Automatic generation of user material subroutines for biomechanical growth analysis.
Young, Jonathan M; Yao, Jiang; Ramasubramanian, Ashok; Taber, Larry A; Perucchio, Renato
2010-10-01
The analysis of the biomechanics of growth and remodeling in soft tissues requires the formulation of specialized pseudoelastic constitutive relations. The nonlinear finite element analysis package ABAQUS allows the user to implement such specialized material responses through the coding of a user material subroutine called UMAT. However, hand coding UMAT subroutines is a challenge even for simple pseudoelastic materials and requires substantial time to debug and test the code. To resolve this issue, we develop an automatic UMAT code generation procedure for pseudoelastic materials using the symbolic mathematics package MATHEMATICA and extend the UMAT generator to include continuum growth. The performance of the automatically coded UMAT is tested by simulating the stress-stretch response of a material defined by a Fung-orthotropic strain energy function, subject to uniaxial stretching, equibiaxial stretching, and simple shear in ABAQUS. The MATHEMATICA UMAT generator is then extended to include continuum growth by adding a growth subroutine to the automatically generated UMAT. The MATHEMATICA UMAT generator correctly derives the variables required in the UMAT code, quickly providing a ready-to-use UMAT. In turn, the UMAT accurately simulates the pseudoelastic response. In order to test the growth UMAT, we simulate the growth-based bending of a bilayered bar with differing fiber directions in a nongrowing passive layer. The anisotropic passive layer, being topologically tied to the growing isotropic layer, causes the bending bar to twist laterally. The results of simulations demonstrate the validity of the automatically coded UMAT, used in both standardized tests of hyperelastic materials and for a biomechanical growth analysis.
Using ABAQUS Scripting Interface for Materials Evaluation and Life Prediction
NASA Technical Reports Server (NTRS)
Powers, Lynn M.; Arnold, Steven M.; Baranski, Andrzej
2006-01-01
An ABAQUS script has been written to aid in the evaluation of the mechanical behavior of viscoplastic materials. The purposes of the script are to: handle complex load histories; control load/displacement with alternate stopping criteria; predict failure and life; and verify constitutive models. Material models from the ABAQUS library may be used or the UMAT routine may specify mechanical behavior. User subroutines implemented include: UMAT for the constitutive model; UEXTERNALDB for file manipulation; DISP for boundary conditions; and URDFIL for results processing. Examples presented include load, strain and displacement control tests on a single element model. The tests are creep with a life limiting strain criterion, strain control with a stress limiting cycle and a complex interrupted cyclic relaxation test. The techniques implemented in this paper enable complex load conditions to be solved efficiently with ABAQUS.
ERIC Educational Resources Information Center
Tubb, Phil
1982-01-01
The repetitious nature of music is thought to be very similar to the repetitious nature of computer algorithms. Subroutines are seen to be very effectively applied to music notation, through reducing repetitious entry and the amount of memory required to represent a musical score. Examples of subroutine use are provided. (MP)
NASA Astrophysics Data System (ADS)
Chen, S.; Al-Muntasheri, G.; Abousleiman, Y. N.
2014-12-01
The critical state concept based bounding surface model is one of the most widely used elastoplastic constitutive models for geomaterials, attributed mainly to its essential feature of allowing plastic deformation to occur for stress points within the bounding surface and thus the capability to represent the realistic non-recoverable behaviour of soils and rocks observed under the cyclic loading. This paper develops an implicit integration algorithm for the bounding surface model, using the standard return mapping approach (elastic predictor-plastic corrector), to obtain the updated stresses for the given strain increments. The formulation of the constitutive integration requires the derivation of a supplementary differential equation to describe the evolution of a key variable, i.e., the ratio between the image stress and the current stress quantities. It is essentially an extension of the integration scheme presented in an earlier work used for the simple bounding surface version of modified Cam Clay associated with a substantially simplified hardening rule. The integration algorithm for the bounding surface model is implemented into the finite element analysis commercial program, ABAQUS, through the material interface of UMAT (user defined material subroutine), and then used for the analysis of wellbore stability problem. The predictions from the ABAQUS simulations are generally in excellent agreement with the available analytical solutions, thus demonstrating the accuracy and robustness of the proposed integration scheme.
Universal Noiseless Coding Subroutines
NASA Technical Reports Server (NTRS)
Schlutsmeyer, A. P.; Rice, R. F.
1986-01-01
Software package consists of FORTRAN subroutines that perform universal noiseless coding and decoding of integer and binary data strings. Purpose of this type of coding to achieve data compression in sense that coded data represents original data perfectly (noiselessly) while taking fewer bits to do so. Routines universal because they apply to virtually any "real-world" data source.
NASA Technical Reports Server (NTRS)
Schiess, James R.; Kerr, Patricia A.; Smith, Olivia C.
1988-01-01
Smooth curves drawn among plotted data easily. Rational-Spline Approximation with Automatic Tension Adjustment algorithm leads to flexible, smooth representation of experimental data. "Tension" denotes mathematical analog of mechanical tension in spline or other mechanical curve-fitting tool, and "spline" as denotes mathematical generalization of tool. Program differs from usual spline under tension, allows user to specify different values of tension between adjacent pairs of knots rather than constant tension over entire range of data. Subroutines use automatic adjustment scheme that varies tension parameter for each interval until maximum deviation of spline from line joining knots less than or equal to amount specified by user. Procedure frees user from drudgery of adjusting individual tension parameters while still giving control over local behavior of spline.
Quadratic spline subroutine package
Rasmussen, Lowell A.
1982-01-01
A continuous piecewise quadratic function with continuous first derivative is devised for approximating a single-valued, but unknown, function represented by a set of discrete points. The quadratic is proposed as a treatment intermediate between using the angular (but reliable, easily constructed and manipulated) piecewise linear function and using the smoother (but occasionally erratic) cubic spline. Neither iteration nor the solution of a system of simultaneous equations is necessary to determining the coefficients. Several properties of the quadratic function are given. A set of five short FORTRAN subroutines is provided for generating the coefficients (QSC), finding function value and derivatives (QSY), integrating (QSI), finding extrema (QSE), and computing arc length and the curvature-squared integral (QSK). (USGS)
NASA Technical Reports Server (NTRS)
Schiess, J. R.
1994-01-01
Scientific data often contains random errors that make plotting and curve-fitting difficult. The Rational-Spline Approximation with Automatic Tension Adjustment algorithm lead to a flexible, smooth representation of experimental data. The user sets the conditions for each consecutive pair of knots:(knots are user-defined divisions in the data set) to apply no tension; to apply fixed tension; or to determine tension with a tension adjustment algorithm. The user also selects the number of knots, the knot abscissas, and the allowed maximum deviations from line segments. The selection of these quantities depends on the actual data and on the requirements of a particular application. This program differs from the usual spline under tension in that it allows the user to specify different tension values between each adjacent pair of knots rather than a constant tension over the entire data range. The subroutines use an automatic adjustment scheme that varies the tension parameter for each interval until the maximum deviation of the spline from the line joining the knots is less than or equal to a user-specified amount. This procedure frees the user from the drudgery of adjusting individual tension parameters while still giving control over the local behavior of the spline The Rational Spline program was written completely in FORTRAN for implementation on a CYBER 850 operating under NOS. It has a central memory requirement of approximately 1500 words. The program was released in 1988.
A parameter estimation subroutine package
NASA Technical Reports Server (NTRS)
Bierman, G. J.; Nead, M. W.
1978-01-01
Linear least squares estimation and regression analyses continue to play a major role in orbit determination and related areas. In this report we document a library of FORTRAN subroutines that have been developed to facilitate analyses of a variety of estimation problems. Our purpose is to present an easy to use, multi-purpose set of algorithms that are reasonably efficient and which use a minimal amount of computer storage. Subroutine inputs, outputs, usage and listings are given along with examples of how these routines can be used. The following outline indicates the scope of this report: Section (1) introduction with reference to background material; Section (2) examples and applications; Section (3) subroutine directory summary; Section (4) the subroutine directory user description with input, output, and usage explained; and Section (5) subroutine FORTRAN listings. The routines are compact and efficient and are far superior to the normal equation and Kalman filter data processing algorithms that are often used for least squares analyses.
Basic Scientific Subroutines, Volume II.
ERIC Educational Resources Information Center
Ruckdeschel, F. R.
This book, second in a series dealing with scientific programing in the BASIC language, provides students, engineers, and scientists with a documented library of subroutines for scientific applications. Subjects of the eight chapters include: (1) least-squares approximation of functions and smoothing of data; (2) approximating functions by series…
Multi Platform Graphics Subroutine Library
Brand, Hal
1992-02-21
DIGLIB is a collection of general graphics subroutines. It was designed to be small, reasonably fast, device-independent, and compatible with DEC-supplied operating systems for VAXes, PDP-11s, and LSI-11s, and the DOS operating system for IBM PCs and IBM-compatible machines. The software is readily usable by casual programmers for two-dimensional plotting.
Jannetti, C.; Becker, R.
2004-02-02
The software is an ABAQUS/Standard UMAT (user defined material behavior subroutine) that implements the constitutive model for shape-memory alloy materials developed by Jannetti et. al. (2003a) using a fully implicit time integration scheme to integrate the constitutive equations. The UMAT is used in conjunction with ABAQUS/Standard to perform a finite-element analysis of SMA materials.
Credit Documentation and the Mark 15 Subroutine
McAllister, J.E.
2001-08-16
This report documents the rewrite of the heat transfer subroutine. Part of the process of preparing the Mark 15 assembly for production operation is the development of thermal-hydraulic limits for the assembly. These limits require, among other items, the development of a Mark 15 assembly subroutine for the CREDIT code.
The Computer Subroutine in Information Handling.
ERIC Educational Resources Information Center
Riggs, Donald E.
Generalized computational subroutines can reduce programing repetitions and wasteful computer storage use. The most useful are those that are flexible enough to handle a wide variety of situations. Subroutines may have details open to change in order to blend into the main program. They may be built into the computer library or supplied by the…
DIGLIB. PC-DOS Graphics Subroutine Library
Brand, H.R.
1989-02-01
DIGLIB is a collection of general graphics subroutines. It was designed to be small, reasonably fast, and device-independent. The software is readily usable by casual programmers for two-dimensional plotting.
ABAQUS 5.4 software configuration
Marlow, R.S.
1995-04-01
ABAQUS 5.4 is a powerful general purpose finite-element computer program for the radioactive waste tank program. This document describes the verification and validation of ABAQUS 5.4 as installed on the Scientific and Engineering Computing Center.
NASA Technical Reports Server (NTRS)
Arnold, S. M.; Saleeb, A. F.; Wilt, T. E.; Trowbridge, D.
2000-01-01
be incorporated directly into a structural finite element code like ABAQUS for cost-effective, micromechanics based, large-scale component design and analysis. Our primary objective here is to report on these recent works conducted over the past decade, in the context of their incorporation into ABAQUS through the various user subroutines. Representative results will be shown to demonstrate the features of the developed schemes.
Seismic transducer modeling using ABAQUS
Stephen R. Novascone
2004-05-01
A seismic transducer, known as an orbital vibrator, consists of a rotating imbalance driven by an electric motor. When suspended in a liquid-filled wellbore, vibrations of the device are coupled to the surrounding geologic media. In this mode, an orbital vibrator can be used as an efficient rotating dipole source for seismic imaging. Alternately, the motion of an orbital vibrator is affected by the physical properties of the surrounding media. From this point of view, an orbital vibrator can be used as a stand-alone sensor. The reaction to the surroundings can be sensed and recorded by geophones inside the orbital vibrator. These reactions are a function of the media’s physical properties such as modulus, damping, and density, thereby identifying the rock type. This presentation shows how the orbital vibrator and surroundings were modeled with an ABAQUS acoustic FEM. The FEM is found to compare favorably with theoretical predictions. A 2D FEM and analytical model are compared to an experimental data set. Each model compares favorably with the data set.
MEAM interatomic force calculation subroutine for LAMMPS
Stukowski, A.
2010-10-25
Interatomic force and energy calculation subroutine tobe used with the molecular dynamics simulation code LAMMPS (Ref a.). The code evaluates the total energy and atomic forces (energy gradient) according to cubic spine-based variant (Ref b.) of the Modified Embedded Atom Method (MEAM).
DIGLIB. PC-DOS Graphics Subroutine Library
Brand, H.R.
1989-02-01
DIGLIB is a collection of general graphics subroutines. It was designed to be small, reasonably fast, device-independent, and compatible with DEC-supplied operating systems for VAXes, PDP-11s, and LSI-11s, and the DOS operating system for IBM PCs and IBM-compatible machines. DIGLIB/VMS runs on the VAX and MicroVAX series of computers under VMS. The software is readily usable by casual programmers for two-dimensional plotting.
DIGLIB. PC-DOS Graphics Subroutine Library
Burleson, R.R.
1989-02-01
DIGLIB is a collection of general graphics subroutines. It was designed to be small, reasonably fast, device-independent, and compatible with DEC-supplied operating systems for VAXes, PDP-11s, and LSI-11s, and the DOS operating system for IBM PCs and IBM-compatible machines. DIGLIB/PC runs on IBM PCs under PC-DOS or MS-DOS. The software is readily usable by casual programmers for two-dimensional plotting.
On the validity of repeated assessments in the UMAT, a high-stakes admissions test.
Andrich, David; Styles, Irene; Mercer, Annette; Puddey, Ian B
2017-02-04
The possibility that the validity of assessment is compromised by repeated sittings of highly competitive and high profile selection tests has been documented and is of concern to stake-holders. An illustrative example is the Undergraduate Medicine and Health Sciences Admission Test (UMAT) used by some medical and dental courses in Australia and New Zealand. The proficiencies of all applicants who sat the UMAT from one to four sittings between 2006 and 2012 were estimated on the same metric using the probabilistic Rasch model. A fit index characterising each profile's degree of conformity to the model was also calculated. Confirming expectations, mean proficiencies increased with repeated sittings on all three UMAT scales with the greatest difference (which was nevertheless relatively small) between the first two sittings. The fit index showed that the increases in proficiency estimates arose from additional easier items being answered correctly on repeated sittings rather than additional more difficult ones, suggesting that improvements are not on the substantive construct of the variable of assessment but in skills in answering the questions. Although strategies for dealing with the increase in proficiency estimates on repeated sittings could be canvassed, these results suggest that the validity of results on repeated sittings was not compromised. Accordingly, it might be concluded that although particular individuals might improve substantially between sittings, any validity is not likely to be compromised with the possibility that for some applicants, the second sitting might be the most valid.
Abaqus Simulations of Rock Response to Dynamic Loading
Steedman, David W.; Coblentz, David
2012-08-15
The LANL Geodynamics Team has been applying Abaqus modeling to achieve increasingly complex simulations. Advancements in Abaqus model building and simulation tools allows this progress. We use Lab-developed constitutive models, the fully coupled CEL Abaqus and general contact to simulate response of realistic sites to explosively driven shock.
Computer program utilizes FORTRAN 4 subroutines for contour plotting
NASA Technical Reports Server (NTRS)
Block, N.; Garret, R.; Lawson, C.
1967-01-01
Computer program constructs lists of xy-coordinate pairs that define contour curves for an arbitrary given function of two variables and transmits these lists to plotting equipment to produce contour plots. The principal subroutine, CONTUR, is independent of any specific system of plotting subroutines and equipment.
IBM-1620 monitor 2-D disk-storage subroutines
NASA Technical Reports Server (NTRS)
Krejci, H. F.
1969-01-01
Set of subroutines provides the FORTRAN user with protected, permanent, disk storage of data on an IBM 1620 Monitor 11-D system. The program consists of a set of four subroutines and a utility program. It allows block data to be transferred directly between assigned core locations and disk storage.
A SUBROUTINE FOR THE EQUATION OF STATE OF AIR
A ’semi-physical fit’ to the equation of state of air is generated from tabulated values. A listing of the FORTRAN subroutine AIR is given, as well as a graph of tabulated and subroutine-computed values of (gamma - 1)
NASA Technical Reports Server (NTRS)
Gould, Kevin E.; Satyanarayana, Arunkumar; Bogert, Philip B.
2016-01-01
Analysis performed in this study substantiates the need for high fidelity vehicle level progressive damage analyses (PDA) structural models for use in the verification and validation of proposed sub-scale structural models and to support required full-scale vehicle level testing. PDA results are presented that capture and correlate the responses of sub-scale 3-stringer and 7-stringer panel models and an idealized 8-ft diameter fuselage model, which provides a vehicle level environment for the 7-stringer sub-scale panel model. Two unique skin-stringer attachment assumptions are considered and correlated in the models analyzed: the TIE constraint interface versus the cohesive element (COH3D8) interface. Evaluating different interfaces allows for assessing a range of predicted damage modes, including delamination and crack propagation responses. Damage models considered in this study are the ABAQUS built-in Hashin procedure and the COmplete STress Reduction (COSTR) damage procedure implemented through a VUMAT user subroutine using the ABAQUS/Explicit code.
Input Files and Procedures for Analysis of SMA Hybrid Composite Beams in MSC.Nastran and ABAQUS
NASA Technical Reports Server (NTRS)
Turner, Travis L.; Patel, Hemant D.
2005-01-01
A thermoelastic constitutive model for shape memory alloys (SMAs) and SMA hybrid composites (SMAHCs) was recently implemented in the commercial codes MSC.Nastran and ABAQUS. The model is implemented and supported within the core of the commercial codes, so no user subroutines or external calculations are necessary. The model and resulting structural analysis has been previously demonstrated and experimentally verified for thermoelastic, vibration and acoustic, and structural shape control applications. The commercial implementations are described in related documents cited in the references, where various results are also shown that validate the commercial implementations relative to a research code. This paper is a companion to those documents in that it provides additional detail on the actual input files and solution procedures and serves as a repository for ASCII text versions of the input files necessary for duplication of the available results.
Computer Subroutines for Analytic Rotation by Two Gradient Methods.
ERIC Educational Resources Information Center
van Thillo, Marielle
Two computer subroutine packages for the analytic rotation of a factor matrix, A(p x m), are described. The first program uses the Flectcher (1970) gradient method, and the second uses the Polak-Ribiere (Polak, 1971) gradient method. The calculations in both programs involve the optimization of a function of free parameters. The result is a…
Subroutines GEORGE and DRASTC simplify operation of automatic digital plotter
NASA Technical Reports Server (NTRS)
Englel, F., III; Gray, W. H.; Richard, P. J.
1967-01-01
FORTRAN language subroutines enable the production of a tape for a 360-30 tape unit that controls the CALCOMP 566 Digital Incremental Plotter. This provides the plotter with instructions for graphically displaying data points with the proper scaling of axes, numbering, lettering, and tic marking.
FORTRAN plotting subroutines for the space plasma laboratory
NASA Technical Reports Server (NTRS)
Williams, R.
1983-01-01
The computer program known as PLOTRW was custom made to satisfy some of the graphics requirements for the data collected in the Space Plasma Laboratory at the Johnson Space Center (JSC). The general requirements for the program were as follows: (1) all subroutines shall be callable through a FORTRAN source program; (2) all graphs shall fill one page and be properly labeled; (3) there shall be options for linear axes and logarithmic axes; (4) each axis shall have tick marks equally spaced with numeric values printed at the beginning tick mark and at the last tick mark; and (5) there shall be three options for plotting. These are: (1) point plot, (2) line plot and (3) point-line plot. The subroutines were written in FORTRAN IV for the LSI-11 Digital equipment Corporation (DEC) Computer. The program is now operational and can be run on any TEKTRONICX graphics terminal that uses a DEC Real-Time-11 (RT-11) operating system.
Subroutine bundls, a fortran IV program to determine schreinemakers bundles
NASA Astrophysics Data System (ADS)
Linde, J.; Andrew, A. S.
Given an entire set of relevant balanced equations, BUNDLS and associated subroutines select all invariant points and order univariant lines around these points. Invariant points are formed by taking every set of m absent phases from each reaction. All revelant univariant lines are ordered around each invariant point by a direct application of the rules of Schreinemakers. The program also calculates true angular values for PT, P-μ x1 or μ y-μ x diagrams.
Modeling ductile dynamic fracture with ABAQUS/explicit
Anderson, C.A.; Turner, C.
1996-05-01
This paper illustrates the use of advanced constitutive models in ABAQUS/Explicit together with highly focused finite element meshes to simulate the propagation of a fracture in a ductile medium. A double edge-cracked specimen under far field dynamic tensile loading is analyzed, and shows both rectilinear motion or unstable oscillatory motion of the crack depending on the material property constraints. Results are also presented for a simulation of ASTM`s standard fracture test E399. Comparisons of ABAQUS/Explicit results with experiments or other analytical/numerical results are made.
Algorithm-Based Fault Tolerance for Numerical Subroutines
NASA Technical Reports Server (NTRS)
Tumon, Michael; Granat, Robert; Lou, John
2007-01-01
A software library implements a new methodology of detecting faults in numerical subroutines, thus enabling application programs that contain the subroutines to recover transparently from single-event upsets. The software library in question is fault-detecting middleware that is wrapped around the numericalsubroutines. Conventional serial versions (based on LAPACK and FFTW) and a parallel version (based on ScaLAPACK) exist. The source code of the application program that contains the numerical subroutines is not modified, and the middleware is transparent to the user. The methodology used is a type of algorithm- based fault tolerance (ABFT). In ABFT, a checksum is computed before a computation and compared with the checksum of the computational result; an error is declared if the difference between the checksums exceeds some threshold. Novel normalization methods are used in the checksum comparison to ensure correct fault detections independent of algorithm inputs. In tests of this software reported in the peer-reviewed literature, this library was shown to enable detection of 99.9 percent of significant faults while generating no false alarms.
Thermal and flow analysis subroutines for the SINDA-version 9 computer routine
NASA Technical Reports Server (NTRS)
Oren, J. A.; Williams, D. R.
1973-01-01
Fluid flow analysis, special thermal analysis and input/output capabilities of the MOTAR routine were incorporated into the SINDA routine. All the capabilities were added in the form of user subroutines so that they may be added to different versions of SINDA with a minimum of programmer effort. Two modifications were made to the existing subroutines of SINDA/8 to incorporate the above subroutines. These were: (1) A modification to the preprocessor to permit actual values of array numbers, conductor numbers, node numbers or constant numbers supplied as array data to be converted to relative numbers. (2) Modifications to execution subroutine CNFAST to make it compatible with the radiant interchange user subroutine, RADIR. This modified version of SINDA has been designated SINDA/version 9. A detailed discussion of the methods used for the capabilities added is presented. The modifications for the SINDA subroutines are described, as well as user subroutines. All subroutines added or modified are listed.
NASA Technical Reports Server (NTRS)
Allen Phillip A.; Wilson, Christopher D.
2003-01-01
The development of a pressure-dependent constitutive model with combined multilinear kinematic and isotropic hardening is presented. The constitutive model is developed using the ABAQUS user material subroutine (UMAT). First the pressure-dependent plasticity model is derived. Following this, the combined bilinear and combined multilinear hardening equations are developed for von Mises plasticity theory. The hardening rule equations are then modified to include pressure dependency. The method for implementing the new constitutive model into ABAQUS is given.
Comparison between FEBio and Abaqus for biphasic contact problems
Jin, Zhongmin; Fisher, John; Wilcox, Ruth
2013-01-01
Articular cartilage plays an important role in the function of diarthrodial joints. Computational methods have been used to study the biphasic mechanics of cartilage, and Abaqus has been one of the most widely used commercial software packages for this purpose. A newly developed open-source finite element solver, FEBio, has been developed specifically for biomechanical applications. The aim of this study was to undertake a direct comparison between FEBio and Abaqus for some practical contact problems involving cartilage. Three model types, representing a porous flat-ended indentation test, a spherical-ended indentation test, and a conceptual natural joint contact model, were compared. In addition, a parameter sensitivity study was also performed for the spherical-ended indentation test to investigate the effects of changes in the input material properties on the model outputs, using both FEBio and Abaqus. Excellent agreement was found between FEBio and Abaqus for all of the model types and across the range of material properties that were investigated. PMID:23804955
Comparison between FEBio and Abaqus for biphasic contact problems.
Meng, Qingen; Jin, Zhongmin; Fisher, John; Wilcox, Ruth
2013-09-01
Articular cartilage plays an important role in the function of diarthrodial joints. Computational methods have been used to study the biphasic mechanics of cartilage, and Abaqus has been one of the most widely used commercial software packages for this purpose. A newly developed open-source finite element solver, FEBio, has been developed specifically for biomechanical applications. The aim of this study was to undertake a direct comparison between FEBio and Abaqus for some practical contact problems involving cartilage. Three model types, representing a porous flat-ended indentation test, a spherical-ended indentation test, and a conceptual natural joint contact model, were compared. In addition, a parameter sensitivity study was also performed for the spherical-ended indentation test to investigate the effects of changes in the input material properties on the model outputs, using both FEBio and Abaqus. Excellent agreement was found between FEBio and Abaqus for all of the model types and across the range of material properties that were investigated.
AMPHION: Specification-based programming for scientific subroutine libraries
NASA Technical Reports Server (NTRS)
Lowry, Michael; Philpot, Andrew; Pressburger, Thomas; Underwood, Ian; Waldinger, Richard; Stickel, Mark
1994-01-01
AMPHION is a knowledge-based software engineering (KBSE) system that guides a user in developing a diagram representing a formal problem specification. It then automatically implements a solution to this specification as a program consisting of calls to subroutines from a library. The diagram provides an intuitive domain oriented notation for creating a specification that also facilitates reuse and modification. AMPHION'S architecture is domain independent. AMPHION is specialized to an application domain by developing a declarative domain theory. Creating a domain theory is an iterative process that currently requires the joint expertise of domain experts and experts in automated formal methods for software development.
NASA Technical Reports Server (NTRS)
Wohlen, R. L.
1976-01-01
A listing of the source deck of each sparse FORMA subroutine is given to remove the 'black-box' aura of the subroutines so that the analyst may better understand the detailed operations of each subroutine. The format of a sparse matrix on a utility tape is also presented. The FORTRAN 4 programming language is used in all sparse FORMA subroutines.
NASA Technical Reports Server (NTRS)
Wohlen, R. L.
1976-01-01
A listing of the source deck of each finite element FORMA subroutine is given to remove the 'black-box' aura of the subroutines so that the analyst may better understand the detailed operations of each subroutine. The FORTRAN 4 programming language is used in all finite element FORMA subroutines.
Visualizing MCNP Tally Segment Geometry and Coupling Results with ABAQUS
J. R. Parry; J. A. Galbraith
2007-11-01
The Advanced Graphite Creep test, AGC-1, is planned for irradiation in the Advanced Test Reactor (ATR) in support of the Next Generation Nuclear Plant program. The experiment requires very detailed neutronics and thermal hydraulics analyses to show compliance with programmatic and ATR safety requirements. The MCNP model used for the neutronics analysis required hundreds of tally regions to provide the desired detail. A method for visualizing the hundreds of tally region geometries and the tally region results in 3 dimensions has been created to support the AGC-1 irradiation. Additionally, a method was created which would allow ABAQUS to access the results directly for the thermal analysis of the AGC-1 experiment.
Automated Reuse of Scientific Subroutine Libraries through Deductive Synthesis
NASA Technical Reports Server (NTRS)
Lowry, Michael R.; Pressburger, Thomas; VanBaalen, Jeffrey; Roach, Steven
1997-01-01
Systematic software construction offers the potential of elevating software engineering from an art-form to an engineering discipline. The desired result is more predictable software development leading to better quality and more maintainable software. However, the overhead costs associated with the formalisms, mathematics, and methods of systematic software construction have largely precluded their adoption in real-world software development. In fact, many mainstream software development organizations, such as Microsoft, still maintain a predominantly oral culture for software development projects; which is far removed from a formalism-based culture for software development. An exception is the limited domain of safety-critical software, where the high-assuiance inherent in systematic software construction justifies the additional cost. We believe that systematic software construction will only be adopted by mainstream software development organization when the overhead costs have been greatly reduced. Two approaches to cost mitigation are reuse (amortizing costs over many applications) and automation. For the last four years, NASA Ames has funded the Amphion project, whose objective is to automate software reuse through techniques from systematic software construction. In particular, deductive program synthesis (i.e., program extraction from proofs) is used to derive a composition of software components (e.g., subroutines) that correctly implements a specification. The construction of reuse libraries of software components is the standard software engineering solution for improving software development productivity and quality.
Calibrating the Abaqus Crushable Foam Material Model using UNM Data
Schembri, Philip E.; Lewis, Matthew W.
2014-02-27
Triaxial test data from the University of New Mexico and uniaxial test data from W-14 is used to calibrate the Abaqus crushable foam material model to represent the syntactic foam comprised of APO-BMI matrix and carbon microballoons used in the W76. The material model is an elasto-plasticity model in which the yield strength depends on pressure. Both the elastic properties and the yield stress are estimated by fitting a line to the elastic region of each test response. The model parameters are fit to the data (in a non-rigorous way) to provide both a conservative and not-conservative material model. The model is verified to perform as intended by comparing the values of pressure and shear stress at yield, as well as the shear and volumetric stress-strain response, to the test data.
Modeling of MOX Fuel Pellet-Clad Interaction Using ABAQUS
Ambrosek, Richard G.; Pedersen, Robert C.; Maple, Amanda
2002-07-01
Post-irradiation examination (PIE) has indicated an increase in the outer diameter of fuel pins being irradiated in the Advanced Test Reactor (ATR) for the MOX irradiation program. The diameter increase is the largest in the region between fuel pellets. The fuel pellet was modeled using PATRAN and the model was evaluated using ABAQUS, version 6.2. The results from the analysis indicate the non-uniform clad diameter is caused by interaction between the fuel pellet and the clad. The results also demonstrate that the interaction is not uniform over the pellet axial length, with the largest interaction occurring in the region of the pellet-pellet interface. Results were obtained for an axisymmetric model and for a 1/8 pie shaped segment, using the coupled temperature-displacement solution technique. (authors)
NASA Technical Reports Server (NTRS)
Wohlen, R. L.
1976-01-01
A listing of the source deck of each dense FORMA subroutine is given to remove the 'black-box' aura of the subroutines so that the analyst may better understand the detail operations of each subroutine. The FORTRAN 4 programming language is used throughout.
The Accuracy of the ABAQUS FE Numerical Modeling for Sandwich Beams with Foam Core
NASA Astrophysics Data System (ADS)
Papakaliatakis, G. E.; Karavagelas, N.
2009-08-01
The foam of the sandwich core is a compressible material and in ABAQUS FEA is modelled using the crushable foam model. There are crushable foam models with volumetric hardening and with isotropic hardening in ABAQUS standard analysis and the same models for the ABAQUS explicit analysis, for isotropic compressible materials. Also, the Hill's plasticity model for general anisotropic incompressible solids, is available in ABAQUS. All the above modelling cases were performed for sandwich beams with composite faces and PVC foam cores. The specimens were subjected to three-point bending, under quasi-static loading, using the experimental load-deflection curves to compare with ABAQUS FEA predictions. The best modelling case is suggested.
On testing a subroutine for the numerical integration of ordinary differential equations
NASA Technical Reports Server (NTRS)
Krogh, F. T.
1973-01-01
This paper discusses how to numerically test a subroutine for the solution of ordinary differential equations. Results obtained with a variable order Adams method are given for eleven simple test cases.-
Computer subroutines for estimation of human exposure to radiation in low Earth orbit
NASA Technical Reports Server (NTRS)
Cucinotta, F. A.; Wilson, J. W.
1985-01-01
Computer subroutines to calculate human exposure to trapped radiations in low Earth orbit (LEO) on the basis of a simple approximation of the human geometry by spherical shell shields of varying thickness are presented and detailed. The subroutines calculate the dose to critical body organs and the fraction of exposure limit reached as a function of altitude of orbit, degree of inclination, shield thickness, and days in mission. Exposure rates are compared with current exposure limits.
Sullivan, W. N.; Leonard, T. M.
1980-11-01
An important aspect of structural design of the Darrieus rotor is the determination of aerodynamic blade loads. This report describes a load generator which has been used at Sandia for quasi-static and dynamic rotor analyses. The generator is based on the single streamtube aerodynamic flow model and is constructed as a FORTRAN IV subroutine to facilitate its use in finite element structural models. Input and output characteristics of the subroutine are described and a complete listing is attached as an appendix.
Description of a FORTRAN subroutine for plotting three-dimensional data
NASA Technical Reports Server (NTRS)
James, M. R.; Kelley, W. W.
1978-01-01
A FORTRAN subroutine is described which provides the capability to plot three-dimensional data on an interactive cathode-ray-tube computer terminal or conventional plotter. The plotted data, which must be described in terms of a series of two-dimensional curves, appeared to form a surface in three-dimensional space. Features are included of the subroutine's capability for hidden-line computations. User instructions and sample programs are described.
ParaView visualization of Abaqus output on the mechanical deformation of complex microstructures
NASA Astrophysics Data System (ADS)
Liu, Qingbin; Li, Jiang; Liu, Jie
2017-02-01
Abaqus® is a popular software suite for finite element analysis. It delivers linear and nonlinear analyses of mechanical and fluid dynamics, includes multi-body system and multi-physics coupling. However, the visualization capability of Abaqus using its CAE module is limited. Models from microtomography have extremely complicated structures, and datasets of Abaqus output are huge, requiring a visualization tool more powerful than Abaqus/CAE. We convert Abaqus output into the XML-based VTK format by developing a Python script and then using ParaView to visualize the results. Such capabilities as volume rendering, tensor glyphs, superior animation and other filters allow ParaView to offer excellent visualizing manifestations. ParaView's parallel visualization makes it possible to visualize very big data. To support full parallel visualization, the Python script achieves data partitioning by reorganizing all nodes, elements and the corresponding results on those nodes and elements. The data partition scheme minimizes data redundancy and works efficiently. Given its good readability and extendibility, the script can be extended to the processing of more different problems in Abaqus. We share the script with Abaqus users on GitHub.
Verification and benchmarking of ABAQUS and PATRAN for heat transfer applications
Hawkes, G.L.
1989-08-01
This report contains the verification and benchmarking performed at the Idaho National Engineering Laboratory (INEL) on ABAQUS and PATRAN for heat transfer calculations. ABAQUS and PATRAN were used to perform the thermal analysis of the Advanced Test Reactor (ATR) loop 2A piping components. These codes are commercially available and are used extensively within the industry to solve structural and heat transfer problems using finite element methods. They have been extensively verified and documented by the companies developing and providing them. This report documents work performed by EG G Idaho Inc. to further verify that ABAQUS and PATRAN properly solve a variety of heat transfer problems and that performance on the INEL computers was the same as on the developer's computers. Methods employed to verify ABAQUS and PATRAN are presented within this report. Heat transfer problems with known exact solutions are compared to ABAQUS results. Computer output from the ABAQUS introductory workbook was compared to calculations performed on INEL computers using the same input deck. The verification of ABAQUS and PATRAN at INEL has shown the codes applicable to solve heat transfer problems encountered at INEL. 7 refs., 2 figs., 2 tabs.
1993-04-01
models are available in ABAQUS or the material may be described by the user in a UMAT subroutine. The latter option was used in this analysis which... elastoplastic matrix properties were used in the micromechanical analyses. The plastic response of the matrix is initiated with an octahedral shear stress...the load path through these elements (see Figure 5). As in WYO2D, the fiber is considered transversely isotropic. In contrast to the elastoplastic
NASA Technical Reports Server (NTRS)
Wilson, J. W.; Khandelwal, G. S.
1976-01-01
Calculational methods for estimation of dose from external proton exposure of arbitrary convex bodies are briefly reviewed. All the necessary information for the estimation of dose in soft tissue is presented. Special emphasis is placed on retaining the effects of nuclear reaction, especially in relation to the dose equivalent. Computer subroutines to evaluate all of the relevant functions are discussed. Nuclear reaction contributions for standard space radiations are in most cases found to be significant. Many of the existing computer programs for estimating dose in which nuclear reaction effects are neglected can be readily converted to include nuclear reaction effects by use of the subroutines described herein.
Performance Analysis of Memory Transfers and GEMM Subroutines on NVIDIA Tesla GPU Cluster
Allada, Veerendra, Benjegerdes, Troy; Bode, Brett
2009-08-31
Commodity clusters augmented with application accelerators are evolving as competitive high performance computing systems. The Graphical Processing Unit (GPU) with a very high arithmetic density and performance per price ratio is a good platform for the scientific application acceleration. In addition to the interconnect bottlenecks among the cluster compute nodes, the cost of memory copies between the host and the GPU device have to be carefully amortized to improve the overall efficiency of the application. Scientific applications also rely on efficient implementation of the BAsic Linear Algebra Subroutines (BLAS), among which the General Matrix Multiply (GEMM) is considered as the workhorse subroutine. In this paper, they study the performance of the memory copies and GEMM subroutines that are critical to port the computational chemistry algorithms to the GPU clusters. To that end, a benchmark based on the NetPIPE framework is developed to evaluate the latency and bandwidth of the memory copies between the host and the GPU device. The performance of the single and double precision GEMM subroutines from the NVIDIA CUBLAS 2.0 library are studied. The results have been compared with that of the BLAS routines from the Intel Math Kernel Library (MKL) to understand the computational trade-offs. The test bed is a Intel Xeon cluster equipped with NVIDIA Tesla GPUs.
