move to China, India, South Korea and Japan. The central roles of the jet engine as primary or backup flight controller also constitute key relevant issues, especially under post stall conditions involving induced engine-stress while participating in crash prevention or minimal path-time maneuvers to target. And when proper instructors are absent, self-study of the JES-STVS REVOLUTION is an updating must, where STVS stands for wing-engine-airframe-integrated, embedded stealthy-jet-engine-inlets, restructured engines inside Stealth, Tailless, canard-less, Thrust Vectoring IFPC Systems. Anti-terror and Airliners Super-Flight-Safety are anticipated to overcome US legislation red-tape that obstructs JES-add-on-emergency-kits-use.

SSME component assembly and life management expert system

NASA Technical Reports Server (NTRS)

Ali, M.; Dietz, W. E.; Ferber, H. J.

1989-01-01

The space shuttle utilizes several rocket engine systems, all of which must function with a high degree of reliability for successful mission completion. The space shuttle main engine (SSME) is by far the most complex of the rocket engine systems and is designed to be reusable. The reusability of spacecraft systems introduces many problems related to testing, reliability, and logistics. Components must be assembled from parts inventories in a manner which will most effectively utilize the available parts. Assembly must be scheduled to efficiently utilize available assembly benches while still maintaining flight schedules. Assembled components must be assigned to as many contiguous flights as possible, to minimize component changes. Each component must undergo a rigorous testing program prior to flight. In addition, testing and assembly of flight engines and components must be done in conjunction with the assembly and testing of developmental engines and components. The development, testing, manufacture, and flight assignments of the engine fleet involves the satisfaction of many logistical and operational requirements, subject to many constraints. The purpose of the SSME Component Assembly and Life Management Expert System (CALMES) is to assist the engine assembly and scheduling process, and to insure that these activities utilize available resources as efficiently as possible.

Energy efficient engine component development and integration program

NASA Technical Reports Server (NTRS)

1981-01-01

Accomplishments in the Energy Efficient Engine Component Development and Integration program during the period of April 1, 1981 through September 30, 1981 are discussed. The major topics considered are: (1) propulsion system analysis, design, and integration; (2) engine component analysis, design, and development; (3) core engine tests; and (4) integrated core/low spool testing.

Admissions Policies as a Mechanism for Social Engineering: The Case of the Bulgarian Communist Regime

ERIC Educational Resources Information Center

Boyadjieva, Pepka Alexandrova

2013-01-01

This article discusses admissions policies to higher education during the Communist regime in Bulgaria (1946-89). It argues that under the conditions of the Bulgarian Communist regime, admissions policies were not only a component of the higher education system--viewed as an institution--but part and parcel of the process through which power was…

Advanced Energy Storage and Conversion Devices

DTIC Science & Technology

2008-12-01

determined lithium-ion insertion mechanisms. 3.1 Background and Objectives Polymer electrolyte membrane fuel cells ( PEMFCs ) function by permitting...is one of the most critical components in the polymer electrolyte fuel cells. In recent years, PEMFCs have been identified as promising power...and residual hydrocarbons that are commonly produced by internal combustion engines. PEMFCs , due to their high efficiency and modularity of design

Property Screening and Evaluation of Ceramic Turbine Materials

DTIC Science & Technology

1984-04-01

Unless otherwise indicated, the upper and lower spans were 0.875 and 1.750 in., respectively. For room-temperature tests, a stainless steel fixture...Silicon Nitride High Temperature Properties Silicon Carbide Silicon Ceramics Transformation-Toughened Zirconia Structural Ceramics Mechanical Properties...3ilicon carbide and silicon nitride, that have potential as structural components in"advanced gas turbine engines, were evaluated. Thermal and

Viscous-to-viscoelastic transition in phononic crystal and metamaterial band structures.

PubMed

Frazier, Michael J; Hussein, Mahmoud I

2015-11-01

The dispersive behavior of phononic crystals and locally resonant metamaterials is influenced by the type and degree of damping in the unit cell. Dissipation arising from viscoelastic damping is influenced by the past history of motion because the elastic component of the damping mechanism adds a storage capacity. Following a state-space framework, a Bloch eigenvalue problem incorporating general viscoelastic damping based on the Zener model is constructed. In this approach, the conventional Kelvin-Voigt viscous-damping model is recovered as a special case. In a continuous fashion, the influence of the elastic component of the damping mechanism on the band structure of both a phononic crystal and a metamaterial is examined. While viscous damping generally narrows a band gap, the hereditary nature of the viscoelastic conditions reverses this behavior. In the limit of vanishing heredity, the transition between the two regimes is analyzed. The presented theory also allows increases in modal dissipation enhancement (metadamping) to be quantified as the type of damping transitions from viscoelastic to viscous. In conclusion, it is shown that engineering the dissipation allows one to control the dispersion (large versus small band gaps) and, conversely, engineering the dispersion affects the degree of dissipation (high or low metadamping).

Near-term hybrid vehicle program, phase 1. Appendix B: Design trade-off studies. [various hybrid/electric power train configurations and electrical and mechanical drive-line components

NASA Technical Reports Server (NTRS)

1979-01-01

The relative attractiveness of various hybrid/electric power train configurations and electrical and mechanical drive-line components was studied. The initial screening was concerned primarily with total vehicle weight and economic factors and identified the hybrid power train combinations which warranted detailed evaluation over various driving cycles. This was done using a second-by-second vehicle simulation program which permitted the calculations of fuel economy, electricity usage, and emissions as a function of distance traveled in urban and highway driving. Power train arrangement possibilities were examined in terms of their effect on vehicle handling, safety, serviceability, and passenger comfort. A dc electric drive system utilizing a separately excited motor with field control and battery switching was selected for the near term hybrid vehicle. Hybrid vehicle simulations showed that for the first 30 mi (the electric range of the vehicle) in urban driving, the fuel economy was 80 mpg using a gasoline engine and 100 mpg using a diesel engine. In urban driving the hybrid would save about 75% of the fuel used by the conventional vehicle and in combined urban/highway driving the fuel saving is about 50%.

Microstructure of Tablet-Pharmaceutical Significance, Assessment, and Engineering.

PubMed

Sun, Changquan Calvin

2017-05-01

To summarize the microstructure - property relationship of pharmaceutical tablets and approaches to improve tablet properties through tablet microstructure engineering. The main topics reviewed here include: 1) influence of material properties and manufacturing process parameters on the evolution of tablet microstructure; 2) impact of tablet structure on tablet properties; 3) assessment of tablet microstructure; 4) development and engineering of tablet microstructure. Microstructure plays a decisive role on important pharmaceutical properties of a tablet, such as disintegration, drug release, and mechanical strength. Useful information on mechanical properties of a powder can be obtained from analyzing tablet porosity-pressure data. When helium pycnometry fails to accurately measure true density of a water-containing powder, non-linear regression of tablet density-pressure data is a useful alternative method. A component that is more uniformly distributed in a tablet generally exerts more influence on the overall tablet properties. During formulation development, it is highly recommended to examine the relationship between any property of interest and tablet porosity when possible. Tablet microstructure can be engineered by judicious selection of formulation composition, including the use of the optimum solid form of the drug and appropriate type and amount of excipients, and controlling manufacturing process.

Microstructure Evolution and Durability of Advanced Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Evans, Laura J.; McCue, Terry R.; Harder, Bryan

2016-01-01

Environmental barrier coated SiC-SiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. Advanced HfO2 and rare earth silicate environmental barrier coatings (EBCs), along with multicomponent hafnium and rare earth silicide EBC bond coats have been developed. The coating degradation mechanisms in the laboratory simulated engine thermal cycling, and fatigue-creep operating environments are also being investigated. This paper will focus on the microstructural and compositional evolutions of an advanced environmental barrier coating system on a SiC-SiC CMC substrate during the high temperature simulated durability tests, by using a Field Emission Gun Scanning Electron Microscopy, Energy Dispersive Spectroscopy (EDS) and Wavelength Dispersive Spectroscopy (WDS). The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will also be discussed. The detailed analysis results help understand the EBC-CMC system performance, aiming at the durability improvements to achieve more robust, prime-reliant environmental barrier coatings.

A Fully Non-Metallic Gas Turbine Engine Enabled by Additive Manufacturing Part I: System Analysis, Component Identification, Additive Manufacturing, and Testing of Polymer Composites

NASA Technical Reports Server (NTRS)

Grady, Joseph E.; Haller, William J.; Poinsatte, Philip E.; Halbig, Michael C.; Schnulo, Sydney L.; Singh, Mrityunjay; Weir, Don; Wali, Natalie; Vinup, Michael; Jones, Michael G.;

Engine balance apparatus and accessory drive device

NASA Technical Reports Server (NTRS)

Egleston, Robert W. (Inventor)

2002-01-01

A balancing mechanism for an engine that has a rotating crankshaft and reciprocating pistons. The balancing mechanism comprises a primary balance mass assembly non-rotatably and removably affixed to the crankshaft. The primary mass assembly comprises a primary mass affixed to a primary hub portion and a primary cap portion removably affixed to the primary hub portion to clamp a portion of the crankshaft therebetween. A secondary balance mass assembly may be rotatably and removably supported on the crankshaft. A driver assembly is affixed to the crankshaft to cause the secondary balance mass to rotate in a direction that is opposite to the direction in which the crank shaft is rotating. The driver assembly may include auxiliary gears configured to transport rotary power to auxiliary components. The gears are readily detachable from the apparatus to facilitate inspection and repair operations.

Failure Predictions for VHTR Core Components using a Probabilistic Contiuum Damage Mechanics Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fok, Alex

2013-10-30

The proposed work addresses the key research need for the development of constitutive models and overall failure models for graphite and high temperature structural materials, with the long-term goal being to maximize the design life of the Next Generation Nuclear Plant (NGNP). To this end, the capability of a Continuum Damage Mechanics (CDM) model, which has been used successfully for modeling fracture of virgin graphite, will be extended as a predictive and design tool for the core components of the very high- temperature reactor (VHTR). Specifically, irradiation and environmental effects pertinent to the VHTR will be incorporated into the modelmore » to allow fracture of graphite and ceramic components under in-reactor conditions to be modeled explicitly using the finite element method. The model uses a combined stress-based and fracture mechanics-based failure criterion, so it can simulate both the initiation and propagation of cracks. Modern imaging techniques, such as x-ray computed tomography and digital image correlation, will be used during material testing to help define the baseline material damage parameters. Monte Carlo analysis will be performed to address inherent variations in material properties, the aim being to reduce the arbitrariness and uncertainties associated with the current statistical approach. The results can potentially contribute to the current development of American Society of Mechanical Engineers (ASME) codes for the design and construction of VHTR core components.« less

Does Kinematic Alignment and Flexion of a Femoral Component Designed for Mechanical Alignment Reduce the Proximal and Lateral Reach of the Trochlea?

PubMed

Brar, Abheetinder S; Howell, Stephen M; Hull, Maury L; Mahfouz, Mohamed R

2016-08-01

Kinematically aligned total knee arthroplasty uses a femoral component designed for mechanical alignment (MA) and sets the component in more internal, valgus, and flexion rotation than MA. It is unknown how much kinematic alignment (KA) and flexion of the femoral component reduce the proximal and lateral reach of the trochlea; two reductions that could increase the risk of abnormal patella tracking. We simulated MA and KA of the femoral component in 0° of flexion on 20 3-dimensional bone models of normal femurs. The mechanically and kinematically aligned components were then aligned in 5°, 10°, and 15° of flexion and downsized until the flange contacted the anterior femur. The reductions in the proximal and lateral reach from the proximal point of the trochlea of the MA component set in 0° of flexion were computed. KA at 0° of flexion did not reduce the proximal reach and reduced the lateral reach an average of 3 mm. Flexion of the MA and KA femoral component 5°, 10°, and 15° reduced the proximal reach an average of 4 mm, 8 mm, and 12 mm, respectively (0.8 mm/degree of flexion), and reduced the lateral reach an average of 1 mm and 4 mm regardless of the degree of flexion, respectively. Arthroplasty surgeons and biomechanical engineers striving to optimize patella tracking might consider developing surgical techniques to minimize flexion of the femoral component when performing KA and MA total knee arthroplasty to promote early patella engagement and consider designing a femoral component with a trochlea shaped specifically for KA. Copyright © 2016 Elsevier Inc. All rights reserved.

Ceramic technology for advanced heat engines project. Semiannual progress report, October 1985-March 1986

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1986-08-01

Significant accomplishments in fabricating cermaic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DOD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, additional research is needed in materials and processing development, design methodology, and data base and life prediction. An assessment of needs was completed, and a five-year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotivemore » heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines.« less

Simplified Ion Thruster Xenon Feed System for NASA Science Missions

NASA Technical Reports Server (NTRS)

Snyder, John Steven; Randolph, Thomas M.; Hofer, Richard R.; Goebel, Dan M.

2009-01-01

The successful implementation of ion thruster technology on the Deep Space 1 technology demonstration mission paved the way for its first use on the Dawn science mission, which launched in September 2007. Both Deep Space 1 and Dawn used a "bang-bang" xenon feed system which has proven to be highly successful. This type of feed system, however, is complex with many parts and requires a significant amount of engineering work for architecture changes. A simplified feed system, with fewer parts and less engineering work for architecture changes, is desirable to reduce the feed system cost to future missions. An attractive new path for ion thruster feed systems is based on new components developed by industry in support of commercial applications of electric propulsion systems. For example, since the launch of Deep Space 1 tens of mechanical xenon pressure regulators have successfully flown on commercial spacecraft using electric propulsion. In addition, active proportional flow controllers have flown on the Hall-thruster-equipped Tacsat-2, are flying on the ion thruster GOCE mission, and will fly next year on the Advanced EHF spacecraft. This present paper briefly reviews the Dawn xenon feed system and those implemented on other xenon electric propulsion flight missions. A simplified feed system architecture is presented that is based on assembling flight-qualified components in a manner that will reduce non-recurring engineering associated with propulsion system architecture changes, and is compared to the NASA Dawn standard. The simplified feed system includes, compared to Dawn, passive high-pressure regulation, a reduced part count, reduced complexity due to cross-strapping, and reduced non-recurring engineering work required for feed system changes. A demonstration feed system was assembled using flight-like components and used to operate a laboratory NSTAR-class ion engine. Feed system components integrated into a single-string architecture successfully operated the engine over the entire NSTAR throttle range over a series of tests. Flow rates were very stable with variations of at most 0.2%, and transition times between throttle levels were typically 90 seconds or less with a maximum of 200 seconds, both significant improvements over the Dawn bang-bang feed system.

30 CFR 36.48 - Tests of surface temperature of engine and components of the cooling system.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Tests of surface temperature of engine and... temperature of engine and components of the cooling system. (a) The surface temperatures of the engine... components shall have reached their respective equilibrium temperatures. The exhaust cooling system shall be...

30 CFR 36.48 - Tests of surface temperature of engine and components of the cooling system.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Tests of surface temperature of engine and... temperature of engine and components of the cooling system. (a) The surface temperatures of the engine... components shall have reached their respective equilibrium temperatures. The exhaust cooling system shall be...

30 CFR 36.48 - Tests of surface temperature of engine and components of the cooling system.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Tests of surface temperature of engine and... temperature of engine and components of the cooling system. (a) The surface temperatures of the engine... components shall have reached their respective equilibrium temperatures. The exhaust cooling system shall be...

Assessment of Parylene C Thin Films for Heart Valve Tissue Engineering

PubMed Central

Marei, Isra; Chester, Adrian; Carubelli, Ivan; Prodromakis, Themistoklis; Trantidou, Tatiana

2015-01-01

Background: Scaffolds are a key component of tissue-engineered heart valves (TEHVs). Several approaches had been adopted in the design of scaffolds using both natural and synthetic resources. We have investigated the suitability of parylene C (PC), a vapor deposited polymeric material, for the use as a scaffold in TEHV. Aims: To evaluate the adsorption of extracellular matrix components onto plasma-activated PC and study the biocompatibility of PC by measuring cellular adhesion, viability, apoptosis, and phenotypic expression of valve endothelial and interstitial cells. Finally, the mechanical properties of PC were compared with those of native aortic valve cusp tissue. Methods: PC slides were plasma activated and then coated with gelatin, type I collagen, or fibronectin. Porcine pulmonary valve endothelial and interstitial cells were then grown on plasma oxidized PC with different types of coatings and their adhesion was observed after 20 h of incubation. Cell viability was tested using the MTS assay, and apoptosis was estimated using TUNEL staining. The mechanical properties of PC and valve tissue were measured using a Bose Mechanical Tester. Finally, cell-seeded PC films were exposed to pulsatile pressure and aortic shear stress, respectively, to test their durability in a dynamic environment. Results: Our findings show that collagen and fibronectin could bind to plasma oxidized PC. Both valve endothelial and interstitial cells adhered to protein-coated ECM. PC had a profile of mechanical stiffness and ultimate tensile strength that were comparable with or in excess of those seen in porcine aortic valve cusps. Cells were still attached to PC films after 3 days of exposure to up to 50 mmHg pulsatile pressure or aortic levels of shear stress. Conclusion: PC is a promising candidate for use as a scaffold in tissue engineering heart valves. Additional studies are required to determine both the durability and long-term performance of cell-seeded PC when in a similar hemodynamic environment to that of the aortic valve. PMID:26101808

Thin film thermocouples for high temperature turbine application

NASA Technical Reports Server (NTRS)

Martin, Lisa C.

1991-01-01

The objective is to develop thin film thermocouples (TFTC) for Space Shuttle Main Engine (SSME) components such as the high pressure fuel turbopump (HPFTP) blades and to test TFTC survivability and durability in the SSME environment. The purpose for developing TFTC's for SSME components is to obtain blade temperatures for computational models developed for fluid mechanics and structures. The TFTC must be able to withstand the presence of high temperature, high pressure hydrogen as well as a severe thermal transient due to a cryogenic to combustion temperature change. The TFTC's will eventually be installed and tested on SSME propulsion system components in the SSME test bed engine. The TFTC's were successfully fabricated on flat coupons of MAR-M 246 (Hf+), which is the superalloy material used for HPFTP turbine blades. The TFTC's fabricated on flat coupons survived thermal shock cycling as well as testing in a heat flux measurement facility which provided a rapid thermal transient. The same fabrication procedure was used to deposit TFTC's on HPFTP first stage rotor blades. Other results from the experiments are presented, and future testing plans are discussed.

Multiphysics Engineering Analysis for an Integrated Design of ITER Diagnostic First Wall and Diagnostic Shield Module Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Y.; Loesser, G.; Smith, M.

ITER diagnostic first walls (DFWs) and diagnostic shield modules (DSMs) inside the port plugs (PPs) are designed to protect diagnostic instrument and components from a harsh plasma environment and provide structural support while allowing for diagnostic access to the plasma. The design of DFWs and DSMs are driven by 1) plasma radiation and nuclear heating during normal operation 2) electromagnetic loads during plasma events and associate component structural responses. A multi-physics engineering analysis protocol for the design has been established at Princeton Plasma Physics Laboratory and it was used for the design of ITER DFWs and DSMs. The analyses weremore » performed to address challenging design issues based on resultant stresses and deflections of the DFW-DSM-PP assembly for the main load cases. ITER Structural Design Criteria for In-Vessel Components (SDC-IC) required for design by analysis and three major issues driving the mechanical design of ITER DFWs are discussed. The general guidelines for the DSM design have been established as a result of design parametric studies.« less

Advanced General Aviation Turbine Engine (GATE) concepts

NASA Technical Reports Server (NTRS)

Lays, E. J.; Murray, G. L.

1979-01-01

Concepts are discussed that project turbine engine cost savings through use of geometrically constrained components designed for low rotational speeds and low stress to permit manufacturing economies. Aerodynamic development of geometrically constrained components is recommended to maximize component efficiency. Conceptual engines, airplane applications, airplane performance, engine cost, and engine-related life cycle costs are presented. The powerplants proposed offer encouragement with respect to fuel efficiency and life cycle costs, and make possible remarkable airplane performance gains.

Regeneration of the anterior cruciate ligament: Current strategies in tissue engineering

PubMed Central

Nau, Thomas; Teuschl, Andreas

2015-01-01

Recent advancements in the field of musculoskeletal tissue engineering have raised an increasing interest in the regeneration of the anterior cruciate ligament (ACL). It is the aim of this article to review the current research efforts and highlight promising tissue engineering strategies. The four main components of tissue engineering also apply in several ACL regeneration research efforts. Scaffolds from biological materials, biodegradable polymers and composite materials are used. The main cell sources are mesenchymal stem cells and ACL fibroblasts. In addition, growth factors and mechanical stimuli are applied. So far, the regenerated ACL constructs have been tested in a few animal studies and the results are encouraging. The different strategies, from in vitro ACL regeneration in bioreactor systems to bio-enhanced repair and regeneration, are under constant development. We expect considerable progress in the near future that will result in a realistic option for ACL surgery soon. PMID:25621217

Engineered nanomaterials for solar energy conversion.

PubMed

Mlinar, Vladan

2013-02-01

Understanding how to engineer nanomaterials for targeted solar-cell applications is the key to improving their efficiency and could lead to breakthroughs in their design. Proposed mechanisms for the conversion of solar energy to electricity are those exploiting the particle nature of light in conventional photovoltaic cells, and those using the collective electromagnetic nature, where light is captured by antennas and rectified. In both cases, engineered nanomaterials form the crucial components. Examples include arrays of semiconductor nanostructures as an intermediate band (so called intermediate band solar cells), semiconductor nanocrystals for multiple exciton generation, or, in antenna-rectifier cells, nanomaterials for effective optical frequency rectification. Here, we discuss the state of the art in p-n junction, intermediate band, multiple exciton generation, and antenna-rectifier solar cells. We provide a summary of how engineered nanomaterials have been used in these systems and a discussion of the open questions.

Methods of Si based ceramic components volatilization control in a gas turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Crespo, Andres Jose; Delvaux, John; Dion Ouellet, Noemie

A method of controlling volatilization of silicon based components in a gas turbine engine includes measuring, estimating and/or predicting a variable related to operation of the gas turbine engine; correlating the variable to determine an amount of silicon to control volatilization of the silicon based components in the gas turbine engine; and injecting silicon into the gas turbine engine to control volatilization of the silicon based components. A gas turbine with a compressor, combustion system, turbine section and silicon injection system may be controlled by a controller that implements the control method.

Surface morphology and nanomechanical properties of tribological antiwear films derived from zinc dialkyl dithiophosphate compounds

NASA Astrophysics Data System (ADS)

Aktary, Mirwais

The protection of mechanical equipment from wear is of significant economic interest. It has been estimated that up to half of a percent of the gross domestic product of industrialized countries goes to replacing mechanical components that have lost compliance due to wear. Antiwear additives are key ingredients in lubrication oils that assist in protecting components from wear during high loads. These agents form sacrificial films on metal parts that limit the adhesion between the contacting surfaces and reduce the wear rate considerably. One of the most common classes of compounds employed as an antiwear agent is zinc dialkyldithiophosphates (ZDDP). This work will explore the formation, structure, and mechanical properties of ZDDP derived antiwear films on the nanoscale. These studies are important because the macroscopic performance of antiwear coatings is dictated by their nanoscale surface properties. As a first study, scanning force microscopy (SFM) is employed to track the formation of films formed from the thermooxidative decomposition of ZDDP on gold substrates. The SFM analysis is correlated with infrared spectroscopy to relate surface structure to chemical composition. The morphology and mechanical strength of ZDDP tribofilms formed at the interface of sliding stainless steel contacts is also investigated. The tribofilms evolve morphologically with contact time and are characterized by distinct segregated islands at low times that transforms to a full film at longer times. The nanomechanical properties of the tribofilms are evaluated by nanoindentation analysis. It is found that the films are mechanically softer than the underlying steel substrate. SFM and nanoindentation analyses reveal that calcium sulphonate detergents promote the formation of ZDDP tribofilms and impart to them greater mechanical stability. By contrast succinimide dispersants reduce the capacity of ZDDP to form effective antiwear films. The first application of SFM and nanoindentation to the study of automotive engine components obtained directly from vehicles is demonstrated. The wear zone on a rocker arm bridge from a diesel engine is shown to contain a tribofilm at the periphery of contact where the contact load is less. SFM images also reveal wear damage at the center of the wear zone where the contact load is expected to be higher.

Refurbishment and Automation of the Thermal/Vacuum Facilities at the Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Donohue, John T.; Johnson, Chris; Ogden, Rick; Sushon, Janet

1998-01-01

The thermal/vacuum facilities located at the Goddard Space Flight Center (GSFC) have supported both manned and unmanned space flight since the 1960s. Of the 11 facilities, currently 10 of the systems are scheduled for refurbishment and/or replacement as part of a 5-year implementation. Expected return on investment includes the reduction in test schedules, improvements in the safety of facility operations, reduction in the complexity of a test and the reduction in personnel support required for a test. Additionally, GSFC will become a global resource renowned for expertise in thermal engineering, mechanical engineering and for the automation of thermal/vacuum facilities and thermal/vacuum tests. Automation of the thermal/vacuum facilities includes the utilization of Programmable Logic Controllers (PLCs) and the use of Supervisory Control and Data Acquisition (SCADA) systems. These components allow the computer control and automation of mechanical components such as valves and pumps. In some cases, the chamber and chamber shroud require complete replacement while others require only mechanical component retrofit or replacement. The project of refurbishment and automation began in 1996 and has resulted in the computer control of one Facility (Facility #225) and the integration of electronically controlled devices and PLCs within several other facilities. Facility 225 has been successfully controlled by PLC and SCADA for over one year. Insignificant anomalies have occurred and were resolved with minimal impact to testing and operations. The amount of work remaining to be performed will occur over the next four to five years. Fiscal year 1998 includes the complete refurbishment of one facility, computer control of the thermal systems in two facilities, implementation of SCADA and PLC systems to support multiple facilities and the implementation of a Database server to allow efficient test management and data analysis.