2015-11-01
Memorandum Simulation of Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes ...Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes by Charles R. Fisher...Welding- Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes 5a. CONTRACT NUMBER N/A 5b. GRANT NUMBER N/A 5c
Developing an Abaqus *HYPERFOAM Model for M9747 (4003047) Cellular Silicone Foam
Siranosian, Antranik A.; Stevens, R. Robert
2012-04-26
This report documents work done to develop an Abaqus *HYPERFOAM hyperelastic model for M9747 (4003047) cellular silicone foam for use in quasi-static analyses at ambient temperature. Experimental data, from acceptance tests for 'Pad A' conducted at the Kansas City Plant (KCP), was used to calibrate the model. The data includes gap (relative displacement) and load measurements from three locations on the pad. Thirteen sets of data, from pads with different serial numbers, were provided. The thirty-nine gap-load curves were extracted from the thirteen supplied Excel spreadsheets and analyzed, and from those thirty-nine one set of data, representing a qualitative mean, was chosen to calibrate the model. The data was converted from gap and load to nominal (engineering) strain and nominal stress in order to implement it in Abaqus. Strain computations required initial pad thickness estimates. An Abaqus model of a right-circular cylinder was used to evaluate and calibrate the *HYPERFOAM model.
Galluzzi, L; Vitale, I; Abrams, J M; Alnemri, E S; Baehrecke, E H; Blagosklonny, M V; Dawson, T M; Dawson, V L; El-Deiry, W S; Fulda, S; Gottlieb, E; Green, D R; Hengartner, M O; Kepp, O; Knight, R A; Kumar, S; Lipton, S A; Lu, X; Madeo, F; Malorni, W; Mehlen, P; Nuñez, G; Peter, M E; Piacentini, M; Rubinsztein, D C; Shi, Y; Simon, H-U; Vandenabeele, P; White, E; Yuan, J; Zhivotovsky, B; Melino, G; Kroemer, G
2012-01-01
In 2009, the Nomenclature Committee on Cell Death (NCCD) proposed a set of recommendations for the definition of distinct cell death morphologies and for the appropriate use of cell death-related terminology, including ‘apoptosis', ‘necrosis' and ‘mitotic catastrophe'. In view of the substantial progress in the biochemical and genetic exploration of cell death, time has come to switch from morphological to molecular definitions of cell death modalities. Here we propose a functional classification of cell death subroutines that applies to both in vitro and in vivo settings and includes extrinsic apoptosis, caspase-dependent or -independent intrinsic apoptosis, regulated necrosis, autophagic cell death and mitotic catastrophe. Moreover, we discuss the utility of expressions indicating additional cell death modalities. On the basis of the new, revised NCCD classification, cell death subroutines are defined by a series of precise, measurable biochemical features. PMID:21760595
NASA Technical Reports Server (NTRS)
Fleischer, G. E.; Likins, P. W.
1975-01-01
Three computer subroutines designed to solve the vector-dyadic differential equations of rotational motion for systems that may be idealized as a collection of hinge-connected rigid bodies assembled in a tree topology, with an optional flexible appendage attached to each body are reported. Deformations of the appendages are mathematically represented by modal coordinates and are assumed small. Within these constraints, the subroutines provide equation solutions for (1) the most general case of unrestricted hinge rotations, with appendage base bodies nominally rotating at a constant speed, (2) the case of unrestricted hinge rotations between rigid bodies, with the restriction that those rigid bodies carrying appendages are nominally nonspinning, and (3) the case of small hinge rotations and nominally nonrotating appendages. Sample problems and their solutions are presented to illustrate the utility of the computer programs.
Attitude dynamics simulation subroutines for systems of hinge-connected rigid bodies
NASA Technical Reports Server (NTRS)
Fleischer, G. E.; Likins, P. W.
1974-01-01
Several computer subroutines are designed to provide the solution to minimum-dimension sets of discrete-coordinate equations of motion for systems consisting of an arbitrary number of hinge-connected rigid bodies assembled in a tree topology. In particular, these routines may be applied to: (1) the case of completely unrestricted hinge rotations, (2) the totally linearized case (all system rotations are small), and (3) the mixed, or partially linearized, case. The use of the programs in each case is demonstrated using a five-body spacecraft and attitude control system configuration. The ability of the subroutines to accommodate prescribed motions of system bodies is also demonstrated. Complete listings and user instructions are included for these routines (written in FORTRAN V) which are intended as multi- and general-purpose tools in the simulation of spacecraft and other complex electromechanical systems.
The inverse of winnowing: a FORTRAN subroutine and discussion of unwinnowing discrete data
Bracken, Robert E.
2004-01-01
This report describes an unwinnowing algorithm that utilizes a discrete Fourier transform, and a resulting Fortran subroutine that winnows or unwinnows a 1-dimensional stream of discrete data; the source code is included. The unwinnowing algorithm effectively increases (by integral factors) the number of available data points while maintaining the original frequency spectrum of a data stream. This has utility when an increased data density is required together with an availability of higher order derivatives that honor the original data.
Development of a CMAQ Subroutine for Wind-blown Dust Emission Calculation
NASA Astrophysics Data System (ADS)
Park, S.
2011-12-01
A subroutine for calculating the wind-blown dust emission in the framework of the Community Multiscale Air Quality Modeling System (CMAQ) has been developed. This new subroutine, called WDEMIS, is analogous in its use to the recently added sea-salt emission subroutine SSEMIS. To make use of WDEMIS, the subroutine AERO_EMIS has to be modified so that WDEMIS (just like SSEMIS) is called by AERO_EMIS. The threshold friction velocity for smooth dry surface, the drag partitioning effect by non-erodible surface roughness elements, the soil moisture effect, the positive feedback of the saltating soil particles to the friction velocity, the saltation scheme calculating the horizontal soil flux, and the sandblasting scheme calculating the vertical dust emission flux are accounted for in WDEMIS. In order to supply soil characteristics required for wind-blown dust emission calculation, i.e., soil moisture content, land use fraction, and soil texture, the Pleim-Xiu land-surface model [Xiu and Pleim, 2001] is used by the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) combined with MCIP version 3.6. CMAQ modelling using WDEMIS was performed to simulate an Asian dust storm episode that occurred in April 2006 to evaluate the wind-blown dust emission prediction by WDEMIS. Sensitivity analysis showed that the accuracy of land use data and soil property supplied to WDEMIS is critical to performance of WDEMIS. Appropriate size fractioning is considered one of the most important improvement required in the future. Xiu, A., and J.E. Pleim, Development of a land surface model. Part I: Application in a mesoscale meteorology model, Journal of Applied Meteorology, 40, 192-209, 2001.
NASA Technical Reports Server (NTRS)
Arnold, Steven M.; Bednarcyk, Brett A.; Hussain, Aquila; Katiyar, Vivek
2010-01-01
A unified framework is presented that enables coupled multiscale analysis of composite structures and associated graphical pre- and postprocessing within the Abaqus/CAE environment. The recently developed, free, Finite Element Analysis--Micromechanics Analysis Code (FEAMAC) software couples NASA's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with Abaqus/Standard and Abaqus/Explicit to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. The Graphical User Interfaces (FEAMAC-Pre and FEAMAC-Post), developed through collaboration between SIMULIA Erie and the NASA Glenn Research Center, enable users to employ a new FEAMAC module within Abaqus/CAE that provides access to the composite microscale. FEA IAC-Pre is used to define and store constituent material properties, set-up and store composite repeating unit cells, and assign composite materials as sections with all data being stored within the CAE database. Likewise FEAMAC-Post enables multiscale field quantity visualization (contour plots, X-Y plots), with point and click access to the microscale i.e., fiber and matrix fields).
Vande Geest, Jonathan P; Simon, B R; Rigby, Paul H; Newberg, Tyler P
2011-04-01
Finite element models (FEMs) including characteristic large deformations in highly nonlinear materials (hyperelasticity and coupled diffusive/convective transport of neutral mobile species) will allow quantitative study of in vivo tissues. Such FEMs will provide basic understanding of normal and pathological tissue responses and lead to optimization of local drug delivery strategies. We present a coupled porohyperelastic mass transport (PHEXPT) finite element approach developed using a commercially available ABAQUS finite element software. The PHEXPT transient simulations are based on sequential solution of the porohyperelastic (PHE) and mass transport (XPT) problems where an Eulerian PHE FEM is coupled to a Lagrangian XPT FEM using a custom-written FORTRAN program. The PHEXPT theoretical background is derived in the context of porous media transport theory and extended to ABAQUS finite element formulations. The essential assumptions needed in order to use ABAQUS are clearly identified in the derivation. Representative benchmark finite element simulations are provided along with analytical solutions (when appropriate). These simulations demonstrate the differences in transient and steady state responses including finite deformations, total stress, fluid pressure, relative fluid, and mobile species flux. A detailed description of important model considerations (e.g., material property functions and jump discontinuities at material interfaces) is also presented in the context of finite deformations. The ABAQUS-based PHEXPT approach enables the use of the available ABAQUS capabilities (interactive FEM mesh generation, finite element libraries, nonlinear material laws, pre- and postprocessing, etc.). PHEXPT FEMs can be used to simulate the transport of a relatively large neutral species (negligible osmotic fluid flux) in highly deformable hydrated soft tissues and tissue-engineered materials.
NASA Astrophysics Data System (ADS)
Takizawa, Hideo; Kuwabara, Toshihiko; Oide, Kai; Yoshida, Junji
2016-08-01
Numerous types of yield functions have been proposed to describe the shape of a realistic yield surface. Major commercial finite element codes include few anisotropic functions. Alternatively, the codes allow users to implement material models through user- subroutines. We develop the Unified Material Model Driver for Plasticity (UMMDp) subroutine library, which enables users to implement an arbitrary yield function easily. In this paper, the framework of the UMMDp is presented and its availabilities is shown through examples of sheet metal forming analyses.
Toward high-speed 3D nonlinear soft tissue deformation simulations using Abaqus software.
Idkaidek, Ashraf; Jasiuk, Iwona
2015-12-01
We aim to achieve a fast and accurate three-dimensional (3D) simulation of a porcine liver deformation under a surgical tool pressure using the commercial finite element software Abaqus. The liver geometry is obtained using magnetic resonance imaging, and a nonlinear constitutive law is employed to capture large deformations of the tissue. Effects of implicit versus explicit analysis schemes, element type, and mesh density on computation time are studied. We find that Abaqus explicit and implicit solvers are capable of simulating nonlinear soft tissue deformations accurately using first-order tetrahedral elements in a relatively short time by optimizing the element size. This study provides new insights and guidance on accurate and relatively fast nonlinear soft tissue simulations. Such simulations can provide force feedback during robotic surgery and allow visualization of tissue deformations for surgery planning and training of surgical residents.
Enhancing the ABAQUS Thermomechanics Code to Simulate Steady and Transient Fuel Rod Behavior
R. L. Williamson; D. A. Knoll
2009-09-01
A powerful multidimensional fuels performance capability, applicable to both steady and transient fuel behavior, is developed based on enhancements to the commercially available ABAQUS general-purpose thermomechanics code. Enhanced capabilities are described, including: UO2 temperature and burnup dependent thermal properties, solid and gaseous fission product swelling, fuel densification, fission gas release, cladding thermal and irradiation creep, cladding irradiation growth , gap heat transfer, and gap/plenum gas behavior during irradiation. The various modeling capabilities are demonstrated using a 2D axisymmetric analysis of the upper section of a simplified multi-pellet fuel rod, during both steady and transient operation. Computational results demonstrate the importance of a multidimensional fully-coupled thermomechanics treatment. Interestingly, many of the inherent deficiencies in existing fuel performance codes (e.g., 1D thermomechanics, loose thermo-mechanical coupling, separate steady and transient analysis, cumbersome pre- and post-processing) are, in fact, ABAQUS strengths.
R. L. Williamson
2011-08-01
A powerful multidimensional fuels performance analysis capability, applicable to both steady and transient fuel behavior, is developed based on enhancements to the commercially available ABAQUS general-purpose thermomechanics code. Enhanced capabilities are described, including: UO2 temperature and burnup dependent thermal properties, solid and gaseous fission product swelling, fuel densification, fission gas release, cladding thermal and irradiation creep, cladding irradiation growth, gap heat transfer, and gap/plenum gas behavior during irradiation. This new capability is demonstrated using a 2D axisymmetric analysis of the upper section of a simplified multipellet fuel rod, during both steady and transient operation. Comparisons are made between discrete and smeared-pellet simulations. Computational results demonstrate the importance of a multidimensional, multipellet, fully-coupled thermomechanical approach. Interestingly, many of the inherent deficiencies in existing fuel performance codes (e.g., 1D thermomechanics, loose thermomechanical coupling, separate steady and transient analysis, cumbersome pre- and post-processing) are, in fact, ABAQUS strengths.
Implementation of the Müller-Achenbach-Seelecke Model for Shape Memory Alloys in ABAQUS
NASA Astrophysics Data System (ADS)
Richter, Frank; Kastner, Oliver; Eggeler, Gunther
2009-08-01
Temperature changes caused by latent phase transformation heats are an integral part of the behavior of shape memory alloys. The ensuing thermomechanical coupling between the mechanical and thermal fields is covered by the Müller-Achenbach-Seelecke (MAS) model. Its versatility when implemented as a standalone program has been documented extensively in the literature (S. Seelecke and I. Müller, Appl. Mech. Rev., 57(1), 2004, p 23-46; M. Achenbach, Int. J. Plast., 5(4), 1989, p 371-395; I. Müller and S. Seelecke, Mathem. Comp. Mod., 34(12-13), 2001, p 1307-1355). This model has been evaluated within various simulation environments, standalone programs as well as in commercial tools like FEMLAB and ANSYS. Here we present an application of the MAS model within the finite-element (FEM) simulation software ABAQUS. The MAS constitutive equation of state for SMA is ported into ABAQUS via a user material interface. We present the results of simulation examples using this computer model and validate them by comparison with reference solutions. Using ABAQUS finite elements allowing for temperature as a degree of freedom, the effects of the release and the absorption of latent heats in a fully coupled simulation are demonstrated. Further, a FEM implementation of the model extension to polycrystalline materials is presented as these are of greater relevance with regard to engineering applications. The results show that the incorporation of the MAS model into the ABAQUS environment provides a powerful tool useful in the framework of engineering design studies, especially in situations which require nonisothermal conditions and phase transitions.
Evaluation of the finite element software ABAQUS for biomechanical modelling of biphasic tissues.
Wu, J Z; Herzog, W; Epstein, M
1998-02-01
The biphasic cartilage model proposed by Mow et al. (1980) has proven successful to capture the essential mechanical features of articular cartilage. In order to analyse the joint contact mechanics in real, anatomical joints, the cartilage model needs to be implemented into a suitable finite element code to approximate the irregular surface geometries of such joints. However, systematic and extensive evaluation of the capacity of commercial software for modelling the contact mechanics with biphasic cartilage layers has not been made. This research was aimed at evaluating the commercial finite element software ABAQUS for analysing biphasic soft tissues. The solutions obtained using ABAQUS were compared with those obtained using other finite element models and analytical solutions for three numerical tests: an unconfined indentation test, a test with the contact of a spherical cartilage surface with a rigid plate, and an axi-symmetric joint contact test. It was concluded that the biphasic cartilage model can be implemented into the commercial finite element software ABAQUS to analyse practical joint contact problems with biphasic articular cartilage layers.
1996-05-01
AFRL-ML-WP-TR-1998-4143 IMPLEMENTATION OF A NONISOTHERMAL UNIFIED INELASTIC- STRAIN THEORY FOR A TITANIUM ALLOY INTO ABAQUS 5.4 USER GUIDE JOSEPH L... titanium alloy Timetal21 S. The Bodner-Partom form of unified theory satisfactorily describes the Timetal 21S stress- strain response for a range of...other related input files. 14. SUBJECT TERMS 15. NUMBER OF PAGES Titanium , Timetal2l S, Finite element methods, ABAQUS, Unified inelastic strain theory
A general purpose subroutine for fast fourier transform on a distributed memory parallel machine
NASA Technical Reports Server (NTRS)
Dubey, A.; Zubair, M.; Grosch, C. E.
1992-01-01
One issue which is central in developing a general purpose Fast Fourier Transform (FFT) subroutine on a distributed memory parallel machine is the data distribution. It is possible that different users would like to use the FFT routine with different data distributions. Thus, there is a need to design FFT schemes on distributed memory parallel machines which can support a variety of data distributions. An FFT implementation on a distributed memory parallel machine which works for a number of data distributions commonly encountered in scientific applications is presented. The problem of rearranging the data after computing the FFT is also addressed. The performance of the implementation on a distributed memory parallel machine Intel iPSC/860 is evaluated.
UNAERO: A package of FORTRAN subroutines for approximating unsteady aerodynamics in the time domain
NASA Technical Reports Server (NTRS)
Dunn, H. J.
1985-01-01
This report serves as an instruction and maintenance manual for a collection of CDC CYBER FORTRAN IV subroutines for approximating the unsteady aerodynamic forces in the time domain. The result is a set of constant-coefficient first-order differential equations that approximate the dynamics of the vehicle. Provisions are included for adjusting the number of modes used for calculating the approximations so that an accurate approximation is generated. The number of data points at different values of reduced frequency can also be varied to adjust the accuracy of the approximation over the reduced-frequency range. The denominator coefficients of the approximation may be calculated by means of a gradient method or a least-squares approximation technique. Both the approximation methods use weights on the residual error. A new set of system equations, at a different dynamic pressure, can be generated without the approximations being recalculated.
ERIC Educational Resources Information Center
Gales, Larry; Anderson, Lougenia
These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. FFORM is a portable format-free input subroutine package which simplifies the input of values…
ERIC Educational Resources Information Center
Gales, Larry
This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. PLOT3D is a subroutine package which generates a variety of three dimensional hidden…
ERIC Educational Resources Information Center
Gales, Larry
This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. PLOT3D is a subroutine package which generates a variety of three-dimensional hidden…
ERIC Educational Resources Information Center
Gales, Larry
These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. PRNT3D is a subroutine package which generates a variety of printer plot displays. The displays…
ERIC Educational Resources Information Center
Gales, Larry
These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. PRNT3D is a subroutine package which generates a variety of printed plot displays. The displays…
NumSBT: A subroutine for calculating spherical Bessel transforms numerically
NASA Astrophysics Data System (ADS)
Talman, J. D.
2009-02-01
A previous subroutine, LSFBTR, for computing numerical spherical Bessel (Hankel) transforms is updated with several improvements and modifications. The procedure is applicable if the input radial function and the output transform are defined on logarithmic meshes and if the input function satisfies reasonable smoothness conditions. Important aspects of the procedure are that it is simply implemented with two successive applications of the fast Fourier transform, and it yields accurate results at very large values of the transform variable. Applications to the evaluation of overlap integrals and the Coulomb potential of multipolar charge distributions are described. Program summaryProgram title: NumSBT Catalogue identifier: AANZ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AANZ_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 476 No. of bytes in distributed program, including test data, etc.: 4451 Distribution format: tar.gz Programming language: Fortran 90 Computer: Generic Operating system: Linux Classification: 4.6 Catalogue identifier of previous version: AANZ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 30 (1983) 93 Does the new version supersede the previous version?: No Nature of problem: This program is a subroutine which, for a function defined numerically on a logarithmic mesh in the radial coordinate, generates the spherical Bessel, or Hankel, transform on a logarithmic mesh in the transform variable. Accurate results for large values of the transform variable are obtained, that would not be otherwise obtainable. Solution method: The program applies a procedure proposed by the author [1] that treats the problem as a convolution. The calculation then requires two applications of the fast Fourier transform method. Reasons for
Documentation for subroutine REDUC3, an algorithm for the linear filtering of gridded magnetic data
Blakely, Richard J.
1977-01-01
Subroutine REDUC3 transforms a total field anomaly h1(x,y) , measured on a horizontal and rectangular grid, into a new anomaly h2(x,y). This new anomaly is produced by the same source as h1(x,y) , but (1) is observed at a different elevation, (2) has a source with a different direction of magnetization, and/or (3) has a different direction of residual field. Case 1 is tantamount to upward or downward continuation. Cases 2 and 3 are 'reduction to the pole', if the new inclinations of both the magnetization and regional field are 90 degrees. REDUC3 is a filtering operation applied in the wave-number domain. It first Fourier transforms h1(x,y) , multiplies by the appropriate filter, and inverse Fourier transforms the result to obtain h2(x,y). No assumptions are required about the shape of the source or how the intensity of magnetization varies within it.
Simulating Initial and Progressive Failure of Open-Hole Composite Laminates under Tension
NASA Astrophysics Data System (ADS)
Guo, Zhangxin; Zhu, Hao; Li, Yongcun; Han, Xiaoping; Wang, Zhihua
2016-12-01
A finite element (FE) model is developed for the progressive failure analysis of fiber reinforced polymer laminates. The failure criterion for fiber and matrix failure is implemented in the FE code Abaqus using user-defined material subroutine UMAT. The gradual degradation of the material properties is controlled by the individual fracture energies of fiber and matrix. The failure and damage in composite laminates containing a central hole subjected to uniaxial tension are simulated. The numerical results show that the damage model can be used to accurately predicte the progressive failure behaviour both qualitatively and quantitatively.
Choi, Shi-Hoon; Kim, Dae-Wan; Yang, Hoe-Seok; Han, Seong-Ho; Yoon, Jeong Whan
2010-06-15
Planar anisotropy and cup-drawing behavior were investigated for high-strength steel sheets containing different volume fractions of martensite. Macrotexture analysis using XRD was conducted to capture the effect of crystallographic orientation on the planar anisotropy of high-strength steel sheets. A phenomenological yield function, Yld96, which accounts for the anisotropy of yield stress and r-values, was implemented into ABAQUS using the user subroutine UMAT. Cup drawing of high-strength steel sheets was simulated using the FEM code. The profiles of earing and thickness strain were compared with the experimentally measured results.
Simulation of Mechanical Stress on Stainless Steel for Pb-Bi Corrosion Test by Using ABAQUS
NASA Astrophysics Data System (ADS)
Irwanto, D.; Mustari, A. P. A.; Budiman, B. A.
2017-03-01
Pb-Bi eutectic with its advantageous is proposed to be utilized as a coolant in the GEN IV type of rSeactor. However, high temperature corrosion when contact with stainless steels is one of the issues of Pb-Bi eutectic utilization. It is known that in the environment of high temperature Pb-Bi, mechanical strength of stainless steel may decrease. Thus, simulation of mechanical stress working on stainless steel during in-situ bending test by using ABAQUS was conducted. Several bending degrees were simulated at high temperature to obtain the mechanical stress information. Temperature condition was strongly affect the stress vs. displacement profile. The reported mechanical strength reduction percentage was used to draw predicted mechanical stress under high temperature Pb-Bi environment.
EzGET: A library of FORTRAN subroutines to facilitate data retrieval
Taylor, K.E.
1996-04-01
The software described in this document is designed to facilitate retrieval of modeled and observed climate data stored in popular formats including DRS, net CDF, GrADS, and, if a control file is supplied, GRIB. You can specify how the data should be structured and whether it should undergo a grid transformation before you receive it, even when you know little about the structure of the stored data (i.e.. its dimension order, grid, and domain). The software is referred to here as EzGet (pronounced {open_quotes}easy-get{close_quotes}) and it comprise a set of subroutines that can be linked to any FORTRAN program. EzGet reads files through the cdunif interface which is available from the Program for Climate Model Diagnosis and Intercomparison (PCMDI), but use of EzGet does not require familiarity the cdunif. The main advantages of using this software instead of the lower level cdunif library include: Substantial error trapping capabilities and detailed error messages; Versatile capability of conveniently selecting data. from specified regions (e.g.. oceans, North America, all land areas north of 45 degrees latitude, etc.); Ability to map data to a new grid at the time it is retrieved by EzGet; Automatic creation of {open_quotes}weights{close_quotes} for use in subsequent averaging or masking of data; Increased control in specifying the domain. grid and structure of the retrieved data. Taken together these capabilities will simplify the process of writing programs for accessing data stored in different formats and structures, including all the observed data sets and the model output from various model intercomparison projects (AMIP, PMIP, CMIP, etc.) archived at PCMDI.
A Model for Simulating the Response of Aluminum Honeycomb Structure to Transverse Loading
NASA Technical Reports Server (NTRS)
Ratcliffe, James G.; Czabaj, Michael W.; Jackson, Wade C.
2012-01-01
A 1-dimensional material model was developed for simulating the transverse (thickness-direction) loading and unloading response of aluminum honeycomb structure. The model was implemented as a user-defined material subroutine (UMAT) in the commercial finite element analysis code, ABAQUS(Registered TradeMark)/Standard. The UMAT has been applied to analyses for simulating quasi-static indentation tests on aluminum honeycomb-based sandwich plates. Comparison of analysis results with data from these experiments shows overall good agreement. Specifically, analyses of quasi-static indentation tests yielded accurate global specimen responses. Predicted residual indentation was also in reasonable agreement with measured values. Overall, this simple model does not involve a significant computational burden, which makes it more tractable to simulate other damage mechanisms in the same analysis.
Pegg, Elise C; Gill, Harinderjit S
2016-09-06
A new software tool to assign the material properties of bone to an ABAQUS finite element mesh was created and compared with Bonemat, a similar tool originally designed to work with Ansys finite element models. Our software tool (py_bonemat_abaqus) was written in Python, which is the chosen scripting language for ABAQUS. The purpose of this study was to compare the software packages in terms of the material assignment calculation and processing speed. Three element types were compared (linear hexahedral (C3D8), linear tetrahedral (C3D4) and quadratic tetrahedral elements (C3D10)), both individually and as part of a mesh. Comparisons were made using a CT scan of a hemi-pelvis as a test case. A small difference, of -0.05kPa on average, was found between Bonemat version 3.1 (the current version) and our Python package. Errors were found in the previous release of Bonemat (version 3.0 downloaded from www.biomedtown.org) during calculation of the quadratic tetrahedron Jacobian, and conversion of the apparent density to modulus when integrating over the Young׳s modulus field. These issues caused up to 2GPa error in the modulus assignment. For these reasons, we recommend users upgrade to the most recent release of Bonemat. Processing speeds were assessed for the three different element types. Our Python package took significantly longer (110s on average) to perform the calculations compared with the Bonemat software (10s). Nevertheless, the workflow advantages of the package and added functionality makes 'py_bonemat_abaqus' a useful tool for ABAQUS users.
Analysis of SMA Hybrid Composite Structures in MSC.Nastran and ABAQUS
NASA Technical Reports Server (NTRS)
Turner, Travis L.; Patel, Hemant D.
2005-01-01
A thermoelastic constitutive model for shape memory alloy (SMA) actuators and SMA hybrid composite (SMAHC) structures was recently implemented in the commercial finite element codes MSC.Nastran and ABAQUS. The model may be easily implemented in any code that has the capability for analysis of laminated composite structures with temperature dependent material properties. The model is also relatively easy to use and requires input of only fundamental engineering properties. A brief description of the model is presented, followed by discussion of implementation and usage in the commercial codes. Results are presented from static and dynamic analysis of SMAHC beams of two types; a beam clamped at each end and a cantilever beam. Nonlinear static (post-buckling) and random response analyses are demonstrated for the first specimen. Static deflection (shape) control is demonstrated for the cantilever beam. Approaches for modeling SMAHC material systems with embedded SMA in ribbon and small round wire product forms are demonstrated and compared. The results from the commercial codes are compared to those from a research code as validation of the commercial implementations; excellent correlation is achieved in all cases.
Coupled field-structural analysis of HGTR fuel brick using ABAQUS
Mohanty, S.; Jain, R.; Majumdar, S.; Tautges, T. J.; Srinivasa, M.
2012-07-01
High-temperature, gas-cooled reactors (HTGRs) are usually helium-gas cooled, with a graphite core that can operate at reactor outlet temperatures much higher than can conventional light water reactors. In HTGRs, graphite components moderate and reflect neutrons. During reactor operation, high temperature and high irradiation cause damage to the graphite crystal and grains and create other defects. This cumulative structural damage during the reactor lifetime leads to changes in graphite properties, which can alter the ability to support the designed loads. The aim of the present research is to develop a finite-element code using commercially available ABAQUS software for the structural integrity analysis of graphite core components under extreme temperature and irradiation conditions. In addition, the Reactor Geometry Generator tool-kit, developed at Argonne National Laboratory, is used to generate finite-element mesh for complex geometries such as fuel bricks with multiple pin holes and coolant flow channels. This paper presents the proposed concept and discusses results of stress analysis simulations of a fuel block with H-451 grade material properties. (authors)
NASA Astrophysics Data System (ADS)
Muraleedharan, B. V.; Kathirvel, K.; Narasimhan, B.; Nallasamy, N. D.
2014-12-01
Soil Water Assessment Tool (SWAT) is a basin scale, distributed hydrological model commonly used to predict the effect of management decisions on the hydrologic response of watersheds. Hydrologic response is decided by the various components of water balance. In the case of watersheds located in south India as well as in several other tropical countries around the world, paddy is one of the dominant crop controlling the hydrologic response of a watershed. Hence, the suitability of SWAT in replicating the hydrology of paddy fields needs to be verified. Rice paddy fields are subjected to flooding method of irrigation, while the irrigation subroutines in SWAT are developed to simulate crops grown under non flooding conditions. Moreover irrigation is represented well in field scale models, while it is poorly represented within watershed models like SWAT. Reliable simulation of flooding method of irrigation and hydrology of the fields will assist in effective water resources management of rice paddy fields which are one of the major consumers of surface and ground water resources. The current study attempts to modify the irrigation subroutine in SWAT so as to simulate flooded irrigation condition. A field water balance study was conducted on representative fields located within Gadana, a subbasin located in Tamil Nadu (southern part of India) and dominated by rice paddy based irrigation systems. The water balance of irrigated paddy fields simulated with SWAT was compared with the water balance derived by rice paddy based crop growth model named ORYZA. The variation in water levels along with the soil moisture variation predicted by SWAT was evaluated with respect to the estimates derived from ORYZA. The water levels were further validated with field based water balance measurements taken on a daily scale. It was observed that the modified irrigation subroutine was able to simulate irrigation of rice paddy within SWAT in a realistic way compared to the existing method.
Parametric analysis and temperature effect of deployable hinged shells using shape memory polymers
NASA Astrophysics Data System (ADS)
Tao, Ran; Yang, Qing-Sheng; He, Xiao-Qiao; Liew, Kim-Meow
2016-11-01
Shape memory polymers (SMPs) are a class of intelligent materials, which are defined by their capacity to store a temporary shape and recover an original shape. In this work, the shape memory effect of SMP deployable hinged shell is simulated by using compiled user defined material subroutine (UMAT) subroutine of ABAQUS. Variations of bending moment and strain energy of the hinged shells with different temperatures and structural parameters in the loading process are given. The effects of the parameters and temperature on the nonlinear deformation process are emphasized. The entire thermodynamic cycle of SMP deployable hinged shell includes loading at high temperature, load carrying with cooling, unloading at low temperature and recovering the original shape with heating. The results show that the complicated thermo-mechanical deformation and shape memory effect of SMP deployable hinge are influenced by the structural parameters and temperature. The design ability of SMP smart hinged structures in practical application is prospected.
NASA Technical Reports Server (NTRS)
Blakely, R. L.
1973-01-01
A G189A simulation of the shuttle orbiter EC/lSS was prepared and used to study payload support capabilities. Two master program libraries of the G189A computer program were prepared for the NASA/JSC computer system. Several new component subroutines were added to the G189A program library and many existing subroutines were revised to improve their capabilities. A number of special analyses were performed in support of a NASA/JSC shuttle orbiter EC/LSS payload support capability study.
LAMPAT and LAMPATNL User’s Manual
2012-09-01
12 iv 6. LAMPATNL ( VUMAT ) 12 6.1 Material Definition...linear) or LAMPATNL (nonlinear). The answer to the second question leads the user either to UVARM/UMAT (static) or VUSDFLD/ VUMAT (dynamic...LAMPATNL Subroutine: UMAT Subroutine: VUMAT A detailed report on LAMPAT, including theoretical background and example cases, are provided by
Sobrinho, L G; Almeida-Costa, J M
1992-01-01
Pathological hyperprolactinaemia (PH) is significantly associated with: (1) paternal deprivation during childhood, (2) depression, (3) non-specific symptoms including obesity and weight gain. The clinical onset of the symptoms often follows pregnancy or a loss. Prolactin is an insulin antagonist which does not promote weight gain. Hyperprolactinaemia and increased metabolic efficiency are parts of a system of interdependent behavioural and metabolic mechanisms necessary for the care of the young. We call this system, which is available as a whole package, maternal subroutine (MS). An important number of cases of PH are due to activation of the MS that is not induced by pregnancy. The same occurs in surrogate maternity and in some animal models. Most women with PH developed a malignant symbiotic relationship with their mothers in the setting of absence, alcoholism or devaluation of the father. These women may regress to early developmental stages to the point that they identify themselves both with their lactating mother and with the nursing infant as has been found in psychoanalysed patients and in the paradigmatic condition of pseudopregnancy. Such regression can be associated with activation of the MS. Prolactinomas represent the extreme of the spectrum of PH and may result from somatic mutations occurring in hyperstimulated lactotrophs.
Finite element based damage assessment of composite tidal turbine blades
NASA Astrophysics Data System (ADS)
Fagan, Edward M.; Leen, Sean B.; Kennedy, Ciaran R.; Goggins, Jamie
2015-07-01
With significant interest growing in the ocean renewables sector, horizontal axis tidal current turbines are in a position to dominate the marketplace. The test devices that have been placed in operation so far have suffered from premature failures, caused by difficulties with structural strength prediction. The goal of this work is to develop methods of predicting the damage level in tidal turbines under their maximum operating tidal velocity. The analysis was conducted using the finite element software package Abaqus; shell models of three representative tidal turbine blades are produced. Different construction methods will affect the damage level in the blade and for this study models were developed with varying hydrofoil profiles. In order to determine the risk of failure, a user material subroutine (UMAT) was created. The UMAT uses the failure criteria designed by Alfred Puck to calculate the risk of fibre and inter-fibre failure in the blades. The results show that degradation of the stiffness is predicted for the operating conditions, having an effect on the overall tip deflection. The failure criteria applied via the UMAT form a useful tool for analysis of high risk regions within the blade designs investigated.
Failure Analysis of a Sheet Metal Blanking Process Based on Damage Coupling Model
NASA Astrophysics Data System (ADS)
Wen, Y.; Chen, Z. H.; Zang, Y.
2013-11-01
In this paper, a blanking process of sheet metal is studied by the methods of numerical simulation and experimental observation. The effects of varying technological parameters related to the quality of products are investigated. An elastoplastic constitutive equation accounting for isotropic ductile damage is implemented into the finite element code ABAQUS with a user-defined material subroutine UMAT. The simulations of the damage evolution and ductile fracture in a sheet metal blanking process have been carried out by the FEM. In order to guarantee computation accuracy and avoid numerical divergence during large plastic deformation, a specified remeshing technique is successively applied when severe element distortion occurs. In the simulation, the evolutions of damage at different stage of the blanking process have been evaluated and the distributions of damage obtained from simulation are in proper agreement with the experimental results.
Damage Simulation in Non-Crimp Fabric Composite Plates Subjected to Impact Loads
NASA Technical Reports Server (NTRS)
Satyanarayana, Arunkumar; Bogert, Philip B.; Aitharaju, Venkat; Aashat, Satvir; Kia, Hamid
2014-01-01
Progressive failure analysis (PFA) of non-crimp fabric (NCF) composite laminates subjected to low velocity impact loads was performed using the COmplete STress Reduction (COSTR) damage model implemented through VUMAT and UMAT41 user subroutines in the frame works of the commercial finite element programs ABAQUS/Explicit and LS-DYNA, respectively. To validate the model, low velocity experiments were conducted and detailed correlations between the predictions and measurements for both intra-laminar and inter-laminar failures were made. The developed material and damage model predicts the peak impact load and duration very close with the experimental results. Also, the simulation results of delamination damage between the ply interfaces, in-plane matrix damages and fiber damages were all in good agreement with the measurements from the non-destructive evaluation data.