Laser drilling of thermal barrier coated jet-engine components

NASA Astrophysics Data System (ADS)

Sezer, H. K.

Aero engine hot end components are often covered with ceramic Thermal Barrier Coatings (TBCs). Laser drilling in the TBC coated components can be a source of service life TBC degradation and spallation. The present study aims to understand the mechanisms of TBC delamination and develop techniques to drill holes without damaging the TBC, Nimonic 263 workpieces coated with TBC are used in the experiments. Microwave non-destructive testing (NDT) is employed to monitor the integrity of the coating /substrate interfaces of the post-laser drilled materials. A numerical modelling technique is used to investigate the role of melt ejection on TBC delamination. The model accounts for the vapour and the assist gas flow effects in the process. Broadly, melt ejection induced mechanical stresses for the TBC coating / bond coating and thermal effects for the bond coating / substrate interfaces are found the key delamination mechanisms. Experiments are carried out to validate the findings from the model. Various techniques that enable laser drilling without damaging the TBC are demonstrated. Twin jet assisted acute angle laser drilling is one successful technique that has been analysed using the melt ejection simulation. Optimisation of the twin jet assisted acute angle laser drilling process parameters is carried out using Design of Experiments (DoE) and statistical modelling approaches. Finally, an industrial case study to develop a high speed, high quality laser drilling system for combustor cans is described. Holes are drilled by percussion and trepan drilling in TBC coated and uncoated Haynes 230 workpieces. The production rate of percussion drilling is significantly higher than the trepan drilling, however metallurgical hole quality and reproducibility is poor. A number of process parameters are investigated to improve these characteristics. Gas type and gas pressure effects on various characteristics of the inclined laser drilled holes are investigated through theoretical and experimental work.

Development of high performance scientific components for interoperability of computing packages

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gulabani, Teena Pratap

2008-01-01

Three major high performance quantum chemistry computational packages, NWChem, GAMESS and MPQC have been developed by different research efforts following different design patterns. The goal is to achieve interoperability among these packages by overcoming the challenges caused by the different communication patterns and software design of each of these packages. A chemistry algorithm is hard to develop as well as being a time consuming process; integration of large quantum chemistry packages will allow resource sharing and thus avoid reinvention of the wheel. Creating connections between these incompatible packages is the major motivation of the proposed work. This interoperability is achievedmore » by bringing the benefits of Component Based Software Engineering through a plug-and-play component framework called Common Component Architecture (CCA). In this thesis, I present a strategy and process used for interfacing two widely used and important computational chemistry methodologies: Quantum Mechanics and Molecular Mechanics. To show the feasibility of the proposed approach the Tuning and Analysis Utility (TAU) has been coupled with NWChem code and its CCA components. Results show that the overhead is negligible when compared to the ease and potential of organizing and coping with large-scale software applications.« less

Vibro-acoustic condition monitoring of Internal Combustion Engines: A critical review of existing techniques

NASA Astrophysics Data System (ADS)

Delvecchio, S.; Bonfiglio, P.; Pompoli, F.

2018-01-01

This paper deals with the state-of-the-art strategies and techniques based on vibro-acoustic signals that can monitor and diagnose malfunctions in Internal Combustion Engines (ICEs) under both test bench and vehicle operating conditions. Over recent years, several authors have summarized what is known in critical reviews mainly focused on reciprocating machines in general or on specific signal processing techniques: no attempts to deal with IC engine condition monitoring have been made. This paper first gives a brief summary of the generation of sound and vibration in ICEs in order to place further discussion on fault vibro-acoustic diagnosis in context. An overview of the monitoring and diagnostic techniques described in literature using both vibration and acoustic signals is also provided. Different faulty conditions are described which affect combustion, mechanics and the aerodynamics of ICEs. The importance of measuring acoustic signals, as opposed to vibration signals, is due since the former seem to be more suitable for implementation on on-board monitoring systems in view of their non-intrusive behaviour, capability in simultaneously capturing signatures from several mechanical components and because of the possibility of detecting faults affecting airborne transmission paths. In view of the recent needs of the industry to (-) optimize component structural durability adopting long-life cycles, (-) verify the engine final status at the end of the assembly line and (-) reduce the maintenance costs monitoring the ICE life during vehicle operations, monitoring and diagnosing system requests are continuously growing up. The present review can be considered a useful guideline for test engineers in understanding which types of fault can be diagnosed by using vibro-acoustic signals in sufficient time in both test bench and operating conditions and which transducer and signal processing technique (of which the essential background theory is here reported) could be considered the most reliable and informative to be implemented for the fault in question.

Sensor Based Engine Life Calculation: A Probabilistic Perspective

NASA Technical Reports Server (NTRS)

Guo, Ten-Huei; Chen, Philip

2003-01-01

It is generally known that an engine component will accumulate damage (life usage) during its lifetime of use in a harsh operating environment. The commonly used cycle count for engine component usage monitoring has an inherent range of uncertainty which can be overly costly or potentially less safe from an operational standpoint. With the advance of computer technology, engine operation modeling, and the understanding of damage accumulation physics, it is possible (and desirable) to use the available sensor information to make a more accurate assessment of engine component usage. This paper describes a probabilistic approach to quantify the effects of engine operating parameter uncertainties on the thermomechanical fatigue (TMF) life of a selected engine part. A closed-loop engine simulation with a TMF life model is used to calculate the life consumption of different mission cycles. A Monte Carlo simulation approach is used to generate the statistical life usage profile for different operating assumptions. The probabilities of failure of different operating conditions are compared to illustrate the importance of the engine component life calculation using sensor information. The results of this study clearly show that a sensor-based life cycle calculation can greatly reduce the risk of component failure as well as extend on-wing component life by avoiding unnecessary maintenance actions.

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1994-01-01

Reports technical effort by AlliedSignal Engines in sixth year of DOE/NASA funded project. Topics include: gas turbine engine design modifications of production APU to incorporate ceramic components; fabrication and processing of silicon nitride blades and nozzles; component and engine testing; and refinement and development of critical ceramics technologies, including: hot corrosion testing and environmental life predictive model; advanced NDE methods for internal flaws in ceramic components; and improved carbon pulverization modeling during impact. ATTAP project is oriented toward developing high-risk technology of ceramic structural component design and fabrication to carry forward to commercial production by 'bridging the gap' between structural ceramics in the laboratory and near-term commercial heat engine application. Current ATTAP project goal is to support accelerated commercialization of advanced, high-temperature engines for hybrid vehicles and other applications. Project objectives are to provide essential and substantial early field experience demonstrating ceramic component reliability and durability in modified, available, gas turbine engine applications; and to scale-up and improve manufacturing processes of ceramic turbine engine components and demonstrate application of these processes in the production environment.

Performance retention of the RB211 powerplant in service

NASA Technical Reports Server (NTRS)

Astridge, B. L.; Pinder, J. T.

1981-01-01

An understanding of the mechanisms of deterioration is essential in order that features to counteract performance degradation can be built into the basic design of an engine and nacelle. Furthermore, the interpretation must be continued in service for effective feedback to provide modifications which may be necessary in maintaining a satisfactory performance retention program. The in service assessment must be accurate as to magnitude and causes and this requires consideration of: (1) the powerplant as a complete entity, i.e., the engine components and nacelle including the thrust reverser; (2) measurement of performance in flight rather than by sole reliance on the scaling of test cell data to flight conditions (although some correlation should be possible); and (3) the relationship of engine parts condition to overhaul performance and in flight deterioration level of that engine. These aspects are addressed by consideration of the RB211 engine in service in both the Lockheed L1011 Tristar and Boeing 747 aircraft.

Engineered Living Materials: Prospects and Challenges for Using Biological Systems to Direct the Assembly of Smart Materials.

PubMed

Nguyen, Peter Q; Courchesne, Noémie-Manuelle Dorval; Duraj-Thatte, Anna; Praveschotinunt, Pichet; Joshi, Neel S

2018-05-01

Vast potential exists for the development of novel, engineered platforms that manipulate biology for the production of programmed advanced materials. Such systems would possess the autonomous, adaptive, and self-healing characteristics of living organisms, but would be engineered with the goal of assembling bulk materials with designer physicochemical or mechanical properties, across multiple length scales. Early efforts toward such engineered living materials (ELMs) are reviewed here, with an emphasis on engineered bacterial systems, living composite materials which integrate inorganic components, successful examples of large-scale implementation, and production methods. In addition, a conceptual exploration of the fundamental criteria of ELM technology and its future challenges is presented. Cradled within the rich intersection of synthetic biology and self-assembling materials, the development of ELM technologies allows the power of biology to be leveraged to grow complex structures and objects using a palette of bio-nanomaterials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparing two types of engineering visualizations: task-related manipulations matter.

PubMed

Cölln, Martin C; Kusch, Kerstin; Helmert, Jens R; Kohler, Petra; Velichkovsky, Boris M; Pannasch, Sebastian

2012-01-01

This study focuses on the comparison of traditional engineering drawings with a CAD (computer aided design) visualization in terms of user performance and eye movements in an applied context. Twenty-five students of mechanical engineering completed search tasks for measures in two distinct depictions of a car engine component (engineering drawing vs. CAD model). Besides spatial dimensionality, the display types most notably differed in terms of information layout, access and interaction options. The CAD visualization yielded better performance, if users directly manipulated the object, but was inferior, if employed in a conventional static manner, i.e. inspecting only predefined views. An additional eye movement analysis revealed longer fixation durations and a stronger increase of task-relevant fixations over time when interacting with the CAD visualization. This suggests a more focused extraction and filtering of information. We conclude that the three-dimensional CAD visualization can be advantageous if its ability to manipulate is used. Copyright © 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Integrated Turbine Tip Clearance and Gas Turbine Engine Simulation

NASA Technical Reports Server (NTRS)

Chapman, Jeffryes W.; Kratz, Jonathan; Guo, Ten-Huei; Litt, Jonathan

2016-01-01

Gas turbine compressor and turbine blade tip clearance (i.e., the radial distance between the blade tip of an axial compressor or turbine and the containment structure) is a major contributing factor to gas path sealing, and can significantly affect engine efficiency and operational temperature. This paper details the creation of a generic but realistic high pressure turbine tip clearance model that may be used to facilitate active tip clearance control system research. This model uses a first principles approach to approximate thermal and mechanical deformations of the turbine system, taking into account the rotor, shroud, and blade tip components. Validation of the tip clearance model shows that the results are realistic and reflect values found in literature. In addition, this model has been integrated with a gas turbine engine simulation, creating a platform to explore engine performance as tip clearance is adjusted. Results from the integrated model explore the effects of tip clearance on engine operation and highlight advantages of tip clearance management.

Real-Time Aircraft Engine-Life Monitoring

NASA Technical Reports Server (NTRS)

Klein, Richard

2014-01-01

This project developed an inservice life-monitoring system capable of predicting the remaining component and system life of aircraft engines. The embedded system provides real-time, inflight monitoring of the engine's thrust, exhaust gas temperature, efficiency, and the speed and time of operation. Based upon this data, the life-estimation algorithm calculates the remaining life of the engine components and uses this data to predict the remaining life of the engine. The calculations are based on the statistical life distribution of the engine components and their relationship to load, speed, temperature, and time.

Rheological Properties of Cross-Linked Hyaluronan–Gelatin Hydrogels for Tissue Engineering

PubMed Central

Vanderhooft, Janssen L.; Alcoutlabi, Mataz; Magda, Jules J.; Prestwich, Glenn D.

2009-01-01

Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component. PMID:18839402

Knowledge Engineering Aspects of Affective Bi-Modal Educational Applications

NASA Astrophysics Data System (ADS)

Alepis, Efthymios; Virvou, Maria; Kabassi, Katerina

This paper analyses the knowledge and software engineering aspects of educational applications that provide affective bi-modal human-computer interaction. For this purpose, a system that provides affective interaction based on evidence from two different modes has been developed. More specifically, the system's inferences about students' emotions are based on user input evidence from the keyboard and the microphone. Evidence from these two modes is combined by a user modelling component that incorporates user stereotypes as well as a multi criteria decision making theory. The mechanism that integrates the inferences from the two modes has been based on the results of two empirical studies that were conducted in the context of knowledge engineering of the system. The evaluation of the developed system showed significant improvements in the recognition of the emotional states of users.

Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

NASA Technical Reports Server (NTRS)

2005-01-01

The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of the loading conditions. In monotonically strained specimens, deformation during the subsequent fatigue loading was mainly confined to the deformation bands initiated during the prior monotonic straining. This can cause dislocations to move more readily along the previously activated deformation bands and to pile up near grain boundaries, eventually making the grain boundaries susceptible to fatigue crack initiation. The mechanisms inferred from the microstructural investigation were extremely valuable in interpreting the influence of prior monotonic straining on the subsequent fatigue life of Inconel 718 superalloy.

A review of proton exchange membrane water electrolysis on degradation mechanisms and mitigation strategies

NASA Astrophysics Data System (ADS)

Feng, Qi; Yuan, Xiao-Zi; Liu, Gaoyang; Wei, Bing; Zhang, Zhen; Li, Hui; Wang, Haijiang

2017-10-01

Proton exchange membrane water electrolysis (PEMWE) is an advanced and effective solution to the primary energy storage technologies. A better understanding of performance and durability of PEMWE is critical for the engineers and researchers to further advance this technology for its market penetration, and for the manufacturers of PEM water electrolyzers to implement quality control procedures for the production line or on-site process monitoring/diagnosis. This paper reviews the published works on performance degradations and mitigation strategies for PEMWE. Sources of degradation for individual components are introduced. With degradation causes discussed and degradation mechanisms examined, the review emphasizes on feasible strategies to mitigate the components degradation. To avoid lengthy real lifetime degradation tests and their high costs, the importance of accelerated stress tests and protocols is highlighted for various components. In the end, R&D directions are proposed to move the PEMWE technology forward to become a key element in future energy scenarios.

Virtual Laboratories to Achieve Higher-Order Learning in Fluid Mechanics

NASA Astrophysics Data System (ADS)

Ward, A. S.; Gooseff, M. N.; Toto, R.

2009-12-01

Bloom’s higher-order cognitive skills (analysis, evaluation, and synthesis) are recognized as necessary in engineering education, yet these are difficult to achieve in traditional lecture formats. Laboratory components supplement traditional lectures in an effort to emphasize active learning and provide higher-order challenges, but these laboratories are often subject to the constraints of (a) increasing student enrollment, (b) limited funding for operational, maintenance, and instructional expenses and (c) increasing demands on undergraduate student credit requirements. Here, we present results from a pilot project implementing virtual (or online) laboratory experiences as an alternative to a traditional laboratory experience in Fluid Mechanics, a required third year course. Students and faculty were surveyed to identify the topics that were most difficult, and virtual laboratory and design components developed to supplement lecture material. Each laboratory includes a traditional lab component, requiring student analysis and evaluation. The lab concludes with a design exercise, which imposes additional problem constraints and allows students to apply their laboratory observations to a real-world situation.

Stress Intensity Factors for Cracked Metallic Structures Under Rapid Thermal Loading

DTIC Science & Technology

1987-10-01

if applicable ) Flight Dynamics Laboratory (AFWAL/FIBFC) APTECH Engineering Services Air Force Wright Aeronautical Laboratories 6c. ADDRESS (City...SPONSORING Bb OFFICE SYMBOL 9 PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION (If applicable ) DOD SBIR Program Office F33615-86-C-3217 8c...flawed components requires the application of fracture mechanics wherein crack tip -tress intensity factors are used to provide a quantitative means

PHOTOSPHERE EMISSION FROM A HYBRID RELATIVISTIC OUTFLOW WITH ARBITRARY DIMENSIONLESS ENTROPY AND MAGNETIZATION IN GRBs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, He; Zhang, Bing, E-mail: gaohe@physics.unlv.edu, E-mail: zhang@physics.unlv.edu, E-mail: hug18@psu.edu

2015-03-10

In view of the recent Fermi observations of gamma-ray burst (GRB) prompt emission spectra, we develop a theory of photosphere emission of a hybrid relativistic outflow with a hot fireball component (defined by dimensionless entropy η) and a cold Poynting-flux component (defined by magnetization σ{sub 0} at the central engine). We consider the scenarios both without and with sub-photospheric magnetic dissipations. Based on a simplified toy model of jet dynamics, we develop two approaches: a 'bottom-up' approach to predict the temperature (for a non-dissipative photosphere) and luminosity of the photosphere emission and its relative brightness for a given pair ofmore » (η, σ{sub 0}); and a 'top-down' approach to diagnose central engine parameters (η and σ{sub 0}) based on the observed quasi-thermal photosphere emission properties. We show that a variety of observed GRB prompt emission spectra with different degrees of photosphere thermal emission can be reproduced by varying η and σ{sub 0} within the non-dissipative photosphere scenario. In order to reproduce the observed spectra, the outflows of most GRBs need to have a significant σ, both at the central engine and at the photosphere. The σ value at 10{sup 15} cm from the central engine (a possible non-thermal emission site) is usually also greater than unity, so that internal-collision-induced magnetic reconnection and turbulence (ICMART) may be the mechanism to power the non-thermal emission. We apply our top-down approach to GRB 110721A and find that the temporal evolution behavior of its blackbody component can be well interpreted with a time-varying (η, σ{sub 0}) at the central engine, instead of invoking a varying engine base size r {sub 0} as proposed by previous authors.« less

Controls and guidance research

NASA Technical Reports Server (NTRS)

Homaifar, Abdollah; Dunn, Derome; Song, Yong-Duan; Lai, Steven H.-Y.

1992-01-01

The objectives of the control group are concentrated on research and education. The control problem of the hypersonic space vehicle represents an important and challenging issue in aerospace engineering. The work described in this report is part of our effort in developing advanced control strategies for such a system. In order to achieve the objectives stated in the NASA-CORE proposal, the tasks were divided among the group based upon their educational expertise. Within the educational component we are offering a Linear Systems and Control course for students in electrical and mechanical engineering. Also, we are proposing a new course in Digital Control Systems with a corresponding laboratory.

Simulation by bondgraphs

NASA Astrophysics Data System (ADS)

Thoma, Jean Ulrich

The fundamental principles and applications of the bond graph method, in which a system is represented on paper by letter elements and their interconnections (bonds), are presented in an introduction for engineering students. Chapters are devoted to simulation and graphical system models; bond graphs as networks for power and signal exchange; the simulation and design of mechanical engineering systems; the simulation of fluid power systems and hydrostatic devices; electrical circuits, drives, and components; practical procedures and problems of bond-graph-based numerical simulation; and applications to thermodynamics, chemistry, and biology. Also included are worked examples of applications to robotics, shocks and collisions, ac circuits, hydraulics, and a hydropneumatic fatigue-testing machine.

Optimized bio-inspired stiffening design for an engine nacelle.

PubMed

Lazo, Neil; Vodenitcharova, Tania; Hoffman, Mark

2015-11-04

Structural efficiency is a common engineering goal in which an ideal solution provides a structure with optimized performance at minimized weight, with consideration of material mechanical properties, structural geometry, and manufacturability. This study aims to address this goal in developing high performance lightweight, stiff mechanical components by creating an optimized design from a biologically-inspired template. The approach is implemented on the optimization of rib stiffeners along an aircraft engine nacelle. The helical and angled arrangements of cellulose fibres in plants were chosen as the bio-inspired template. Optimization of total displacement and weight was carried out using a genetic algorithm (GA) coupled with finite element analysis. Iterations showed a gradual convergence in normalized fitness. Displacement was given higher emphasis in optimization, thus the GA optimization tended towards individual designs with weights near the mass constraint. Dominant features of the resulting designs were helical ribs with rectangular cross-sections having large height-to-width ratio. Displacement reduction was at 73% as compared to an unreinforced nacelle, and is attributed to the geometric features and layout of the stiffeners, while mass is maintained within the constraint.

Three-dimensional bioprinting is not only about cell-laden structures.

PubMed

Zhang, Hong-Bo; Xing, Tian-Long; Yin, Rui-Xue; Shi, Yong; Yang, Shi-Mo; Zhang, Wen-Jun

2016-08-01

In this review, we focused on a few obstacles that hinder three-dimensional (3D) bioprinting process in tissue engineering. One of the obstacles is the bioinks used to deliver cells. Hydrogels are the most widely used bioink materials; however, they aremechanically weak in nature and cannot meet the requirements for supporting structures, especially when the tissues, such as cartilage, require extracellular matrix to be mechanically strong. Secondly and more importantly, tissue regeneration is not only about building all the components in a way that mimics the structures of living tissues, but also about how to make the constructs function normally in the long term. One of the key issues is sufficient nutrient and oxygen supply to the engineered living constructs. The other is to coordinate the interplays between cells, bioactive agents and extracellular matrix in a natural way. This article reviews the approaches to improve the mechanical strength of hydrogels and their suitability for 3D bioprinting; moreover, the key issues of multiple cell lines coprinting with multiple growth factors, vascularization within engineered living constructs etc. were also reviewed.

Biomaterials, fibrosis, and the use of drug delivery systems in future antifibrotic strategies.

PubMed

Love, Ryan J; Jones, Kim S

2009-01-01

All biomaterials, when implanted into the body, elicit an inflammatory response that evolves into fibrovascular tissue formation on and around the material. As a result, material scientists and tissue engineers should be concerned about host response to tissue-engineered constructs that have a biomaterial component, because the host response to this component will interfere with device function and reduce the lifespan of tissue engineering devices in vivo. The fibrotic response to biomaterials is not unlike pathological fibrosis of the liver, lung, kidney, and peritoneum in many ways: i) the presence of mononuclear leukocytes are common in the local environment of both pathological fibrosis and biomaterial-induced fibrosis even though cells of mesenchymal origin are responsible for laying the majority of the extracellular matrix; ii) paracrine-signaling molecules, such as transforming growth factor beta;1, are essential mediators of fibrosis, whether it is pathological or biomaterial induced; and iii) injury and/or the presence of foreign materials (including bacterial components, toxins, or man-made objects) are essential initiators for the development of the fibrotic response. This review discusses mechanisms and research methodology related to pathological fibrosis that is of interest to researchers focused on biomaterials. Potential research models for the study of fibrosis from the fields of biomaterials and drug delivery are also discussed, which may be of interest to scientists working on the pathology of fibrotic disease.

An optimized ensemble local mean decomposition method for fault detection of mechanical components

NASA Astrophysics Data System (ADS)

Zhang, Chao; Li, Zhixiong; Hu, Chao; Chen, Shuai; Wang, Jianguo; Zhang, Xiaogang

2017-03-01

Mechanical transmission systems have been widely adopted in most of industrial applications, and issues related to the maintenance of these systems have attracted considerable attention in the past few decades. The recently developed ensemble local mean decomposition (ELMD) method shows satisfactory performance in fault detection of mechanical components for preventing catastrophic failures and reducing maintenance costs. However, the performance of ELMD often heavily depends on proper selection of its model parameters. To this end, this paper proposes an optimized ensemble local mean decomposition (OELMD) method to determinate an optimum set of ELMD parameters for vibration signal analysis. In OELMD, an error index termed the relative root-mean-square error (Relative RMSE) is used to evaluate the decomposition performance of ELMD with a certain amplitude of the added white noise. Once a maximum Relative RMSE, corresponding to an optimal noise amplitude, is determined, OELMD then identifies optimal noise bandwidth and ensemble number based on the Relative RMSE and signal-to-noise ratio (SNR), respectively. Thus, all three critical parameters of ELMD (i.e. noise amplitude and bandwidth, and ensemble number) are optimized by OELMD. The effectiveness of OELMD was evaluated using experimental vibration signals measured from three different mechanical components (i.e. the rolling bearing, gear and diesel engine) under faulty operation conditions.

Engine diagnostics program: CF6-50 engine performance deterioration

NASA Technical Reports Server (NTRS)

Wulf, R. H.

1980-01-01

Cockpit cruise recordings and test cell data in conjunction with hardware inspection results from airline overhaul shops were analyzed to define the extent and magnitude of performance deterioration of the General Electric CF6-50 high bypass turbofan engine. The magnitude of short term deterioration was isolated from the long term, and the individual damage mechanisms that were the cause for the majority of the performance deterioration was identified. It was determined that the long term engine performance deterioration characteristics were different for the 3 aircraft types currently powered by the CF6-50 engine, but these differences were due to operational considerations (flight length and takeoff derate) and not to differences associated with the aircraft type. Unrestored losses, that is, performance deterioration which remains after engine refurbishment, represents over 70 percent of the total performance deterioration at engine shop visit. Superficial damage, such as, increased surface roughness, leading edge shape changes on airfoils, and increases in the average clearances between rotating and stationary components is the major contributor to these losses. Seventy one percent of the unrestored losses are cost effective to restore, and if implemented could reduce fuel consumed by CF6-50 engines by 26 million gallons in 1980.

Viscoelastic Properties of Human Tracheal Tissues.