Shape memory polymers: three-dimensional isotropic modeling
NASA Astrophysics Data System (ADS)
Balogun, Olaniyi; Mo, Changki
2014-04-01
This paper presents a comprehensive three-dimensional isotropic numerical simulation for a thermo-mechanical constitutive model of shape memory polymers (SMPs). In order to predict the thermo-mechanical behavior of SMPs, a one-dimensional rheological thermo-mechanical constitutive model is adopted, translated into a three-dimensional form and a time discrete form of the three-dimensional model is then presented. Numerical simulation of this model was developed using the UMAT subroutine capabilities of the finite element software ABAQUS. Evolution of the analysis was conducted by making use of the backward difference scheme, which was applied to all quantities within the model, including the material properties. A comparison of the numerical simulation results was carried out with the available experimental data. Numerical simulation results clearly exhibit the thermo-mechanical properties of the material which include shape fixity, shape recovery, and recovery stress. Finally, a prediction for the transverse and shear directions of the material is presented.
Micromechanical modeling of rate-dependent behavior of Connective tissues.
Fallah, A; Ahmadian, M T; Firozbakhsh, K; Aghdam, M M
2017-03-07
In this paper, a constitutive and micromechanical model for prediction of rate-dependent behavior of connective tissues (CTs) is presented. Connective tissues are considered as nonlinear viscoelastic material. The rate-dependent behavior of CTs is incorporated into model using the well-known quasi-linear viscoelasticity (QLV) theory. A planar wavy representative volume element (RVE) is considered based on the tissue microstructure histological evidences. The presented model parameters are identified based on the available experiments in the literature. The presented constitutive model introduced to ABAQUS by means of UMAT subroutine. Results show that, monotonic uniaxial test predictions of the presented model at different strain rates for rat tail tendon (RTT) and human patellar tendon (HPT) are in good agreement with experimental data. Results of incremental stress-relaxation test are also presented to investigate both instantaneous and viscoelastic behavior of connective tissues.
Development and parameter identification of a visco-hyperelastic model for the periodontal ligament.
Huang, Huixiang; Tang, Wencheng; Tan, Qiyan; Yan, Bin
2017-01-31
The present study developed and implemented a new visco-hyperelastic model that is capable of predicting the time-dependent biomechanical behavior of the periodontal ligament. The constitutive model has been implemented into the finite element package ABAQUS by means of a user-defined material subroutine (UMAT). The stress response is decomposed into two constitutive parts in parallel which are a hyperelastic and a time-dependent viscoelastic stress response. In order to identify the model parameters, the indentation equation based on V-W hyperelastic model and the indentation creep model are developed. Then the parameters are determined by fitting them to the corresponding nanoindentation experimental data of the PDL. The nanoindentation experiment was simulated by finite element analysis to validate the visco-hyperelastic model. The simulated results are in good agreement with the experimental data, which demonstrates that the visco-hyperelastic model developed is able to accurately predict the time-dependent mechanical behavior of the PDL.
Crack density and electrical resistance in indium-tin-oxide/polymer thin films under cyclic loading
NASA Astrophysics Data System (ADS)
Mora, Angel; Khan, Kamran A.; El Sayed, Tamer
2014-11-01
Here, we propose a damage model that describes the degradation of the material properties of indium-tin-oxide (ITO) thin films deposited on polymer substrates under cyclic loading. We base this model on our earlier tensile test model and show that the new model is suitable for cyclic loading. After calibration with experimental data, we are able to capture the stress-strain behavior and changes in electrical resistance of ITO thin films. We are also able to predict the crack density using calibrations from our previous model. Finally, we demonstrate the capabilities of our model based on simulations using material properties reported in the literature. Our model is implemented in the commercially available finite element software ABAQUS using a user subroutine UMAT. [Figure not available: see fulltext.
NASA Astrophysics Data System (ADS)
Jin, BoCheng
2011-12-01
Organic and inorganic fiber reinforced composites with innumerable fiber orientation distributions and fiber geometries are abundantly available in several natural and synthetic structures. Inorganic glass fiber composites have been introduced to numerous applications due to their economical fabrication and tailored structural properties. Numerical characterization of such composite material systems is necessitated due to their intrinsic statistical nature, which renders extensive experimentation prohibitively time consuming and costly. To predict various mechanical behavior and characterizations of Uni-Directional Fiber Composites (UDFC) and Random Fiber Composites (RaFC), we numerically developed Representative Volume Elements (RVE) with high accuracy and efficiency and with complex fiber geometric representations encountered in uni-directional and random fiber networks. In this thesis, the numerical simulations of unidirectional RaFC fiber strand RVE models (VF>70%) are first presented by programming in ABAQUS PYTHON. Secondly, when the cross sectional aspect ratios (AR) of the second phase fiber inclusions are not necessarily one, various types of RVE models with different cross sectional shape fibers are simulated and discussed. A modified random sequential absorption algorithm is applied to enhance the volume fraction number (VF) of the RVE, which the mechanical properties represents the composite material. Thirdly, based on a Spatial Segment Shortest Distance (SSSD) algorithm, a 3-Dimentional RaFC material RVE model is simulated in ABAQUS PYTHON with randomly oriented and distributed straight fibers of high fiber aspect ratio (AR=100:1) and volume fraction (VF=31.8%). Fourthly, the piecewise multi-segments fiber geometry is obtained in MATLAB environment by a modified SSSD algorithm. Finally, numerical methods including the polynomial curve fitting and piecewise quadratic and cubic B-spline interpolation are applied to optimize the RaFC fiber geometries
User-Defined Material Model for Progressive Failure Analysis
NASA Technical Reports Server (NTRS)
Knight, Norman F. Jr.; Reeder, James R. (Technical Monitor)
2006-01-01
An overview of different types of composite material system architectures and a brief review of progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model (or UMAT) for use with the ABAQUS/Standard1 nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details and use of the UMAT subroutine are described in the present paper. Parametric studies for composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented.
An Implicit Algorithm for the Numerical Simulation of Shape-Memory Alloys
Becker, R; Stolken, J; Jannetti, C; Bassani, J
2003-10-16
Shape-memory alloys (SMA) have the potential to be used in a variety of interesting applications due to their unique properties of pseudoelasticity and the shape-memory effect. However, in order to design SMA devices efficiently, a physics-based constitutive model is required to accurately simulate the behavior of shape-memory alloys. The scope of this work is to extend the numerical capabilities of the SMA constitutive model developed by Jannetti et. al. (2003), to handle large-scale polycrystalline simulations. The constitutive model is implemented within the finite-element software ABAQUS/Standard using a user defined material subroutine, or UMAT. To improve the efficiency of the numerical simulations, so that polycrystalline specimens of shape-memory alloys can be modeled, a fully implicit algorithm has been implemented to integrate the constitutive equations. Using an implicit integration scheme increases the efficiency of the UMAT over the previously implemented explicit integration method by a factor of more than 100 for single crystal simulations.
NSWC Library of Mathematics Subroutines
1993-01-01
Eckhardt, Ulrich,"Algorithm 549, Weierstrass’ Ellip’ic Functions," ACM Trans. Matk . Software 4 (1980’, pp. 112-i20. (2) ,"A Rational Approximation to...ill-conditioned. lII such situatioMS one 0C inst use a more gen eral equation solver. Ih T()tPIX and I)T()IPI,X 4(11 1)( floating additions and 4n (n 1
PROCESS SIMULATION OF COLD PRESSING OF ARMSTRONG CP-Ti POWDERS
Sabau, Adrian S; Gorti, Sarma B; Peter, William H; Yamamoto, Yukinori
2010-01-01
A computational methodology is presented for the process simulation of cold pressing of Armstrong CP-Ti Powders. The computational model was implemented in the commercial finite element program ABAQUSTM. Since the powder deformation and consolidation is governed by specific pressure-dependent constitutive equations, several solution algorithms were developed for the ABAQUS user material subroutine, UMAT. The solution algorithms were developed for computing the plastic strain increments based on an implicit integration of the nonlinear yield function, flow rule, and hardening equations that describe the evolution of the state variables. Since ABAQUS requires the use of a full Newton-Raphson algorithm for the stress-strain equations, an algorithm for obtaining the tangent/linearization moduli, which is consistent with the return-mapping algorithm, also was developed. Numerical simulation results are presented for the cold compaction of the Ti powders. Several simulations were conducted for cylindrical samples with different aspect ratios. The numerical simulation results showed that for the disk samples, the minimum von Mises stress was approximately half than its maximum value. The hydrostatic stress distribution exhibits a variation smaller than that of the von Mises stress. It was found that for the disk and cylinder samples the minimum hydrostatic stresses were approximately 23 and 50% less than its maximum value, respectively. It was also found that the minimum density was noticeably affected by the sample height.
NASA Astrophysics Data System (ADS)
Shrivastava, Sachin; Mohite, P. M.
2015-01-01
The minimization of weight and maximization of payload is an ever challenging design procedure for air vehicles. The present study has been carried out with an objective to redesign control surface of an advanced all-metallic fighter aircraft. In this study, the structure made up of high strength aluminum, titanium and ferrous alloys has been attempted to replace by carbon fiber composite (CFC) skin, ribs and stiffeners. This study presents an approach towards development of a methodology for optimization of first-ply failure index (FI) in unidirectional fibrous laminates using Genetic-Algorithms (GA) under quasi-static loading. The GAs, by the application of its operators like reproduction, cross-over, mutation and elitist strategy, optimize the ply-orientations in laminates so as to have minimum FI of Tsai-Wu first-ply failure criterion. The GA optimization procedure has been implemented in MATLAB and interfaced with commercial software ABAQUS using python scripting. FI calculations have been carried out in ABAQUS with user material subroutine (UMAT). The GA's application gave reasonably well-optimized ply-orientations combination at a faster convergence rate. However, the final optimized sequence of ply-orientations is obtained by tweaking the sequences given by GA's based on industrial practices and experience, whenever needed. The present study of conversion of an all metallic structure to partial CFC structure has led to 12% of weight reduction. Therefore, the approach proposed here motivates designer to use CFC with a confidence.
Micromechanics and constitutive modeling of connective soft tissues.
Fallah, A; Ahmadian, M T; Firozbakhsh, K; Aghdam, M M
2016-07-01
In this paper, a micromechanical model for connective soft tissues based on the available histological evidences is developed. The proposed model constituents i.e. collagen fibers and ground matrix are considered as hyperelastic materials. The matrix material is assumed to be isotropic Neo-Hookean while the collagen fibers are considered to be transversely isotropic hyperelastic. In order to take into account the effects of tissue structure in lower scales on the macroscopic behavior of tissue, a strain energy density function (SEDF) is developed for collagen fibers based on tissue hierarchical structure. Macroscopic response and properties of tissue are obtained using the numerical homogenization method with the help of ABAQUS software. The periodic boundary conditions and the proposed constitutive models are implemented into ABAQUS using the DISP and the UMAT subroutines, respectively. The existence of the solution and stable material behavior of proposed constitutive model for collagen fibers are investigated based on the poly-convexity condition. Results of the presented micromechanics model for connective tissues are compared and validated with available experimental data. Effects of geometrical and material parameters variation at microscale on macroscopic mechanical behavior of tissues are investigated. The results show that decrease in collagen content of the connective tissues like the tendon due to diseases leads 20% more stretch than healthy tissue under the same load which can results in connective tissue malfunction and hypermobility in joints.
Evaluation of Parameters Affecting Thermal Stresses in Mass Concrete
1991-01-01
ABAQUS , a finite-element program capable of performing complete incremental construction analyses of complex mass concrete structures during and...following construction. ’The report describes a user-defined aging creep material model, UMAT, used with ABAQUS to account for the changes in concrete...model to evolve the onset and effects of cracking. In addition to material aging, ABAQUS includes the (Continued) 14. SUBJECT TERMS 15. NUMBER OF PAGES
Energy Based Multiscale Modeling with Non-Periodic Boundary Conditions
2013-05-13
was implemented numerically utilizing Python scripting to invoke the nested FE solution within the commercial FE software ABAQUS. To reduce initial...between Python and the ABAQUS solver. The left-hand side of Figure 8 highlights the localization process which involves passing of the macroscopic...deformation gradient from the UMAT to the custom Python script which then modifies the boundary conditions to a unit-cell, or RVE, ABAQUS input file
2009-01-01
in the material user subroutine, VUMAT , of the commer- cial finite-element program ABAQUS/Explicit [30]. This subroutine is compiled and linked with...solver and the VUMAT Material User Subroutine at each time incre- ment at each integration point of each element can be summarized as follows. 1. The...variables at the end of the time increment are determined within the VUMAT and returned to the ABAQUS/Explicit finite-element solver. In addition, the
Sham, Sam; Walker, Kevin P.
2008-01-01
The expected service life of the Next Generation Nuclear Plant is 60 years. Structural analyses of the Intermediate Heat Exchanger (IHX) will require the development of unified viscoplastic constitutive models that address the material behavior of Alloy 617, a construction material of choice, over a wide range of strain rates. Many unified constitutive models employ a yield stress state variable which is used to account for cyclic hardening and softening of the material. For low stress values below the yield stress state variable these constitutive models predict that no inelastic deformation takes place which is contrary to experimental results. The ability to model creep deformation at low stresses for the IHX application is very important as the IHX operational stresses are restricted to very small values due to the low creep strengths at elevated temperatures and long design lifetime. This paper presents some preliminary work in modeling the unified viscoplastic constitutive behavior of Alloy 617 which accounts for the long term, low stress, creep behavior and the hysteretic behavior of the material at elevated temperatures. The preliminary model is presented in one-dimensional form for ease of understanding, but the intent of the present work is to produce a three-dimensional model suitable for inclusion in the user subroutines UMAT and USERPL of the ABAQUS and ANSYS nonlinear finite element codes. Further experiments and constitutive modeling efforts are planned to model the material behavior of Alloy 617 in more detail.
NASA Astrophysics Data System (ADS)
Hamim, Salah Uddin Ahmed
Nanoindentation involves probing a hard diamond tip into a material, where the load and the displacement experienced by the tip is recorded continuously. This load-displacement data is a direct function of material's innate stress-strain behavior. Thus, theoretically it is possible to extract mechanical properties of a material through nanoindentation. However, due to various nonlinearities associated with nanoindentation the process of interpreting load-displacement data into material properties is difficult. Although, simple elastic behavior can be characterized easily, a method to characterize complicated material behavior such as nonlinear viscoelasticity is still lacking. In this study, a nanoindentation-based material characterization technique is developed to characterize soft materials exhibiting nonlinear viscoelasticity. Nanoindentation experiment was modeled in finite element analysis software (ABAQUS), where a nonlinear viscoelastic behavior was incorporated using user-defined subroutine (UMAT). The model parameters were calibrated using a process called inverse analysis. In this study, a surrogate model-based approach was used for the inverse analysis. The different factors affecting the surrogate model performance are analyzed in order to optimize the performance with respect to the computational cost.
Hydrostatic Stress Effect on the Yield Behavior of Inconel 100
NASA Technical Reports Server (NTRS)
Allen, Phillip A.; Wilson, Christopher D.
2003-01-01
Classical metal plasticity theory assumes that hydrostatic stress has negligible effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of various geometries. Fatigue tests and nonlinear finite element analyses (FEA) of Inconel 100 (IN100) equal-arm bend specimens and new monotonic tests and nonlinear finite element analyses of IN100 smooth tension, smooth compression, and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions were performed. A new FEA constitutive model was developed that incorporates a pressure-dependent yield function with combined multilinear kinematic and multilinear isotropic hardening using the ABAQUS user subroutine (UMAT) utility. In all monotonic tensile test cases, the von Mises constitutive model, overestimated the load for a given displacement or strain. Considering the failure displacements or strains for the DENT specimen, the Drucker-Prager FEM s predicted loads that were approximately 3% lower than the von Mises values. For the failure loads, the Drucker Prager FEM s predicted strains that were up to 35% greater than the von Mises values. Both the Drucker-Prager model and the von Mises model performed equally-well in simulating the equal-arm bend fatigue test.
Analysis of interfacial debonding in shape memory alloy wire-reinforced composites
NASA Astrophysics Data System (ADS)
Miramini, A.; Kadkhodaei, M.; Alipour, A.; Mashayekhi, M.
2016-01-01
One of the common types of failure in shape memory alloy (SMA) wire-reinforced composites is interfacial debonding between the fiber and the matrix. In this paper, a three dimensional finite element model for an SMA wire-reinforced composite is developed based on cohesive zone modeling to predict interfacial debonding between the SMA wire and the surrounding matrix. The interfacial debonding is also experimentally investigated by conducting a number of pull-out tests on steel as well as Nitinol wires embedded in an epoxy matrix. To evaluate the presented method, the developed finite element analysis is employed to simulate a single wire pull-out test for ordinary (e.g. steel) wires. In order to simulate SMA wire pull-out, a 3D SMA constitutive model is implemented into the commercial finite element software ABAQUS using a user material subroutine (UMAT). An acceptable agreement is shown to exist between the theoretical results and the experimental data, indicating the efficiency of the proposed approach to model interfacial debonding in SMA wire-reinforced composites.
NASA Astrophysics Data System (ADS)
Li, Wangnan; Cai, Hongneng; Li, Chao
2014-11-01
This paper deals with the characterization of the strength of the constituents of carbon fiber reinforced plastic laminate (CFRP), and a prediction of the static compressive strength of open-hole structure of polymer composites. The approach combined with non-linear analysis in macro-level and a linear elastic micromechanical failure analysis in microlevel (non-linear MMF) is proposed to improve the prediction accuracy. A face-centered cubic micromechanics model is constructed to analyze the stresses in fiber and matrix in microlevel. Non-interactive failure criteria are proposed to characterize the strength of fiber and matrix. The non-linear shear behavior of the laminate is studied experimentally, and a novel approach of cubic spline interpolation is used to capture significant non-linear shear behavior of laminate. The user-defined material subroutine UMAT for the non-linear share behavior is developed and combined in the mechanics analysis in the macro-level using the Abaqus Python codes. The failure mechanism and static strength of open-hole compressive (OHC) structure of polymer composites is studied based on non-linear MMF. The UTS50/E51 CFRP is used to demonstrate the application of theory of non-linear MMF.
K.R. Rajagopal; I.J. Rao
2006-05-05
The demand for increased efficiency of gas turbines used in power generation and aircraft applications has fueled research into advanced materials for gas turbine blades that can withstand higher temperatures in that they have excellent resistance to creep. The term ''Superalloys'' describes a group of alloys developed for applications that require high performance at elevated temperatures. Superalloys have a load bearing capacity up to 0.9 times their melting temperature. The objective of the investigation was to develop a thermodynamic model that can be used to describe the response of single crystal superalloys that takes into account the microstructure of the alloy within the context of a continuum model. Having developed the model, its efficacy was to be tested by corroborating the predictions of the model with available experimental data. Such a model was developed and it is implemented in the finite element software ABAQUS/STANDARD through a user subroutine (UMAT) so that the model can be used in realistic geometries that correspond to turbine blades.
Li, Kai; Xin, Haitao; Zhao, Yanfang; Zhang, Zhiyuan; Wu, Yulu
2016-05-01
The objective of this study was to investigate the process of mandibular bone remodeling induced by implant-supported overdentures. computed tomography (CT) images were collected from edentulous patients to reconstruct the geometry of the mandibular bone and overdentures supported by implants. Based on the theory of strain energy density (SED), bone remodeling models were established using the user material subroutine (UMAT) in abaqus. The stress distribution in the mandible and bone density change was investigated to determine the effect of implant number on the remodeling of the mandibular bone. The results indicated that the areas where high Mises stress values were observed were mainly situated around the implants. The stress was concentrated in the distal neck region of the distal-most implants. With an increased number of implants, the biting force applied on the dentures was almost all taken up by implants. The stress and bone density in peri-implant bone increased. When the stress reached the threshold of remodeling, the bone density began to decrease. In the posterior mandible area, the stress was well distributed but increased with decreased implant numbers. Changes in bone density were not observed in this area. The computational results were consistent with the clinical data. The results demonstrate that the risk of bone resorption around the distal-most implants increases with increased numbers of implants and that the occlusal force applied to overdentures should be adjusted to be distributed more in the distal areas of the mandible.
Characteristics of Creep Damage for 60Sn-40Pb Solder Material
Wei, Y.; Chow, C.L.; Fang, H.E.; Neilsen, M.K.
1999-08-26
This paper presents a viscoplasticity model taking into account the effects of change in grain or phase size and damage on the characterization of creep damage in 60Sn-40Pb solder. Based on the theory of damage mechanics, a two-scalar damage model is developed for isotropic materials by introducing the free energy equivalence principle. The damage evolution equations are derived in terms of the damage energy release rates. In addition, a failure criterion is developed based on the postulation that a material element is said to have ruptured when the total damage accumulated in the element reaches a critical value. The damage coupled viscoplasticity model is discretized and coded in a general-purpose finite element program known as ABAQUS through its user-defined material subroutine UMAT. To illustrate the application of the model, several example cases are introduced to analyze, both numerically and experimentally, the tensile creep behaviors of the material at three stress levels. The model is then applied to predict the deformation of a notched specimen under monotonic tension at room temperature (22 C). The results demonstrate that the proposed model can successfully predict the viscoplastic behavior of the solder material.
Nonlinear, finite deformation, finite element analysis
NASA Astrophysics Data System (ADS)
Nguyen, Nhung; Waas, Anthony M.
2016-06-01
The roles of the consistent Jacobian matrix and the material tangent moduli, which are used in nonlinear incremental finite deformation mechanics problems solved using the finite element method, are emphasized in this paper, and demonstrated using the commercial software ABAQUS standard. In doing so, the necessity for correctly employing user material subroutines to solve nonlinear problems involving large deformation and/or large rotation is clarified. Starting with the rate form of the principle of virtual work, the derivations of the material tangent moduli, the consistent Jacobian matrix, the stress/strain measures, and the objective stress rates are discussed and clarified. The difference between the consistent Jacobian matrix (which, in the ABAQUS UMAT user material subroutine is referred to as DDSDDE) and the material tangent moduli ( C e ) needed for the stress update is pointed out and emphasized in this paper. While the former is derived based on the Jaumann rate of the Kirchhoff stress, the latter is derived using the Jaumann rate of the Cauchy stress. Understanding the difference between these two objective stress rates is crucial for correctly implementing a constitutive model, especially a rate form constitutive relation, and for ensuring fast convergence. Specifically, the implementation requires the stresses to be updated correctly. For this, the strains must be computed directly from the deformation gradient and corresponding strain measure (for a total form model). Alternatively, the material tangent moduli derived from the corresponding Jaumann rate of the Cauchy stress of the constitutive relation (for a rate form model) should be used. Given that this requirement is satisfied, the consistent Jacobian matrix only influences the rate of convergence. Its derivation should be based on the Jaumann rate of the Kirchhoff stress to ensure fast convergence; however, the use of a different objective stress rate may also be possible. The error associated
Micromechanics and constitutive models for soft active materials with phase evolution
NASA Astrophysics Data System (ADS)
Wang, Binglian
Soft active materials, such as shape memory polymers, liquid crystal elastomers, soft tissues, gels etc., are materials that can deform largely in response to external stimuli. Micromechanics analysis of heterogeneous materials based on finite element method is a typically numerical way to study the thermal-mechanical behaviors of soft active materials with phase evolution. While the constitutive models that can precisely describe the stress and strain fields of materials in the process of phase evolution can not be found in the databases of some commercial finite element analysis (FEA) tools such as ANSYS or Abaqus, even the specific constitutive behavior for each individual phase either the new formed one or the original one has already been well-known. So developing a computationally efficient and general three dimensional (3D) thermal-mechanical constitutive model for soft active materials with phase evolution which can be implemented into FEA is eagerly demanded. This paper first solved this problem theoretically by recording the deformation history of each individual phase in the phase evolution process, and adopted the idea of effectiveness by regarding all the new formed phase as an effective phase with an effective deformation to make this theory computationally efficient. A user material subroutine (UMAT) code based on this theoretical constitutive model has been finished in this work which can be added into the material database in Abaqus or ANSYS and can be easily used for most soft active materials with phase evolution. Model validation also has been done through comparison between micromechanical FEA and experiments on a particular composite material, shape memory elastomeric composite (SMEC) which consisted of an elastomeric matrix and the crystallizable fibre. Results show that the micromechanics and the constitutive models developed in this paper for soft active materials with phase evolution are completely relied on.
NASA Technical Reports Server (NTRS)
Pineda, Evan, J.; Bednarcyk, Brett, A.; Arnold, Steven, M.
2012-01-01
A mesh objective crack band model is implemented in the generalized method of cells (GMC) micromechanics model to predict failure of a composite repeating unit cell (RUC). The micromechanics calculations are achieved using the MAC/GMC core engine within the ImMAC suite of micromechanics codes, developed at the NASA Glenn Research Center. The microscale RUC is linked to a macroscale Abaqus/Standard finite element model using the FEAMAC multiscale framework (included in the ImMAC suite). The effects of the relationship between the characteristic length of the finite element and the size of the microscale RUC on the total energy dissipation of the multiscale model are investigated. A simple 2-D composite square subjected to uniaxial tension is used to demonstrate the effects of scaling the dimensions of the RUC such that the length of the sides of the RUC are equal to the characteristic length of the finite element. These results are compared to simulations where the size of the RUC is fixed, independent of the element size. Simulations are carried out for a variety of mesh densities and element shapes, including square and triangular. Results indicate that a consistent size and shape must be used to yield preserve energy dissipation across the scales.
Process Simulation of Cold Pressing and Sintering of Armstrong CP-Ti Powders
Gorti, Sarma B; Sabau, Adrian S; Peter, William H; Nunn, Stephen D; Yamamoto, Yukinori; Chen, Wei
2011-01-01
A computational methodology is presented for the process simulation of cold pressing and sintering of Armstrong CP-Ti powders. Since the powder consolidation is governed by specific pressure-dependent constitutive equations, solution algorithms were developed for the ABAQUS user material subroutine, UMAT, for computing the plastic strain increments based on an implicit integration of the nonlinear yield function, flow rule, and hardening equations. Sintering was simulated using a model based on diffusional creep using the user subroutine CREEP. The initial mesh, stress, and density for the simulation of sintering were obtained from the results of the cold pressing simulation, minimizing the errors from decoupling the cold pressing and sintering simulations. Numerical simulation results are presented for the cold compaction followed by a sintering step of the Ti powders. The numerical simulation results for the relative density were compared to those measured from experiments before and after sintering, showing that the relative density can be accurately predicted. Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. ACKNOWLEDGEMENTS This research was sponsored by the U.S. DOE, and carried out at ORNL, under Contract DE-AC05-00OR22725 with UT-Battelle, LLC. This research was sponsored by the U.S. DOE, EERE Industrial Technology Program Office under CPS Agreement # 17881.
Enhanced Schapery Theory Software Development for Modeling Failure of Fiber-Reinforced Laminates
NASA Technical Reports Server (NTRS)
Pineda, Evan J.; Waas, Anthony M.
2013-01-01
Progressive damage and failure analysis (PDFA) tools are needed to predict the nonlinear response of advanced fiber-reinforced composite structures. Predictive tools should incorporate the underlying physics of the damage and failure mechanisms observed in the composite, and should utilize as few input parameters as possible. The purpose of the Enhanced Schapery Theory (EST) was to create a PDFA tool that operates in conjunction with a commercially available finite element (FE) code (Abaqus). The tool captures the physics of the damage and failure mechanisms that result in the nonlinear behavior of the material, and the failure methodology employed yields numerical results that are relatively insensitive to changes in the FE mesh. The EST code is written in Fortran and compiled into a static library that is linked to Abaqus. A Fortran Abaqus UMAT material subroutine is used to facilitate the communication between Abaqus and EST. A clear distinction between damage and failure is imposed. Damage mechanisms result in pre-peak nonlinearity in the stress strain curve. Four internal state variables (ISVs) are utilized to control the damage and failure degradation. All damage is said to result from matrix microdamage, and a single ISV marks the micro-damage evolution as it is used to degrade the transverse and shear moduli of the lamina using a set of experimentally obtainable matrix microdamage functions. Three separate failure ISVs are used to incorporate failure due to fiber breakage, mode I matrix cracking, and mode II matrix cracking. Failure initiation is determined using a failure criterion, and the evolution of these ISVs is controlled by a set of traction-separation laws. The traction separation laws are postulated such that the area under the curves is equal to the fracture toughness of the material associated with the corresponding failure mechanism. A characteristic finite element length is used to transform the traction-separation laws into stress-strain laws
3-D Nonlinear Constitutive Modeling Approach for Composite Materials
1992-05-01
material nonlinearities, damage , and interfacial debonding [1]. These nonlinearities must be considered for accurate prediction of strength or stability...the overall nonlinear behavior covers plasticity and damage effects, both of which could have significant impact on structural analysis results...through a user-written material ( UMAT ) subroutine. D Micromechanical Analyse Micromechanical methods and selective experimentation are used to develop an
Chambers, Robert S.; Adolf, Douglas B.
2005-03-07
Sandia NLVEabq is a FORTRAN subroutine that defines a user supplied material model for the ABAQUS commercial finite element code. It must be compiled and linked with the ABAQUS libraries under the user supplied subroutine option of the ABAQUS executable script. The subroutine is an implementation of Sandia National Laboratories nonlinear viscoelastic material model that is used to analyze the thermomechanicat behavior of polymers. It is thermodynamically consistent, incorporates finite strains and is applicable to isotropic materials. The model is capable of predicting such diverse phenomena as stress relaxation, yielding, physical aging, thermal straining and enthalpy relaxation under arbitrary thermal and mechanical loading histories. This subroutine enables the ABAQUS finite element code to be sued for analyzing the performance of samples and structures that are made from polymers,
Chambers, Robert S.; Neidigk, Matthew A.
2016-02-02
Sandia SPECabq is FORTRAN code that defines the user supplied subroutines needed to perform nonlinear viscoelastic analyses in the ABAQUS commercial finite element code based on the Simplified Potential Energy Clock (SPEC) Model. The SPEC model was published in the open literature in 2009. It must be compiled and linked with the ABAQUS libraries under the user supplied subroutine option of the ABAQUS executable script. The subroutine is used to analyze the thermomechanical behavior of isotropic polymers predicting things like how a polymer may undergo stress or volume relaxation under different temperature and loading environments. This subroutine enables the ABAQUS finite element code to be used for analyzing the thermo-mechanical behavior of samples and parts that are made from glassy polymers.
2012-01-01
enhanced material model was coded using the Intel Fortran computational language and implemented as a VUMAT Material User Subroutine within the commercial...ABAQUS/Explicit finite- element solver with the VUMAT Material User Subroutine at each time increment at each integration point of each element can be...current time-step incremental strains are passed to the VUMAT by the ABAQUS/Explicit finite-element solver. Spe- cifically, the glass material model
2010-02-01
analyses, the model is next implemented in the material user subroutine, VUMAT , of the commercial finite element program ABAQUS/Explicit (Ref 24). This...compromise between computational efficiency and accuracy. The coupling algorithm between the ABAQUS/Explicit finite element solver and the VUMAT Material...material state variables at the end of the time increment are determined within the VUMAT and returned to the ABAQUS/Explicit finite element solver. In
Shear degradation in fiber reinforced laminates due to matrix damage
NASA Astrophysics Data System (ADS)
Salavatian, Mohammedmahdi
relation between matrix damage variables do not sufficiently describe shear response. Therefore, a modified damage model for matrix failure was developed and implemented in ABAQUS using a UMAT subroutine.
NASA Astrophysics Data System (ADS)
Karimi, Mohammad M.; Tabatabaee, Nader; Jahanbakhsh, H.; Jahangiri, Behnam
2016-11-01
Asphalt binder is responsible for the thermo-viscoelastic mechanical behavior of asphalt concrete. Upon application of pure compressive stress to an asphalt concrete specimen, the stress is transferred by mechanisms such as aggregate interlock and the adhesion/cohesion properties of asphalt mastic. In the pure tensile stress mode, aggregate interlock plays a limited role in stress transfer, and the mastic phase plays the dominant role through its adhesive/cohesive and viscoelastic properties. Under actual combined loading patterns, any coordinate direction may experience different stress modes; therefore, the mechanical behavior is not the same in the different directions and the asphalt specimen behaves as an anisotropic material. The present study developed an anisotropic nonlinear viscoelastic constitutive relationship that is sensitive to the tension/compression stress mode by extending Schapery's nonlinear viscoelastic model. The proposed constitutive relationship was implemented in Abaqus using a user material (UMAT) subroutine in an implicit scheme. Uniaxial compression and indirect tension (IDT) testing were used to characterize the viscoelastic properties of the bituminous materials and to calibrate and validate the proposed constitutive relationship. Compressive and tensile creep compliances were calculated using uniaxial compression, as well as IDT test results, for different creep-recovery loading patterns at intermediate temperature. The results showed that both tensile creep compliance and its rate were greater than those of compression. The calculated deflections based on these IDT test simulations were compared with experimental measurements and were deemed acceptable. This suggests that the proposed viscoelastic constitutive relationship correctly demonstrates the viscoelastic response and is more accurate for analysis of asphalt concrete in the laboratory or in situ.
Green-Naghdi rate of the Kirchhoff stress and deformation rate: the elasticity tensor
NASA Astrophysics Data System (ADS)
Bellini, Chiara; Federico, Salvatore
2015-06-01
The elasticity tensor providing the power-conjugation of the Green-Naghdi rate of the Kirchhoff stress and the deformation rate is required, e.g. by the commercially available Finite Element package ABAQUS/Standard for the material user subroutine UMAT, used to input material behaviours other than those included in the libraries of the package. This elasticity tensor had been studied in the literature, but its symmetries have only been briefly discussed, and only its component form in Cartesian coordinates was known. In this work, we derived a covariant, component-free expression of this elasticity tensor and thoroughly studied its symmetries. We found that, although symmetry on both pair of feet (indices) has been deemed to be desirable in the literature, the expression of the tensor available to-date in fact possesses only symmetry on the first pair of feet (indices), whereas the second pair lacks symmetry, and therefore carries a skew-symmetric contribution. This contribution is unnecessary, as it is automatically filtered in the contraction of the elasticity tensor with the symmetric deformation rate tensor. In order to avoid carrying this unnecessary skew-symmetric contribution in the computations, we employ a tensor identity that naturally symmetrises the second pair of feet of the elasticity tensor. We demonstrated the validity and robustness of the implementation of the user-defined material based on this tensor representation by simulating a benchmark problem consisting in biaxial tests of porcine and human atrial tissue, with material properties taken from previously performed experiments. We compared the results obtained by means of our user-defined material and those obtained through an equivalent built-in material, and obtained identical results.
NASA Astrophysics Data System (ADS)
Figiel, Łukasz; Dunne, Fionn P. E.; Buckley, C. Paul
2010-01-01
Layered-silicate nanoparticles offer a cost-effective reinforcement for thermoplastics. Computational modelling has been employed to study large deformations in layered-silicate/poly(ethylene terephthalate) (PET) nanocomposites near the glass transition, as would be experienced during industrial forming processes such as thermoforming or injection stretch blow moulding. Non-linear numerical modelling was applied, to predict the macroscopic large deformation behaviour, with morphology evolution and deformation occurring at the microscopic level, using the representative volume element (RVE) approach. A physically based elasto-viscoplastic constitutive model, describing the behaviour of the PET matrix within the RVE, was numerically implemented into a finite element solver (ABAQUS) using an UMAT subroutine. The implementation was designed to be robust, for accommodating large rotations and stretches of the matrix local to, and between, the nanoparticles. The nanocomposite morphology was reconstructed at the RVE level using a Monte-Carlo-based algorithm that placed straight, high-aspect ratio particles according to the specified orientation and volume fraction, with the assumption of periodicity. Computational experiments using this methodology enabled prediction of the strain-stiffening behaviour of the nanocomposite, observed experimentally, as functions of strain, strain rate, temperature and particle volume fraction. These results revealed the probable origins of the enhanced strain stiffening observed: (a) evolution of the morphology (through particle re-orientation) and (b) early onset of stress-induced pre-crystallization (and hence lock-up of viscous flow), triggered by the presence of particles. The computational model enabled prediction of the effects of process parameters (strain rate, temperature) on evolution of the morphology, and hence on the end-use properties.
Sensitivity of polycrystal [local] plasticity to slip system kinematic hardening laws for Al 7075-T6
Hennessey, Conor; Castelluccio, Gustavo M.; McDowell, David L.