PubMed

Safshekan, Farzaneh; Tafazzoli-Shadpour, Mohammad; Abdouss, Majid; Shadmehr, Mohammad B

2017-01-01

The physiological performance of trachea is highly dependent on its mechanical behavior, and therefore, the mechanical properties of its components. Mechanical characterization of trachea is key to succeed in new treatments such as tissue engineering, which requires the utilization of scaffolds which are mechanically compatible with the native human trachea. In this study, after isolating human trachea samples from brain-dead cases and proper storage, we assessed the viscoelastic properties of tracheal cartilage, smooth muscle, and connective tissue based on stress relaxation tests (at 5% and 10% strains for cartilage and 20%, 30%, and 40% for smooth muscle and connective tissue). After investigation of viscoelastic linearity, constitutive models including Prony series for linear viscoelasticity and quasi-linear viscoelastic, modified superposition, and Schapery models for nonlinear viscoelasticity were fitted to the experimental data to find the best model for each tissue. We also investigated the effect of age on the viscoelastic behavior of tracheal tissues. Based on the results, all three tissues exhibited a (nonsignificant) decrease in relaxation rate with increasing the strain, indicating viscoelastic nonlinearity which was most evident for cartilage and with the least effect for connective tissue. The three-term Prony model was selected for describing the linear viscoelasticity. Among different models, the modified superposition model was best able to capture the relaxation behavior of the three tracheal components. We observed a general (but not significant) stiffening of tracheal cartilage and connective tissue with aging. No change in the stress relaxation percentage with aging was observed. The results of this study may be useful in the design and fabrication of tracheal tissue engineering scaffolds.

Orbit Transfer Vehicle (OTV) advanced expander cycle engine point design study. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Mellish, J. A.

1980-01-01

Engine control techniques were established and new technology requirements were identified. The designs of the components and engine were prepared in sufficient depth to calculate engine and component weights and envelopes, turbopump efficiencies and recirculation leakage rates, and engine performance. Engine design assumptions are presented along with the structural design criteria.

14 CFR 33.53 - Engine system and component tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine system and component tests. 33.53 Section 33.53 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.53 Engine system and...

14 CFR 33.91 - Engine system and component tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine system and component tests. 33.91 Section 33.91 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.91 Engine system and...

14 CFR 33.91 - Engine system and component tests.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine system and component tests. 33.91 Section 33.91 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.91 Engine system and...

14 CFR 33.91 - Engine system and component tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine system and component tests. 33.91 Section 33.91 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.91 Engine system and...

Thermal and Environmental Barrier Coating Development for Advanced Propulsion Engine Systems

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.; Fox, Dennis S.

2008-01-01

Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. Advanced TEBCs that have significantly lower thermal conductivity, better thermal stability and higher toughness than current coatings will be beneficial for future low emission and high performance propulsion engine systems. In this paper, ceramic coating design and testing considerations will be described for turbine engine high temperature and high-heat-flux applications. Thermal barrier coatings for metallic turbine airfoils and thermal/environmental barrier coatings for SiC/SiC ceramic matrix composite (CMC) components for future supersonic aircraft propulsion engines will be emphasized. Further coating capability and durability improvements for the engine hot-section component applications can be expected by utilizing advanced modeling and design tools.

Plasma facing materials and components for future fusion devices—development, characterization and performance under fusion specific loading conditions

NASA Astrophysics Data System (ADS)

Linke, J.

2006-04-01

The plasma exposed components in existing and future fusion devices are strongly affected by the plasma material interaction processes. These mechanisms have a strong influence on the plasma performance; in addition they have major impact on the lifetime of the plasma facing armour and the joining interface between the plasma facing material (PFM) and the heat sink. Besides physical and chemical sputtering processes, high heat quasi-stationary fluxes during normal and intense thermal transients are of serious concern for the engineers who develop reliable wall components. In addition, the material and component degradation due to intense fluxes of energetic neutrons is another critical issue in D-T-burning fusion devices which requires extensive R&D. This paper presents an overview on the materials development and joining, the testing of PFMs and components, and the analysis of the neutron irradiation induced degradation.

Aerodynamic and engineering design of a 1.5 s high quality microgravity drop tower facility

NASA Astrophysics Data System (ADS)

Belser, Valentin; Breuninger, Jakob; Reilly, Matthew; Laufer, René; Dropmann, Michael; Herdrich, Georg; Hyde, Truell; Röser, Hans-Peter; Fasoulas, Stefanos

2016-12-01

Microgravity experiments are essential for research in space science, biology, fluid mechanics, combustion, and material sciences. One way to conduct microgravity experiments on Earth is by using drop tower facilities. These facilities combine a high quality of microgravity, adequate payload masses and have the advantage of virtually unlimited repeatability under same experimental conditions, at a low cost. In a collaboration between the Institute of Space Systems (IRS) at the University of Stuttgart and Baylor University (BU) in Waco, Texas, a new drop tower is currently under development at the Center for Astrophysics, Space Physics and Engineering Research (CASPER). The design parameters of the drop tower ask for at least 1.5 s in free fall duration while providing a quality of at least 10-5 g. Previously, this quality has only been achieved in vacuum drop tower facilities where the capsule experiences virtually zero aerodynamic drag during its free fall. Since this design comes at high costs, a different drop tower design concept, which does not require an evacuated drop shaft, was chosen. It features a dual-capsule system in which the experiment capsule is shielded from aerodynamic forces by surrounding it with a drag shield during the drop. As no other dual-capsule drop tower has been able to achieve a quality as good as or better than 10-5 g previous work optimized the design with an aerodynamic perspective by using computational fluid dynamics (CFD) simulations to determine the ideal shape and size of the outer capsule and to specify the aerodynamically crucial dimensions for the overall system. Experiments later demonstrated that the required quality of microgravity can be met with the proposed design. The main focus of this paper is the mechanical realization of the capsule as well as the development and layout of the surrounding components, such as the release mechanism, the deceleration device and the drop shaft. Because the drop tower facility is a complex system with many interdependencies between all of the components, several engineering challenges had to be addressed. For example, initial disturbances that are caused by the release mechanism are a common issue that arises at drop tower facilities. These vibrations may decrease the quality of microgravity during the initial segment of free fall. Because this would reduce the free fall time experiencing high quality microgravity, a mechanism has been developed to provide a soft release. Challenges and proposed solutions for all components are highlighted in this paper.

High temperature alkali corrosion of ceramics in coal gas: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pickrell, G.R.; Sun, T.; Brown, J.J. Jr.

1994-12-31

There are several ceramic materials which are currently being considered for use as structural elements in coal combustion and coal conversion systems because of their thermal and mechanical properties. These include alumina (refractories, membranes, heat engines); silicon carbide and silicon nitride (turbine engines, internal combustion engines, heat exchangers, particulate filters); zirconia (internal combustion engines, turbine engines, refractories); and mullite and cordierite (particulate filters, refractories, heat exchangers). High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and highmore » efficiency heat engines. The objective of this research is to systematically evaluate the alkali corrosion resistance of the most commonly used structural ceramics including silicon carbide, silicon nitride, cordierite, mullite, alumina, aluminum titanate, and zirconia. The study consists of identification of the alkali reaction products and determination of the kinetics of the alkali reactions as a function of temperature and time. 145 refs., 29 figs., 12 tabs.« less

Controllable degradation kinetics of POSS nanoparticle-integrated poly(ε-caprolactone urea)urethane elastomers for tissue engineering applications

PubMed Central

Yildirimer, Lara; Buanz, Asma; Gaisford, Simon; Malins, Edward L.; Remzi Becer, C.; Moiemen, Naiem; Reynolds, Gary M.; Seifalian, Alexander M.

2015-01-01

Biodegradable elastomers are a popular choice for tissue engineering scaffolds, particularly in mechanically challenging settings (e.g. the skin). As the optimal rate of scaffold degradation depends on the tissue type to be regenerated, next-generation scaffolds must demonstrate tuneable degradation patterns. Previous investigations mainly focussed on the integration of more or less hydrolysable components to modulate degradation rates. In this study, however, the objective was to develop and synthesize a family of novel biodegradable polyurethanes (PUs) based on a poly(ε-caprolactone urea)urethane backbone integrating polyhedral oligomeric silsesquioxane (POSS-PCLU) with varying amounts of hard segments (24%, 28% and 33% (w/v)) in order to investigate the influence of hard segment chemistry on the degradation rate and profile. PUs lacking POSS nanoparticles served to prove the important function of POSS in maintaining the mechanical structures of the PU scaffolds before, during and after degradation. Mechanical testing of degraded samples revealed hard segment-dependent modulation of the materials’ viscoelastic properties, which was attributable to (i) degradation-induced changes in the PU crystallinity and (ii) either the presence or absence of POSS. In conclusion, this study presents a facile method of controlling degradation profiles of PU scaffolds used in tissue engineering applications. PMID:26463421

Self-lubricating Al-WS2 composites for efficient and greener tribological parts.

PubMed

Niste, Vlad Bogdan; Ratoi, Monica; Tanaka, Hiroyoshi; Xu, Fang; Zhu, Yanqiu; Sugimura, Joichi

2017-11-07

Due to their mechanical and physical properties, aluminium alloys possess wide potential in the automotive industry, particularly in hot reciprocating applications such as pistons for diesel and petrol engines. WS 2 particle-reinforced composites could bring further improvements by reducing friction and wear between moving parts. Reducing friction improves efficiency by lowering energy/fuel use, ultimately leading to lower greenhouse gas emissions, while antiwear properties can prolong component life. This study compares for the first time the tribological performance of powder metallurgy-consolidated Al composites reinforced with either IF- or 2H-WS 2 particles, so as to elucidate their mechanism of action in test conditions similar to those encountered in engine applications. The composites were tested in lubricated reciprocating contacts against AISI52100 steel balls and the impact of WS 2 could be seen at both 25 and 100 °C. The reduced friction and wear at ambient temperature is due to the predominantly physical mechanism of action of WS 2 , while the best antiwear performance is measured at elevated (standard operating engine) temperatures that promote the chemical reaction of WS 2 with the aluminium matrix. The investigation focused on studying the wear tracks/scars and the tribofilms generated on the composite and ball with optical profilometry, SEM, XPS and Auger spectroscopy.

Heart valve scaffold fabrication: Bioinspired control of macro-scale morphology, mechanics and micro-structure.

PubMed

D'Amore, Antonio; Luketich, Samuel K; Raffa, Giuseppe M; Olia, Salim; Menallo, Giorgio; Mazzola, Antonino; D'Accardi, Flavio; Grunberg, Tamir; Gu, Xinzhu; Pilato, Michele; Kameneva, Marina V; Badhwar, Vinay; Wagner, William R

2018-01-01

Valvular heart disease is currently treated with mechanical valves, which benefit from longevity, but are burdened by chronic anticoagulation therapy, or with bioprosthetic valves, which have reduced thromboembolic risk, but limited durability. Tissue engineered heart valves have been proposed to resolve these issues by implanting a scaffold that is replaced by endogenous growth, leaving autologous, functional leaflets that would putatively eliminate the need for anticoagulation and avoid calcification. Despite the diversity in fabrication strategies and encouraging results in large animal models, control over engineered valve structure-function remains at best partial. This study aimed to overcome these limitations by introducing double component deposition (DCD), an electrodeposition technique that employs multi-phase electrodes to dictate valve macro and microstructure and resultant function. Results in this report demonstrate the capacity of the DCD method to simultaneously control scaffold macro-scale morphology, mechanics and microstructure while producing fully assembled stent-less multi-leaflet valves composed of microscopic fibers. DCD engineered valve characterization included: leaflet thickness, biaxial properties, bending properties, and quantitative structural analysis of multi-photon and scanning electron micrographs. Quasi-static ex-vivo valve coaptation testing and dynamic organ level functional assessment in a pressure pulse duplicating device demonstrated appropriate acute valve functionality. Copyright © 2017. Published by Elsevier Ltd.

Extracellular Matrix Degradation and Remodeling in Development and Disease

PubMed Central

Lu, Pengfei; Takai, Ken; Weaver, Valerie M.; Werb, Zena

2011-01-01

The extracellular matrix (ECM) serves diverse functions and is a major component of the cellular microenvironment. The ECM is a highly dynamic structure, constantly undergoing a remodeling process where ECM components are deposited, degraded, or otherwise modified. ECM dynamics are indispensible during restructuring of tissue architecture. ECM remodeling is an important mechanism whereby cell differentiation can be regulated, including processes such as the establishment and maintenance of stem cell niches, branching morphogenesis, angiogenesis, bone remodeling, and wound repair. In contrast, abnormal ECM dynamics lead to deregulated cell proliferation and invasion, failure of cell death, and loss of cell differentiation, resulting in congenital defects and pathological processes including tissue fibrosis and cancer. Understanding the mechanisms of ECM remodeling and its regulation, therefore, is essential for developing new therapeutic interventions for diseases and novel strategies for tissue engineering and regenerative medicine. PMID:21917992

Numerical investigation of spray ignition of a multi-component fuel surrogate

NASA Astrophysics Data System (ADS)

Backer, Lara; Narayanaswamy, Krithika; Pepiot, Perrine

2014-11-01

Simulating turbulent spray ignition, an important process in engine combustion, is challenging, since it combines the complexity of multi-scale, multiphase turbulent flow modeling with the need for an accurate description of chemical kinetics. In this work, we use direct numerical simulation to investigate the role of the evaporation model on the ignition characteristics of a multi-component fuel surrogate, injected as droplets in a turbulent environment. The fuel is represented as a mixture of several components, each one being representative of a different chemical class. A reduced kinetic scheme for the mixture is extracted from a well-validated detailed chemical mechanism, and integrated into the multiphase turbulent reactive flow solver NGA. Comparisons are made between a single-component evaporation model, in which the evaporating gas has the same composition as the liquid droplet, and a multi-component model, where component segregation does occur. In particular, the corresponding production of radical species, which are characteristic of the ignition of individual fuel components, is thoroughly analyzed.