2017-01-22
The prediction of formation and early growth of microstructurally small fatigue cracks requires use of constitutive models that accurately estimate local states of stress, strain, and cyclic plastic strain. However, few research efforts have attempted to systematically consider the sensitivity of overall cyclic stress-strain hysteresis and higher order mean stress relaxation and plastic strain ratcheting responses introduced by the slip system back-stress formulation in crystal plasticity, even for face centered cubic (FCC) crystal systems. This paper explores the performance of two slip system level kinematic hardening models using a finite element crystal plasticity implementation as a User Material Subroutine (UMAT)more » within ABAQUS, with fully implicit numerical integration. The two kinematic hardening formulations aim to reproduce the cyclic deformation of polycrystalline Al 7075-T6 in terms of both macroscopic cyclic stress-strain hysteresis loop shape, as well as ratcheting and mean stress relaxation under strain- or stress-controlled loading with mean strain or stress, respectively. The first formulation is an Armstrong-Frederick type hardening-dynamic recovery law for evolution of the back stress. This approach is capable of reproducing observed deformation under completely reversed uniaxial loading conditions, but overpredicts the rate of cyclic ratcheting and associated mean stress relaxation. The second formulation corresponds to a multiple back stress Ohno-Wang type hardening law with nonlinear dynamic recovery. The adoption of this back stress evolution law greatly improves the capability to model experimental results for polycrystalline specimens subjected to cycling with mean stress or strain. As a result, the relation of such nonlinear dynamic recovery effects are related to slip system interactions with dislocation substructures.« less
Sensitivity of polycrystal plasticity to slip system kinematic hardening laws for Al 7075-T6
Hennessey, Conor; Castelluccio, Gustavo M.; McDowell, David L.
2017-02-01
The prediction of formation and early growth of microstructurally small fatigue cracks requires use of constitutive models that accurately estimate local states of stress, strain, and cyclic plastic strain. However, few research efforts have attempted to systematically consider the sensitivity of overall cyclic stress-strain hysteresis and higher order mean stress relaxation and plastic strain ratcheting responses introduced by the slip system back-stress formulation in crystal plasticity, even for face centered cubic (FCC) crystal systems. This paper explores the performance of two slip system level kinematic hardening models using a finite element crystal plasticity implementation as a User Material Subroutine (UMAT)more » within ABAQUS, with fully implicit numerical integration. The two kinematic hardening formulations aim to reproduce the cyclic deformation of polycrystalline Al 7075-T6 in terms of both macroscopic cyclic stress-strain hysteresis loop shape, as well as ratcheting and mean stress relaxation under strain- or stress-controlled loading with mean strain or stress, respectively. The first formulation is an Armstrong-Frederick type hardening-dynamic recovery law for evolution of the back stress. This approach is capable of reproducing observed deformation under completely reversed uniaxial loading conditions, but overpredicts the rate of cyclic ratcheting and associated mean stress relaxation. The second formulation corresponds to a multiple back stress Ohno-Wang type hardening law with nonlinear dynamic recovery. The adoption of this back stress evolution law greatly improves the capability to model experimental results for polycrystalline specimens subjected to cycling with mean stress or strain. As a result, the relation of such nonlinear dynamic recovery effects are related to slip system interactions with dislocation substructures.« less
A Computer Subroutine for Evaluating Polygamma Functions for Complex Arguments.
1983-07-01
13 s DISTRIBUTION LIST...... . .... ooo *ooo*...... .. *.... . ........ 21 S.T 701o For Di 5- r - :,7 By / Ave ilabilitY Codles - -Avail and/or it...Organization Copies Organization Headquarters 1 State University of New York National Aeronautics and Department of Mathematics Space Administration ATTN: Dr... Moth . Sciences 901 W. Franklin Southwest Research Institute Richmond, VA 23284 ATTN: P. Cox 8500 Culebra Road San Antonio, TX 78228 1 West Virginia
Two subroutines used in processing of arrayed data files
NASA Astrophysics Data System (ADS)
Wu, Guang-Jie
Arrayed data files are commonly used in astronomy. It may be a text file compiled by the software "EDIT" in common use, or a table compiled by Microsoft WORD, Excel, or a FITS format etc. In the database of CDS (Centre de Données astronomiques de Strasbourg), there are over thousands star catalogues. Sometimes you may get a star catalogue from a colleague or friend of you, which may be done by multivarious computer software and may have peculiarity of sorts. Especially, the star catalogue had been compiled several years ago. You may often need to deal with such listed multidimensional data files, and you may need to make new listed data files by yourself. This processing for reduce-dimension or add-dimension, if it was a kind of row treatment, is very easy to do with some famous software like "EDIT". However, maybe you are facing a column treatment. It may bring some trouble to you. In some cases, a character "Tab" may exist in the file. Different software, even different printers made by a certain company, may give dissimilar treatment to the character "Tab". The problem is that a Table-key can denote a single space-key, or can be up to eight space-keys. Sometimes, it may not be easy to find a ready-made program in your hands. If this data file could be opened by the software "EDIT", two programs in this paper can help you to understand what happened there, and help you to solve the problem conveniently and easily. It includes to convert all of the Table-keys to be corresponding space-keys, to pick-up, delete, add blanks, or link two data files as two columns in one file.
Function algorithms for MPP scientific subroutines, volume 1
NASA Technical Reports Server (NTRS)
Gouch, J. G.
1984-01-01
Design documentation and user documentation for function algorithms for the Massively Parallel Processor (MPP) are presented. The contract specifies development of MPP assembler instructions to perform the following functions: natural logarithm; exponential (e to the x power); square root; sine; cosine; and arctangent. To fulfill the requirements of the contract, parallel array and solar implementations for these functions were developed on the PDP11/34 Program Development and Management Unit (PDMU) that is resident at the MPP testbed installation located at the NASA Goddard facility.
CHEMEQ - A Subroutine for Solving Stiff Ordinary Differential Equations
1980-02-26
been coded in Fortran which may be implemented on any digital computer of moderate size. It is intended as a very fast but moderately accurate...location for specific J. L I/L Index DO loop subscript. LO IiA Numerical value for the logica ]. unit for the printed output. 33 Fortran Mathematical
Simulation of a Canard in Fluid Flow Driven by a Piezoelectric Beam with a Software Control Loop
2014-04-01
is unlimited. i CONTENTS Page Introduction 1 Model Description 1 Fluid Model 2 Structural Model 3 Control Subroutine 4 Results 4...canard angle 7 13 Plot comparing canard angles 8 UNCLASSIFIED Approved for public release; distribution is unlimited. 1 INTRODUCTION ...version. 6.11, section 7.1 “Piezoelectric Analysis,” 2011. 2. ABAQUS Introduction of Abaqus/CFD for Multiphysics Applications, version. 6.11
An Experimental and Computational Investigation of Dynamic Ductile Fracture in Stainless Steel Welds
2002-05-01
su- peralloy ......... ................................... 59 3.3 Model parameters for integration of user-material subroutine VUMAT . 84 4.1 Void...post-coalescence flow potential 4+ ........... .......................... 75 3.13 ABAQUS/ VUMAT integration of the material model for 1 C3D8R Finite...Element ........ ............................... 82 3.14 ABAQUS/ VUMAT integration for 1 C3D8R element: Macroscopic flow stress
A Computational Investigation of Impact into Multi-Plies of Plain-Woven Fabric
2008-01-01
transverse shear stiffness moduli which is done within the main finite- element model/analysis input file. Out-of-plane Bending Since within the VUMAT ...Implementation in a User-material Subroutine The meso-scale unit- cell based material model is next implemented in the material user subroutine, VUMAT , of...integration point of each element. The essential features of the coupling between the ABAQUS/Explicit finite-element solver and the VUMAT Material User
Simulating Underbelly Blast Events using Abaqus/Explicit - CEL
2013-01-15
simplified hybrid elastic-plastic material model for geologic materials developed by the U.S. Army – ERDC was implemented as a VUMAT and used to describe...as a VUMAT and used to describe the soil. The simulations agree favorably with the test results and produce higher fidelity solutions than traditional
NASA Astrophysics Data System (ADS)
Arshadi, Amir
Image-based simulation of complex materials is a very important tool for understanding their mechanical behavior and an effective tool for successful design of composite materials. In this thesis an image-based multi-scale finite element approach is developed to predict the mechanical properties of asphalt mixtures. In this approach the "up-scaling" and homogenization of each scale to the next is critically designed to improve accuracy. In addition to this multi-scale efficiency, this study introduces an approach for consideration of particle contacts at each of the scales in which mineral particles exist. One of the most important pavement distresses which seriously affects the pavement performance is fatigue cracking. As this cracking generally takes place in the binder phase of the asphalt mixture, the binder fatigue behavior is assumed to be one of the main factors influencing the overall pavement fatigue performance. It is also known that aggregate gradation, mixture volumetric properties, and filler type and concentration can affect damage initiation and progression in the asphalt mixtures. This study was conducted to develop a tool to characterize the damage properties of the asphalt mixtures at all scales. In the present study the Viscoelastic continuum damage model is implemented into the well-known finite element software ABAQUS via the user material subroutine (UMAT) in order to simulate the state of damage in the binder phase under the repeated uniaxial sinusoidal loading. The inputs are based on the experimentally derived measurements for the binder properties. For the scales of mastic and mortar, the artificially 2-Dimensional images of mastic and mortar scales were generated and used to characterize the properties of those scales. Finally, the 2D scanned images of asphalt mixtures are used to study the asphalt mixture fatigue behavior under loading. In order to validate the proposed model, the experimental test results and the simulation results were
NASA Technical Reports Server (NTRS)
Nemeth, Noel N.; Bednarcyk, Brett A.; Pineda, Evan; Arnold, Steven; Mital, Subodh; Murthy, Pappu; Walton, Owen
2015-01-01
Reported here is a coupling of two NASA developed codes: CARES (Ceramics Analysis and Reliability Evaluation of Structures) with the MACGMC composite material analysis code. The resulting code is called FEAMACCARES and is constructed as an Abaqus finite element analysis UMAT (user defined material). Here we describe the FEAMACCARES code and an example problem (taken from the open literature) of a laminated CMC in off-axis loading is shown. FEAMACCARES performs stochastic-strength-based damage simulation response of a CMC under multiaxial loading using elastic stiffness reduction of the failed elements.
Stochastic-Strength-Based Damage Simulation Tool for Ceramic Matrix Composite
NASA Technical Reports Server (NTRS)
Nemeth, Noel; Bednarcyk, Brett; Pineda, Evan; Arnold, Steven; Mital, Subodh; Murthy, Pappu
2015-01-01
Reported here is a coupling of two NASA developed codes: CARES (Ceramics Analysis and Reliability Evaluation of Structures) with the MAC/GMC (Micromechanics Analysis Code/ Generalized Method of Cells) composite material analysis code. The resulting code is called FEAMAC/CARES and is constructed as an Abaqus finite element analysis UMAT (user defined material). Here we describe the FEAMAC/CARES code and an example problem (taken from the open literature) of a laminated CMC in off-axis loading is shown. FEAMAC/CARES performs stochastic-strength-based damage simulation response of a CMC under multiaxial loading using elastic stiffness reduction of the failed elements.
FEAMAC/CARES Stochastic-Strength-Based Damage Simulation Tool for Ceramic Matrix Composites
NASA Technical Reports Server (NTRS)
Nemeth, Noel; Bednarcyk, Brett; Pineda, Evan; Arnold, Steven; Mital, Subodh; Murthy, Pappu; Bhatt, Ramakrishna
2016-01-01
Reported here is a coupling of two NASA developed codes: CARES (Ceramics Analysis and Reliability Evaluation of Structures) with the MAC/GMC (Micromechanics Analysis Code/ Generalized Method of Cells) composite material analysis code. The resulting code is called FEAMAC/CARES and is constructed as an Abaqus finite element analysis UMAT (user defined material). Here we describe the FEAMAC/CARES code and an example problem (taken from the open literature) of a laminated CMC in off-axis loading is shown. FEAMAC/CARES performs stochastic-strength-based damage simulation response of a CMC under multiaxial loading using elastic stiffness reduction of the failed elements.
NASA Technical Reports Server (NTRS)
Bogert, Philip B.; Satyanarayana, Arunkumar; Chunchu, Prasad B.
2006-01-01
Splitting, ultimate failure load and the damage path in center notched composite specimens subjected to in-plane tension loading are predicted using progressive failure analysis methodology. A 2-D Hashin-Rotem failure criterion is used in determining intra-laminar fiber and matrix failures. This progressive failure methodology has been implemented in the Abaqus/Explicit and Abaqus/Standard finite element codes through user written subroutines "VUMAT" and "USDFLD" respectively. A 2-D finite element model is used for predicting the intra-laminar damages. Analysis results obtained from the Abaqus/Explicit and Abaqus/Standard code show good agreement with experimental results. The importance of modeling delamination in progressive failure analysis methodology is recognized for future studies. The use of an explicit integration dynamics code for simple specimen geometry and static loading establishes a foundation for future analyses where complex loading and nonlinear dynamic interactions of damage and structure will necessitate it.
Verification of design rules for EUROFER under TBM operating conditions
NASA Astrophysics Data System (ADS)
Sunyk, R.; Aktaa, J.
2007-08-01
The aim of the activity presented in this work is, firstly, an evaluation of existing design rules considered for austenitic steels exhibiting cycle-by-cycle hardening, in contrast to the reduced-activation ferritic-martensitic steels (RAFM), which soften under cyclic loading. Secondly, we are aimed in a definition of the range of operating temperatures and loads for the current design of the test blanket module (TBM). Results of cycling tests of the EUROFER 97 have been thereby used to adjust material parameters needed for an ABAQUS-own combined non-linear isotropic-kinematic hardening model. Furthermore, a visco-plastic material model considering material damage and implemented recently as an ABAQUS user material (UMAT) has been also applied for simulations. Some important design rules within the elastic route have been evaluated and their predictions have been compared to results of cyclic simulations using the advanced material models mentioned above.
NASA Technical Reports Server (NTRS)
Nemeth, Noel N.; Bednarcyk, Brett A.; Pineda, Evan J.; Walton, Owen J.; Arnold, Steven M.
2016-01-01
Stochastic-based, discrete-event progressive damage simulations of ceramic-matrix composite and polymer matrix composite material structures have been enabled through the development of a unique multiscale modeling tool. This effort involves coupling three independently developed software programs: (1) the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC), (2) the Ceramics Analysis and Reliability Evaluation of Structures Life Prediction Program (CARES/ Life), and (3) the Abaqus finite element analysis (FEA) program. MAC/GMC contributes multiscale modeling capabilities and micromechanics relations to determine stresses and deformations at the microscale of the composite material repeating unit cell (RUC). CARES/Life contributes statistical multiaxial failure criteria that can be applied to the individual brittle-material constituents of the RUC. Abaqus is used at the global scale to model the overall composite structure. An Abaqus user-defined material (UMAT) interface, referred to here as "FEAMAC/CARES," was developed that enables MAC/GMC and CARES/Life to operate seamlessly with the Abaqus FEA code. For each FEAMAC/CARES simulation trial, the stochastic nature of brittle material strength results in random, discrete damage events, which incrementally progress and lead to ultimate structural failure. This report describes the FEAMAC/CARES methodology and discusses examples that illustrate the performance of the tool. A comprehensive example problem, simulating the progressive damage of laminated ceramic matrix composites under various off-axis loading conditions and including a double notched tensile specimen geometry, is described in a separate report.
Multiple IMU system test plan, volume 4. [subroutines for space shuttle requirements
NASA Technical Reports Server (NTRS)
Landey, M.; Vincent, K. T., Jr.; Whittredge, R. S.
1974-01-01
Operating procedures for this redundant system are described. A test plan is developed with two objectives. First, performance of the hardware and software delivered is demonstrated. Second, applicability of multiple IMU systems to the space shuttle mission is shown through detailed experiments with FDI algorithms and other multiple IMU software: gyrocompassing, calibration, and navigation. Gimbal flip is examined in light of its possible detrimental effects on FDI and navigation. For Vol. 3, see N74-10296.
Calculation of stellar structure. IV. Results using a detailed energy generation subroutine.
NASA Astrophysics Data System (ADS)
Rouse, C. A.
1995-12-01
The results from two solar model calculations using the "energy.for" energy generation and neutrino flux code (Bahcall & Pinsonneault 1992) are presented. The models of the present Sun were generated using the program described in the first three papers of this series and using only the helium abundance profile from the Bahcall & Ulrich (1988) (BU) standard model in the present model structure calculations. One model is a simulation of the BU model and yields a ^37^Cl solar neutrino counting rate of 7.0SNU (compared to 7.9SNU for the BU model) and a ^71^Ga neutrino experiment counting rate between 112 and 137SNU (compared to 132SNU for the BU model). The second model has a postulated small high-Z core (Rouse 1983) and yields a ^37^Cl neutrino experiment counting rate of 2.45SNU that is within one sigma of the Homestake Collaboration observed rate of (2.55+/-0.25)SNU (see Parke 1995). It yields a ^71^Ga neutrino experiment counting rate between 89 and 103SNU that is within one sigma of the GALLEX Collaboration neutrino experiment observed rate of (79+/-12)SNU (see Parke 1995). The theoretical ^8^B solar neutrino flux and the observed Kamiokande ^8^B flux (Hirata et al. 1989) are discussed regarding the puzzle of explaining both the chlorine experiment results and the Kamiokande results. The modification of the energy.for code for use in the current Rouse program is described. Consistency of a high-Z core solar model with theories of star formation from pre-stellar nuclei (Krat 1952; Urey 1956; Huang 1957) is suggested.
An ASCII FORTRAN Subroutine for Computing the Electromagnetic Radiation Scattered by a Sphere.
1981-11-01
4 $. ;CZ o: W7T-0 w &1 0 1 10 z 2 Z:Z X0 _j a -VI ; w 3-W .- I.-. 3 - I U SX tZ u - - _ 3(W I- D4 A+0 ZZ z I 4- I- P-Nw - -C m. P.0W - o zZ W 3 -1...01 -3 11- c sL S lo . :;- "I ’ I .- I 4-A 0" N 2 z, x UjxX- CDP 0 0L l* -3 X3 !", +* &I 6-cc0L IL 1 K Z A - 2,C Cd Liia 9z ou. - K �)4 X " 2O - "A
CODAP: Programmer Notes for the Subroutine Library on the Univac 1108.
ERIC Educational Resources Information Center
Weissmuller, Johnny J.; And Others
The Comprehensive Occupational Data Analysis Programs (CODAP) package is a highly interactive and efficient system of computer routines for analyzing, organizing, and reporting occupational information. Since its inception in 1960, CODAP has grown in tandem with advances in job analysis methodology and is now capable of answering most of the wide…
NASA Technical Reports Server (NTRS)
Mall, G. H.
1983-01-01
Modifications to a multi-degree-of-freedom flexible aircraft take-off and landing analysis (FATOLA) computer program, including a provision for actively controlled landing gears to expand the programs simulation capabilities, are presented. Supplemental instructions for preparation of data and for use of the modified program are included.
1985-08-01
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Simulation of sheet-bulk metal forming processes with simufact.forming using user-subroutines
NASA Astrophysics Data System (ADS)
Beese, Steffen; Beyer, Florian; Blum, Heribert; Isik, Kerim; Kumor, Dustin; Löhnert, Stefan; Rademacher, Andreas; Tekkaya, A. Erman; Willner, Kai; Wriggers, Peter; Zeller, Sebastian
2016-10-01
In this article, we consider the simulation of sheet-bulk metal forming processes, which makes high demands on the underlying models and on the simulation software. We present our approach to incorporate new modelling approaches from various fields in a commercial simulation software, in our case Simufact.forming. Here, we discuss material, damage, and friction models as well as model adaptive techniques.
FORTRAN subroutines for out-of-core solutions of large complex linear systems
NASA Technical Reports Server (NTRS)
Yip, E. L.
1979-01-01
The design and usage of two main subprograms using direct methods to solve large linear complex systems, of the form Ax = b, whose coeffficient matrices are too large to be stored in core are described. The first main subprogram is for systems whose coefficient matrices are of a particular sparse structure, namely, the matrix A can be written in the form B + D, where B is a block-banded system, and D has only a few columns of nonzeros. Key elements of the algorithms used in the subprograms include: the data structure, the strategy for preserving numerical stability, the adaptability of the algorithms for dense systems as well as for block-profile systems.
Non local damage model based on micromorphic formulation
NASA Astrophysics Data System (ADS)
Evangelia, Diamantopoulou; Carl, Labergere; Khemais, Saanouni
2016-10-01
This paper presents an experimental-numerical study based on simple tensile test of a high strength metallic sheet, including the diffuse necking stage, up to the large plastic strain and damage localization. A micromorphic approach including nonlocal damage can overcome the mesh dependency problem. The numerical implementation into ABAQUS/Explicit is made for 2D quadrangular elements thanks to the VUEL user's subroutine. Promising results are obtained which qualitatively are compatible with the experiments.
A Computational Investigation of Nanoelectromechnical Switches
2011-03-12
failure modes. (a) Schematic of switch consisting of a CNT cantilevered over a metal thin film electrode. (b) Equivalent lumped- element circuit for...substrate was used as an electrode as reported devices ubiquitously use metal thin film electrodes3,8,16-18. 5 Two common modes of failure were... finite element model of the device was developed using ABAQUS/Explicit and appropriate user-defined subroutines. This model, which includes consideration
A Meso-Scale Unit-Cell Based Material Model for the Single-Ply Flexible-Fabric Armor
2009-01-01
next implemented in the material user subrou- tine, VUMAT , of the commercial finite element program ABAQUS/ Explicit [24]. This subroutine is compiled... VUMAT Material User Subrou- tine at each time increment at each integration point of each element can be summarized as follows: (a) The corresponding...values of the mate- rial state variables at the end of the time increment are determined within the VUMAT and returned to the ABA- QUS/Explicit finite
NASA Astrophysics Data System (ADS)
Deng, Bin; Shen, ZhiBin; Duan, JingBo; Tang, GuoJin
2014-05-01
This paper studies the damage-viscoelastic behavior of composite solid propellants of solid rocket motors (SRM). Based on viscoelastic theories and strain equivalent hypothesis in damage mechanics, a three-dimensional (3-D) nonlinear viscoelastic constitutive model incorporating with damage is developed. The resulting viscoelastic constitutive equations are numerically discretized by integration algorithm, and a stress-updating method is presented by solving nonlinear equations according to the Newton-Raphson method. A material subroutine of stress-updating is made up and embedded into commercial code of Abaqus. The material subroutine is validated through typical examples. Our results indicate that the finite element results are in good agreement with the analytical ones and have high accuracy, and the suggested method and designed subroutine are efficient and can be further applied to damage-coupling structural analysis of practical SRM grain.
Novel Approach to Conducting Blast Load Analyses Using Abaqus/Explicit-CEL
2010-05-01
ground burst of a cylindrical projectile filled with Comp-B explosive at 6500ft elevation– i.e. not TNT, not spherical, not free air, not uncased...11 reflect off the slanted roof at the rear of the vehicle before impacting the armor panels. As a...the armor panels and brackets were meshed using SC8R 8-node continuum shell elements. The remainder of the brackets and the windows were meshed
Effects of Injected CO2 on Geomechanical Properties Due to Mineralogical Changes
NASA Astrophysics Data System (ADS)
Nguyen, B. N.; Hou, Z.; Bacon, D. H.; Murray, C. J.; White, J. A.
2013-12-01
Long-term injection and storage of CO2 in deep underground reservoirs may significantly modify the geomechanical behavior of rocks since CO2 can react with the constituent phases of reservoir rocks and modify their composition. This can lead to modifications of their geomechanical properties (i.e., elastic moduli, Biot's coefficients, and permeability). Modifications of rock geomechanical properties have important consequences as these directly control stress and strain distributions, affect conditions for fracture initiation and development and/or fault healing. This paper attempts to elucidate the geochemical effects of CO2 on geomechanical properties of typical reservoir rocks by means of numerical analyses using the STOMP-ABAQUS sequentially coupled simulator that includes the capability to handle geomechanics and the reactive transport of CO2 together with a module (EMTA) to compute the homogenized rock poroelastic properties as a function of composition changes. EMTA, a software module developed at PNNL, implements the standard and advanced Eshelby-Mori-Tanaka approaches to compute the thermoelastic properties of composite materials. In this work, EMTA will be implemented in the coupled STOMP-ABAQUS simulator as a user subroutine of ABAQUS and used to compute local elastic stiffness based on rock composition. Under the STOMP-ABAQUS approach, STOMP models are built to simulate aqueous and CO2 multiphase fluid flows, and relevant chemical reactions of pore fluids with minerals in the reservoirs. The ABAQUS models then read STOMP output data for cell center coordinates, gas pressures, aqueous pressures, temperatures, saturations, constituent volume fractions, as well as permeability and porosity that are affected by chemical reactions. These data are imported into ABAQUS meshes using a mapping procedure developed for the exchange of data between STOMP and ABAQUS. Constitutive models implemented in ABAQUS via user subroutines then compute stiffness, stresses
Coupled Finite Element ? Potts Model Simulations of Grain Growth in Copper Interconnects
Radhakrishnan, Balasubramaniam; Gorti, Sarma B
2009-01-01
The paper addresses grain growth in copper interconnects in the presence of thermal expansion mismatch stresses. The evolution of grain structure and texture in copper in the simultaneous presence of two driving forces, curvature and elastic stored energy difference, is modeled by using a hybrid Potts model simulation approach. The elastic stored energy is calculated by using the commercial finite element code ABAQUS, where the effect of elastic anisotropy on the thermal mismatch stress and strain distribution within a polycrystalline grain structure is modeled through a user material (UMAT) interface. Parametric studies on the effect of trench width and the height of the overburden were carried out. The results show that the grain structure and texture evolution are significantly altered by the presence of elastic strain energy.
Gan, Yixiang; Kamlah, Marc
2008-07-01
In this investigation, a thermo-mechanical model of pebble beds is adopted and developed based on experiments by Dr. Reimann at Forschungszentrum Karlsruhe (FZK). The framework of the present material model is composed of a non-linear elastic law, the Drucker-Prager-Cap theory, and a modified creep law. Furthermore, the volumetric inelastic strain dependent thermal conductivity of beryllium pebble beds is taken into account and full thermo-mechanical coupling is considered. Investigation showed that the Drucker-Prager-Cap model implemented in ABAQUS can not fulfill the requirements of both the prediction of large creep strains and the hardening behaviour caused by creep, which are of importance with respect to the application of pebble beds in fusion blankets. Therefore, UMAT (user defined material's mechanical behaviour) and UMATHT (user defined material's thermal behaviour) routines are used to re-implement the present thermo-mechanical model in ABAQUS. An elastic predictor radial return mapping algorithm is used to solve the non-associated plasticity iteratively, and a proper tangent stiffness matrix is obtained for cost-efficiency in the calculation. An explicit creep mechanism is adopted for the prediction of time-dependent behaviour in order to represent large creep strains in high temperature. Finally, the thermo-mechanical interactions are implemented in a UMATHT routine for the coupled analysis. The oedometric compression tests and creep tests of pebble beds at different temperatures are simulated with the help of the present UMAT and UMATHT routines, and the comparison between the simulation and the experiments is made. (authors)
NASA Astrophysics Data System (ADS)
Salajegheh, Nima; Abedrabbo, Nader; Pourboghrat, Farhang
2005-08-01
An efficient integration algorithm for continuum damage based elastoplastic constitutive equations is implemented in LS-DYNA. The isotropic damage parameter is defined as the ratio of the damaged surface area over the total cross section area of the representative volume element. This parameter is incorporated into the integration algorithm as an internal variable. The developed damage model is then implemented in the FEM code LS-DYNA as user material subroutine (UMAT). Pure stretch experiments of a hemispherical punch are carried out for copper sheets and the results are compared against the predictions of the implemented damage model. Evaluation of damage parameters is carried out and the optimized values that correctly predicted the failure in the sheet are reported. Prediction of failure in the numerical analysis is performed through element deletion using the critical damage value. The set of failure parameters which accurately predict the failure behavior in copper sheets compared to experimental data is reported as well.
BOOK REVIEW: Introduction to Computational Plasticity
NASA Astrophysics Data System (ADS)
Hartley, P.
2006-04-01
Jaumann rate of stress. It is tempting here to suggest that a more complete description should be given together with other measures of strain and stress, of which there are several, but there would be a danger of changing the book from an `introduction' to a more comprehensive text, and examples of such exist already. Chapter four begins the process of developing the plasticity theories into a form suitable for inclusion in the finite-element method. The starting point is Hamilton's principle for equilibrium of a dynamic system. A very brief introduction to the finite-element method is then given, followed by the finite-element equilibrium equations and a description of how they are incorporated into Hamilton's principle. A useful clarification is provided by comparing tensor notation and the form normally used in finite-element expressions, i.e. Voigt notation. The chapter concludes with a brief overview of implicit integration methods, i.e. tangent stiffness, initial tangent stiffness and Newton Raphson. Chapter five deals with the more specialized topic of implicit and explicit integration of von Mises plasticity. One of the techniques described is the radial-return method which ensures that the stresses at the end of an increment of deformation always lie on the expanded yield surface. Although this method guarantees a solution it may not always be the most accurate for large deformation, this is one area where reference to alternative methods would have been a helpful addition. Chapter six continues with further detail of how the plasticity models may be incorporated into finite-element codes, with particular reference to the Abaqus package and the use of user-defined subroutines, introduced via a `UMAT' subroutine. This completes part I of the book. Part II focuses on plasticity models, each chapter dealing with a particular process or material model. For example, chapter seven deals with superplasticity, chapter eight with porous plasticity, chapter nine with
NASA Technical Reports Server (NTRS)
Schneider, Steven J.
2015-01-01
Heat transfer correlations of data on flat plates are used to explore the parameters in the Coolit program used for calculating the quantity of cooling air for controlling turbine blade temperature. Correlations for both convection and film cooling are explored for their relevance to predicting blade temperature as a function of a total cooling flow which is split between external film and internal convection flows. Similar trends to those in Coolit are predicted as a function of the percent of the total cooling flow that is in the film. The exceptions are that no film or 100 percent convection is predicted to not be able to control blade temperature, while leaving less than 25 percent of the cooling flow in the convection path results in nearing a limit on convection cooling as predicted by a thermal effectiveness parameter not presently used in Coolit.
Aspnäs, Mats; Mattila, Kimmo; Osowski, Kristoffer; Westerholm, Jan
2010-06-01
A central task in protein sequence characterization is the use of a sequence database homology search tool to find similar protein sequences in other individuals or species. PSI-BLAST is a widely used module of the BLAST package that calculates a position-specific score matrix from the best matching sequences and performs iterated searches using a method to avoid many similar sequences for the score. For some queries and parameter settings, PSI-BLAST may find many similar high-scoring matches, and therefore up to 80% of the total run time may be spent in this procedure. In this article, we present code optimizations that improve the cache utilization and the overall performance of this procedure. Measurements show that, for queries where the number of similar matches is high, the optimized PSI-BLAST program may be as much as 2.9 times faster than the original program.
An explicit model of expanding cylindrical shells subjected to high explosive detonations
Martineau, R.L.; Prime, M.B.; Anderson, C.A.; Smith, F.W.
1999-04-01
A viscoplastic constitutive model was formulated to model the high strain-rate expansion of thin cylindrical shells subjected to internal explosive detonations. This model provides insight into the development of plastic instabilities, which occur on the surface of the shells prior to failure. The effects of shock heating and damage in the form of microvoid nucleation, growth, and coalescence were incorporated using the Johnson-Cook strength model with the Mie-Grueneisen equation of state and a modified Gurson yield surface. This model was implemented into ABAQUS/Explicit as a user material subroutine. A cylindrical copper shell was modeled using both axisymmetric and plane strain elements. The high explosive material inside of the cylinder was simulated using the high explosive burn model in ABAQUS/Explicit. Two experiments were conducted involving explosive-filled, copper cylinders and good agreement was obtained between the numerical results and experimental data.
Modeling and Simulation of Miniature Piezoelectric Motors
Mahoney, J.F.
1998-06-01
The use of piezo materials is becoming common in both commercial and retail products. Motors designed using piezo materials as actuators are also being utilized where either space or magnetic materials are limited. This paper discusses the use of ABAQUS/Standard and ABAQUS/Explicit toward the development and production of small piezo motors. Analytical techniques are the only methods possible to determine motor design parameters and performance issues prior to prototype production and testing. The use of ABAQUS/Standard to solve baseline Eigenvalue extractions and transient dynamics for stator motion has made it possible to evaluate motor designs much quicker than physical evaluations. The use of the ''VUMAT'' subroutine in ABAQUS/Explicit has been used to create strains driven by the piezo effects, thus allowing for many thousands of cyclic loads to be applied to contacting 3D continuum structures. The use of viscous pressure techniques for near-perfect static loading under explicit dynamics will also be presented and discussed.
Progressive Failure And Life Prediction of Ceramic and Textile Composites
NASA Technical Reports Server (NTRS)
Xue, David Y.; Shi, Yucheng; Katikala, Madhu; Johnston, William M., Jr.; Card, Michael F.
1998-01-01
An engineering approach to predict the fatigue life and progressive failure of multilayered composite and textile laminates is presented. Analytical models which account for matrix cracking, statistical fiber failures and nonlinear stress-strain behavior have been developed for both composites and textiles. The analysis method is based on a combined micromechanics, fracture mechanics and failure statistics analysis. Experimentally derived empirical coefficients are used to account for the interface of fiber and matrix, fiber strength, and fiber-matrix stiffness reductions. Similar approaches were applied to textiles using Repeating Unit Cells. In composite fatigue analysis, Walker's equation is applied for matrix fatigue cracking and Heywood's formulation is used for fiber strength fatigue degradation. The analysis has been compared with experiment with good agreement. Comparisons were made with Graphite-Epoxy, C/SiC and Nicalon/CAS composite materials. For textile materials, comparisons were made with triaxial braided and plain weave materials under biaxial or uniaxial tension. Fatigue predictions were compared with test data obtained from plain weave C/SiC materials tested at AS&M. Computer codes were developed to perform the analysis. Composite Progressive Failure Analysis for Laminates is contained in the code CPFail. Micromechanics Analysis for Textile Composites is contained in the code MicroTex. Both codes were adapted to run as subroutines for the finite element code ABAQUS and CPFail-ABAQUS and MicroTex-ABAQUS. Graphic user interface (GUI) was developed to connect CPFail and MicroTex with ABAQUS.
Advanced finite element analysis of L4-L5 implanted spine segment
NASA Astrophysics Data System (ADS)
Pawlikowski, Marek; Domański, Janusz; Suchocki, Cyprian
2015-09-01
In the paper finite element (FE) analysis of implanted lumbar spine segment is presented. The segment model consists of two lumbar vertebrae L4 and L5 and the prosthesis. The model of the intervertebral disc prosthesis consists of two metallic plates and a polyurethane core. Bone tissue is modelled as a linear viscoelastic material. The prosthesis core is made of a polyurethane nanocomposite. It is modelled as a non-linear viscoelastic material. The constitutive law of the core, derived in one of the previous papers, is implemented into the FE software Abaqus®. It was done by means of the User-supplied procedure UMAT. The metallic plates are elastic. The most important parts of the paper include: description of the prosthesis geometrical and numerical modelling, mathematical derivation of stiffness tensor and Kirchhoff stress and implementation of the constitutive model of the polyurethane core into Abaqus® software. Two load cases were considered, i.e. compression and stress relaxation under constant displacement. The goal of the paper is to numerically validate the constitutive law, which was previously formulated, and to perform advanced FE analyses of the implanted L4-L5 spine segment in which non-standard constitutive law for one of the model materials, i.e. the prosthesis core, is implemented.
Numerical implementation of energy-based models in finite element analysis
NASA Astrophysics Data System (ADS)
Chattonjai, Piyachat
2016-06-01
Soil is one of the most complex materials including several characteristics which are not only effect on stress-strain relationship but also volume changed such as contraction and dilation. Those characteristics depend on so many factors such as stress history, drained condition, current effective stress state, stress paths as well as void ratio, etc. In finite element analysis, the relevant constitutive model which includes relevant factors as mentioned above is one of the main key that will provide the accurate predicting of strength and deformation characteristic of geotechnical structure. For modern finite element program, the user-defined material subroutines have been provided when the material models included in the material library could not accurately predict the rather complex behavior of material. The objective of this study is to implement the elasto-plastic work-hardening-softening constitutive model into ABAQUS via VUMAT subroutine. The simulated results were verified by the experimental results of Toyoura sand under plane strain condition.
Ballistic impact behaviour of woven fabric composite: Finite element analysis and experiments
NASA Astrophysics Data System (ADS)
Phadnis, V. A.; Pandya, K. S.; Naik, N. K.; Roy, A.; Silberschmidt, V. V.
2013-07-01
A mechanical behaviour of plain-weave E-glass fabric/epoxy laminate composite plate exposed to ballistic impact is studied using a finite-element (FE) code Abaqus/Explicit. A ply-level FE model is developed, where a fabric-reinforced ply is modelled as a homogeneous orthotropic elastic material with potential to sustain progressive stiffness degradation due to fiber/matrix cracking, and plastic deformation under shear loading. The model is implemented as a VUMAT user subroutine. Ballistic experiments were carried out to validate the FE model. A parametric study for varying panel thickness is performed to compare impact resistance of the studied composite.