Cell Microenvironment Engineering and Monitoring for Tissue Engineering and Regenerative Medicine: The Recent Advances

PubMed Central

Barthes, Julien; Özçelik, Hayriye; Hindié, Mathilde; Ndreu-Halili, Albana; Hasan, Anwarul

2014-01-01

In tissue engineering and regenerative medicine, the conditions in the immediate vicinity of the cells have a direct effect on cells' behaviour and subsequently on clinical outcomes. Physical, chemical, and biological control of cell microenvironment are of crucial importance for the ability to direct and control cell behaviour in 3-dimensional tissue engineering scaffolds spatially and temporally. In this review, we will focus on the different aspects of cell microenvironment such as surface micro-, nanotopography, extracellular matrix composition and distribution, controlled release of soluble factors, and mechanical stress/strain conditions and how these aspects and their interactions can be used to achieve a higher degree of control over cellular activities. The effect of these parameters on the cellular behaviour within tissue engineering context is discussed and how these parameters are used to develop engineered tissues is elaborated. Also, recent techniques developed for the monitoring of the cell microenvironment in vitro and in vivo are reviewed, together with recent tissue engineering applications where the control of cell microenvironment has been exploited. Cell microenvironment engineering and monitoring are crucial parts of tissue engineering efforts and systems which utilize different components of the cell microenvironment simultaneously can provide more functional engineered tissues in the near future. PMID:25143954

Cell microenvironment engineering and monitoring for tissue engineering and regenerative medicine: the recent advances.

PubMed

Barthes, Julien; Özçelik, Hayriye; Hindié, Mathilde; Ndreu-Halili, Albana; Hasan, Anwarul; Vrana, Nihal Engin

2014-01-01

In tissue engineering and regenerative medicine, the conditions in the immediate vicinity of the cells have a direct effect on cells' behaviour and subsequently on clinical outcomes. Physical, chemical, and biological control of cell microenvironment are of crucial importance for the ability to direct and control cell behaviour in 3-dimensional tissue engineering scaffolds spatially and temporally. In this review, we will focus on the different aspects of cell microenvironment such as surface micro-, nanotopography, extracellular matrix composition and distribution, controlled release of soluble factors, and mechanical stress/strain conditions and how these aspects and their interactions can be used to achieve a higher degree of control over cellular activities. The effect of these parameters on the cellular behaviour within tissue engineering context is discussed and how these parameters are used to develop engineered tissues is elaborated. Also, recent techniques developed for the monitoring of the cell microenvironment in vitro and in vivo are reviewed, together with recent tissue engineering applications where the control of cell microenvironment has been exploited. Cell microenvironment engineering and monitoring are crucial parts of tissue engineering efforts and systems which utilize different components of the cell microenvironment simultaneously can provide more functional engineered tissues in the near future.

Toward Reusable Graphics Components in Ada

DTIC Science & Technology

1993-03-01

Then alternatives for obtaining well- engineered reusable software components were examined. Finally, the alternatives were analyzed, and the most...reusable software components. Chapter 4 describes detailed design and implementation strategies in building a well- engineered reusable set of components in...study. 2.2 The Object-Oriented Paradigm 2.2.1 The Need for Object-Oriented Techniques. Among software engineers the software crisis is a well known

Impeller leakage flow modeling for mechanical vibration control

NASA Technical Reports Server (NTRS)

Palazzolo, Alan B.

1996-01-01

HPOTP and HPFTP vibration test results have exhibited transient and steady characteristics which may be due to impeller leakage path (ILP) related forces. For example, an axial shift in the rotor could suddenly change the ILP clearances and lengths yielding dynamic coefficient and subsequent vibration changes. ILP models are more complicated than conventional-single component-annular seal models due to their radial flow component (coriolis and centrifugal acceleration), complex geometry (axial/radial clearance coupling), internal boundary (transition) flow conditions between mechanical components along the ILP and longer length, requiring moment as well as force coefficients. Flow coupling between mechanical components results from mass and energy conservation applied at their interfaces. Typical components along the ILP include an inlet seal, curved shroud, and an exit seal, which may be a stepped labyrinth type. Von Pragenau (MSFC) has modeled labyrinth seals as a series of plain annular seals for leakage and dynamic coefficient prediction. These multi-tooth components increase the total number of 'flow coupled' components in the ILP. Childs developed an analysis for an ILP consisting of a single, constant clearance shroud with an exit seal represented by a lumped flow-loss coefficient. This same geometry was later extended to include compressible flow. The objective of the current work is to: supply ILP leakage-force impedance-dynamic coefficient modeling software to MSFC engineers, base on incompressible/compressible bulk flow theory; design the software to model a generic geometry ILP described by a series of components lying along an arbitrarily directed path; validate the software by comparison to available test data, CFD and bulk models; and develop a hybrid CFD-bulk flow model of an ILP to improve modeling accuracy within practical run time constraints.

Preload Loss in a Spacecraft Fastener via Vibration-Induced Unwinding

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Howard, S. Adam; Hess, Daniel P.

2018-01-01

Sound engineering practice requires that fasteners and bolted joints maintain preload in service. NASA recently concluded a series of vibration tests of a multicomponent structure intended to simulate an upper stage section of a launch vehicle. The stacked components were joined through six circumferentially placed bolted cup-cone-style pyrotechnic joint mechanisms designed to share spacecraft structural loads and then enable separation during ascent. Over the course of the vibration test campaign, all six bolted cup-cone mechanisms experienced some degree of preload loss with two mechanisms losing half of their original bolt preload. A subsequent forensic anomaly investigation concluded that vibration-induced unwinding of the preload nut-and-bolt assemblies occurred despite the use of safety wire and high levels of thread friction. A series of experiments were done to better understand how large, heavily preloaded fasteners could unwind. Additionally, thread friction torque was measured and the fastener locking capability of safety wire was evaluated. The friction coefficient between the clamped cup-cone components was characterized and finally a highly instrumented mechanism-level vibration test was done to reproduce the unwinding phenomenon to better understand the mechanism's behavior. The conclusion drawn was that vibration and structural forces led to relative motion (sliding) of the clamped components, resulting in self-loosening and unwinding effects on the nut-and-bolt assembly. To counter this phenomenon, more effective fastener locking methodologies were recommended and a follow-on effort was initiated to quantify the relationship between preload, component motion, and resulting unwinding forces. It is hoped that elucidation of these effects can be used to design more effective fastener locking features.

Numerical and Experimental Study on Manufacture of a Novel High-Capacity Engine Oil Pan Subjected to Hydro-Mechanical Deep Drawing

NASA Astrophysics Data System (ADS)

Chen, D. Y.; Xu, Y.; Zhang, S. H.; El-Aty, A. Abd; Ma, Y.

2017-09-01

The oil pan is equipped at the bottom of engine crankcase of the automobile to prevent impurity and collect the lubrication oil from the surfaces of the engine which is helpful for heat dissipation and oxidation prevention. The present study aims at manufacturing a novel high-capacity engine oil pan, which is considered as a complex shaped component with features of thin wall, large size and asymmetric deep cavity through both numerical and experimental methods. The result indicated that it is difficult to form the current part through the common deep drawing process. Accordingly, the hydro-mechanical deep drawing technology was conducted, which consisted of two steps, previous local drawing and the final integral deep drawing with hydraulic pressure. The finite element analysis (FEA) was carried out to investigate the influence of initial blank dimension and the key process parameters such as loading path, draw-bead force and fillet radius on the formability of the sheet blank. Compared with the common deep drawing, the limit drawing ratio by hydro-mechanical deep drawing can be increased from 2.34 to 2.77, while the reduction in blank wall thickness can be controlled in the range of 28%. The formability is greatly improved without any defects such as crack and wrinkle by means of parameters optimisation. The results gained from simulation keep a reasonable agreement with that obtained from experiment trials.

At a glance: cellular biology for engineers.

PubMed

Khoshmanesh, K; Kouzani, A Z; Nahavandi, S; Baratchi, S; Kanwar, J R

2008-10-01

Engineering contributions have played an important role in the rise and evolution of cellular biology. Engineering technologies have helped biologists to explore the living organisms at cellular and molecular levels, and have created new opportunities to tackle the unsolved biological problems. There is now a growing demand to further expand the role of engineering in cellular biology research. For an engineer to play an effective role in cellular biology, the first essential step is to understand the cells and their components. However, the stumbling block of this step is to comprehend the information given in the cellular biology literature because it best suits the readers with a biological background. This paper aims to overcome this bottleneck by describing the human cell components as micro-plants that form cells as micro-bio-factories. This concept can accelerate the engineers' comprehension of the subject. In this paper, first the structure and function of different cell components are described. In addition, the engineering attempts to mimic various cell components through numerical modelling or physical implementation are highlighted. Next, the interaction of different cell components that facilitate complicated chemical processes, such as energy generation and protein synthesis, are described. These complex interactions are translated into simple flow diagrams, generally used by engineers to represent multi-component processes.

Oxygen Compatibility Assessment of Components and Systems

NASA Technical Reports Server (NTRS)

Stoltzfus, Joel; Sparks, Kyle

2010-01-01

Fire hazards are inherent in oxygen systems and a storied history of fires in rocket engine propulsion components exists. To detect and mitigate these fire hazards requires careful, detailed, and thorough analyses applied during the design process. The oxygen compatibility assessment (OCA) process designed by NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) can be used to determine the presence of fire hazards in oxygen systems and the likelihood of a fire. This process may be used as both a design guide and during the approval process to ensure proper design features and material selection. The procedure for performing an OCA is a structured step-by-step process to determine the most severe operating conditions; assess the flammability of the system materials at the use conditions; evaluate the presence and efficacy of ignition mechanisms; assess the potential for a fire to breach the system; and determine the reaction effect (the potential loss of life, mission, and system functionality as the result of a fire). This process should be performed for each component in a system. The results of each component assessment, and the overall system assessment, should be recorded in a report that can be used in the short term to communicate hazards and their mitigation and to aid in system/component development and, in the long term, to solve anomalies that occur during engine testing and operation.

LARGE STRAIN STIMULATION PROMOTES EXTRACELLULAR MATRIX PRODUCTION AND STIFFNESS IN AN ELASTOMERIC SCAFFOLD MODEL

PubMed Central

D’more, Antonio; Soares, Joao; Stella, John A.; Zhang, Will; Amoroso, Nicholas J.; Mayer, John E.; Wagner, William R.; Sacks, Michael S.

2016-01-01

Mechanical conditioning of engineered tissue constructs is widely recognized as one of the most relevant methods to enhance tissue accretion and microstructure, leading to improved mechanical behaviors. The understanding of the underlying mechanisms remains rather limited, restricting the development of in silico models of these phenomena, and the translation of engineered tissues into clinical application. In the present study, we examined the role of large strip-biaxial strains (up to 50%) on ECM synthesis by vascular smooth muscle cells (VSMCs) micro-integrated into electrospun polyester urethane urea (PEUU) constructs over the course of 3 weeks. Experimental results indicated that VSMC biosynthetic behavior was quite sensitive to tissue strain maximum level, and that collagen was the primary ECM component synthesized. Moreover, we found that while a 30% peak strain level achieved maximum ECM synthesis rate, further increases in strain level lead to a reduction in ECM biosynthesis. Subsequent mechanical analysis of the formed collagen fiber network was performed by removing the scaffold mechanical responses using a strain-energy based approach, showing that the de-novo collagen also demonstrated mechanical behaviors substantially better than previously obtained with small strain training and comparable to mature collagenous tissues. We conclude that the application of large deformations can play a critical role not only in the quantity of ECM synthesis (i.e. the rate of mass production), but also on the modulation of the stiffness of the newly formed ECM constituents. The improved understanding of the process of growth and development of ECM in these mechano-sensitive cell-scaffold systems will lead to more rational design and manufacturing of engineered tissues operating under highly demanding mechanical environments. PMID:27344402

Controlling exhaust gas recirculation

DOEpatents

Zurlo, James Richard [Madison, WI; Konkle, Kevin Paul [West Bend, WI; May, Andrew [Milwaukee, WI

2012-01-31

In controlling an engine, an amount of an intake charge provided, during operation of the engine, to a combustion chamber of the engine is determined. The intake charge includes an air component, a fuel component and a diluent component. An amount of the air component of the intake charge is determined. An amount of the diluent component of the intake charge is determined utilizing the amount of the intake charge, the amount of the air component and, in some instances, the amount of the fuel component. An amount of a diluent supplied to the intake charge is adjusted based at least in part on the determined amount of diluent component of the intake charge.

Self-assembled three dimensional network designs for soft electronics

PubMed Central

Jang, Kyung-In; Li, Kan; Chung, Ha Uk; Xu, Sheng; Jung, Han Na; Yang, Yiyuan; Kwak, Jean Won; Jung, Han Hee; Song, Juwon; Yang, Ce; Wang, Ao; Liu, Zhuangjian; Lee, Jong Yoon; Kim, Bong Hoon; Kim, Jae-Hwan; Lee, Jungyup; Yu, Yongjoon; Kim, Bum Jun; Jang, Hokyung; Yu, Ki Jun; Kim, Jeonghyun; Lee, Jung Woo; Jeong, Jae-Woong; Song, Young Min; Huang, Yonggang; Zhang, Yihui; Rogers, John A.

2017-01-01

Low modulus, compliant systems of sensors, circuits and radios designed to intimately interface with the soft tissues of the human body are of growing interest, due to their emerging applications in continuous, clinical-quality health monitors and advanced, bioelectronic therapeutics. Although recent research establishes various materials and mechanics concepts for such technologies, all existing approaches involve simple, two-dimensional (2D) layouts in the constituent micro-components and interconnects. Here we introduce concepts in three-dimensional (3D) architectures that bypass important engineering constraints and performance limitations set by traditional, 2D designs. Specifically, open-mesh, 3D interconnect networks of helical microcoils formed by deterministic compressive buckling establish the basis for systems that can offer exceptional low modulus, elastic mechanics, in compact geometries, with active components and sophisticated levels of functionality. Coupled mechanical and electrical design approaches enable layout optimization, assembly processes and encapsulation schemes to yield 3D configurations that satisfy requirements in demanding, complex systems, such as wireless, skin-compatible electronic sensors. PMID:28635956

Implantable Cardiac Defibrillator Lead Failure and Management.

PubMed

Swerdlow, Charles D; Kalahasty, Gautham; Ellenbogen, Kenneth A

2016-03-22

The implantable-cardioverter defibrillator (ICD) lead is the most vulnerable component of the ICD system. Despite advanced engineering design, sophisticated manufacturing techniques, and extensive bench, pre-clinical, and clinical testing, lead failure (LF) remains the Achilles' heel of the ICD system. ICD LF has a broad range of adverse outcomes, ranging from intermittent inappropriate pacing to proarrhythmia leading to patient mortality. ICD LF is often considered in the context of design or construction defects, but is more appropriately considered in the context of the finite service life of a mechanical component placed in chemically stressful environment and subjected to continuous mechanical stresses. This clinical review summarizes LF mechanisms, assessment, and differential diagnosis of LF, including lead diagnostics, recent prominent lead recalls, and management of LF and functioning, but recalled leads. Despite recent advances in lead technology, physicians will likely continue to need to understand how to manage patients with transvenous ICD leads. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Self-assembled three dimensional network designs for soft electronics

NASA Astrophysics Data System (ADS)

Jang, Kyung-In; Li, Kan; Chung, Ha Uk; Xu, Sheng; Jung, Han Na; Yang, Yiyuan; Kwak, Jean Won; Jung, Han Hee; Song, Juwon; Yang, Ce; Wang, Ao; Liu, Zhuangjian; Lee, Jong Yoon; Kim, Bong Hoon; Kim, Jae-Hwan; Lee, Jungyup; Yu, Yongjoon; Kim, Bum Jun; Jang, Hokyung; Yu, Ki Jun; Kim, Jeonghyun; Lee, Jung Woo; Jeong, Jae-Woong; Song, Young Min; Huang, Yonggang; Zhang, Yihui; Rogers, John A.

2017-06-01

Low modulus, compliant systems of sensors, circuits and radios designed to intimately interface with the soft tissues of the human body are of growing interest, due to their emerging applications in continuous, clinical-quality health monitors and advanced, bioelectronic therapeutics. Although recent research establishes various materials and mechanics concepts for such technologies, all existing approaches involve simple, two-dimensional (2D) layouts in the constituent micro-components and interconnects. Here we introduce concepts in three-dimensional (3D) architectures that bypass important engineering constraints and performance limitations set by traditional, 2D designs. Specifically, open-mesh, 3D interconnect networks of helical microcoils formed by deterministic compressive buckling establish the basis for systems that can offer exceptional low modulus, elastic mechanics, in compact geometries, with active components and sophisticated levels of functionality. Coupled mechanical and electrical design approaches enable layout optimization, assembly processes and encapsulation schemes to yield 3D configurations that satisfy requirements in demanding, complex systems, such as wireless, skin-compatible electronic sensors.

A review of fracture mechanics life technology

NASA Technical Reports Server (NTRS)

Besuner, P. M.; Harris, D. O.; Thomas, J. M.

1986-01-01

Lifetime prediction technology for structural components subjected to cyclic loads is examined. The central objectives of the project are: (1) to report the current state of the art, and (2) recommend future development of fracture mechanics-based analytical tools for modeling subcritical fatigue crack growth in structures. Of special interest is the ability to apply these tools to practical engineering problems and the developmental steps necessary to bring vital technologies to this stage. The authors conducted a survey of published literature and numerous discussions with experts in the field of fracture mechanics life technology. One of the key points made is that fracture mechanics analyses of crack growth often involve consideration of fatigue and fracture under extreme conditions. Therefore, inaccuracies in predicting component lifetime will be dominated by inaccuracies in environment and fatigue crack growth relations, stress intensity factor solutions, and methods used to model given loads and stresses. Suggestions made for reducing these inaccuracies include development of improved models of subcritical crack growth, research efforts aimed at better characterizing residual and assembly stresses that can be introduced during fabrication, and more widespread and uniform use of the best existing methods.

A review of fracture mechanics life technology

NASA Technical Reports Server (NTRS)

Thomas, J. M.; Besuner, P. M.; Harris, D. O.

1985-01-01

Current lifetime prediction technology for structural components subjected to cyclic loads was reviewed. The central objectives of the project were to report the current state of and recommend future development of fracture mechanics-based analytical tools for modeling and forecasting subcritical fatigue crack growth in structures. Of special interest to NASA was the ability to apply these tools to practical engineering problems and the developmental steps necessary to bring vital technologies to this stage. A survey of published literature and numerous discussions with experts in the field of fracture mechanics life technology were conducted. One of the key points made is that fracture mechanics analyses of crack growth often involve consideration of fatigue and fracture under extreme conditions. Therefore, inaccuracies in predicting component lifetime will be dominated by inaccuracies in environment and fatigue crack growth relations, stress intensity factor solutions, and methods used to model given loads and stresses. Suggestions made for reducing these inaccuracies include: development of improved models of subcritical crack growth, research efforts aimed at better characterizing residual and assembly stresses that can be introduced during fabrication, and more widespread and uniform use of the best existing methods.

Ceramic Composite Development for Gas Turbine Engine Hot Section Components

NASA Technical Reports Server (NTRS)

DiCarlo, James A.; VANrOODE, mARK

2006-01-01

The development of ceramic materials for incorporation into the hot section of gas turbine engines has been ongoing for about fifty years. Researchers have designed, developed, and tested ceramic gas turbine components in rigs and engines for automotive, aero-propulsion, industrial, and utility power applications. Today, primarily because of materials limitations and/or economic factors, major challenges still remain for the implementation of ceramic components in gas turbines. For example, because of low fracture toughness, monolithic ceramics continue to suffer from the risk of failure due to unknown extrinsic damage events during engine service. On the other hand, ceramic matrix composites (CMC) with their ability to display much higher damage tolerance appear to be the materials of choice for current and future engine components. The objective of this paper is to briefly review the design and property status of CMC materials for implementation within the combustor and turbine sections for gas turbine engine applications. It is shown that although CMC systems have advanced significantly in thermo-structural performance within recent years, certain challenges still exist in terms of producibility, design, and affordability for commercial CMC turbine components. Nevertheless, there exist some recent successful efforts for prototype CMC components within different engine types.

PRA and Risk Informed Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernsen, Sidney A.; Simonen, Fredric A.; Balkey, Kenneth R.

2006-01-01

The Boiler and Pressure Vessel Code (BPVC) of the American Society of Mechanical Engineers (ASME) has introduced a risk based approach into Section XI that covers Rules for Inservice Inspection of Nuclear Power Plant Components. The risk based approach requires application of the probabilistic risk assessments (PRA). Because no industry consensus standard existed for PRAs, ASME has developed a standard to evaluate the quality level of an available PRA needed to support a given risk based application. The paper describes the PRA standard, Section XI application of PRAs, and plans for broader applications of PRAs to other ASME nuclear codesmore » and standards. The paper addresses several specific topics of interest to Section XI. Important consideration are special methods (surrogate components) used to overcome the lack of PRA treatments of passive components in PRAs. The approach allows calculations of conditional core damage probabilities both for component failures that cause initiating events and failures in standby systems that decrease the availability of these systems. The paper relates the explicit risk based methods of the new Section XI code cases to the implicit consideration of risk used in the development of Section XI. Other topics include the needed interactions of ISI engineers, plant operating staff, PRA specialists, and members of expert panels that review the risk based programs.« less

Component-specific modeling. [jet engine hot section components

NASA Technical Reports Server (NTRS)

Mcknight, R. L.; Maffeo, R. J.; Tipton, M. T.; Weber, G.

1992-01-01

Accomplishments are described for a 3 year program to develop methodology for component-specific modeling of aircraft hot section components (turbine blades, turbine vanes, and burner liners). These accomplishments include: (1) engine thermodynamic and mission models, (2) geometry model generators, (3) remeshing, (4) specialty three-dimensional inelastic structural analysis, (5) computationally efficient solvers, (6) adaptive solution strategies, (7) engine performance parameters/component response variables decomposition and synthesis, (8) integrated software architecture and development, and (9) validation cases for software developed.

Toughening Mechanisms in Nanolayered MAX Phase Ceramics—A Review

PubMed Central

Chen, Xinhua; Bei, Guoping

2017-01-01

Advanced engineering and functional ceramics are sensitive to damage cracks, which delay the wide applications of these materials in various fields. Ceramic composites with enhanced fracture toughness may trigger a paradigm for design and application of the brittle components. This paper reviews the toughening mechanisms for the nanolayered MAX phase ceramics. The main toughening mechanisms for these ternary compounds were controlled by particle toughening, phase-transformation toughening and fiber-reinforced toughening, as well as texture toughening. Based on the various toughening mechanisms in MAX phase, models of SiC particles and fibers toughening Ti3SiC2 are established to predict and explain the toughening mechanisms. The modeling work provides insights and guidance to fabricate MAX phase-related composites with optimized microstructures in order to achieve the desired mechanical properties required for harsh application environments. PMID:28772723

Probabilistic Multi-Scale, Multi-Level, Multi-Disciplinary Analysis and Optimization of Engine Structures

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Abumeri, Galib H.

2000-01-01

Aircraft engines are assemblies of dynamically interacting components. Engine updates to keep present aircraft flying safely and engines for new aircraft are progressively required to operate in more demanding technological and environmental requirements. Designs to effectively meet those requirements are necessarily collections of multi-scale, multi-level, multi-disciplinary analysis and optimization methods and probabilistic methods are necessary to quantify respective uncertainties. These types of methods are the only ones that can formally evaluate advanced composite designs which satisfy those progressively demanding requirements while assuring minimum cost, maximum reliability and maximum durability. Recent research activities at NASA Glenn Research Center have focused on developing multi-scale, multi-level, multidisciplinary analysis and optimization methods. Multi-scale refers to formal methods which describe complex material behavior metal or composite; multi-level refers to integration of participating disciplines to describe a structural response at the scale of interest; multidisciplinary refers to open-ended for various existing and yet to be developed discipline constructs required to formally predict/describe a structural response in engine operating environments. For example, these include but are not limited to: multi-factor models for material behavior, multi-scale composite mechanics, general purpose structural analysis, progressive structural fracture for evaluating durability and integrity, noise and acoustic fatigue, emission requirements, hot fluid mechanics, heat-transfer and probabilistic simulations. Many of these, as well as others, are encompassed in an integrated computer code identified as Engine Structures Technology Benefits Estimator (EST/BEST) or Multi-faceted/Engine Structures Optimization (MP/ESTOP). The discipline modules integrated in MP/ESTOP include: engine cycle (thermodynamics), engine weights, internal fluid mechanics, cost, mission and coupled structural/thermal, various composite property simulators and probabilistic methods to evaluate uncertainty effects (scatter ranges) in all the design parameters. The objective of the proposed paper is to briefly describe a multi-faceted design analysis and optimization capability for coupled multi-discipline engine structures optimization. Results are presented for engine and aircraft type metrics to illustrate the versatility of that capability. Results are also presented for reliability, noise and fatigue to illustrate its inclusiveness. For example, replacing metal rotors with composites reduces the engine weight by 20 percent, 15 percent noise reduction, and an order of magnitude improvement in reliability. Composite designs exist to increase fatigue life by at least two orders of magnitude compared to state-of-the-art metals.