NASA Astrophysics Data System (ADS)
Lestriez, P.; Cherouat, A.; Saanouni, K.; Mariage, J. F.
2004-06-01
A fully coupled (strong coupling) thermo-elasto-visco-plastic-damage constitutive equations based on the state variables under large plastic deformation developed for metal forming simulation are presented. The relevant numerical aspects concerning either the local integration scheme as well as the global resolution strategy are discussed. This model is implemented into ABAQUS/EXPLICIT using the Vumat user subroutine. Applications are made to the orthogonal metal cutting by chip formation and segmentation. The interaction between hardening plasticity, ductile damage and thermal effects are carefully analyzed. The numerical results obtained with this procedure based on the damage coupling are compared with those obtained with the classical procedure neglecting the damage effect.
1979-10-01
readback memory writing, alphanumeric graphics, vector graphics, and internal test pat- terns. Channel and subchannel masks allow only selected bits...and subchannel mask (LSM) selection, 2) Write (LWM) and update (LUM) modes, 3) Element (LER, LEA, LEB, and LEC) and line (LLR, LLA, LLB, and LLC...Mnemonic Value Name (octal) (bit) OOdddd WID 0 000 DDD DDD DDD DDD Write Image Data Olmmmm LSM 0 001 MMM MMM MMM MMM Load Subchannel Mask 020ddd WGD 0
NASA Technical Reports Server (NTRS)
Utku, S.
1969-01-01
A general purpose digital computer program for the in-core solution of linear equilibrium problems of structural mechanics is documented. The program requires minimum input for the description of the problem. The solution is obtained by means of the displacement method and the finite element technique. Almost any geometry and structure may be handled because of the availability of linear, triangular, quadrilateral, tetrahedral, hexahedral, conical, triangular torus, and quadrilateral torus elements. The assumption of piecewise linear deflection distribution insures monotonic convergence of the deflections from the stiffer side with decreasing mesh size. The stresses are provided by the best-fit strain tensors in the least squares at the mesh points where the deflections are given. The selection of local coordinate systems whenever necessary is automatic. The core memory is used by means of dynamic memory allocation, an optional mesh-point relabelling scheme and imposition of the boundary conditions during the assembly time.
Kammoun, S.; Brassart, L.; Doghri, I.; Delannay, L.; Robert, G.
2011-05-04
A micromechanical damage modeling approach is presented to predict the overall elasto-plastic behavior and damage evolution in short fiber reinforced composite materials. The practical use of the approach is for injection molded thermoplastic parts reinforced with short glass fibers. The modeling is proceeded as follows. The representative volume element is decomposed into a set of pseudograins, the damage of which affects progressively the overall stiffness and strength up to total failure. Each pseudograin is a two-phase composite with aligned inclusions having same aspect ratio. A two-step mean-field homogenization procedure is adopted. In the first step, the pseudograins are homogenized individually according to the Mori-Tanaka scheme. The second step consists in a self-consistent homogenization of homogenized pseudograins. An isotropic damage model is applied at the pseudograin level. The model is implemented as a UMAT in the finite element code ABAQUS. Model is shown to reproduce the strength and the anisotropy (Lankford coefficient) during uniaxial tensile tests on samples cut under different directions relative to the injection flow direction.
NASA Technical Reports Server (NTRS)
Goldberg, Robert K.; Carney, Kelly S.
2004-01-01
An analysis method based on a deformation (as opposed to damage) approach has been developed to model the strain rate dependent, nonlinear deformation of woven ceramic matrix composites with a plain weave fiber architecture. In the developed model, the differences in the tension and compression response have also been considered. State variable based viscoplastic equations originally developed for metals have been modified to analyze the ceramic matrix composites. To account for the tension/compression asymmetry in the material, the effective stress and effective inelastic strain definitions have been modified. The equations have also been modified to account for the fact that in an orthotropic composite the in-plane shear stiffness is independent of the stiffness in the normal directions. The developed equations have been implemented into a commercially available transient dynamic finite element code, LS-DYNA, through the use of user defined subroutines (UMATs). The tensile, compressive, and shear deformation of a representative plain weave woven ceramic matrix composite are computed and compared to experimental results. The computed values correlate well to the experimental data, demonstrating the ability of the model to accurately compute the deformation response of woven ceramic matrix composites.
NASA Technical Reports Server (NTRS)
Goldberg, Robert K.; Carney, Kelly S.
2004-01-01
An analysis method based on a deformation (as opposed to damage) approach has been developed to model the strain rate dependent, nonlinear deformation of woven ceramic matrix composites, such as the Reinforced Carbon Carbon (RCC) material used on the leading edges of the Space Shuttle. In the developed model, the differences in the tension and compression deformation behaviors have also been accounted for. State variable viscoplastic equations originally developed for metals have been modified to analyze the ceramic matrix composites. To account for the tension/compression asymmetry in the material, the effective stress and effective inelastic strain definitions have been modified. The equations have also been modified to account for the fact that in an orthotropic composite the in-plane shear response is independent of the stiffness in the normal directions. The developed equations have been implemented into LS-DYNA through the use of user defined subroutines (UMATs). Several sample qualitative calculations have been conducted, which demonstrate the ability of the model to qualitatively capture the features of the deformation response present in woven ceramic matrix composites.
NASA Astrophysics Data System (ADS)
Nie, Zhenguo; Wang, Gang; Lin, Yongliang; Rong, Yiming (Kevin)
2015-12-01
Distortion resulting from heat treatment may cause serious problems for precision parts. A precision component made from 30CrNi3Mo steel with internal threads distorts slightly after quenching-tempering treatment. Such a small distortion results in serious difficulties in the subsequent assembly process. The distortion of the internal thread was measured using semi-destructive testing with video measuring system. Periodic wavy distortions emerged in the internal threads after heat treatment. Then both XRD analysis and hardness testing were conducted. A numerical simulation of the complete quenching-tempering process was conducted by DANTE, which is a set of user subroutines that link into the ABAQUS/STD solver. The results from the simulations are in good agreement with the measurement in distortion, microstructure field, and hardness. The effects of the technological parameters including quenchant, immersion orientation, and grooves were discussed on the basis of the simulation results. Finally, strategies to significantly decrease distortion and residual stress are proposed.
Use of a hyperelastic constitutive law for dry woven forming simulations
Vidal-Salle, Emmanuelle; Boisse, Philippe; Aimene, Yamina
2011-05-04
The increasing use of composite materials in industry implies an increasing use of automatic processes between which LCM processes take a large place. The improvement of such processes needs an extensive use of numerical simulations for all the stages of the process. In particular, it is necessary to know how the dry reinforcement is shaped. This paper presents a hyperelastic constitutive model for textile composite reinforcement at large strain based on an additive potential representative to tension and in-plane shearing. The proposed potential is a function of the right Cauchy Green and structural tensor invariants whose choice corresponds to textile composite reinforcement mechanical behaviour. The model is implemented in a user subroutine of ABAQUS/Explicit. The accuracy of the model has been checked and some simulations are performed on deep drawing with hemispheric punch. A good agreement is obtained with experimental forming experiments.
Damage and Failure Analysis of AZ31 Alloy Sheet in Warm Stamping Processes
NASA Astrophysics Data System (ADS)
Zhao, P. J.; Chen, Z. H.; Dong, C. F.
2016-07-01
In this study, a combined experimental-numerical investigation on the failure of AZ31 Mg alloy sheet in the warm stamping process was carried out based on modified GTN damage model which integrated Yld2000 anisotropic yield criterion. The constitutive equations of material were implemented into a VUMAT subroutine for solver ABAQUS/Explicit and applied to the formability analysis of mobile phone shell. The morphology near the crack area was observed using SEM, and the anisotropic damage evolution at various temperatures was simulated. The distributions of plastic strain, damage evolution, thickness, and fracture initiation obtained from FE simulation were analyzed. The corresponding forming limit diagrams were worked out, and the comparison with the experimental data showed a good agreement.
A Thermo-Plastic-Martensite Transformation Coupled Constitutive Model for Hot Stamping
NASA Astrophysics Data System (ADS)
Bin, Zhu; WeiKang, Liang; Zhongxiang, Gui; Kai, Wang; Chao, Wang; Yilin, Wang; Yisheng, Zhang
2017-01-01
In this study, a thermo-plastic-martensite transformation coupled model based on the von Mises yield criterion and the associated plastic flow rule is developed to further improve the accuracy of numerical simulation during hot stamping. The constitutive model is implemented into the finite element program ABAQUS using user subroutine VUMAT. The martensite transformation, transformation-induced plasticity and volume expansion during the austenite-to-martensite transformation are included in the constitutive model. For this purpose, isothermal tensile tests are performed to obtain the flow stress, and non-isothermal tensile tests were carried out to validate the constitutive model. The non-isothermal tensile numerical simulation demonstrates that the thermo-plastic-martensite transformation coupled constitutive model provides a reasonable prediction of force-displacement curves upon loading, which is expected to be applied for modeling and simulation of hot stamping.
NASA Astrophysics Data System (ADS)
Ahn, Hyunchul; An, Yongsan; Yu, Woong-Ryeol
2016-10-01
A new numerical method for analyzing the mechanical behavior of three-dimensional (3D) woven carbon fiber-reinforced composites was developed by considering changes in the fiber orientation and calculating the stress increments due to incremental deformations. The model consisted of four steps, starting update of the yarn orientation based on incremental deformation gradient. The stiffness matrix was then computed using the updated yarn orientation. Next, partial damage and propagation were incorporated into the stress calculation using modified ply discount method. The failure conditions were obtained by testing the unidirectional composites and formulated using Puck's criterion. This numerical model was finally implemented into commercial finite element software, ABAQUS, as a user material subroutine. As for experiment, 3D woven composite samples was manufactured using laboratory built-in system and characterized, the results of which were compared with simulated results, demonstrating that the current numerical model can properly predict the mechanical behavior of 3D fiber-reinforced composites.
Damage evaluation of reinforced concrete frame based on a combined fiber beam model
NASA Astrophysics Data System (ADS)
Shang, Bing; Liu, ZhanLi; Zhuang, Zhuo
2014-04-01
In order to analyze and simulate the impact collapse or seismic response of the reinforced concrete (RC) structures, a combined fiber beam model is proposed by dividing the cross section of RC beam into concrete fiber and steel fiber. The stress-strain relationship of concrete fiber is based on a model proposed by concrete codes for concrete structures. The stress-strain behavior of steel fiber is based on a model suggested by others. These constitutive models are implemented into a general finite element program ABAQUS through the user defined subroutines to provide effective computational tools for the inelastic analysis of RC frame structures. The fiber model proposed in this paper is validated by comparing with experiment data of the RC column under cyclical lateral loading. The damage evolution of a three-dimension frame subjected to impact loading is also investigated.
Investigation of the stress distribution around a mode 1 crack with a novel strain gradient theory
NASA Astrophysics Data System (ADS)
Lederer, M.; Khatibi, G.
2017-01-01
Stress concentrations at the tip of a sharp crack have extensively been investigated in the past century. According to the calculations of Inglis, the stress ahead of a mode 1 crack shows the characteristics of a singularity. This solution is exact in the framework of linear elastic fracture mechanics (LEFM). From the viewpoint of multiscale modelling, however, it is evident that the stress at the tip of a stable crack cannot be infinite, because the strengths of atomic bonds are finite. In order to prevent the problem of this singularity, a new version of strain gradient elasticity is employed here. This theory is implemented in the commercial FEM code ABAQUS through user subroutine UEL. Convergence of the model is proved through consecutive mesh refinement. In consequence, the stresses ahead of a mode 1 crack become finite. Furthermore, the model predicts a size effect in the sense “smaller is stronger”.
Li Dayong; Peng Yinghong; Zhang Shaorui; Tang Weiqin; Huang Shiyao
2010-06-15
In this paper, a constitutive framework based on a crystalline plasticity model is employed to simulate the plastic deformation of AZ31 magnesium alloy, which posses the hexagonal close packed (HCP) crystal structure. Dislocation slip and mechanical twinning are taken into account in the model. The successive integration method is used to determine the active slip systems, and the contribution of twinning to the grain reorientation is treated by the PTR method. The FE model is introduced into ABAQUS/Explicit through a user material subroutine (VUMAT). Three deformation processes of AZ31 magnesium alloy, including tension, compression and a stamping process, are simulated with the present method. The simulation results are compared with experiment and those presented in the literature.
NASA Astrophysics Data System (ADS)
Mazaheri, H.; Baghani, M.; Naghdabadi, R.; Sohrabpour, S.
2016-08-01
In this work, a model is developed to continuously predict homogeneous and inhomogeneous swelling behavior of pH/temperature sensitive PNIPAM hydrogels. Employing the model, homogeneous swelling of the pH/temperature sensitive hydrogel is investigated for free and biaxial constrained swelling cases. Comparing the model results with the experimental data available in the literature, the validity of the model is confirmed. The model is then employed to investigate inhomogeneous swelling of a spherical shell on a hard core both analytically and numerically for pH or temperature variations. In this regard, numerical tools are developed via preparing a user defined subroutine in ABAQUS software. Then, the complicated problem of contact between the hydrogel shell and a micro-channel with rigid walls is also investigated. Considering the results, we can say that the model is applicable for solving engineering boundary value problem of pH/temperature sensitive hydrogels.
A Thermo-Plastic-Martensite Transformation Coupled Constitutive Model for Hot Stamping
NASA Astrophysics Data System (ADS)
Bin, Zhu; WeiKang, Liang; Zhongxiang, Gui; Kai, Wang; Chao, Wang; Yilin, Wang; Yisheng, Zhang
2017-03-01
In this study, a thermo-plastic-martensite transformation coupled model based on the von Mises yield criterion and the associated plastic flow rule is developed to further improve the accuracy of numerical simulation during hot stamping. The constitutive model is implemented into the finite element program ABAQUS using user subroutine VUMAT. The martensite transformation, transformation-induced plasticity and volume expansion during the austenite-to-martensite transformation are included in the constitutive model. For this purpose, isothermal tensile tests are performed to obtain the flow stress, and non-isothermal tensile tests were carried out to validate the constitutive model. The non-isothermal tensile numerical simulation demonstrates that the thermo-plastic-martensite transformation coupled constitutive model provides a reasonable prediction of force-displacement curves upon loading, which is expected to be applied for modeling and simulation of hot stamping.
Vibration-assisted machining of single crystal
NASA Astrophysics Data System (ADS)
Zahedi, S. A.; Roy, A.; Silberschmidt, V. V.
2013-07-01
Vibration-assisted machining offers a solution to expanding needs for improved machining, especially where accuracy and precision are of importance, such as in micromachining of single crystals of metals and alloys. Crystallographic anisotropy plays a crucial role in determining on overall response to machining. In this study, we intend to address the matter of ultra-precision machining of material at the micron scale using computational modelling. A hybrid modelling approach is implemented that combines two discrete schemes: smoothed particle hydrodynamics and continuum finite elements. The model is implemented in a commercial software ABAQUS/Explicit employing a user-defined subroutine (VUMAT) and used to elucidate the effect of crystallographic anisotropy on a response of face centred cubic (f.c.c.) metals to machining.
NASA Astrophysics Data System (ADS)
Jiang, Yunpeng
2016-05-01
In this article, a systematic numerical study was conducted to study the detailed shear banding evolution in bulk metallic glasses (BMGs) with various sample aspect ratios under uniaxial compression, and whereby the effect of the sample aspect ratio on the compressive ductility was elucidated. A finite strain viscoelastic model was employed to describe the shear banding nucleation, growth, and coalescence in BMG samples with the help of Anand and Su's theory, which was incorporated into the ABAQUS finite element method code as a user material subroutine VUMAT. The present numerical method was first verified by comparing with the corresponding experimental results, and then parameter analysis was performed to discuss the impact of microstructure parameters on the predicted results. The present modeling will shed some light on enhancing the toughness of BMG structures in the engineering applications.
NASA Astrophysics Data System (ADS)
Labergere, C.; Saanouni, K.; Benafia, S.; Galmiche, J.; Sulaiman, H.
2013-05-01
This paper presents the modelling and adaptive numerical simulation of the fine blanking process. Thermodynamically-consistent constitutive equations, strongly coupled with ductile damage, together with specific boundary conditions (particular command of forces on blank holder and counterpunch) are presented. This model is implemented into ABAQUS/EXPLICIT using the Vumat user subroutine and connected with an adaptive 2D remeshing procedure. The different material parameters are identified for the steel S600MC using experimental tensile tests conducted until the final fracture. A parametric study aiming to examine the sensitivity of the process parameters (die radius, clearance die/punch) to the punch force and fracture surfaces topology (convex zone, sheared zone, fracture zone and the burr).
NASA Astrophysics Data System (ADS)
Jia, Yueqian; Bai, Yuanli
2016-08-01
A fully modularized framework was established to combine isotropic, kinematic, and cross hardening behaviors under non-monotonic loading conditions. Three sets of state variables were defined and applied to consider the effects of, a) loading history, b) twinning and de-twinning and c) different pre-strain. Experiments under two types of non-proportional loading conditions were conducted along different orientations, 1) uniaxial compression-tension reversal loading with different amounts of compressive strains, and 2) two-step uniaxial tension, known as cross-loading conditions, with different pre-strains. No apparent cross-hardening effect was observed for this material. The calibrated new hardening model, with an anisotropic CPB06ex2 yield criterion and an eMMC anisotropic fracture model, has been implemented into Abaqus/ Explicit as a user material subroutine (VUMAT). Good correlation was observed between experimental and simulation results.
Predicting Failure Progression and Failure Loads in Composite Open-Hole Tension Coupons
NASA Technical Reports Server (NTRS)
Arunkumar, Satyanarayana; Przekop, Adam
2010-01-01
Failure types and failure loads in carbon-epoxy [45n/90n/-45n/0n]ms laminate coupons with central circular holes subjected to tensile load are simulated using progressive failure analysis (PFA) methodology. The progressive failure methodology is implemented using VUMAT subroutine within the ABAQUS(TradeMark)/Explicit nonlinear finite element code. The degradation model adopted in the present PFA methodology uses an instantaneous complete stress reduction (COSTR) approach to simulate damage at a material point when failure occurs. In-plane modeling parameters such as element size and shape are held constant in the finite element models, irrespective of laminate thickness and hole size, to predict failure loads and failure progression. Comparison to published test data indicates that this methodology accurately simulates brittle, pull-out and delamination failure types. The sensitivity of the failure progression and the failure load to analytical loading rates and solvers precision is demonstrated.
NASA Astrophysics Data System (ADS)
Li, Dayong; Zhang, Shaorui; Tang, Weiqin; Huang, Shiyao; Peng, Yinghong
2010-06-01
In this paper, a constitutive framework based on a crystalline plasticity model is employed to simulate the plastic deformation of AZ31 magnesium alloy, which posses the hexagonal close packed (HCP) crystal structure. Dislocation slip and mechanical twinning are taken into account in the model. The successive integration method is used to determine the active slip systems, and the contribution of twinning to the grain reorientation is treated by the PTR method. The FE model is introduced into ABAQUS/Explicit through a user material subroutine (VUMAT). Three deformation processes of AZ31 magnesium alloy, including tension, compression and a stamping process, are simulated with the present method. The simulation results are compared with experiment and those presented in the literature.
Damage Evolution On Mechanical Parts Under Cyclic Loading
NASA Astrophysics Data System (ADS)
Lestriez, P.; Bogard, F.; Shan, J. L.; Guo, Y. Q.
2007-05-01
This paper presents a fatigue damage model, based on the continuum damage mechanics and general thermodynamic theory, proposed by Lemaitre and Chaboche, for rolling bearings under very numerous loading cycles. A flow surface of fatigue using the Sines criterion is adopted. The coupling between the hardening plasticity and damage effects is considered in the constitutive equations. An explicit algorithm of weak coupling leads to a calculation very fast. This fatigue damage model is implemented into Abaqus/Explicit using a Vumat user's subroutine. Moreover, the damage variable in function of time is transformed into a function of number of cycles. An algorithm of cycle jump, with a criterion for choosing the number increment of cycles, is proposed, which allows to largely reduce the CPU time. The present damage simulation allows to determine the lifetime of mechanical parts under cyclic loading.
Simulation of ratcheting in straight pipes using ANSYS with an improved cyclic plasticity model
Hassan, T.; Zhu, Y.; Matzen, V.C.
1996-12-01
Ratcheting has been shown to be a contributing cause of failure in several seismic experiments on piping components and systems. Most commercial finite element codes have been unable to simulate the ratcheting in those tests accurately. The reason for this can be traced to inadequate plasticity constitutive models in the analysis codes. The authors have incorporated an improved cyclic plasticity model, based on an Armstrong-Frederick kinematic hardening rule in conjunction with the Drucker-Palgen plastic modulus equation, into an ANSYS user subroutine. This modified analysis code has been able to simulate quite accurately the ratcheting behavior of a tube subjected to a constant internal pressure and axially strain controlled cycling. This paper describes simulations obtained form this modified ANSYS code for two additional tests: (1) a tube subjected to constant axial stress and prescribed torsional cycling, and (2) a straight pipe subjected to constant internal pressure and quasi-static cyclic bending. The analysis results from the modified ANSYS code are compared to the experimental data, as well as results from ABAQUS and the original ANSYS code. The resulting correlation shows a significant improvement over the original ANSYS and the ABAQUS codes.
NASA Technical Reports Server (NTRS)
Satyanarayana, Arunkumar; Bogert, Philip B.; Chunchu, Prasad B.
2007-01-01
The influence of delamination on the progressing damage path and initial failure load in composite laminates is investigated. Results are presented from a numerical and an experimental study of center-notched tensile-loaded coupons. The numerical study includes two approaches. The first approach considers only intralaminar (fiber breakage and matrix cracking) damage modes in calculating the progression of the damage path. In the second approach, the model is extended to consider the effect of interlaminar (delamination) damage modes in addition to the intralaminar damage modes. The intralaminar damage is modeled using progressive damage analysis (PDA) methodology implemented with the VUMAT subroutine in the ABAQUS finite element code. The interlaminar damage mode has been simulated using cohesive elements in ABAQUS. In the experimental study, 2-3 specimens each of two different stacking sequences of center-notched laminates are tensile loaded. The numerical results from the two different modeling approaches are compared with each other and the experimentally observed results for both laminate types. The comparisons reveal that the second modeling approach, where the delamination damage mode is included together with the intralaminar damage modes, better simulates the experimentally observed damage modes and damage paths, which were characterized by splitting failures perpendicular to the notch tips in one or more layers. Additionally, the inclusion of the delamination mode resulted in a better prediction of the loads at which the failure took place, which were higher than those predicted by the first modeling approach which did not include delaminations.
A Nonlinear Viscoelastic Model for Ceramics at High Temperatures
NASA Technical Reports Server (NTRS)
Powers, Lynn M.; Panoskaltsis, Vassilis P.; Gasparini, Dario A.; Choi, Sung R.
2002-01-01
High-temperature creep behavior of ceramics is characterized by nonlinear time-dependent responses, asymmetric behavior in tension and compression, and nucleation and coalescence of voids leading to creep rupture. Moreover, creep rupture experiments show considerable scatter or randomness in fatigue lives of nominally equal specimens. To capture the nonlinear, asymmetric time-dependent behavior, the standard linear viscoelastic solid model is modified. Nonlinearity and asymmetry are introduced in the volumetric components by using a nonlinear function similar to a hyperbolic sine function but modified to model asymmetry. The nonlinear viscoelastic model is implemented in an ABAQUS user material subroutine. To model the random formation and coalescence of voids, each element is assigned a failure strain sampled from a lognormal distribution. An element is deleted when its volumetric strain exceeds its failure strain. Element deletion has been implemented within ABAQUS. Temporal increases in strains produce a sequential loss of elements (a model for void nucleation and growth), which in turn leads to failure. Nonlinear viscoelastic model parameters are determined from uniaxial tensile and compressive creep experiments on silicon nitride. The model is then used to predict the deformation of four-point bending and ball-on-ring specimens. Simulation is used to predict statistical moments of creep rupture lives. Numerical simulation results compare well with results of experiments of four-point bending specimens. The analytical model is intended to be used to predict the creep rupture lives of ceramic parts in arbitrary stress conditions.
Chen, G; Fan, W; Mishra, S; El-Atem, A; Schuetz, M A; Xiao, Y
2012-10-01
The finite element (FE) analysis is an effective method to study the strength and predict the fracture risk of endodontically-treated teeth. This paper presents a rapid method developed to generate a comprehensive tooth FE model using data retrieved from micro-computed tomography (μCT). With this method, the inhomogeneity of material properties of teeth was included into the model without dividing the tooth model into different regions. The material properties of the tooth were assumed to be related to the mineral density. The fracture risk at different tooth portions was assessed for root canal treatments. The micro-CT images of a tooth were processed by a Matlab software programme and the CT numbers were retrieved. The tooth contours were obtained with thresholding segmentation using Amira. The inner and outer surfaces of the tooth were imported into Solidworks and a three-dimensional (3D) tooth model was constructed. An assembly of the tooth model with the periodontal ligament (PDL) layer and surrounding bone was imported into ABAQUS. The material properties of the tooth were calculated from the retrieved CT numbers via ABAQUS user's subroutines. Three root canal geometries (original and two enlargements) were investigated. The proposed method in this study can generate detailed 3D finite element models of a tooth with different root canal enlargements and filling materials, and would be very useful for the assessment of the fracture risk at different tooth portions after root canal treatments.
Chen, G; Wu, F Y; Liu, Z C; Yang, K; Cui, F
2015-08-01
Subject-specific finite element (FE) models can be generated from computed tomography (CT) datasets of a bone. A key step is assigning material properties automatically onto finite element models, which remains a great challenge. This paper proposes a node-based assignment approach and also compares it with the element-based approach in the literature. Both approaches were implemented using ABAQUS. The assignment procedure is divided into two steps: generating the data file of the image intensity of a bone in a MATLAB program and reading the data file into ABAQUS via user subroutines. The node-based approach assigns the material properties to each node of the finite element mesh, while the element-based approach assigns the material properties directly to each integration point of an element. Both approaches are independent from the type of elements. A number of FE meshes are tested and both give accurate solutions; comparatively the node-based approach involves less programming effort. The node-based approach is also independent from the type of analyses; it has been tested on the nonlinear analysis of a Sawbone femur. The node-based approach substantially improves the level of automation of the assignment procedure of bone material properties. It is the simplest and most powerful approach that is applicable to many types of analyses and elements.
Choi, Kyoo Sil; Pan, Jwo
2009-07-27
In this paper, a generalized anisotropic hardening rule based on the Mroz multi-yield-surface model is derived. The evolution equation for the active yield surface is obtained by considering the continuous expansion of the active yield surface during the unloading/reloading process. The incremental constitutive relation based on the associated flow rule is then derived for a general yield function. As a special case, detailed incremental constitutive relations are derived for the Mises yield function. The closed-form solutions for one-dimensional stress-plastic strain curves are also derived and plotted for the Mises materials under cyclic loading conditions. The stress-plastic strain curves show closed hysteresis loops under uniaxial cyclic loading conditions and the Masing hypothesis is applicable. A user material subroutine based on the Mises yield function, the anisotropic hardening rule and the constitutive relations was then written and implemented into ABAQUS. Computations were conducted for a simple plane strain finite element model under uniaxial monotonic and cyclic loading conditions based on the anisotropic hardening rule and the isotropic and nonlinear kinematic hardening rules of ABAQUS. The results indicate that the plastic response of the material follows the intended input stress-strain data for the anisotropic hardening rule whereas the plastic response depends upon the input strain ranges of the stress-strain data for the nonlinear kinematic hardening rule.
Viscoelastic behaviour of pumpkin balloons
NASA Astrophysics Data System (ADS)
Gerngross, T.; Xu, Y.; Pellegrino, S.
2008-11-01
The lobes of the NASA ULDB pumpkin-shaped super-pressure balloons are made of a thin polymeric film that shows considerable time-dependent behaviour. A nonlinear viscoelastic model based on experimental measurements has been recently established for this film. This paper presents a simulation of the viscoelastic behaviour of ULDB balloons with the finite element software ABAQUS. First, the standard viscoelastic modelling capabilities available in ABAQUS are examined, but are found of limited accuracy even for the case of simple uniaxial creep tests on ULDB films. Then, a nonlinear viscoelastic constitutive model is implemented by means of a user-defined subroutine. This approach is verified by means of biaxial creep experiments on pressurized cylinders and is found to be accurate provided that the film anisotropy is also included in the model. A preliminary set of predictions for a single lobe of a ULDB is presented at the end of the paper. It indicates that time-dependent effects in a balloon structure can lead to significant stress redistribution and large increases in the transverse strains in the lobes.
Impact Damage of 3D Orthogonal Woven Composite Circular Plates
NASA Astrophysics Data System (ADS)
Ji, Changgan; Sun, Baozhong; Qiu, Yiping; Gu, Bohong
2007-11-01
The damages of 3D orthogonal woven composite circular plate under quasi-static indentation and transverse impact were tested with Materials Test System (MTS) and modified split Hopkinson bar (SHPB) apparatus. The load vs. displacement curves during quasi-static penetration and impact were obtained to study the energy absorption of the composite plate. The fluctuation of the impact stress waves has been unveiled. Differences of the load-displacement curves between the quasi-static and impact loading are discussed. This work also aims at establishing a unit-cell model to analyze the damage of composites. A user material subroutine which named VUMAT for characterizing the constitutive relationship of the 3-D orthogonal woven composite and the damage evolution is incorporated with a finite element code ABAQUS/Explicit to simulate the impact damage process of the composite plates. From the comparison of the load-displacement curves and energy absorption curves of the composite plate between experimental and FEM simulation, it is shown that the unit-cell model of the 3D woven composite and the VUMAT combined with the ABAQUS/Explicit can calculate the impact responses of the circular plate precisely. Furthermore, the model can also be extended to simulate the impact behavior of the 3D woven composite structures.
Comprehensively simulating the mixed-mode progressive delamination in composite laminates
NASA Astrophysics Data System (ADS)
Gao, Zhenyuan
Delamination, or interlaminar debonding, is a commonly observed failure mechanism in composite laminates. It is of great significance to comprehensively simulate the mixed-mode progressive delamination in composite structures because by doing this, people can save a lot of effort in evaluating the safe load which a composite structure can endure. The objective of this thesis is to develop a numerical approach to simulating double-cantilever beam (DCB) and mixed-mode bending (MMB) tests and also of specifying/validating various cohesive models. A finite element framework, which consists of properly selecting time integration scheme (explicit dynamic), viscosity, load rate and mass scaling, is developed to yield converged and accurate results. Two illustrative cohesive laws (linear and power-law) are programmed with a user- defined material subroutine for ABAQUS/Explicit, VUMAT, and implemented into the finite element framework. Parameters defined in cohesive laws are studied to evaluate their effects on the predicted load-displacement curves. The finite element model, together with the predetermined model parameters, is found to be capable of producing converged and accurate results. The finite element framework, embedded with the illustrative cohesive laws, is found to be capable of handling various interfacial models. The present approach is concluded to be useful in simulating delamination with more sophisticated material models. Together with the method for determining model parameters, it can be used by computer codes other than ABAQUS.
Pierrat, B; Murphy, J G; MacManus, D B; Gilchrist, M D
2016-01-01
Modelling transversely isotropic materials in finite strain problems is a complex task in biomechanics, and is usually addressed by using finite element (FE) simulations. The standard method developed to account for the quasi-incompressible nature of soft tissues is to decompose the strain energy function (SEF) into volumetric and deviatoric parts. However, this decomposition is only valid for fully incompressible materials, and its use for slightly compressible materials yields an unphysical response during the simulation of hydrostatic tension/compression of a transversely isotropic material. This paper presents the FE implementation as subroutines of a new volumetric model solving this deficiency in two FE codes: Abaqus and FEBio. This model also has the specificity of restoring the compatibility with small strain theory. The stress and elasticity tensors are first derived for a general SEF. This is followed by a successful convergence check using a particular SEF and a suite of single-element tests showing that this new model does not only correct the hydrostatic deficiency but may also affect stresses during shear tests (Poynting effect) and lateral stretches during uniaxial tests (Poisson's effect). These FE subroutines have numerous applications including the modelling of tendons, ligaments, heart tissue, etc. The biomechanics community should be aware of specificities of the standard model, and the new model should be used when accurate FE results are desired in the case of compressible materials.
Crystallographic effects during micromachining — A finite-element model
NASA Astrophysics Data System (ADS)
Song, Shin-Hyung; Choi, Woo Chun
2015-07-01
Mechanical micromachining is a powerful and effective way for manufacturing small sized machine parts. Even though the micromachining process is similar to the traditional machining, the material behavior during the process is much different. In particular, many researchers report that the basic mechanics of the work material is affected by microstructures and their crystallographic orientations. For example, crystallographic orientations of the work material have significant influence on force response, chip formation and surface finish. In order to thoroughly understand the effect of crystallographic orientations on the micromachining process, finite-element model (FEM) simulating orthogonal cutting process of single crystallographic material was presented. For modeling the work material, rate sensitive single crystal plasticity of face-centered cubic (FCC) crystal was implemented. For the chip formation during the simulation, element deletion technique was used. The simulation model is developed using ABAQUS/explicit with user material subroutine via user material subroutine (VUMAT). Simulations showed that variation of the specific cutting energy at different crystallographic orientations of work material shows significant anisotropy. The developed FEM model can be a useful prediction tool of micromachining of crystalline materials.
An incrementally non-linear model for clays with directional stiffness and a small strain emphasis
NASA Astrophysics Data System (ADS)
Tu, Xuxin
In response to construction activities and loads from permanent structures, soil generally is subjected to a variety of loading modes varying both in time and location. It also has been increasingly appreciated that the strains around well-designed foundations, excavations and tunnels are mostly small, with soil responses at this strain level generally being non-linear and anisotropic. To make accurate prediction of the performance of a geo-system, it is highly desirable to understand soil behavior at small strains along multiple loading directions, and accordingly to incorporate these responses in an appropriate constitutive model implemented in a finite element analysis. This dissertation presents a model based on a series of stress probe tests with small strain measurements performed on compressible Chicago glacial clays. The proposed model is formulated in an original constitutive framework, in which the tangent stiffness matrix is constructed in accordance with the mechanical nature of frictional materials and the tangent moduli therein are described explicitly. The stiffness description includes evolution relations with regard to length of stress path, and directionality relations in terms of stress path direction. The former relations provide distinctive definitions for small-strain and large-strain behaviors, and distinguish soil responses in shearing and compression. The latter relations make this model incrementally non-linear and thus capable of modeling inelastic behavior. A new algorithm based on a classical substepping scheme is developed to numerically integrate this model. A consistent tangent matrix is derived for the proposed model with the upgraded substepping scheme. The code is written in FORTRAN and implemented in FEM via UMAT of ABAQUS. The model is exercised in a variety of applications ranging from oedometer, triaxial and biaxial test simulations to a C-class prediction for a well-instrumented excavation. The computed results indicate that
Hambli, Ridha
2014-01-01
Bone adaptation occurs as a response to external loadings and involves bone resorption by osteoclasts followed by the formation of new bone by osteoblasts. It is directly triggered by the transduction phase by osteocytes embedded within the bone matrix. The bone remodeling process is governed by the interactions between osteoblasts and osteoclasts through the expression of several autocrine and paracrine factors that control bone cell populations and their relative rate of differentiation and proliferation. A review of the literature shows that despite the progress in bone remodeling simulation using the finite element (FE) method, there is still a lack of predictive models that explicitly consider the interaction between osteoblasts and osteoclasts combined with the mechanical response of bone. The current study attempts to develop an FE model to describe the bone remodeling process, taking into consideration the activities of osteoclasts and osteoblasts. The mechanical behavior of bone is described by taking into account the bone material fatigue damage accumulation and mineralization. A coupled strain-damage stimulus function is proposed, which controls the level of autocrine and paracrine factors. The cellular behavior is based on Komarova et al.'s (2003) dynamic law, which describes the autocrine and paracrine interactions between osteoblasts and osteoclasts and computes cell population dynamics and changes in bone mass at a discrete site of bone remodeling. Therefore, when an external mechanical stress is applied, bone formation and resorption is governed by cells dynamic rather than adaptive elasticity approaches. The proposed FE model has been implemented in the FE code Abaqus (UMAT routine). An example of human proximal femur is investigated using the model developed. The model was able to predict final human proximal femur adaptation similar to the patterns observed in a human proximal femur. The results obtained reveal complex spatio-temporal bone
Hambli, Ridha
2014-01-01
Bone adaptation occurs as a response to external loadings and involves bone resorption by osteoclasts followed by the formation of new bone by osteoblasts. It is directly triggered by the transduction phase by osteocytes embedded within the bone matrix. The bone remodeling process is governed by the interactions between osteoblasts and osteoclasts through the expression of several autocrine and paracrine factors that control bone cell populations and their relative rate of differentiation and proliferation. A review of the literature shows that despite the progress in bone remodeling simulation using the finite element (FE) method, there is still a lack of predictive models that explicitly consider the interaction between osteoblasts and osteoclasts combined with the mechanical response of bone. The current study attempts to develop an FE model to describe the bone remodeling process, taking into consideration the activities of osteoclasts and osteoblasts. The mechanical behavior of bone is described by taking into account the bone material fatigue damage accumulation and mineralization. A coupled strain–damage stimulus function is proposed, which controls the level of autocrine and paracrine factors. The cellular behavior is based on Komarova et al.’s (2003) dynamic law, which describes the autocrine and paracrine interactions between osteoblasts and osteoclasts and computes cell population dynamics and changes in bone mass at a discrete site of bone remodeling. Therefore, when an external mechanical stress is applied, bone formation and resorption is governed by cells dynamic rather than adaptive elasticity approaches. The proposed FE model has been implemented in the FE code Abaqus (UMAT routine). An example of human proximal femur is investigated using the model developed. The model was able to predict final human proximal femur adaptation similar to the patterns observed in a human proximal femur. The results obtained reveal complex spatio-temporal bone
Hambli, Ridha; Boughattas, Mohamed Hafedh; Daniel, Jean-Luc; Kourta, Azeddine
2016-07-01
Denosumab is a fully human monoclonal antibody that inhibits receptor activator of nuclearfactor-kappa B ligand (RANKL). This key mediator of osteoclast activities has been shown to inhibit osteoclast differentiation and hence, to increase bone mineral density (BMD) in treated patients. In the current study, we develop a computer model to simulate the effects of denosumab treatments (dose and duration) on the proximal femur bone remodeling process quantified by the variation in proximal femur BMD. The simulation model is based on a coupled pharmacokinetics model of denosumab with a pharmacodynamics model consisting of a mechanobiological finite element remodeling model which describes the activities of osteoclasts and osteoblasts. The mechanical behavior of bone is described by taking into account the bone material fatigue damage accumulation and mineralization. A coupled strain-damage stimulus function is proposed which controls the level of bone cell autocrine and paracrine factors. The cellular behavior is based on Komarova et al.׳s (2003) dynamic law which describes the autocrine and paracrine interactions between osteoblasts and osteoclasts and computes cell population dynamics and changes in bone mass at a discrete site of bone remodeling. Therefore, when an external mechanical stress is applied, bone formation and resorption is governed by cell dynamics rather than by adaptive elasticity approaches. The proposed finite element model was implemented in the finite element code Abaqus (UMAT routine). In order to perform a preliminary validation, in vivo human proximal femurs were selected and scanned at two different time intervals (at baseline and at a 36-month interval). Then, a 3D FE model was generated and the denosumab-remodeling algorithm was applied to the scans at t0 simulating daily walking activities for a duration of 36 months. The predicted results (density variation) were compared to existing published ones performed on a human cohort (FREEDOM).
NASA Astrophysics Data System (ADS)
Fein, Jonathan
Woven fabric composite materials are widely used in the construction of aircraft engine fan containment systems, mostly due to their high strength to weight ratios and ease of implementation. The development of a predictive model for fan blade containment would provide great benefit to engine manufactures in shortened development cycle time, less risk in certification and fewer dollars lost to redesign/recertification cycles. A mechanistic user-defined material model subroutine has been developed at Arizona State University (ASU) that captures the behavioral response of these fabrics, namely Kevlar ® 49, under ballistic loading. Previously developed finite element models used to validate the consistency of this material model neglected the effects of the physical constraints imposed on the test setup during ballistic testing performed at NASA Glenn Research Center (NASA GRC). Part of this research was to explore the effects of these boundary conditions on the results of the numerical simulations. These effects were found to be negligible in most instances. Other material models for woven fabrics are available in the LS-DYNA finite element code. One of these models, MAT234: MAT_VISCOELASTIC_LOOSE_FABRIC (Ivanov & Tabiei, 2004) was studied and implemented in the finite element simulations of ballistic testing associated with the FAA ASU research. The results from these models are compared to results obtained from the ASU UMAT as part of this research. The results indicate an underestimation in the energy absorption characteristics of the Kevlar 49 fabric containment systems. More investigation needs to be performed in the implementation of MAT234 for Kevlar 49 fabric. Static penetrator testing of Kevlar® 49 fabric was performed at ASU in conjunction with this research. These experiments are designed to mimic the type of loading experienced during fan blade out events. The resulting experimental strains were measured using a non-contact optical strain measurement
1980-05-22
Subroutine PLOTDATA .............................. 633 8.9.1 Subroutine PICS .............................. 651 8.9.2 Subroutine PROJCT...629 126 Subroutine PLOTDATA ................................... 634 127 Subroutine PICS .............................. 652 128...POMFL C’.te.S,63t1bPXO/DUAL/OSJECTIPLOTOATA S, SELECT 63115P501£UALDSOURCE/EIM/PLOTOATA s SELECT 6311OPXOIDUALISOUPCE/EIMf/ PICS S SELECT
Nonlinear mesomechanics of composites with periodic microstructure
NASA Technical Reports Server (NTRS)
Walker, Kevin P.; Jordan, Eric H.; Freed, Alan D.
1989-01-01
This work is concerned with modeling the mechanical deformation or constitutive behavior of composites comprised of a periodic microstructure under small displacement conditions at elevated temperature. A mesomechanics approach is adopted which relates the microimechanical behavior of the heterogeneous composite with its in-service macroscopic behavior. Two different methods, one based on a Fourier series approach and the other on a Green's function approach, are used in modeling the micromechanical behavior of the composite material. Although the constitutive formulations are based on a micromechanical approach, it should be stressed that the resulting equations are volume averaged to produce overall effective constitutive relations which relate the bulk, volume averaged, stress increment to the bulk, volume averaged, strain increment. As such, they are macromodels which can be used directly in nonlinear finite element programs such as MARC, ANSYS and ABAQUS or in boundary element programs such as BEST3D. In developing the volume averaged or efective macromodels from the micromechanical models, both approaches will require the evaluation of volume integrals containing the spatially varying strain distributions throughout the composite material. By assuming that the strain distributions are spatially constant within each constituent phase-or within a given subvolume within each constituent phase-of the composite material, the volume integrals can be obtained in closed form. This simplified micromodel can then be volume averaged to obtain an effective macromodel suitable for use in the MARC, ANSYS and ABAQUS nonlinear finite element programs via user constitutive subroutines such as HYPELA and CMUSER. This effective macromodel can be used in a nonlinear finite element structural analysis to obtain the strain-temperature history at those points in the structure where thermomechanical cracking and damage are expected to occur, the so called damage critical points of
Effects of cavern depth on surface subsidence and storage loss of oil-filled caverns
Hoffman, E L
1992-01-01
Finite element analyses of oil-filled caverns were performed to investigate the effects of cavern depth on surface subsidence and storage loss, a primary performance criteria of SPR caverns. The finite element model used for this study was axisymmetric, approximating an infinite array of caverns spaced at 750 ft. The stratigraphy and cavern size were held constant while the cavern depth was varied between 1500 ft and 3000 ft in 500 ft increments. Thirty year simulations, the design life of the typical SPR cavern, were performed with boundary conditions modeling the oil pressure head applied to the cavern lining. A depth dependent temperature gradient of 0.012{degrees}F/ft was also applied to the model. The calculations were performed using ABAQUS, a general purpose of finite element analysis code. The user-defined subroutine option in ABAQUS was used to enter an elastic secondary creep model which includes temperature dependence. The calculations demonstrated that surface subsidence and storage loss rates increase with increasing depth. At lower depths the difference between the lithostatic stress and the oil pressure is greater. Thus, the effective stresses are greater, resulting in higher creep rates. Furthermore, at greater depths the cavern temperatures are higher which also produce higher creep rates. Together, these factors result in faster closure of the cavern. At the end of the 30 year simulations, a 1500 ft-deep cavern exhibited 4 percent storage loss and 4 ft of subsidence while a 3000 ft-deep cavern exhibited 33 percent storage loss and 44 ft of subsidence. The calculations also demonstrated that surface subsidence is directly related to the amount of storage loss. Deeper caverns exhibit more subsidence because the caverns exhibit more storage loss. However, for a given amount of storage loss, nearly the same magnitude of surface subsidence was exhibited, independent of cavern depth.
A numerical study on intended and unintended failure mechanisms in blanking of sandwich plates
NASA Astrophysics Data System (ADS)
Chen, L.; Soyarslan, C.; Tekkaya, A. E.
2013-05-01
Metal-polymer-metal sandwich plates are widely used in the automotive and aerospace industry. As for different applications the sandwich plates can be divided into two types. They are sound-damping laminates with a polymer core much thinner than the metallic faces and low-density laminates with a core thickness of approximately 40-60% of the total thickness. One frequent process step in production of parts made of these plates is the blanking process whose hereditary effects draw the limits of further forming stages or service performance and life; e.g. the failure of the adhesive in the thermoplastic polymer interface affects the sound-damping efficiency intensively. With this motivation, we present FE simulation of an axi-symmetric blanking process of steel/polyethylene/steel sound-damping laminates. The mechanical behavior of the metallic layers was characterized by finite strain rate independent elasto-plasticity where progressive material deterioration and fracture are given account for using continuum damage mechanics (CDM). This material model is made accessible via implementations as VUMAT subroutines for ABAQUS/Explicit. Possible failure of the thermoplastic polymer which may lead to delamination of the metallic layers is modeled using ABAQUS built-in cohesive zone elements. The results show that existing intended and unintended failure modes, e.g. blanking of the metallic and thermoplastic polymer constituents as well as failure of polymer layer under shear and compression, can be effectively studied with the proposed framework for process enhancement. As a future work, a damage coupled nonlinear visco-elastic constitutive model will be devised for the simulation of the thermoplastic layer in low-density laminates.
Flight dynamics analysis and simulation of heavy lift airships. Volume 5: Programmer's manual
NASA Technical Reports Server (NTRS)
Ringland, R. F.; Tischler, M. B.; Jex, H. R.; Emmen, R. D.; Ashkenas, I. L.
1982-01-01
The Programmer's Manual contains explanations of the logic embodied in the various program modules, a dictionary of program variables, a subroutine listing, subroutine/common block/cross reference listing, and a calling/called subroutine cross reference listing.
Investigation of FE model size definition for surface coating application
NASA Astrophysics Data System (ADS)
Chen, Yanhong; Zhuang, Weimin; Wang, Shiwen; Lin, Jianguo; Balint, Daniel; Shan, Debin
2012-09-01
An efficient prediction mechanical performance of coating structures has been a constant concern since the dawn of surface engineering. However, predictive models presented by initial research are normally based on traditional solid mechanics, and thus cannot predict coating performance accurately. Also, the high computational costs that originate from the exclusive structure of surface coating systems (a big difference in the order of coating and substrate) are not well addressed by these models. To fill the needs for accurate prediction and low computational costs, a multi-axial continuum damage mechanics (CDM)-based constitutive model is introduced for the investigation of the load bearing capacity and fracture properties of coatings. Material parameters within the proposed constitutive model are determined for a typical coating (TiN) and substrate (Cu) system. An efficient numerical subroutine is developed to implement the determined constitutive model into the commercial FE solver, ABAQUS, through the user-defined subroutine, VUMAT. By changing the geometrical sizes of FE models, a series of computations are carried out to investigate (1) loading features, (2) stress distributions, and (3) failure features of the coating system. The results show that there is a critical displacement corresponding to each FE model size, and only if the applied normal loading displacement is smaller than the critical displacement, a reasonable prediction can be achieved. Finally, a 3D map of the critical displacement is generated to provide guidance for users to determine an FE model with suitable geometrical size for surface coating simulations. This paper presents an effective modelling approach for the prediction of mechanical performance of surface coatings.
NASA Technical Reports Server (NTRS)
Wang, John T.; Pineda, Evan J.; Ranatunga, Vipul; Smeltzer, Stanley S.
2015-01-01
A simple continuum damage mechanics (CDM) based 3D progressive damage analysis (PDA) tool for laminated composites was developed and implemented as a user defined material subroutine to link with a commercially available explicit finite element code. This PDA tool uses linear lamina properties from standard tests, predicts damage initiation with an easy-to-implement Hashin-Rotem failure criteria, and in the damage evolution phase, evaluates the degradation of material properties based on the crack band theory and traction-separation cohesive laws. It follows Matzenmiller et al.'s formulation to incorporate the degrading material properties into the damaged stiffness matrix. Since nonlinear shear and matrix stress-strain relations are not implemented, correction factors are used for slowing the reduction of the damaged shear stiffness terms to reflect the effect of these nonlinearities on the laminate strength predictions. This CDM based PDA tool is implemented as a user defined material (VUMAT) to link with the Abaqus/Explicit code. Strength predictions obtained, using this VUMAT, are correlated with test data for a set of notched specimens under tension and compression loads.
Penalty-Based Interface Technology for Prediction of Delamination Growth in Laminated Structures
NASA Technical Reports Server (NTRS)
Averill, Ronald C.
2004-01-01
An effective interface element technology has been developed for connecting and simulating crack growth between independently modeled finite element subdomains (e.g., composite plies). This method has been developed using penalty constraints and allows coupling of finite element models whose nodes do not necessarily coincide along their common interface. Additionally, the present formulation leads to a computational approach that is very efficient and completely compatible with existing commercial software. The present interface element has been implemented in the commercial finite element code ABAQUS as a User Element Subroutine (UEL), making it easy to test the approach for a wide range of problems. The interface element technology has been formulated to simulate delamination growth in composite laminates. Thanks to its special features, the interface element approach makes it possible to release portions of the interface surface whose length is smaller than that of the finite elements. In addition, the penalty parameter can vary within the interface element, allowing the damage model to be applied to a desired fraction of the interface between the two meshes. Results for double cantilever beam DCB, end-loaded split (ELS) and fixed-ratio mixed mode (FRMM) specimens are presented. These results are compared to measured data to assess the ability of the present damage model to simulate crack growth.
Rapid implementation of advanced constitutive models
NASA Astrophysics Data System (ADS)
Starman, Bojan; Halilovič, Miroslav; Vrh, Marko; Štok, Boris
2013-12-01
This paper presents a methodology based on the NICE integration scheme [1, 2] for simple and rapid numerical implementation of a class of plasticity constitutive models. In this regard, an algorithm is purposely developed for the implementation of newly developed advanced constitutive models into explicit finite element framework. The methodology follows the organization of the problem state variables into an extended form, which allows the constitutive models' equations to be organized in such a way, that the algorithm can be optionally extended with minimal effort to integrate also evolution equations related to a description of other specific phenomena, such as damage, distortional hardening, phase transitions, degradation etc. To confirm simplicity of the program implementation, computational robustness, effectiveness and improved accuracy of the implemented integration algorithm, a deep drawing simulation of the cylindrical cup is considered as the case study, performed in ABAQUS/Explicit. As a fairly complex considered model, the YLD2004-18p model [3, 4] is first implemented via external subroutine VUMAT. Further, to give additional proof of the simplicity of the proposed methodology, a combination of the YLD2004-18p model and Gurson-Tvergaard-Needleman model (GTN) is considered. As demonstrated, the implementation is really obtained in a very simple way.
Failure analysis of AZ31 magnesium alloy sheets based on the extended GTN damage model
NASA Astrophysics Data System (ADS)
Wang, Rui-ze; Chen, Zhang-hua; Li, Yu-jie; Dong, Chao-fang
2013-12-01
Based on the Gurson-Tvergaard-Needleman (GTN) model and Hill's quadratic anisotropic yield criterion, a combined experimental-numerical study on fracture initiation in the process of thermal stamping of Mg alloy AZ31 sheets was carried out. The aim is to predict the formability of thermal stamping of the Mg alloy sheets at different temperatures. The presented theoretical framework was implemented into a VUMAT subroutine for ABAQUS/EXPLICIT. Internal damage evolution due to void growth and coalescence developed at different temperatures in the Mg alloy sheets was observed by scanning electron microscopy (SEM). Moreover, the thermal effects on the void growth, coalescence, and fracture behavior of the Mg alloy sheets were analyzed by the extended GTN model and forming limit diagrams (FLD). Parameters employed in the GTN model were determined from tensile tests and numerical iterative computation. The distribution of major and minor principal strains in the specimens was determined from the numerical results. Therefore, the corresponding forming limit diagrams at different stress levels and temperatures were drawn. The comparison between the predicted forming limits and the experimental data shows a good agreement.
Constitutive modeling of polycarbonate over a wide range of strain rates and temperatures
NASA Astrophysics Data System (ADS)
Wang, Haitao; Zhou, Huamin; Huang, Zhigao; Zhang, Yun; Zhao, Xiaoxuan
2016-06-01
The mechanical behavior of polycarbonate was experimentally investigated over a wide range of strain rates ( 10^{-4} to 5× 103 s^{-1}) and temperatures (293 to 353 K). Compression tests under these conditions were performed using a SHIMADZU universal testing machine and a split Hopkinson pressure bar. Falling weight impact testing was carried out on an Instron Dynatup 9200 drop tower system. The rate- and temperature-dependent deformation behavior of polycarbonate was discussed in detail. Dynamic mechanical analysis (DMA) tests were utilized to observe the glass ( α ) transition and the secondary ( β ) transition of polycarbonate. The DMA results indicate that the α and β transitions have a dramatic influence on the mechanical behavior of polycarbonate. The decompose/shift/reconstruct (DSR) method was utilized to decompose the storage modulus into the α and β components and extrapolate the entire modulus, the α-component modulus and the β-component modulus. Based on three previous models, namely, Mulliken-Boyce, G'Sell-Jonas and DSGZ, an adiabatic model is proposed to predict the mechanical behavior of polycarbonate. The model considers the contributions of both the α and β transitions to the mechanical behavior, and it has been implemented in ABAQUS/Explicit through a user material subroutine VUMAT. The model predictions are proven to essentially coincide with the experimental results during compression testing and falling weight impact testing.
An efficient FE-SBFE coupled method for mesoscale cohesive fracture modelling of concrete
NASA Astrophysics Data System (ADS)
Huang, Y. J.; Yang, Z. J.; Liu, G. H.; Chen, X. W.
2016-10-01
This study develops a method coupling the finite element method (FEM) and the scaled boundary finite element method (SBFEM) for efficient meso-scale fracture modelling of concrete for the first time. In this method, the aggregates are modelled by SBFE polygons with boundaries discretised only, while the mortar matrix is modelled by conventional finite elements. The semi-analytical SBFEM is implemented in ABAQUS by a user-defined element subroutine for the first time. Nonlinear cohesive interface elements with normal and shear traction-separation constitutive laws are pre-inserted within the mortar and on the aggregate-mortar interfaces to simulate potential cracks. Various meso-structures generated from both random aggregates and X-ray computed tomography images are modelled. The results demonstrate that the coupled method leads to considerable reductions in degrees of freedom and computational time against the conventional FEM, and these reductions become more significant when the aggregate volume fraction increases. The modelled crack paths and load-carrying capacities of a three-point bending beam and an L-shaped panel are in excellent agreement with the experimental data.
NASA Astrophysics Data System (ADS)
Bong, Hyuk Jong; Barlat, Frédéric; Lee, Myoung-Gyu
2016-08-01
Formability increase in non-conventional forming profiles programmed in the servo-press was investigated using finite element analysis. As an application, forming experiment on a 0.15-mm-thick ferritic stainless steel sheet for a bipolar plate, a primary component of a proton exchange membrane fuel cell, was conducted. Four different forming profiles were considered to investigate the effects of forming profiles on formability and shape accuracy. The four motions included conventional V motion, holding motion, W motion, and oscillating motion. Among the four motions, the holding motion, in which the slide was held for a certain period at the bottom dead point, led to the best formability. Finite element simulations were conducted to validate the experimental results and to probe the formability improvement in the non-conventional forming profiles. A creep model to address stress relaxation effect along with tool elastic recovery was implemented using a user-material subroutine, CREEP in ABAQUS finite element software. The stress relaxation and variable contact conditions during the holding and oscillating profiles were found to be the main mechanism of formability improvement.
A Simulation for the Punchless Piercing Process using Lemaitre Damage Model
Lee, Sang Wook; Pourboghrat, Farhang
2005-08-05
The punchless piercing is a process that uses highly pressurized fluid instead of the conventional punch to make holes into the sheet metal. This process has many advantages over the conventional method for piercing various shaped holes into very thin strips of metal, composite, etc. An important cost advantage comes from not having to use a punch. Another important advantage comes from the top quality of pierced holes produced by punchless piercing, as no secondary finishing process will be needed for removing burrs typically found in conventional cutting processes. The ABAQUS/Explicit FEM code coupled with Lemaitre damage model has been used to more precisely characterize the punchless piercing process. The formulation adopted for this purpose focuses on the development of an efficient stress integration algorithm and development of a user material subroutine (VUMAT). For verification, the computed results have been compared with those of the experimental results in the literature and shown to be in good agreement with each other. The results obtained from this work are expected to be of significant interest to automotive and aerospace industries interested in using the punchless piercing process.
Meso-Scale Damage Simulation of 3D Braided Composites under Quasi-Static Axial Tension
NASA Astrophysics Data System (ADS)
Zhang, Chao; Mao, Chunjian; Zhou, Yexin
2017-01-01
The microstructure of 3D braided composites is composed of three phases: braiding yarn, matrix and interface. In this paper, a representative unit-cell (RUC) model including these three phases is established. Coupling with the periodical boundary condition, the damage behavior of 3D braided composites under quasi-static axial tension is simulated by using finite element method based on this RUC model. An anisotropic damage model based on Murakami damage theory is proposed to predict the damage evolution of yarns and matrix; a damage-friction combination interface constitutive model is adopted to predict the interface debonding behavior. A user material subroutine (VUMAT) involving these damage models is developed and implemented in the finite element software ABAQUS/Explicit. The whole process of damage evolution of 3D braided composites under quasi-static axial tension with typical braiding angles is simulated, and the damage mechanisms are revealed in detail in the simulation process. The tensile strength properties of the braided composites are predicted from the calculated stress-strain curves. Numerical results agree with the available experiment data and thus validates the proposed damage analysis model. The effects of certain material parameters on the predicted stress-strain responses are also discussed by numerical parameter study.
A viscoelastic poromechanical model of the knee joint in large compression.
Kazemi, M; Li, L P
2014-08-01
The elastic response of the knee joint in various loading and pathological conditions has been investigated using anatomically accurate geometry. However, it is still challenging to predict the poromechanical response of the knee in realistic loading conditions. In the present study, a viscoelastic, poromechanical model of the knee joint was developed for soft tissues undergoing large deformation. Cartilages and menisci were modeled as fibril-reinforced porous materials and ligaments were considered as fibril-reinforced hyperelastic solids. Quasi-linear viscoelasticty was formulated for the collagen network of these tissues and nearly incompressible Neo-Hookean hyperelasticity was used for the non-fibrillar matrix. The constitutive model was coded with a user defined FORTRAN subroutine, in order to use ABAQUS for the finite element analysis. Creep and stress relaxation were investigated with large compression of the knee in full extension. The contact pressure distributions were found similar in creep and stress relaxation. However, the load transfer in the joint was completely different in these two loading scenarios. During creep, the contact pressure between cartilages decreased but the pressure between cartilage and meniscus increased with time. This led to a gradual transfer of some loading from the central part of cartilages to menisci. During stress relaxation, however, both contact pressures decreased monotonically.
NASA Technical Reports Server (NTRS)
Leone, Frank A., Jr.
2015-01-01
A method is presented to represent the large-deformation kinematics of intraply matrix cracks and delaminations in continuum damage mechanics (CDM) constitutive material models. The method involves the additive decomposition of the deformation gradient tensor into 'crack' and 'bulk material' components. The response of the intact bulk material is represented by a reduced deformation gradient tensor, and the opening of an embedded cohesive interface is represented by a normalized cohesive displacement-jump vector. The rotation of the embedded interface is tracked as the material deforms and as the crack opens. The distribution of the total local deformation between the bulk material and the cohesive interface components is determined by minimizing the difference between the cohesive stress and the bulk material stress projected onto the cohesive interface. The improvements to the accuracy of CDM models that incorporate the presented method over existing approaches are demonstrated for a single element subjected to simple shear deformation and for a finite element model of a unidirectional open-hole tension specimen. The material model is implemented as a VUMAT user subroutine for the Abaqus/Explicit finite element software. The presented deformation gradient decomposition method reduces the artificial load transfer across matrix cracks subjected to large shearing deformations, and avoids the spurious secondary failure modes that often occur in analyses based on conventional progressive damage models.
Multiscale Concrete Modeling of Aging Degradation
Hammi, Yousseff; Gullett, Philipp; Horstemeyer, Mark F.
2015-07-31
In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Giner et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].
NASA Astrophysics Data System (ADS)
Morelle, X. P.; Chevalier, J.; Bailly, C.; Pardoen, T.; Lani, F.
2017-01-01
The nonlinear deformation and fracture of RTM6 epoxy resin is characterized as a function of strain rate and temperature under various loading conditions involving uniaxial tension, notched tension, uniaxial compression, torsion, and shear. The parameters of the hardening law depend on the strain-rate and temperature. The pressure-dependency and hardening law, as well as four different phenomenological failure criteria, are identified using a subset of the experimental results. Detailed fractography analysis provides insight into the competition between shear yielding and maximum principal stress driven brittle failure. The constitutive model and a stress-triaxiality dependent effective plastic strain based failure criterion are readily introduced in the standard version of Abaqus, without the need for coding user subroutines, and can thus be directly used as an input in multi-scale modeling of fibre-reinforced composite material. The model is successfully validated against data not used for the identification and through the full simulation of the crack propagation process in the V-notched beam shear test.
Progressive Damage Modeling of Durable Bonded Joint Technology
NASA Technical Reports Server (NTRS)
Leone, Frank A.; Davila, Carlos G.; Lin, Shih-Yung; Smeltzer, Stan; Girolamo, Donato; Ghose, Sayata; Guzman, Juan C.; McCarville, Duglas A.
2013-01-01
The development of durable bonded joint technology for assembling composite structures for launch vehicles is being pursued for the U.S. Space Launch System. The present work is related to the development and application of progressive damage modeling techniques to bonded joint technology applicable to a wide range of sandwich structures for a Heavy Lift Launch Vehicle. The joint designs studied in this work include a conventional composite splice joint and a NASA-patented Durable Redundant Joint. Both designs involve a honeycomb sandwich with carbon/epoxy facesheets joined with adhesively bonded doublers. Progressive damage modeling allows for the prediction of the initiation and evolution of damage. For structures that include multiple materials, the number of potential failure mechanisms that must be considered increases the complexity of the analyses. Potential failure mechanisms include fiber fracture, matrix cracking, delamination, core crushing, adhesive failure, and their interactions. The joints were modeled using Abaqus parametric finite element models, in which damage was modeled with user-written subroutines. Each ply was meshed discretely, and layers of cohesive elements were used to account for delaminations and to model the adhesive layers. Good correlation with experimental results was achieved both in terms of load-displacement history and predicted failure mechanisms.
CREEP MODELING FOR INJECTION-MOLDED LONG-FIBER THERMOPLASTICS
Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.
2008-06-30
This paper proposes a model to predict the creep response of injection-molded long-fiber thermoplastics (LFTs). The model accounts for elastic fibers embedded in a thermoplastic resin that exhibits the nonlinear viscoelastic behavior described by the Schapery’s model. It also accounts for fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber length and orientation distributions were measured and used in the analysis that applies the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption (termed as the Eshelby-Mori-Tanaka approach) and the fiber orientation averaging technique to compute the overall strain increment resulting from an overall constant applied stress during a given time increment. The creep model for LFTs has been implemented in the ABAQUS finite element code via user-subroutines and has been validated against the experimental creep data obtained for long-glass-fiber/polypropylene specimens. The effects of fiber orientation and length distributions on the composite creep response are determined and discussed.
NASA Astrophysics Data System (ADS)
Liu, P. F.; Gu, Z. P.; Hu, Z. H.
2016-11-01
Delamination is the dominating failure mechanism in composite adhesive joints. A deep insight into the delamination failure mechanism requires advanced numerical methods. Currently, cohesive-zone models (CZMs), in combination with the finite-element analysis (FEA), have become powerful tools for modeling the initiation and growth of delaminations in composites. However, ensuring the numerical convergence in the CZMs used for a delamination analysis of three-dimensional (3D) composite structures is always a challenging issue due to the "snap-back" instability in the nonlinear implicit FEA, which arises mainly from the cohesive softening behavior. Based on the midplane interpolation technique, first numerical techniques for implementing 3D bilinear and exponential CZMs by using ABAQUS-UEL (user element subroutine) are developed in this paper. In particular, a viscous regularization by introducing the damping effect into the stiffness equation is used to improve the convergence. Two examples, a single-lap composite joint and a composite skin/stiffener panel under tension, demonstrate the numerical technique developed. Then, the effect of cohesion parameters on the numerical convergence based on the viscous regularization is studied.
Li, N.; Mohamed, M. S.; Cai, J.; Lin, J.; Balint, D.; Dean, T. A.
2011-05-04
Formability of steel and aluminium alloys in hot stamping and cold die quenching processes is studied in this research. Viscoplastic-damage constitutive equations are developed and determined from experimental data for the prediction of viscoplastic flow and ductility of the materials. The determined unified constitutive equations are then implemented into the commercial Finite Element code Abaqus/Explicit via a user defined subroutine, VUMAT. An FE process simulation model and numerical procedures are established for the modeling of hot stamping processes for a spherical part with a central hole. Different failure modes (failure takes place either near the central hole or in the mid span of the part) are obtained. To validate the simulation results, a test programme is developed, a test die set has been designed and manufactured, and tests have been carried out for the materials with different forming rates. It has been found that very close agreements between experimental and numerical process simulation results are obtained for the ranges of temperatures and forming rates carried out.
NASA Technical Reports Server (NTRS)
De Carvalho, Nelson V.; Krueger, Ronald
2016-01-01
A new methodology is proposed to model the onset and propagation of matrix cracks and delaminations in carbon-epoxy composites subject to fatigue loading. An extended interface element, based on the Floating Node Method, is developed to represent delaminations and matrix cracks explicitly in a mesh independent fashion. Crack propagation is determined using an element-based Virtual Crack Closure Technique approach to determine mixed-mode energy release rates, and the Paris-Law relationship to obtain crack growth rate. Crack onset is determined using a stressbased onset criterion coupled with a stress vs. cycle curve and Palmgren-Miner rule to account for fatigue damage accumulation. The approach is implemented in Abaqus/Standard® via the user subroutine functionality. Verification exercises are performed to assess the accuracy and correct implementation of the approach. Finally, it was demonstrated that this approach captured the differences in failure morphology in fatigue for two laminates of identical stiffness, but with layups containing ?deg plies that were either stacked in a single group, or distributed through the laminate thickness.
Experimental and Numerical Analysis of Notched Composites Under Tension Loading
NASA Astrophysics Data System (ADS)
Aidi, Bilel; Case, Scott W.
2015-12-01
Experimental quasi-static tests were performed on center notched carbon fiber reinforced polymer (CFRP) composites having different stacking sequences made of G40-600/5245C prepreg. The three-dimensional Digital Image Correlation (DIC) technique was used during quasi-static tests conducted on quasi-isotropic notched samples to obtain the distribution of strains as a function of applied stress. A finite element model was built within Abaqus to predict the notched strength and the strain profiles for comparison with measured results. A user-material subroutine using the multi-continuum theory (MCT) as a failure initiation criterion and an energy-based damage evolution law as implemented by Autodesk Simulation Composite Analysis (ASCA) was used to conduct a quantitative comparison of strain components predicted by the analysis and obtained in the experiments. Good agreement between experimental data and numerical analyses results are observed. Modal analysis was carried out to investigate the effect of static damage on the dominant frequencies of the notched structure using the resulted degraded material elements. The first in-plane mode was found to be a good candidate for tracking the level of damage.
NASA Astrophysics Data System (ADS)
Abghary, Mohammad Javad; Nedoushan, Reza Jafari; Hasani, Hossein
2016-11-01
In this paper a multi-scale numerical model for simulating the mechanical behavior of biaxial weft knitted fabrics produced based on 1×1 rib structure is presented. Fabrics were produced on a modern flat knitting machine using polyester as stitch yarns and nylon as straight yarns. A macro constitutive equation was presented to model the fabric mechanical behavior as a continuum material. User defined material subroutines were provided to implement the constitutive behavior in Abaqus software. The constitutive equation needs remarkable tensile tests on the fabric as the inputs. To solve this drawbacks meso scale modeling of the fabric was used to predict stress-strain curves of the fabric in three different directions (course, wale and 45°). In these simulations only the yarn properties are needed. To evaluate the accuracy of the proposed macro and meso models, fabric tensile behavior in 22.5 and 67.5° directions were simulated by the calibrated macro model and compared with experimental results. Spherical deformation was also simulated by the multi scale model and compared with experimental results. The results showed that the multi-scale modeling can successfully predict the tensile and spherical deformation of the biaxial weft knitted fabric with least required experiments. This model will be useful for composite applications.
NASA Astrophysics Data System (ADS)
Lee, C. H.; Yang, D. Y.; Lee, S. R.; Chang, I. G.; Lee, T. W.
2011-08-01
The shielded slot plate, which has a sheared corrugated trapezoidal pattern, is a component of the metallic bipolar plate for the molten carbonate fuel cell (MCFC). In order to increase the efficiency of the fuel cell, the unit cell of the shielded slot plate should have a relatively large upper area. Additionally, defects from the forming process should be minimized. In order to simulate the slitting process, whereby sheared corrugated patterns are formed, ductile fracture criteria based on the histories of stress and strain are employed. The user material subroutine VUMAT is employed for implementation of the material and ductile fracture criteria in the commercial FEM software ABAQUS. The variables of the ductile fracture criteria were determined by comparing the simulation results and the experimental results of the tension test and the shearing test. Parametric studies were conducted to determine the critical value of the ductile fracture criterion. Employing these ductile fracture criteria, the three dimensional forming process of the shielded slot plate was numerically simulated. The effects of the slitting process in the forming process of the shielded slot plate were analyzed through a FEM simulation and experimental studies. Finally, experiments involving microscopic and macroscopic observations were conducted to verify the numerical simulations of the 3-step forming process.
NASA Astrophysics Data System (ADS)
Li, N.; Mohamed, M. S.; Cai, J.; Lin, J.; Balint, D.; Dean, T. A.
2011-05-01
Formability of steel and aluminium alloys in hot stamping and cold die quenching processes is studied in this research. Viscoplastic-damage constitutive equations are developed and determined from experimental data for the prediction of viscoplastic flow and ductility of the materials. The determined unified constitutive equations are then implemented into the commercial Finite Element code Abaqus/Explicit via a user defined subroutine, VUMAT. An FE process simulation model and numerical procedures are established for the modeling of hot stamping processes for a spherical part with a central hole. Different failure modes (failure takes place either near the central hole or in the mid span of the part) are obtained. To validate the simulation results, a test programme is developed, a test die set has been designed and manufactured, and tests have been carried out for the materials with different forming rates. It has been found that very close agreements between experimental and numerical process simulation results are obtained for the ranges of temperatures and forming rates carried out.
Constitutive modeling of polycarbonate over a wide range of strain rates and temperatures
NASA Astrophysics Data System (ADS)
Wang, Haitao; Zhou, Huamin; Huang, Zhigao; Zhang, Yun; Zhao, Xiaoxuan
2017-02-01
The mechanical behavior of polycarbonate was experimentally investigated over a wide range of strain rates (10^{-4} to 5× 103 s^{-1}) and temperatures (293 to 353 K). Compression tests under these conditions were performed using a SHIMADZU universal testing machine and a split Hopkinson pressure bar. Falling weight impact testing was carried out on an Instron Dynatup 9200 drop tower system. The rate- and temperature-dependent deformation behavior of polycarbonate was discussed in detail. Dynamic mechanical analysis (DMA) tests were utilized to observe the glass (α ) transition and the secondary (β ) transition of polycarbonate. The DMA results indicate that the α and β transitions have a dramatic influence on the mechanical behavior of polycarbonate. The decompose/shift/reconstruct (DSR) method was utilized to decompose the storage modulus into the α and β components and extrapolate the entire modulus, the α-component modulus and the β-component modulus. Based on three previous models, namely, Mulliken-Boyce, G'Sell-Jonas and DSGZ, an adiabatic model is proposed to predict the mechanical behavior of polycarbonate. The model considers the contributions of both the α and β transitions to the mechanical behavior, and it has been implemented in ABAQUS/Explicit through a user material subroutine VUMAT. The model predictions are proven to essentially coincide with the experimental results during compression testing and falling weight impact testing.
Mechanical modeling of self-expandable stent fabricated using braiding technology.