Methods Developed by the Tools for Engine Diagnostics Task to Monitor and Predict Rotor Damage in Real Time

NASA Technical Reports Server (NTRS)

Baaklini, George Y.; Smith, Kevin; Raulerson, David; Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Brasche, Lisa

2003-01-01

Tools for Engine Diagnostics is a major task in the Propulsion System Health Management area of the Single Aircraft Accident Prevention project under NASA s Aviation Safety Program. The major goal of the Aviation Safety Program is to reduce fatal aircraft accidents by 80 percent within 10 years and by 90 percent within 25 years. The goal of the Propulsion System Health Management area is to eliminate propulsion system malfunctions as a primary or contributing factor to the cause of aircraft accidents. The purpose of Tools for Engine Diagnostics, a 2-yr-old task, is to establish and improve tools for engine diagnostics and prognostics that measure the deformation and damage of rotating engine components at the ground level and that perform intermittent or continuous monitoring on the engine wing. In this work, nondestructive-evaluation- (NDE-) based technology is combined with model-dependent disk spin experimental simulation systems, like finite element modeling (FEM) and modal norms, to monitor and predict rotor damage in real time. Fracture mechanics time-dependent fatigue crack growth and damage-mechanics-based life estimation are being developed, and their potential use investigated. In addition, wireless eddy current and advanced acoustics are being developed for on-wing and just-in-time NDE engine inspection to provide deeper access and higher sensitivity to extend on-wing capabilities and improve inspection readiness. In the long run, these methods could establish a base for prognostic sensing while an engine is running, without any overt actions, like inspections. This damage-detection strategy includes experimentally acquired vibration-, eddy-current- and capacitance-based displacement measurements and analytically computed FEM-, modal norms-, and conventional rotordynamics-based models of well-defined damages and critical mass imbalances in rotating disks and rotors.

The use of a novel bone allograft wash process to generate a biocompatible, mechanically stable and osteoinductive biological scaffold for use in bone tissue engineering.

PubMed

Smith, C A; Richardson, S M; Eagle, M J; Rooney, P; Board, T; Hoyland, J A

2015-05-01

Fresh-frozen biological allograft remains the most effective substitute for the 'gold standard' autograft, sharing many of its osteogenic properties but, conversely, lacking viable osteogenic cells. Tissue engineering offers the opportunity to improve the osseointegration of this material through the addition of mesenchymal stem cells (MSCs). However, the presence of dead, immunogenic and potentially harmful bone marrow could hinder cell adhesion and differentiation, graft augmentation and incorporation, and wash procedures are therefore being utilized to remove the marrow, thereby improving the material's safety. To this end, we assessed the efficiency of a novel wash technique to produce a biocompatible, biological scaffold void of cellular material that was mechanically stable and had osteoinductive potential. The outcomes of our investigations demonstrated the efficient removal of marrow components (~99.6%), resulting in a biocompatible material with conserved biomechanical stability. Additionally, the scaffold was able to induce osteogenic differentiation of MSCs, with increases in osteogenic gene expression observed following extended culture. This study demonstrates the efficiency of the novel wash process and the potential of the resultant biological material to serve as a scaffold in bone allograft tissue engineering. © 2014 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons Ltd.

Engineering a humanized bone organ model in mice to study bone metastases.

PubMed

Martine, Laure C; Holzapfel, Boris M; McGovern, Jacqui A; Wagner, Ferdinand; Quent, Verena M; Hesami, Parisa; Wunner, Felix M; Vaquette, Cedryck; De-Juan-Pardo, Elena M; Brown, Toby D; Nowlan, Bianca; Wu, Dan Jing; Hutmacher, Cosmo Orlando; Moi, Davide; Oussenko, Tatiana; Piccinini, Elia; Zandstra, Peter W; Mazzieri, Roberta; Lévesque, Jean-Pierre; Dalton, Paul D; Taubenberger, Anna V; Hutmacher, Dietmar W

2017-04-01

Current in vivo models for investigating human primary bone tumors and cancer metastasis to the bone rely on the injection of human cancer cells into the mouse skeleton. This approach does not mimic species-specific mechanisms occurring in human diseases and may preclude successful clinical translation. We have developed a protocol to engineer humanized bone within immunodeficient hosts, which can be adapted to study the interactions between human cancer cells and a humanized bone microenvironment in vivo. A researcher trained in the principles of tissue engineering will be able to execute the protocol and yield study results within 4-6 months. Additive biomanufactured scaffolds seeded and cultured with human bone-forming cells are implanted ectopically in combination with osteogenic factors into mice to generate a physiological bone 'organ', which is partially humanized. The model comprises human bone cells and secreted extracellular matrix (ECM); however, other components of the engineered tissue, such as the vasculature, are of murine origin. The model can be further humanized through the engraftment of human hematopoietic stem cells (HSCs) that can lead to human hematopoiesis within the murine host. The humanized organ bone model has been well characterized and validated and allows dissection of some of the mechanisms of the bone metastatic processes in prostate and breast cancer.

Recent Status of SIM Lite Astrometric Observatory Mission: Flight Engineering Risk Reduction Activities

NASA Technical Reports Server (NTRS)

Goullioud, Renaud; Dekens, Frank; Nemati, Bijan; An, Xin; Carson, Johnathan

2010-01-01

The SIM Lite Astrometric Observatory is a mission concept for a space-borne instrument to perform micro-arc-second narrow-angle astrometry to search 60 to 100 nearby stars for Earth-like planets, and to perform global astrometry for a broad astrophysics program. The instrument consists of two Michelson stellar interferometers and a telescope. The first interferometer chops between the target star and a set of reference stars. The second interferometer monitors the attitude of the instrument in the direction of the target star. The telescope monitors the attitude of the instrument in the other two directions. The main enabling technology development for the mission was completed during phases A & B. The project is currently implementing the developed technology onto flight-ready engineering models. These key engineering tasks will significantly reduce the implementation risks during the flight phases C & D of the mission. The main optical interferometer components, including the astrometric beam combiner, the fine steering optical mechanism, the path-length-control and modulation optical mechanisms, focal-plane camera electronics and cooling heat pipe, are currently under development. Main assemblies are built to meet flight requirements and will be subjected to flight qualification level environmental testing (random vibration and thermal cycling) and performance testing. This paper summarizes recent progress in engineering risk reduction activities.

Durability and Design Issues of Thermal/environmental Barrier Coatings on Sic/sic Ceramic Matrix Composites Under 1650 C Test Conditions

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Choi, Sung R.; Ghosn, Louis J.; Miller, Robert A.

2004-01-01

Ceramic thermal/environmental barrier coatings for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating durability remains a major concern with the ever-increasing temperature requirements. Currently, advanced T/EBC systems, which typically include a high temperature capable zirconia- (or hahia-) based oxide top coat (thermal barrier) on a less temperature capable mullite/barium-strontium-aluminosilicate (BSAS)/Si inner coat (environmental barrier), are being developed and tested for higher temperature capability Sic combustor applications. In this paper, durability of several thermal/environmental barrier coating systems on SiC/SiC ceramic matrix composites was investigated under laser simulated engine thermal gradient cyclic, and 1650 C (3000 F) test conditions. The coating cracking and delamination processes were monitored and evaluated. The effects of temperature gradients and coating configurations on the ceramic coating crack initiation and propagation were analyzed using finite element analysis (FEA) models based on the observed failure mechanisms, in conjunction with mechanical testing results. The environmental effects on the coating durability will be discussed. The coating design approach will also be presented.

Flow Control Opportunities for Propulsion Systems

NASA Technical Reports Server (NTRS)

Cutley, Dennis E.

2008-01-01

The advancement of technology in gas turbine engines used for aerospace propulsion has been focused on achieving significant performance improvements. At the system level, these improvements are expressed in metrics such as engine thrust-to-weight ratio and system and component efficiencies. The overall goals are directed at reducing engine weight, fuel burn, emissions, and noise. At a component level, these goals translate into aggressive designs of each engine component well beyond the state of the art.

Ceramic composites for rocket engine turbines

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Eckel, Andrew J.

1991-01-01

The use of ceramic materials in the hot section of the fuel turbopump of advanced reusable rocket engines promises increased performance and payload capability, improved component life and economics, and greater design flexibility. Severe thermal transients present during operation of the Space Shuttle Main Engine (SSME), push metallic components to the limit of their capabilities. Future engine requirements might be even more severe. In phase one of this two-phase program, performance benefits were quantified and continuous fiber reinforced ceramic matrix composite components demonstrated a potential to survive the hostile environment of an advanced rocket engine turbopump.

Ceramic composites for rocket engine turbines

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Eckel, Andrew J.

1991-01-01

The use of ceramic materials in the hot section of the fuel turbopump of advanced reusable rocket engines promises increased performance and payload capability, improved component life and economics, and greater design flexibility. Severe thermal transients present during operation of the Space Shuttle Main Engine (SSME), push metallic components to the limit of their capabilities. Future engine requirements might be even more severe. In phase one of this two-phase program, performance benefits were quantified and continuous fiber reinforced ceramic matrix composite components demonstrated a potential to survive the hostile environment of an advaced rocket engine turbopump.

Tuning Material and Component Properties to Reduce Weight and Increase Blastworthiness of a Notional V-Hull Structure

DTIC Science & Technology

2015-04-24

for designing blast-resistant structures [16]. The failure mechanisms in unidirectional fiber -reinforced composites of delamination, fiber -matrix...Batra, R.C., and Hassan, N.M., “Blast resistance of unidirectional fiber reinforced composites ,” Composites Part B: Engineering, 2008 18. Liu, X...feature a lighter weight structure, because this enables faster transport, higher mobility, greater fuel conservation, higher payload capacity, and

Study of phenomena related to the sintering process of silicon nitride at atmospheric pressure

NASA Technical Reports Server (NTRS)

Bertani, A.

1982-01-01

A procedure was perfected for the production of components used in engineering applications of silicon nitride. Particles of complex geometry that combine remarkable mechanical properties with a high density are obtained. The process developed, in contrast to the "hot pressing" method, does not use external pressures, and in contrast to the reaction bonding method, final densities close to the theoretical value are obtained.

Mechanical engineering and design criteria for the Magnetically Insulated Transmission Experiment Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Staller, G.E.; Hamilton, I.D.; Aker, M.F.

1978-02-01

A single-unit electron beam accelerator was designed, fabricated, and assembled in Sandia's Technical Area V to conduct magnetically insulated transmission experiments. Results of these experiments will be utilized in the future design of larger, more complex accelerators. This design makes optimum use of existing facilities and equipment. When designing new components, possible future applications were considered as well as compatibility with existing facilities and hardware.

Hybrid, experimental and computational, investigation of mechanical components

NASA Astrophysics Data System (ADS)

Furlong, Cosme; Pryputniewicz, Ryszard J.

1996-07-01

Computational and experimental methodologies have unique features for the analysis and solution of a wide variety of engineering problems. Computations provide results that depend on selection of input parameters such as geometry, material constants, and boundary conditions which, for correct modeling purposes, have to be appropriately chosen. In addition, it is relatively easy to modify the input parameters in order to computationally investigate different conditions. Experiments provide solutions which characterize the actual behavior of the object of interest subjected to specific operating conditions. However, it is impractical to experimentally perform parametric investigations. This paper discusses the use of a hybrid, computational and experimental, approach for study and optimization of mechanical components. Computational techniques are used for modeling the behavior of the object of interest while it is experimentally tested using noninvasive optical techniques. Comparisons are performed through a fringe predictor program used to facilitate the correlation between both techniques. In addition, experimentally obtained quantitative information, such as displacements and shape, can be applied in the computational model in order to improve this correlation. The result is a validated computational model that can be used for performing quantitative analyses and structural optimization. Practical application of the hybrid approach is illustrated with a representative example which demonstrates the viability of the approach as an engineering tool for structural analysis and optimization.

MAGNESIUM ALLOYS IN US MILITARY APPLICATIONS: PAST, CURRENT AND FUTURE SOLUTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathaudhu, Suveen N.; Nyberg, Eric A.

2010-02-26

Since the 1940’s Mg-alloys have been used for military applications, from aircraft components to ground vehicles. The drive for usage was primarily availability and lightweighting of military systems. But the promise of widespread military usage was not met largely based on corrosion and flammability concerns, poor mechanical behavior and inferior ballistic response. This review paper will cover historical, current and potential future applications with a focus on scientific, engineering and social barriers relevant to integration of Mg-alloy. It will also present mechanical and physical property improvements solutions which are currently being developed to address these issues.

Ceramic automotive Stirling engine program

NASA Technical Reports Server (NTRS)

1986-01-01

The Ceramic Automotive Stirling Engine Program evaluated the application of advanced ceramic materials to an automotive Stirling engine. The objective of the program was to evaluate the technical feasibility of utilizing advanced ceramics to increase peak engine operating temperature, and to evaluate the performance benefits of such an increase. Manufacturing cost estimates were also developed for various ceramic engine components and compared with conventional metallic engine component costs.