Kim, Ju Hyun; Kang, Tae Jin; Yu, Woong-Ryeol
2008-11-14
The mechanical behavior of a stent is one of the important factors involved in ensuring its opening within arterial conduits. This study aimed to develop a mechanical model for designing self-expandable stents fabricated using braiding technology. For this purpose, a finite element model was constructed by developing a preprocessing program for the three-dimensional geometrical modeling of the braiding structure inside stents, and validated for various stents with different braiding structures. The constituent wires (Nitinol) in the braided stents were assumed to be superelastic material and their mechanical behavior was incorporated into the finite element software through a user material subroutine (VUMAT in ABAQUS) employing a one-dimensional superelastic model. For the verification of the model, several braided stents were manufactured using an automated braiding machine and characterized focusing on their compressive behavior. It was observed that the braided stents showed a hysteresis between their loading and unloading behavior when a compressive load was applied to the braided tube. Through the finite element analysis, it was concluded that the current mechanical model can appropriately predict the mechanical behavior of braided stents including such hysteretic behavior, and that the hysteresis was caused by the slippage between the constituent wires and their superelastic property.
NASA Astrophysics Data System (ADS)
Yang, Dong-Yol; Lee, Chang-Whan; Kang, Dong-Woo; Chang, In-Gab; Lee, Tae-Won
2013-05-01
The shielded slot plate, a repeated structure of high sheared protrusions, is a major component of metallic bipolar plates for the molten carbonate fuel cell (MCFC). In order to increase the efficiency of the MCFC and long-term operation capability, the sheared protrusion should have a relatively large flat contact area. In addition, defects from the forming process such as local thinning should be minimized. In this work, the preform shape in the three-stage forming process that integrates the slitting process, the preforming process, and the final forming process was optimized to minimize the effective plastic strain. In the simulation of the forming process, the ductile fracture criterion was employed to the user material subroutine VUMAT in ABAQUS/Explicit. Steepest descent method was utilized in the design of the forming process to minimize equivalent plastic strain. High sheared protrusions were manufactured without defects from the three-stage forming process using the optimized preform shape. The minimum thickness of one sheared protrusion was increased by 25% over that of the two-stage forming process. The three-stage forming process using the optimized preform shape enables more uniformly distributed deformation and reduces localized deformation.
Wang, XinJie; Wu, YanQing; Huang, FengLei
2017-01-05
A mesoscopic framework is developed to quantify the thermal-mechanical-chemical responses of polymer-bonded explosive (PBX) samples under impact loading. A mesoscopic reactive model is developed for the cyclotetramethylenetetranitramine (HMX) crystal, which incorporates nonlinear elasticity, crystal plasticity, and temperature-dependent chemical reaction. The proposed model was implemented in the finite element code ABAQUS by the user subroutine VUMAT. A series of three-dimensional mesoscale models were constructed and calculated under low-strength impact loading scenarios from 100m/s to 600m/s where only the first wave transit is studied. Crystal anisotropy and microstructural heterogeneity are responsible for the nonuniform stress field and fluctuations of the stress wave front. At a critical impact velocity (≥300m/s), a chemical reaction is triggered because the temperature contributed by the volumetric and plastic works is sufficiently high. Physical quantities, including stress, temperature, and extent of reaction, are homogenized from those across the microstructure at the mesoscale to compare with macroscale measurements, which will advance the continuum-level models. The framework presented in this study has important implications in understanding hot spot ignition processes and improving predictive capabilities in energetic materials.
Hosseinzadeh, M; Ghoreishi, M; Narooei, K
2016-06-01
In this study, the hyperelastic models of demineralized and deproteinized bovine cortical femur bone were investigated and appropriate models were developed. Using uniaxial compression test data, the strain energy versus stretch was calculated and the appropriate hyperelastic strain energy functions were fitted on data in order to calculate the material parameters. To obtain the mechanical behavior in other loading conditions, the hyperelastic strain energy equations were investigated for pure shear and equi-biaxial tension loadings. The results showed the Mooney-Rivlin and Ogden models cannot predict the mechanical response of demineralized and deproteinized bovine cortical femur bone accurately, while the general exponential-exponential and general exponential-power law models have a good agreement with the experimental results. To investigate the sensitivity of the hyperelastic models, a variation of 10% in material parameters was performed and the results indicated an acceptable stability for the general exponential-exponential and general exponential-power law models. Finally, the uniaxial tension and compression of cortical femur bone were studied using the finite element method in VUMAT user subroutine of ABAQUS software and the computed stress-stretch curves were shown a good agreement with the experimental data.
A Simulation for the Punchless Piercing Process using Lemaitre Damage Model
NASA Astrophysics Data System (ADS)
Lee, Sang Wook; Pourboghrat, Farhang
2005-08-01
The punchless piercing is a process that uses highly pressurized fluid instead of the conventional punch to make holes into the sheet metal. This process has many advantages over the conventional method for piercing various shaped holes into very thin strips of metal, composite, etc. An important cost advantage comes from not having to use a punch. Another important advantage comes from the top quality of pierced holes produced by punchless piercing, as no secondary finishing process will be needed for removing burrs typically found in conventional cutting processes. The ABAQUS/Explicit FEM code coupled with Lemaitre damage model has been used to more precisely characterize the punchless piercing process. The formulation adopted for this purpose focuses on the development of an efficient stress integration algorithm and development of a user material subroutine (VUMAT). For verification, the computed results have been compared with those of the experimental results in the literature and shown to be in good agreement with each other. The results obtained from this work are expected to be of significant interest to automotive and aerospace industries interested in using the punchless piercing process.
Failure Analysis of Warm Stamping of Magnesium Alloy Sheet Based on an Anisotropic Damage Model
NASA Astrophysics Data System (ADS)
Zhao, P. J.; Chen, Z. H.; Dong, C. F.
2014-11-01
Based on the frame work of continuum damage mechanics, a research work of anisotropic damage evolution in warm stamping process of magnesium alloy sheets has been carried out by means of a combined experimental-numerical method. The aim was to predict formability of warm stamping of AZ31 Mg alloy sheets by taking the thermal and damage effects into account. In the presented work, a temperature-dependent anisotropic yield function suitable for cold rolling sheet metals together with an anisotropic damage model was implemented into the a VUMAT subroutine for ABAQUS/EXPLICIT. The evolution of internal damage in the form of void growth and coalescence in AZ31 Mg alloy sheet was observed by means of scanning electron microscopy (SEM). Moreover, a coupled thermo-mechanical simulation of the stamping process was performed using the implemented code at different temperatures. The parameters employed in the simulation were determined by the standard tensile tests and algebraic manipulation. The overall anisotropic damage process from crack initiation to final propagation in local area of blank was simulated. Numerical results show that the prediction of the site of crack initiation and the orientation of crack propagation are consistent with the data observed in warm stamping experiments.
Investigation on low velocity impact resistance of SMA composite material
NASA Astrophysics Data System (ADS)
Hu, Dianyin; Zhang, Long; Wang, Rongqiao; Zhang, Xiaoyong
2016-04-01
A method to improve low velocity impact resistance of aeroengine composite casing using shape memory alloy's properties of shape memory(SM) and super-elasticity(SE) is proposed in this study. Firstly, a numerical modeling of SMA reinforced composite laminate under low velocity impact load with impact velocity of 10 m/s is established based on its constitutive model implemented by the VUMAT subroutine of commercial software ABAQUS. Secondly, the responses of SMA composite laminate including stress and deflection distributions were achieved through transient analysis under low velocity impact load. Numerical results show that both peak stress and deflection values of SMA composite laminate are less than that without SMA, which proves that embedding SMA into the composite structure can effectively improve the low velocity impact performance of composite structure. Finally, the influence of SM and SE on low velocity impact resistance is quantitatively investigated. The values of peak stress and deflection of SMA composite based on SM property decrease by 18.28% and 9.43% respectively, compared with those without SMA, instead of 12.87% and 5.19% based on SE. In conclusion, this proposed model described the impact damage of SMA composite structure and turned to be a more beneficial method to enhance the impact resistance by utilizing SM effect.
Identification and comparison of different constitutive laws for high speed solicitation
NASA Astrophysics Data System (ADS)
Sattouf, C.; Dalverny, O.; Rakotomalala, R.
2003-09-01
This paper deals with a methodology for the identification of constitutive laws for metallic materials under dynamic loading at high strain rates. Different constitutive elastoplastic behaviors are compared to represent several materials such as 42CD4 steel or aluminum alloy A2017T3. The classical radial return algorithm is used to integrate the elastoplasticity law with a mixed isotropic/kinematic hardening. The theory has been used to implement the constitutive law in Abaqus/Explicit Vumat subroutine. In the second part we present the different types of elastoplastic hardening laws such as Johnson-Cook, modified Johnson-Cook, Zerilli-Armstrong or Simo. We discuss the different forms of the laws and their taking into account of strain rates, speed and temperature. The iterative procedure for the identification uses an experimental set of parameters (from a Taylor impact test) which are compared with an other set of numerical values. The method to converge to the optimal solution uses a combined Monte-Carlo and Levenberg-Marquardt algorithm. The study ends with a comparative discussion about the laws and the problems encountered during their identification for two materials: a 42CD4 steel, and an aluminum 2017T3.
Low-Velocity Impact Response and Finite Element Analysis of Four-Step 3-D Braided Composites
NASA Astrophysics Data System (ADS)
Sun, Baozhong; Zhang, Yan; Gu, Bohong
2013-08-01
The low-velocity impact characters of 3-D braided carbon/epoxy composites were investigated from experimental and finite element simulation approaches. The quasi-static tests were carried out at a constant velocity of 2 mm/min on MTS 810.23 material tester system to obtain the indentation load-displacement curves and indentation damages. The low-velocity tests were conducted at the velocities from 1 m/s to 6 m/s (corresponding to the impact energy from 3.22 J to 116 J) on Instron Dynatup 9250 impact tester. The peak force, energy for peak force, time to peak force, and total energy absorption were obtained to determine the impact responses of 3-D braided composites. A unit cell model was established according to the microstructure of 3-D braided composites to derive the constitutive equation. Based on the model, a user-defined material subroutine (VUMAT) has been compiled by FORTRAN and connected with commercial finite element code ABAQUS/Explicit to calculate the impact damage. The unit cell model successfully predicted the impact response of 3-D braided composites. Furthermore, the stress wave propagation and failure mechanisms have been revealed from the finite element simulation results and ultimate damage morphologies of specimens.
DAMAGE MODELING OF INJECTION-MOLDED SHORT- AND LONG-FIBER THERMOPLASTICS
Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.; Phelps, Jay; Tucker III, Charles L.
2009-10-30
This article applies the recent anisotropic rotary diffusion – reduced strain closure (ARD-RSC) model for predicting fiber orientation and a new damage model for injection-molded long-fiber thermoplastics (LFTs) to analyze progressive damage leading to total failure of injection-molded long-glass-fiber/polypropylene (PP) specimens. The ARD-RSC model was implemented in a research version of the Autodesk Moldflow Plastics Insight (MPI) processing code, and it has been used to simulate injection-molding of a long-glass-fiber/PP plaque. The damage model combines micromechanical modeling with a continuum damage mechanics description to predict the nonlinear behavior due to plasticity coupled with damage in LFTs. This model has been implemented in the ABAQUS finite element code via user-subroutines and has been used in the damage analyses of tensile specimens removed from the injection-molded long-glass-fiber/PP plaques. Experimental characterization and mechanical testing were performed to provide input data to support and validate both process modeling and damage analyses. The predictions are in agreement with the experimental results.
NASA Astrophysics Data System (ADS)
Alsaleh, Mustafa I.; Voyiadjis, George Z.; Alshibli, Khalid A.
2006-12-01
It has been known that classical continuum mechanics laws fail to describe strain localization in granular materials due to the mathematical ill-posedness and mesh dependency. Therefore, a non-local theory with internal length scales is needed to overcome such problems. The micropolar and high-order gradient theories can be considered as good examples to characterize the strain localization in granular materials. The fact that internal length scales are needed requires micromechanical models or laws; however, the classical constitutive models can be enhanced through the stress invariants to incorporate the Micropolar effects. In this paper, Lade's single hardening model is enhanced to account for the couple stress and Cosserat rotation and the internal length scales are incorporated accordingly. The enhanced Lade's model and its material properties are discussed in detail; then the finite element formulations in the Updated Lagrangian Frame (UL) are used. The finite element formulations were implemented into a user element subroutine for ABAQUS (UEL) and the solution method is discussed in the companion paper. The model was found to predict the strain localization in granular materials with low dependency on the finite element mesh size. The shear band was found to reflect on a certain angle when it hit a rigid boundary. Applications for the model on plane strain specimens tested in the laboratory are discussed in the companion paper. Copyright
Computer Simulation of Digital Signal Modulation Techniques in Satellite Communications.
1985-09-01
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Meso-damage modelling of polymer based particulate composites using finite element technique
NASA Astrophysics Data System (ADS)
Tsui, Chi Pong
To develop a new particulate polymer composite (PPC) with desired mechanical properties is usually accomplished by an experimental trial-and-error approach. A new technique, which predicts the damage mechanism and its effects on the mechanical properties of PPC, has been proposed. This meso-mechanical modelling technique, which offers a means to bridge the micro-damage mechanism and the macro-structural behaviour, has been implemented in a finite element code. A three-dimensional finite element meso-cell model has been designed and constructed to simulate the damage mechanism of PPC. The meso-cell model consists of a micro-particle, an interface, and a matrix. The initiation of the particle/polymer matrix debonding process has been predicted on the basis of a tensile criterion. By considering the meso-cell model as a representative volume element (RVE), the effects of damage on the macro-structural constitutive behaviour of PPC have been determined. An experimental investigation has been made on glass beads (GB) reinforced polyphenylene oxides (PPO) for verification of the meso-cell model and the meso-mechanical finite element technique. The predicted constitutive relation has been found to be in good agreement with the experimental results. The results of the in-situ microscopic test also verify the correctness of the meso-cell model. The application of the meso-mechanical finite element modelling technique has been extended to a macro-structural analysis to simulate the response an engineering structure made of PPC under a static load. In the simulation, a damage variable has been defined in terms of the computational results of the cell model in meso-scale. Hence, the damage-coupled constitutive relation of the GB/PPO composite could be derived. A user-defined subroutine VUMAT in FORTRAN language describing the damage-coupled constitutive behaviour has then been incorporated into the ABAQUS finite element code. On a macro-scale, the ABAQUS finite element code
On the mechanics of growing thin biological membranes
NASA Astrophysics Data System (ADS)
Rausch, Manuel K.; Kuhl, Ellen
2014-02-01
Despite their seemingly delicate appearance, thin biological membranes fulfill various crucial roles in the human body and can sustain substantial mechanical loads. Unlike engineering structures, biological membranes are able to grow and adapt to changes in their mechanical environment. Finite element modeling of biological growth holds the potential to better understand the interplay of membrane form and function and to reliably predict the effects of disease or medical intervention. However, standard continuum elements typically fail to represent thin biological membranes efficiently, accurately, and robustly. Moreover, continuum models are typically cumbersome to generate from surface-based medical imaging data. Here we propose a computational model for finite membrane growth using a classical midsurface representation compatible with standard shell elements. By assuming elastic incompressibility and membrane-only growth, the model a priori satisfies the zero-normal stress condition. To demonstrate its modular nature, we implement the membrane growth model into the general-purpose non-linear finite element package Abaqus/Standard using the concept of user subroutines. To probe efficiently and robustness, we simulate selected benchmark examples of growing biological membranes under different loading conditions. To demonstrate the clinical potential, we simulate the functional adaptation of a heart valve leaflet in ischemic cardiomyopathy. We believe that our novel approach will be widely applicable to simulate the adaptive chronic growth of thin biological structures including skin membranes, mucous membranes, fetal membranes, tympanic membranes, corneoscleral membranes, and heart valve membranes. Ultimately, our model can be used to identify diseased states, predict disease evolution, and guide the design of interventional or pharmaceutic therapies to arrest or revert disease progression.
Alemi-Ardakani, M; Milani, A S; Yannacopoulos, S
2014-01-01
Impact modeling of fiber reinforced polymer composites is a complex and challenging task, in particular for practitioners with less experience in advanced coding and user-defined subroutines. Different numerical algorithms have been developed over the past decades for impact modeling of composites, yet a considerable gap often exists between predicted and experimental observations. In this paper, after a review of reported sources of complexities in impact modeling of fiber reinforced polymer composites, two simplified approaches are presented for fast simulation of out-of-plane impact response of these materials considering four main effects: (a) strain rate dependency of the mechanical properties, (b) difference between tensile and flexural bending responses, (c) delamination, and (d) the geometry of fixture (clamping conditions). In the first approach, it is shown that by applying correction factors to the quasistatic material properties, which are often readily available from material datasheets, the role of these four sources in modeling impact response of a given composite may be accounted for. As a result a rough estimation of the dynamic force response of the composite can be attained. To show the application of the approach, a twill woven polypropylene/glass reinforced thermoplastic composite laminate has been tested under 200 J impact energy and was modeled in Abaqus/Explicit via the built-in Hashin damage criteria. X-ray microtomography was used to investigate the presence of delamination inside the impacted sample. Finally, as a second and much simpler modeling approach it is shown that applying only a single correction factor over all material properties at once can still yield a reasonable prediction. Both advantages and limitations of the simplified modeling framework are addressed in the performed case study.
A viscoplastic model of expanding cylindrical shells subjected to internal explosive detonations
Martineau, Rick L.
1998-04-01
Magnetic flux compression generators rely on the expansion of thin ductile shells to generate magnetic fields. These thin shells are filled with high explosives, which when detonated, cause the shell to expand to over 200% strain at strain-rates on the order of 10^{4} s^{-1}. Experimental data indicate the development and growth of multiple plastic instabilities which appear in a quasi-periodic pattern on the surfaces of the shells. These quasi-periodic instabilities are connected by localized zones of intense shear that are oriented approximately 45° from the outward radial direction. The quasi-periodic instabilities continue to develop and eventually become through-cracks, causing the shell to fragment. A viscoplastic constitutive model is formulated to model the high strain-rate expansion and provide insight into the development of plastic instabilities. The formulation of the viscoplastic constitutive model includes the effects of shock heating and damage in the form of microvoid nucleation, growth, and coalescence in the expanding shell. This model uses the Johnson-Cook strength model with the Mie-Grueneisen equation of state and a modified Gurson yield surface. The constitutive model includes the modifications proposed by Tvergaard and the plastic strain controlled nucleation introduced by Neeleman. The constitutive model is implemented as a user material subroutine into ABAQUS/Explicit, which is a commercially available nonlinear explicit dynamic finite element program. A cylindrical shell is modeled using both axisymmetric and plane strain elements. Two experiments were conducted involving plane wave detonated, explosively filled, copper cylinders. Instability, displacement, and velocity data were recorded using a fast framing camera and a Fabry-Perot interferometer. Good agreement is shown between the numerical results and experimental data. An additional explosively bulged cylinder experiment was also performed and a photomicrograph of an
Mechanical behavior of silica nanoparticle-impregnated Kevlar fabrics
NASA Astrophysics Data System (ADS)
Dong, Zhaoxu
Plain woven Kevlar fabrics are widely used as body protection materials. The present study investigated the impact performance of five styles of Kevlar fabrics K310, K706, K720, K745 and K779 from Hexcel. The fabrics are different in many aspects, i.e., weight per square meter, yarn counts, yarn size, Kevlar fiber type, friction and breaking strength. Silica nanoparticles were impregnated into the fabric to enhance the ballistic impact performance. The fabric impregnated with nanoparticles exhibit significant enhancement in impact performance over their neat counterparts. Fabrics experience large deformation under impact. More or less yarn pull-out was observed on all the fabrics. The in-plane yarn pull-out force has good correlation to the impact performance: fabrics with higher pull-out force performed better in impact tests. A two-dimensional finite element model was proposed to simulate the single yarn pull-out procedure and predict the maximum pull-out force. The most important fabric features are included in this model: yarn count, yarn size, fabric thickness, yarn waviness, fiber modulus, fiber diameter and coefficients of friction et al. The numerical results show good agreement with the experimentally measured pull-out forces. To understand the impact process, a constitutive model was developed to characterize the nonlinear anisotropic properties of the fabric in large deformation. The nanoparticles largely increase the shear stiffness, while only slightly affect the tension behavior along warp and weft yarn directions. This constitutive model was incorporated in the commercial FEA software ABAQUS through the user-defined material subroutine and used to simulate deformations with various loads. Finally the out-of-plane yarn pull-out force was predicted from the in-plane yarn pull-out results using finite element method and the proposed constitutive model.
Influence of Finite Element Size in Residual Strength Prediction of Composite Structures
NASA Technical Reports Server (NTRS)
Satyanarayana, Arunkumar; Bogert, Philip B.; Karayev, Kazbek Z.; Nordman, Paul S.; Razi, Hamid
2012-01-01
The sensitivity of failure load to the element size used in a progressive failure analysis (PFA) of carbon composite center notched laminates is evaluated. The sensitivity study employs a PFA methodology previously developed by the authors consisting of Hashin-Rotem intra-laminar fiber and matrix failure criteria and a complete stress degradation scheme for damage simulation. The approach is implemented with a user defined subroutine in the ABAQUS/Explicit finite element package. The effect of element size near the notch tips on residual strength predictions was assessed for a brittle failure mode with a parametric study that included three laminates of varying material system, thickness and stacking sequence. The study resulted in the selection of an element size of 0.09 in. X 0.09 in., which was later used for predicting crack paths and failure loads in sandwich panels and monolithic laminated panels. Comparison of predicted crack paths and failure loads for these panels agreed well with experimental observations. Additionally, the element size vs. normalized failure load relationship, determined in the parametric study, was used to evaluate strength-scaling factors for three different element sizes. The failure loads predicted with all three element sizes provided converged failure loads with respect to that corresponding with the 0.09 in. X 0.09 in. element size. Though preliminary in nature, the strength-scaling concept has the potential to greatly reduce the computational time required for PFA and can enable the analysis of large scale structural components where failure is dominated by fiber failure in tension.
On the mechanics of growing thin biological membranes
Rausch, Manuel K.; Kuhl, Ellen
2013-01-01
Despite their seemingly delicate appearance, thin biological membranes fulfill various crucial roles in the human body and can sustain substantial mechanical loads. Unlike engineering structures, biological membranes are able to grow and adapt to changes in their mechanical environment. Finite element modeling of biological growth holds the potential to better understand the interplay of membrane form and function and to reliably predict the effects of disease or medical intervention. However, standard continuum elements typically fail to represent thin biological membranes efficiently, accurately, and robustly. Moreover, continuum models are typically cumbersome to generate from surface-based medical imaging data. Here we propose a computational model for finite membrane growth using a classical midsurface representation compatible with standard shell elements. By assuming elastic incompressibility and membrane-only growth, the model a priori satisfies the zero-normal stress condition. To demonstrate its modular nature, we implement the membrane growth model into the general-purpose non-linear finite element package Abaqus/Standard using the concept of user subroutines. To probe efficiently and robustness, we simulate selected benchmark examples of growing biological membranes under different loading conditions. To demonstrate the clinical potential, we simulate the functional adaptation of a heart valve leaflet in ischemic cardiomyopathy. We believe that our novel approach will be widely applicable to simulate the adaptive chronic growth of thin biological structures including skin membranes, mucous membranes, fetal membranes, tympanic membranes, corneoscleral membranes, and heart valve membranes. Ultimately, our model can be used to identify diseased states, predict disease evolution, and guide the design of interventional or pharmaceutic therapies to arrest or revert disease progression. PMID:24563551
A study of hyperelastic models for predicting the mechanical behavior of extensor apparatus.
Elyasi, Nahid; Taheri, Kimia Karimi; Narooei, Keivan; Taheri, Ali Karimi
2017-01-16
In this research, the nonlinear elastic behavior of human extensor apparatus was investigated. To this goal, firstly the best material parameters of hyperelastic strain energy density functions consisting of the Mooney-Rivlin, Ogden, invariants, and general exponential models were derived for the simple tension experimental data. Due to the significance of stress response in other deformation modes of nonlinear models, the calculated parameters were used to study the pure shear and balance biaxial tension behavior of the extensor apparatus. The results indicated that the Mooney-Rivlin model predicts an unstable behavior in the balance biaxial deformation of the extensor apparatus, while the Ogden order 1 represents a stable behavior, although the fitting of experimental data and theoretical model was not satisfactory. However, the Ogden order 6 model was unstable in the simple tension mode and the Ogden order 5 and general exponential models presented accurate and stable results. In order to reduce the material parameters, the invariants model with four material parameters was investigated and this model presented the minimum error and stable behavior in all deformation modes. The ABAQUS Explicit solver was coupled with the VUMAT subroutine code of the invariants model to simulate the mechanical behavior of the central and terminal slips of the extensor apparatus during the passive finger flexion, which is important in the prediction of boutonniere deformity and chronic mallet finger injuries, respectively. Also, to evaluate the adequacy of constitutive models in simulations, the results of the Ogden order 5 were presented. The difference between the predictions was attributed to the better fittings of the invariants model compared with the Ogden model.
Earing Prediction in Cup Drawing using the BBC2008 Yield Criterion
NASA Astrophysics Data System (ADS)
Vrh, Marko; Halilovič, Miroslav; Starman, Bojan; Štok, Boris; Comsa, Dan-Sorin; Banabic, Dorel
2011-08-01
The paper deals with constitutive modelling of highly anisotropic sheet metals. It presents FEM based earing predictions in cup drawing simulation of highly anisotropic aluminium alloys where more than four ears occur. For that purpose the BBC2008 yield criterion, which is a plane-stress yield criterion formulated in the form of a finite series, is used. Thus defined criterion can be expanded to retain more or less terms, depending on the amount of given experimental data. In order to use the model in sheet metal forming simulations we have implemented it in a general purpose finite element code ABAQUS/Explicit via VUMAT subroutine, considering alternatively eight or sixteen parameters (8p and 16p version). For the integration of the constitutive model the explicit NICE (Next Increment Corrects Error) integration scheme has been used. Due to the scheme effectiveness the CPU time consumption for a simulation is comparable to the time consumption of built-in constitutive models. Two aluminium alloys, namely AA5042-H2 and AA2090-T3, have been used for a validation of the model. For both alloys the parameters of the BBC2008 model have been identified with a developed numerical procedure, based on a minimization of the developed cost function. For both materials, the predictions of the BBC2008 model prove to be in very good agreement with the experimental results. The flexibility and the accuracy of the model together with the identification and integration procedure guarantee the applicability of the BBC2008 yield criterion in industrial applications.
NASA Astrophysics Data System (ADS)
Wang, Changsheng; Chen, Jun; Xia, Cedric; Ren, Feng; Chen, Jieshi
2014-04-01
A new approach is presented in this paper to calculate the critical threshold value of fracture initiation. It is based on the experimental data for forming limit curves and fracture forming limit curves. The deformation path for finally a fractured material point is assumed as two-stage proportional loading: biaxial loading from the beginning to the onset of incipient necking, followed plane strain deformation within the incipient neck until the final fracture. The fracture threshold value is determined by analytical integration and validated by numerical simulation. Four phenomenological models for ductile fracture are selected in this study, i.e., Brozzo, McClintock, Rice-Tracey, and Oyane models. The threshold value for each model is obtained through best-fitting of experimental data. The results are compared with each other and test data. These fracture criteria are implemented in ABAQUS/EXPLICIT through user subroutine VUMAT to simulate the blanking process of advanced high-strength steels. The simulated fracture surfaces are examined to determine the initiation of ductile fracture during the process, and compared with experimental results for DP780 sheet steel blanking. The comparisons between FE simulated results coupled with different fracture models and experimental one show good agreements on punching edge quality. The study demonstrates that the proposed approach to calculate threshold values of fracture models is efficient and reliable. The results also suggest that the McClintock and Oyane fracture models are more accurate than the Rice-Tracey or Brozzo models in predicting load-stroke curves. However, the predicted blanking edge quality does not have appreciable differences.
Alemi-Ardakani, M.; Milani, A. S.; Yannacopoulos, S.
2014-01-01
Impact modeling of fiber reinforced polymer composites is a complex and challenging task, in particular for practitioners with less experience in advanced coding and user-defined subroutines. Different numerical algorithms have been developed over the past decades for impact modeling of composites, yet a considerable gap often exists between predicted and experimental observations. In this paper, after a review of reported sources of complexities in impact modeling of fiber reinforced polymer composites, two simplified approaches are presented for fast simulation of out-of-plane impact response of these materials considering four main effects: (a) strain rate dependency of the mechanical properties, (b) difference between tensile and flexural bending responses, (c) delamination, and (d) the geometry of fixture (clamping conditions). In the first approach, it is shown that by applying correction factors to the quasistatic material properties, which are often readily available from material datasheets, the role of these four sources in modeling impact response of a given composite may be accounted for. As a result a rough estimation of the dynamic force response of the composite can be attained. To show the application of the approach, a twill woven polypropylene/glass reinforced thermoplastic composite laminate has been tested under 200 J impact energy and was modeled in Abaqus/Explicit via the built-in Hashin damage criteria. X-ray microtomography was used to investigate the presence of delamination inside the impacted sample. Finally, as a second and much simpler modeling approach it is shown that applying only a single correction factor over all material properties at once can still yield a reasonable prediction. Both advantages and limitations of the simplified modeling framework are addressed in the performed case study. PMID:25431787
Failure behavior for composite single-bolted joints in double shear tension
NASA Astrophysics Data System (ADS)
Tang, Zhanwen; Liu, Hanyang; Yang, Zhiyong; Shi, Hanqiao; Sun, Baogang
2016-05-01
In order to improve the reliability and load carrying capacity of composite laminates structures which were lap jointed by bolt, in this paper, the failure strength and failure mode of laminated composite pinned-joints is investigated. To determine the effects of joint geometry and stacking sequence on the bearing strength and damage mode, the multi-scale numerical model combining with the Generalized Method of Cells (GMC) and considering the failure and the damage of constituent materials was created based on the ABAQUS and its user subroutine (USDFLD). A three-dimensional finite element technique was used for the stress analysis. Based on the three-dimensional state of stress of each element, different failure modes were detected by the failure theories of constituent materials, all of which are applied at the fiber, matrix and fiber-matrix interface constituent level. Numerical simulations have been carried out by which edge distance-to-hole diameter ratio, and plate width-to-hole diameter ratio are varied, The composite laminated plates are stacked with the following four different orientations: [+45/-45]2s, [90/+45/-45]s, and [0/90/0]s, the results show that failure mode and bearing strength are closely related to by stacking sequence of plates and geometrical parameters. Finally, the ultimate strength and failure modes of composite bolted joints in static tension double-shear loading conditions are predicted by using the progressive damage method established and the effects of layup and dimension of laminates on the properties of the connection structure were researched in this paper. An excellent agreement is found between data obtained from this study and the experiment.
NASA Astrophysics Data System (ADS)
Liu, Hanyang; Tang, Zhanwen; Pan, Lingying; Zhao, Weidong; Sun, Baogang; Jiang, Wenge
2016-05-01
Impact damage has been identified as a critical form of the defects that constantly threatened the reliability of composite structures, such as those used in the aerospace structures and systems. Low energy impacts can introduce barely visible damage and cause the degradation of structural stiffness, furthermore, the flaws caused by low-velocity impact are so dangerous that they can give rise to the further extended delaminations. In order to improve the reliability and load carrying capacity of composite laminates under low-velocity impact, in this paper, the numerical simulatings and experimental studies on the woven fiber-reinforced composite laminates under low-velocity impact with impact energy 16.7J were discussed. The low velocity impact experiment was carried out through drop-weight system as the reason of inertia effect. A numerical progressive damage model was provided, in which the damages of fiber, matrix and interlamina were considered by VUMT subroutine in ABAQUS, to determine the damage modes. The Hashin failure criteria were improved to cover the failure modes of fiber failure in the directions of warp/weft and delaminations. The results of Finite Element Analysis (FEA) were compared with the experimental results of nondestructive examination including the results of ultrasonic C-scan, cross-section stereomicroscope and contact force - time history curves. It is found that the response of laminates under low-velocity impact could be divided into stages with different damage. Before the max-deformation of the laminates occurring, the matrix cracking, fiber breakage and delaminations were simulated during the impactor dropping. During the releasing and rebounding period, matrix cracking and delaminations areas kept increasing in the laminates because of the stress releasing of laminates. Finally, the simulating results showed the good agreements with the results of experiment.
Akterations/corrections to the BRASS Program
NASA Technical Reports Server (NTRS)
Brand, S. N.
1985-01-01
Corrections applied to statistical programs contained in two subroutines of the Bed Rest Analysis Software System (BRASS) are summarized. Two subroutines independently calculate significant values within the BRASS program.
Determination of Semiconductor Junction Vulnerability to Second Breakdown
1977-06-01
141 B.21 Listing for Subroutine GION .... ............... ... 143 B.22 Listing for Subroutine GSHR .... ............... ... 145 B.23 Listing...Source listing for GION is presented in Fig. B.21. Subroutine GSHR GHSR evaluates Shockley-Read-Hall generation-recombination through mid-energy...at nodes M and M-1. Source listing for GSHR is presented in Fig. B.22. Subroutine BANDA3 BANDA3 uses the Gaussian elimination technique in
NASA Technical Reports Server (NTRS)
Svalbonas, V.; Ogilvie, P.
1973-01-01
The engineering programming information for the digital computer program for analyzing shell structures is presented. The program is designed to permit small changes such as altering the geometry or a table size to fit the specific requirements. Each major subroutine is discussed and the following subjects are included: (1) subroutine description, (2) pertinent engineering symbols and the FORTRAN coded counterparts, (3) subroutine flow chart, and (4) subroutine FORTRAN listing.
Six Degree of Freedom Flight Dynamic Model of a MK-82 Store
1994-01-01
were calculated in subroutine AERO2 , which retrieves the appropriate aerodynamic coefficients from the wind tunnel database using database access...23 * . * *! *1 2;3 • 0 6, Appendix B - Additional Subroutines Developed for Mk-82 ( - Simulation -. Subroutine AERO2 The AEitO2 subroutine is...is called front AERO2 and has angle of attack and sideslip as its inputs. The outputs are the Euler angles Theta and Phi, with Psi being set at zero
Hand-Held Computer Programs for Preliminary Helicopter Design.
1982-10-01
programmable calculator a series of programs that give acceptable results during the preliminary phases of the helicopter design process. The project consists of three parts. The first part consists of several short programs and their subroutine form. These programs and subroutines compute density altitude, density, disc area, solidity, tip velocity, induced velocity, coefficient of thrust, tip loss factor, equivalent chord, and ground effect. The second part consists of major subroutines. These subroutines compute profile power, induced power, climb power, parasite power,
Improved Simulations of Mesoscale Meteorology.
1983-01-01
O 1a I k~ N m 16 It should be mentioned that there is a time-lag between the measurements at different levels, which is inherent in rawin- sonde type...requirements. Further relief could be obtained by deleting the plotting subroutines (CONTUR, PLOTER, AND VEEJVER) and adding the dummy subroutines...CALW, because their names appear as dummy parameters in calls to INT routiie. CAPPZ SUBROUTINE This subroutine function provides the value of the
Software development guidelines
NASA Technical Reports Server (NTRS)
Kovalevsky, N.; Underwood, J. M.
1979-01-01
Analysis, modularization, flowcharting, existing programs and subroutines, compatibility, input and output data, adaptability to checkout, and general-purpose subroutines are summarized. Statement ordering and numbering, specification statements, variable names, arrays, arithemtical expressions and statements, control statements, input/output, and subroutines are outlined. Intermediate results, desk checking, checkout data, dumps, storage maps, diagnostics, and program timing are reviewed.
NASA Technical Reports Server (NTRS)
Roth, D. J.; Hull, D. R.
1994-01-01
IMAGEP manipulates digital image data to effect various processing, analysis, and enhancement functions. It is keyboard-driven program organized into nine subroutines. Within subroutines are sub-subroutines also selected via keyboard. Algorithm has possible scientific, industrial, and biomedical applications in study of flows in materials, analysis of steels and ores, and pathology, respectively.
ERIC Educational Resources Information Center
Donohue, Nanette
2008-01-01
No other category of library materials has grown more quickly in the last several decades than audiovisual (AV), nor has any other category undergone so many changes in format. The transitions from vinyl records to 8-tracks to audiocassettes to CDs and from film reel to 3/4" U-Matic to VHS to DVD have impacted library services tremendously. The…
Unidirectional Core-Shell Hybrids for Concrete Reinforcement - A preliminary Study
1994-02-01
Both faces were free to displace radial’ y but axial rotations were prevented. Two finite element programs, ADINA (Ref 47) and ABAQUS (Ref 48), were...used with the same discretization of the rel-a section. A small strain formulation was employed in both cases. In the ABAQUS model the axes of...the local axes of orthotropy can rotate, although, for small deformations, the difference is small. The ABAQUS model was run once with and once without
Finite Element Modeling of Tire-Terrain Interaction
2001-11-01
cent advancements in the contact formulations of general-purpose finite element codes (e.g. ABAQUS , HKS 1998) and increases in computer processing...are based on the models as implemented in ABAQUS (HKS 1998). Additional information on soil plasticity and critical state soil mechanics is given...snow interaction, however, the model must simulate snow deformation in a three-dimensional stress field. Initial simulations using the ABAQUS
2008-01-01
Autodyn [ANSYS/ Autodyn version 11.0, User Documentation, Century Dynamics Inc., a subsidiary of ANSYS Inc., 2007] and ABAQUS/Explicit 1. REPORT...laminates. The model is constructed in such away that it can be readily integrated into commercial finite-element programs like ANSYS/ Autodyn [ANSYS... Autodyn version 11.0, User Documentation, Century Dynamics Inc., a subsidiary of ANSYS Inc., 2007] and ABAQUS/Explicit [ABAQUS version 6.7, User
Characterization of Deformation and Failure of Stainless Steel Welds
2006-02-17
weld as been developed and implemented as a material routine VUMAT in ABAQUS/Explicit. The FE model involves a 3urson-type constitutive description for...ductile fracture near the weld has been developed and implemented as a material routine VUMAT in ABAQUS/Explicit. The FE model involves a Gurson-type...temperatures. This computational model was implemented in ABAQUS/Explicit, using 8-noded C3D8R elements and a material routine VUMAT . The validity of the
Shape Memory Alloy Modeling and Applications to Porous and Composite Structures
NASA Astrophysics Data System (ADS)
Zhu, Pingping
There has been a growing concern about an exciting class of advanced material -- shape memory alloys (SMAs) since their discovery several decades ago. SMAs exhibit large reversible stresses and strains owing to a thermoelastic phase transformation. They have been widely used in many engineering fields including aerospace, biomedical, and automotive engineering, especially as sensors, actuators, bone implants and deployable switches. The behavior of SMAs is very complex due to the coupling between thermal and mechanical effects. Theoretical and computational tools are used in this dissertation to investigate the mechanical behavior of SMA and its related structures for seeking better and wider application of this material. In the first part of this dissertation, we proposed an improved macroscopic phenomenological constitutive model of SMA that accounts for all major mechanical behaviors including elasticity, phase transformation, reorientation and plasticity. The model is based on some previous work developed in the Brinson group, and the current efforts are focused on plasticity, the application of a pre-defined strain, unification of notations, and other coding-related work. A user subroutine script VUMAT is developed to implement the constitutive model to the commercial finite element software Abaqus. Typical simulation results based on the model are presented, as well as verification with some experimental results. In the second part, we apply the developed constitutive model to a series of two-dimensional SMA plates with structured arrays of pores to investigate the structural response, especially the stress, strain, phase transformation, and plastic fields. Results are documented about the coupling of the elastic, transformation and plastic fields about the arrays of pores. Theoretical and experimental DIC results are also utilized to validate some simulation results. Conclusions are then drawn to provide understanding in the effect of pores and the
Finite Element Models for Electron Beam Freeform Fabrication Process
NASA Technical Reports Server (NTRS)
Chandra, Umesh
2012-01-01
Electron beam freeform fabrication (EBF3) is a member of an emerging class of direct manufacturing processes known as solid freeform fabrication (SFF); another member of the class is the laser deposition process. Successful application of the EBF3 process requires precise control of a number of process parameters such as the EB power, speed, and metal feed rate in order to ensure thermal management; good fusion between the substrate and the first layer and between successive layers; minimize part distortion and residual stresses; and control the microstructure of the finished product. This is the only effort thus far that has addressed computer simulation of the EBF3 process. The models developed in this effort can assist in reducing the number of trials in the laboratory or on the shop floor while making high-quality parts. With some modifications, their use can be further extended to the simulation of laser, TIG (tungsten inert gas), and other deposition processes. A solid mechanics-based finite element code, ABAQUS, was chosen as the primary engine in developing these models whereas a computational fluid dynamics (CFD) code, Fluent, was used in a support role. Several innovative concepts were developed, some of which are highlighted below. These concepts were implemented in a number of new computer models either in the form of stand-alone programs or as user subroutines for ABAQUS and Fluent codes. A database of thermo-physical, mechanical, fluid, and metallurgical properties of stainless steel 304 was developed. Computing models for Gaussian and raster modes of the electron beam heat input were developed. Also, new schemes were devised to account for the heat sink effect during the deposition process. These innovations, and others, lead to improved models for thermal management and prediction of transient/residual stresses and distortions. Two approaches for the prediction of microstructure were pursued. The first was an empirical approach involving the
NASA Astrophysics Data System (ADS)
Zampaloni, Michael A.
This work focuses on the development of a constitutive relationship for the modeling of a multi-preferred fiber orientation sheet that has several different primary fiber orientations, none of which are necessarily mutually perpendicular prior to, or during, deformation. One of the goals was to develop the constitutive relationship for the deformation behavior of the fiber mat reinforced thermoplastics with a random orientation, a material that is starting to gain in popularity but has not been extensively investigated. Two different types of mat fiber reinforced material were investigated; one a continuous fiber mat and one a chopped fiber mat, both with a polypropylene matrix. Both materials were characterized through a series of squeeze flow and uniaxial tensile tests to determine the preferred fiber orientations as well as the material properties. The constitutive model was implemented through a user-subroutine into the commercial finite element analysis code ABAQUS/Explicit and the numerical results were validated against experimental stamping results. Overall, the multi-preferred fiber orientation constitutive relationship was able to accurately capture the material instabilities that occurred during the stamping process. Since the mat fiber reinforced materials have not been extensively investigated this research creates one of the building blocks that can be used to develop more accurate models in the future. With the addition of a constitutive relationship for the interaction between the layers, this single layer model could be expanded into a constitutive relationship for the full sheet. In addition to the constitutive modeling aspect of this work there is also an experimental portion that deals with the development, design, build and verification of a new processing method for the shaping and forming of fiber reinforced thermoplastic materials, stamp thermo-hydroforming. Experimentation demonstrated that the process provides a 7--10 percent increase in
Nguyen, Ba Nghiep; Wang, Jin
2012-12-01
Under the Predictive Engineering effort, PNNL developed linear and nonlinear property prediction models for long-fiber thermoplastics (LFTs). These models were implemented in PNNL’s EMTA and EMTA-NLA codes. While EMTA is a standalone software for the computation of the composites thermoelastic properties, EMTA-NLA presents a series of nonlinear models implemented in ABAQUS® via user subroutines for structural analyses. In all these models, it is assumed that the fibers are linear elastic while the matrix material can exhibit a linear or typical nonlinear behavior depending on the loading prescribed to the composite. The key idea is to model the constitutive behavior of the matrix material and then to use an Eshelby-Mori-Tanaka approach (EMTA) combined with numerical techniques for fiber length and orientation distributions to determine the behavior of the as-formed composite. The basic property prediction models of EMTA and EMTA-NLA have been subject for implementation in the Autodesk® Moldflow® software packages. These models are the elastic stiffness model accounting for fiber length and orientation distributions, the fiber/matrix interface debonding model, and the elastic-plastic models. The PNNL elastic-plastic models for LFTs describes the composite nonlinear stress-strain response up to failure by an elastic-plastic formulation associated with either a micromechanical criterion to predict failure or a continuum damage mechanics formulation coupling damage to plasticity. All the models account for fiber length and orientation distributions as well as fiber/matrix debonding that can occur at any stage of loading. In an effort to transfer the technologies developed under the Predictive Engineering project to the American automotive and plastics industries, PNNL has obtained the approval of the DOE Office of Vehicle Technologies to provide Autodesk, Inc. with the technical support for the implementation of the basic property prediction models of EMTA and
Towards an improved understanding of strength and anisotropy of cold compacted powder
NASA Astrophysics Data System (ADS)
Wang, Wenhai
The strength of powder compacts after cold compaction is known to be anisotropic, which comes from the directionality of microstructure resulting from initial particle morphology and/or from particle deformation during compaction. Current work focuses on multi-scale numerical analysis of powder compaction with emphasis on the role of interparticle cohesion on post-compaction mechanical properties. At macroscopic level, we applied phenomenological model to describe the mechanical behavior of powder, in which the material is considered to be continuum medium. A user subroutine (VUMAT) was successfully developed for ABAQUS/Explicit analysis, in which one of the popular phenomenological models for powder compaction---Drucker Prager/Cap model---is implemented. By studying of pharmaceutical powder die compaction and subsequent diametrical compression test via finite element analysis, the capabilities and limitations of current constitutive models are evaluated on predicting such as density, stress and tool force evolution, as well as the strength and fracture tendency. Our results illustrate that current model has good predictive capability of powder densification (e.g. density evolution) but can not predict post-compaction strength well. The following studies focus on evaluating the physics and mechanics occurring at particle level. The compaction of granular media was explored by using MPFEM approach. In the new model, individual particles discretized with a finite element mesh allow for a full description of contact mechanics and local and global particle kinematics. The introduction of a layer of degrading material on the surface of each particle provides the means of introducing variable cohesion and its effect on the final strength of compacts. The simulations show that the unloading creates tensile stresses at the root of the contact necks, which may cause partial or full separation of contact interface when the cohesion developed during loading is not strong
Bracken, Robert E.
2004-01-01
A subroutine (FFTDC2) coded in Fortran 77 is described, which performs a Fast Fourier Transform or Discrete Fourier Transform together with necessary conditioning steps of trend removal, extension, and windowing. The source code for the entire library of required subroutines is provided with the digital release of this report. But, there is only one required entry point, the subroutine call to FFTDC2; all the other subroutines are operationally transparent to the user. Complete instructions for use of FFTDC2.F (as well as for all the other subroutines) and some practical theoretical discussions are included as comments at the beginning of the source code. This subroutine is intended to be an efficient tool for the programmer in a variety of production-level signal-processing applications.
1982-10-01
7A1-Ai24 9877 FINITE ELEMENT PROGRRM FOR C ALCULATING FLOWS IN / 3 UN C((U) TURBOMACHINES WITH RESULTS FOR NASA TASK-i COMPRESSOR 98 IU) NAVAL...Aeronaut cs ean of Sdience and Engineering 3 C. ~% h~.c. c . .. . . . . ._ . . .. ABSTRACT A general mash generation code (MESHGEN) and finite ele...DESCRIPTION. ......... 36 B. SUBROUTINE DESCRIPTIONS . . . . . . . . . . 38 1. Subroutine INITI . . . . . . . . . . . 38 2. Subroutine INPUT ........... 39 3
NASA Technical Reports Server (NTRS)
Labudde, R. A.
1972-01-01
An attempt has been made to keep the programs as subroutine oriented as possible. Usually only the main programs are directly concerned with the problem of total cross sections. In particular the subroutines POLFIT, BILINR, GASS59/MAXLIK, SYMOR, MATIN, STUDNT, DNTERP, DIFTAB, FORDIF, EPSALG, REGFAL and ADSIMP are completely general, and are concerned only with the problems of numerical analysis and statistics. Each subroutine is independently documented.
Godson, Richard H.
1974-01-01
GEOPAC .consists of a series of subroutines to primarily process potential-field geophysical data but other types of data can also be used with the program. The package contains routines to reduce, store, process and display information in two-dimensional or three-dimensional form. Input and output formats are standardized and temporary disk storage permits data sets to be processed by several subroutines in one job step. The subroutines are link-edited in an overlay mode to form one program and they can be executed by submitting a card containing the subroutine name in the input stream.
SYMAT, COVAR: Test Procedures for Matrix Calculations
NASA Technical Reports Server (NTRS)
Morris, W. L.; Wiginton, C. L.; Lowell, D. K.
1972-01-01
The FORTRAN subroutine SYMAT and related subroutines are described. In essence SYMAT is an iterative algorithm in which the problem of finding eigenvalues and eigenvectors of a real symmetric matrix is transformed into an equivalent problem of finding eigenvalues and eigenvectors of an infinite sequence of matrices of order two. A DEMO PROGRAM contains a subroutine COVAR which is used to compute the covariance matrix (denoted by A) of a data matrix (denoted by X). Since a covariance matrix is symmetric it can be analyzed by using subroutine SYMAT.
Computer program for natural gas flow through nozzles
NASA Technical Reports Server (NTRS)
Johnson, R. C.
1972-01-01
Subroutines, FORTRAN 4 type, were developed for calculating isentropic natural gas mass flow rate through nozzle. Thermodynamic functions covering compressibility, entropy, enthalpy, and specific heat are included.
LS-DYNA Implementation of Polymer Matrix Composite Model Under High Strain Rate Impact
NASA Technical Reports Server (NTRS)
Zheng, Xia-Hua; Goldberg, Robert K.; Binienda, Wieslaw K.; Roberts, Gary D.
2003-01-01
A recently developed constitutive model is implemented into LS-DYNA as a user defined material model (UMAT) to characterize the nonlinear strain rate dependent behavior of polymers. By utilizing this model within a micromechanics technique based on a laminate analogy, an algorithm to analyze the strain rate dependent, nonlinear deformation of a fiber reinforced polymer matrix composite is then developed as a UMAT to simulate the response of these composites under high strain rate impact. The models are designed for shell elements in order to ensure computational efficiency. Experimental and numerical stress-strain curves are compared for two representative polymers and a representative polymer matrix composite, with the analytical model predicting the experimental response reasonably well.
Wide Area Search and Engagement Simulation Validation
2007-03-01
69 Appendix A: MultiUAV Target Discovery Time Subroutines.........................................70 Appendix B ...MultiUAV confusion matrix subroutine is shown in Appendix B . ROC Curve Modification An additional modification made to the MultiUAV was to...TargetDiscoveryTimes %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% return 71 Appendix B : MultiUAV Classify Targets
The Marshall Engineering Thermosphere (MET) Model. Volume 1; Technical Description
NASA Technical Reports Server (NTRS)
Smith, R. E.
1998-01-01
Volume 1 presents a technical description of the Marshall Engineering Thermosphere (MET) model atmosphere and a summary of its historical development. Various programs developed to augment the original capability of the model are discussed in detail. The report also describes each of the individual subroutines developed to enhance the model. Computer codes for these subroutines are contained in four appendices.
GASP- General Aviation Synthesis Program. Volume 5: Weight
NASA Technical Reports Server (NTRS)
Hague, D.
1978-01-01
Subroutines for determining the weights of propulsion system related components and the airframe components of an aircraft configuration are presented. Subroutines that deal with design load conditions, aircraft balance, and tail sizing are included. Options for turbine and internal combustion engines are provided.
Algorithms to Reveal Properties of Floating-Point Arithmetic
Two algorithms are presented in the form of Fortran subroutines. Each subroutine computes the radix and number of digits of the floating - point numbers...and whether rounding or chopping is done by the machine on which it is run. The methods are shown to work on any ’reasonable’ floating - point computer.
User’s Manual for the Flow-Field Diagnostics Code EMABIC (Emission/Absorption Inversion Codes)
1983-01-01
1911. Other * requests for this document must be referred to AFRPLITSPR (Stop 24 ). Edwards AF8. CA 93523. DTIC ELECTE Q. prepared for the: Air Force...Subroutine-Calling Flow Diagram for PARICI ......................... 24 6. Subroutine-Calling Flow Diagram for PARIC2 .......................... 25 7...FIGURES (Continued) 24 . Differential Scattering Cross Section for A1203 ...................... 71 25. Coverage of the Scattering Integral Weighting
GEMPAK5. Part 1: GEMPAK5 programmer's guide, version 5.0
NASA Technical Reports Server (NTRS)
Desjardins, Mary L.; Brill, Keith F.; Schotz, Steven S.
1991-01-01
GEMPAK is a general meteorological software package used to analyze and display conventional meteorological data as well as satellite derived parameters. The Programmer's Guide describes the subroutines which can be used to build new GEMPAK programs. Part 1 contains GEMPAK subroutines.
Computer program for high pressure real gas effects
NASA Technical Reports Server (NTRS)
Johnson, R. C.
1969-01-01
Computer program obtains the real-gas isentropic flow functions and thermodynamic properties of gases for which the equation of state is known. The program uses FORTRAN 4 subroutines which were designed for calculations of nitrogen and helium. These subroutines are easily modified for calculations of other gases.
Thermal Radiation Analysis System (TRASYS)
NASA Technical Reports Server (NTRS)
Connor, R. J.; Paulson, R. E.; Goble, R. G.; Jensen, C. L.
1974-01-01
A user's manual is presented for TRASYS, which is a digital software system with a generalized capability for solving radiation problems. Subroutines, file, and variable definitions are presented along with subroutine and function descriptions for the preprocessor. Definitions and descriptions of components of the processor are also presented.
EZDRAW. An Interactive Computer Graphics Program to Design Bar, Line, or Pie Graphs.
1982-12-01
Figure Page 1 EZDRAW System Configuration . . . . . . . . . )15 2 Representation of EZDRAW Levels by Menus . .16 * 3 GRAFMAKER Design...Graph . . . .. . . .. 47 8 EZDRAW Pie Graph ... 48 * 9 Main Module .. . . . . . .. B-2 10 Starting EZDR A’. . .. . . . .. B- 3 11 Initializing EZDRAW...Design Attributes . . . . A- 3 II EZDRAW Variables .......... ........ C-1 III EZDRAW Subroutines ..... .............. .D-1 IV DI-3000 Subroutines
Modifications to the Flexible Spacecraft Dynamics Program
NASA Technical Reports Server (NTRS)
1980-01-01
Modifications to existing subroutines are briefly described and a detailed description of new subroutines is given. The capability to simulate the Dynamics Explorer-B control system new developed and the formulation for this addition is given. The program variables in new labelled COMMON blocks are described in detail and the modified input and output for the d Flexible Spacecraft Dynamics Program is described.
1994-05-01
implemented by Mr. Dave V. Ledvina based on work done by Dr. Chris W. Fairall, was crucial to Julie’s development of the boundary conditions. Dr. Young also...The parameter values z. and L are determined from a subroutine supplied by Dr. George S. Young. This subroutine was implemented by Mr. Dave V. Ledvina
1985-04-01
subroutine contains data on friction factors correlated by Sieder and Tate for fluids which are being heated or cooled in tubes. The subroutine uses a linear...inter- -". polation algorithm to calculate the friction factor depending on the Reynolds Number of the tube-side fluid. The Sieder and Tate correlated
Development of a weight/sizing design synthesis computer program. Volume 2: Program Description
NASA Technical Reports Server (NTRS)
Garrison, J. M.
1973-01-01
The program for the computerized analysis of weight estimation relationships for those elements of the space shuttle vehicle which contribute a significant portion of the inert weight is discussed. A listing of each module and subroutine of the program is presented. Included are a generalized flow chart describing the subroutine linkage of the complete program and detailed flow charts for each subprogram.
A computer algorithm for performing interactive algebraic computation on the GE Image-100 system
NASA Technical Reports Server (NTRS)
Hart, W. D.; Kim, H. H.
1979-01-01
A subroutine which performs specialized algebraic computations upon ocean color scanner multispectral data is presented. The computed results are displayed on a video display. The subroutine exists as a component of the aircraft sensor analysis package. The user specifies the parameters of the computations by directly interacting with the computer. A description of the conversational options is also given.
A Posteriori Error Bounds for Two-Point Boundary Value Problems.
1978-01-01
numerical solutions were obtained by a collocation method. The subroutine LOBATO by deBoor and Weiss [4] was used to obtain the numerical solutions...subroutine LOBATO at 101 equally spaced points. We computed with = 7 and 01 = 1. Note that ~ 2 - = 48. The bounds we obtained are: K B h 4 2.0l54x10~~ l
ERIC Educational Resources Information Center
Corporation for Public Broadcasting, Washington, DC.
This report documents the first year of a 3-year evaluation which was designed to (1) determine the status of small-format (1/2" reel-to-reel, 3/4" U-Matic, 1/2" VHS, and 1/2" Beta) videotape in the schools; (2) reveal what impact such videotape has on educational television utilization; and (3) examine the distribution of…
GKS-EZ programming manual for FORTRAN-77
Beach, R.C.
1992-01-01
A standard has now been adopted for subroutine packages that drive graphic devices. It is known as the Graphical Kernel system (GKS), and many commercial implementations of it are available. Unfortunately, it is a difficult system to learn, and certain functions that are important for scientific use are not provided. Although GKS can be used to achieve portability of graphic applications between graphic devices, computers, and operating systems, it can also be misused in this respect. In addition, it introduces the very real problem of portability between the various implementations of GKS. This document describes a set of FORTRAN-77 subroutines that may be used to control a wide variety of graphic devices and overcome most of these problems. Some of these subroutines are from GKS itself, while others are higher-level subroutines that call GKS subroutines. These subroutines are collectively known as GKS-EZ. The purpose is to supply someone who is not a specialist in computer graphics with a flexible, robust, and easy to learn graphics system. Users of GKS-EZ should not have much need for a full GKS manual; this document will supply all of the information to use GKS-EZ except for a few items. These missing items include the numeric identification of the supported graphic devices and the procedure for linking the GKS subroutines into a executable module.
2012-09-01
Cook elastoplastic material in ABAQUS, while the metallic structure of the fan case is made of aluminum alloy also modeled as an elastoplastic ...alloy modeled by a Johnson-Cook elastoplastic material in ABAQUS, while the metallic structure of the fan case is made of aluminum alloy also...modeled as an elastoplastic material. A multilayered Kevlar woven dry fabric structure is wrapped around the thin aluminum shell to form a soft hybrid
Introductory User’s Guide to the ARL Supercomputer Facility at APG
1993-06-01
16-11 16.15 ABAQUS ................................. .16-12 16.16 MSC/NASTRAN ............................... 16-12 16.17 MSC/DYNA... abaqus nqs.policy disspla.imagen restorations tmpdir express.que G.lupgrade arlscf-policy news flint sysadmin patton> date* Fri Nov 6 10:30:15 EST...metacharacters apply. Detailed information may be found in the on-line manual pages and in the Cray publications, CFW Corn- piling System, Volume 1: Fortran
1992-09-01
PAGES Creep Shrinkage 193 Incremental construction Thermal loads 16. PRICE CODE Pile loads 17. SECURITY CLASSIFICATION . SECURITY CLASSIFICATION 19...Summary of Previous Study The Phase I study resulted in the selection of the general-purpose struc- tural and heat transfer FE program, ABAQUS (Hibbitt...Karlsson, and Sorensen, Inc., 1987). The ABAQUS program was selected because of it flexibility and capability to perform the desired heat transfer and
Dynamic Failure Processes Under Confining Stress in AlON, a Transparent Polycrystalline Ceramic
2008-12-01
commercial ABAQUS FE package showed that this appreciably reduces the stress concentrations in the specimen. The inset in Fig. 1 shows the assembly...obtain given the sizes and tolerances required in the assembly. Hence, 3D finite element simulations were performed using ABAQUS / STANDARD and EXPLICIT...systems and extensive grain boundary dislocation pile -ups with no apparent macro-cracking. Such plasticity dominated behavior was ascribed to the
Fretting Fatigue Behavior of the Titanium Alloy Ti-6AL-4V Under Seawater Conditions
2004-03-01
continuously broken up by the mechanical action. The oxide debris piles up and can become trapped in a valley between two contacting asperities. Pits...element analysis used in this study was similar to the one utilized by Lykins [42] and Yuksel [40]. A commercially available finite element code, ABAQUS ...Strip (With Particular Reference to Fretting Experiments),” Wear, 185: 235-238 (1995). 113 51. ABAQUS Standard User’s Manual. Vol. 2. Hibbit
1992-09-01
done since ABAQUS only allows piles to be placed at defined nodes. 138. In reference to a technical report published by the US Army Corps of Engineers...Report K-83-1, Case Task Group on Pile Foundation, Wash- ington, DC. _ 1987. " ABAQUS - Structural and Heat Transfer Finite Element Code," User’s Manual...effects on massive concrete structures. The structural models for each monolith and its pile /soil foundation for both the thermal and mechanical analy
Dynamic Failure Processes Under Confining Stress in AlON, a Transparent Polycrystalline Ceramic
2009-09-01
T-blocks. Numerical simulations performed using the commercial ABAQUS FE package showed that this appreciably reduces the stress concentrations in...simulations were performed using ABAQUS / STANDARD and EXPLICIT to determine the level of the confinement in the specimen during the experiments. The...995specimen suggested the activation of multiple slip systems and extensive grain boundary dislocation pile -ups with no apparent macro-cracking. Such
Spherical Indentation in Elastoplastic Materials: Modeling and Simulation
2005-05-01
and Recommendations 14 6. References 16 Appendix A. ABAQUS Input Deck 19 Distribution List 22 iv List of Figures Figure 1. Initial (a...Furthermore, local effects of microstructural heterogeneity at the scale of the contact region (e.g., grain and phase 10 boundaries, dislocation “ pile ...et al., 1999) or atomistically informed fully finite element methods (Zhu et al., 2004). 16 6. References ABAQUS , 2002. Version 6.3.5
1994-06-01
developed in the ABAQUS finite element package. In ABAQUS , the delamination is modelled as two beams, made of solid elements, above and below the plane...Maryland, Involves varying the location of the discontinuous and continuous; piles through the thickness of the laminate. Thus, the plies may no...of the discontinuous plies are no longer located in the plane of the Inclusion. Thecontinuous pIles laced over the plezocerarnic are capable of
Dynamic Impact Analysis of Bagless Transfer System 3013 Can in Drops at Various Inclination Angles
Gong, C.
2001-02-22
The purpose of this analysis is to provide rational judgment for the most pernicious impact angle of dropping. A numerical simulation method, finite element analysis, is adopted for this study. The general-purpose finite element analysis code, ABAQUS(R) [HKS, 1998], facilitates the numerical computation. The geometrical finite element modeling is developed with the software PATRAN(R) [MSC, 1999]. The finite element code ABAQUS(R)has been verified according to the QA plans.
Stress and Heat Transfer Analyses for Different Channel Arrangements of PCHE
Jong B. Lim; Robert G. Shrake; Eung S. Kim; Chang H. Oh
2008-11-01
Stress and heat transfer analyses are being performed on the different channel arrangements of Printed Circuit Heat Exchanger (PCHE) proposed for application of VHTRs using ABAQUS [ABAQUS, 2007] and COMSOL [COMSOL, 2007], respectively. The work is being done to determine the configuration that would result in minimum stress for the same heat performance. This paper discusses the effects of shifting the coolant channels in every other row to reduce stress.
SINDA/SINFLO computer routine, volume 1, revision A. [for fluid flow system analysis
NASA Technical Reports Server (NTRS)
Oren, J. A.; Williams, D. R.
1975-01-01
The SINFLO package was developed to modify the SINDA preprocessor to accept and store the input data for fluid flow systems analysis and adding the FLOSOL user subroutine to perform the flow solution. This reduced and simplified the user input required for analysis of flow problems. A temperature calculation method, the flow-hybrid method which was developed in previous VSD thermal simulator routines, was incorporated for calculating fluid temperatures. The calculation method accuracy was improved by using fluid enthalpy rather than specific heat for the convective term of the fluid temperature equation. Subroutines and data input requirements are described along with user subroutines, flow data storage, and usage of the plot program.
NASA Technical Reports Server (NTRS)
Lutzky, D.; Bjorkman, W. S.
1973-01-01
The Mission Analysis Evaluation and Space Trajectory Operations program known as MAESTRO is described. MAESTRO is an all FORTRAN, block style, computer program designed to perform various mission control tasks. This manual is a guide to MAESTRO, providing individuals the capability of modifying the program to suit their needs. Descriptions are presented of each of the subroutines descriptions consist of input/output description, theory, subroutine description, and a flow chart where applicable. The programmer's manual also contains a detailed description of the common blocks, a subroutine cross reference map, and a general description of the program structure.
A study of commuter airplane design optimization
NASA Technical Reports Server (NTRS)
Keppel, B. V.; Eysink, H.; Hammer, J.; Hawley, K.; Meredith, P.; Roskam, J.
1978-01-01
The usability of the general aviation synthesis program (GASP) was enhanced by the development of separate computer subroutines which can be added as a package to this assembly of computerized design methods or used as a separate subroutine program to compute the dynamic longitudinal, lateral-directional stability characteristics for a given airplane. Currently available analysis methods were evaluated to ascertain those most appropriate for the design functions which the GASP computerized design program performs. Methods for providing proper constraint and/or analysis functions for GASP were developed as well as the appropriate subroutines.
NASA Astrophysics Data System (ADS)
Lai, William
Inspired by nature, the development of soft actuators has drawn large attention to provide higher flexibility and allow adaptation to more complex environment. This thesis is focused on utilizing electroactive polymers as active materials to develop soft planar dielectric elastomer actuators capable of complex 3D deformation. The potential applications of such soft actuators are in flexible robotic arms and grippers, morphing structures and flapping wings for micro aerial vehicles. The embraces design for a freestanding actuator utilizes the constrained deformation imposed by surface stiffeners on an electroactive membrane to avert the requirement of membrane pre-stretch and the supporting frames. The proposed design increases the overall actuator flexibility and degrees-of-freedom. Actuator design, fabrication, and performance are presented for different arrangement of stiffeners. Digital images correlation technique were utilized to evaluate the in-plane finite strain components, in order to elucidate the role of the stiffeners in controlling the three dimensional deformation. It was found that a key controlling factor was the localized deformation near the stiffeners, while the rest of the membrane would follow through. A detailed finite element modeling framework was developed with a user-material subroutine, built into the ABAQUS commercial finite element package. An experimentally calibrated Neo-Hookean based material model that coupled the applied electrical field to the actuator mechanical deformation was employed. The numerical model was used to optimize different geometrical features, electrode layup and stacking sequence of actuators. It was found that by splitting the stiffeners into finer segments, the force-stroke characteristics of actuator were able to be adjusted with stiffener configuration, while keeping the overall bending stiffness. The efficacy of actuators could also be greatly improved by increasing the stiffener periodicity. The developed
SUTIL: system utilities routines programmer's reference manual
NASA Technical Reports Server (NTRS)
Harper, D.
1976-01-01
A package of FORTRAN callable subroutines which allows efficient communication of data between users and programs is described. Proper utilization of the SUTIL package to reduce program core requirements and expedite program development is emphasized.
Geometric field-line calculations
NASA Technical Reports Server (NTRS)
Stassinopoulos, E. G.; Mead, G. D.
1972-01-01
Procedure for calculating three components of vector field from spherical harmonic using either geocentric or geodetic coordinates as input and output is described. Three subroutines of computer program are explained. Program is written in FORTRAN for IBM 360 computer.
NASTRAN hydroelastic modal studies. Volume 2: Programmer documentation
NASA Technical Reports Server (NTRS)
1977-01-01
The operational steps, data descriptions, and program code for the new NASTRAN hydroelastic analysis system are described. The overall flow of the system is described, followed by the descriptions of the individual modules and their subroutines.
Supplement to the ICRPG turbulent boundary layer nozzle analysis computer program
NASA Technical Reports Server (NTRS)
Omori, S.; Gross, K. W.
1972-01-01
A supplement is presented for a turbulent boundary layer nozzle analysis computer program. It describes the program calculation sequence and presents a detailed documentation of each subroutine. Important equations are derived explicitly, and improvements to the program are discussed.
Low-thrust solar electric propulsion navigation simulation program
NASA Technical Reports Server (NTRS)
Hagar, H. J.; Eller, T. J.
1973-01-01
An interplanetary low-thrust, solar electric propulsion mission simulation program suitable for navigation studies is presented. The mathematical models for trajectory simulation, error compensation, and tracking motion are described. The languages, input-output procedures, and subroutines are included.
Mathematical computer programs: A compilation
NASA Technical Reports Server (NTRS)
1972-01-01
Computer programs, routines, and subroutines for aiding engineers, scientists, and mathematicians in direct problem solving are presented. Also included is a group of items that affords the same users greater flexibility in the use of software.
Mars Global Reference Atmospheric Model (Mars-GRAM 3.34): Programmer's Guide
NASA Technical Reports Server (NTRS)
Justus, C. G.; James, Bonnie F.; Johnson, Dale L.
1996-01-01
This is a programmer's guide for the Mars Global Reference Atmospheric Model (Mars-GRAM 3.34). Included are a brief history and review of the model since its origin in 1988 and a technical discussion of recent additions and modifications. Examples of how to run both the interactive and batch (subroutine) forms are presented. Instructions are provided on how to customize output of the model for various parameters of the Mars atmosphere. Detailed descriptions are given of the main driver programs, subroutines, and associated computational methods. Lists and descriptions include input, output, and local variables in the programs. These descriptions give a summary of program steps and 'map' of calling relationships among the subroutines. Definitions are provided for the variables passed between subroutines through common lists. Explanations are provided for all diagnostic and progress messages generated during execution of the program. A brief outline of future plans for Mars-GRAM is also presented.
Computer program for the analysis of the cross flow in a radial inflow turbine scroll
NASA Technical Reports Server (NTRS)
Hamed, A.; Abdallah, S.; Tabakoff, W.
1977-01-01
A computer program was used to solve the governing of the potential flow in the cross sectional planes of a radial inflow turbine scroll. A list of the main program, the subroutines, and typical output example are included.
NASA Technical Reports Server (NTRS)
Rustay, R. C.; Gajjar, J. T.; Rankin, R. W.; Wentz, R. C.; Wooding, R.
1982-01-01
Listings of source programs and some illustrative examples of various ASCII data base files are presented. The listings are grouped into the following categories: main programs, subroutine programs, illustrative ASCII data base files. Within each category files are listed alphabetically.
GEMPAK5. Part 2: GEMPLT programmer's guide, version 5.0
NASA Technical Reports Server (NTRS)
Desjardins, Mary L.; Brill, Keith F.; Schotz, Steven S.
1991-01-01
GEMPAK is a general meteorological software package used to analyze and display conventional meteorological data as well as satellite derived parameters. The GEMPAK Programmer's Guide describes the subroutines which can be used in the GEMPAK graphics and transformation subsystem, GEMPLT.
A new version of the full-wave ICRH code FISIC for plasmas with noncircular flux surfaces
NASA Astrophysics Data System (ADS)
Kruecken, T.
1988-12-01
A user manual for a new version of the FISIC code which is now applicable to arbitrary (toroidal) geometry is presented. It describes the input parameters and quantities of all subroutines and contains a list of all common blocks.
NASA Technical Reports Server (NTRS)
Neal, L.
1981-01-01
A simple numerical algorithm was developed for use in computer simulations of systems which are both stiff and stable. The method is implemented in subroutine form and applied to the simulation of physiological systems.
Mission Analysis Program for Solar Electric Propulsion (MAPSEP). Volume 3: Program manual
NASA Technical Reports Server (NTRS)
Huling, K. R.; Boain, R. J.; Wilson, T.; Hong, P. E.; Shults, G. L.
1974-01-01
The internal structure of MAPSEP is described. Topics discussed include: macrologic, variable definition, subroutines, and logical flow. Information is given to facilitate modifications to the models and algorithms of MAPSEP.
NASA Technical Reports Server (NTRS)
Horton, W.; Kinsey, M.
1967-01-01
Computerized parts list system compiles and summarize all pertinent and available information on complex new systems. The parts list system consists of three computer subroutines - list of parts, parts numerical sequence list, and specifications list.
Brand, H.R. )
1989-02-20
DIGLIB is a collection of general graphics subroutines. It was designed to be small, reasonably fast, and device-independent. The software is readily usable by casual programmers for two-dimensional plotting.
NASA Technical Reports Server (NTRS)
1975-01-01
Major developments are examined which have taken place to date in the analysis of the power and energy demands on the APU/Hydraulic/Actuator Subsystem for space shuttle during the entry-to-touchdown (not including rollout) flight regime. These developments are given in the form of two subroutines which were written for use with the Space Shuttle Functional Simulator. The first subroutine calculates the power and energy demand on each of the three hydraulic systems due to control surface (inboard/outboard elevons, rudder, speedbrake, and body flap) activity. The second subroutine incorporates the R. I. priority rate limiting logic which limits control surface deflection rates as a function of the number of failed hydraulic. Typical results of this analysis are included, and listings of the subroutines are presented in appendicies.
Shock-Induced Martensite Reversal in Fe/30%Ni.
1980-02-14
Reed (1961) (88) 95 8.032 2016 -- Graham et al. (1967) 95 8.020±.003 2315 541 1594 Present work 5 8.158 HuOoniot modulus: 1163 Graham et al. (1967) 95...stress deviators (Subroutine DEVIAT). h h T h AV Vh ,S Z At are transferred from F- subroutine EXSTAT2 a. - x h )a,, + xh bo = (1-x )b,, + xhb112 h hcp
Parafrase restructuring of FORTRAN code for parallel processing
NASA Technical Reports Server (NTRS)
Wadhwa, Atul
1988-01-01
Parafrase transforms a FORTRAN code, subroutine by subroutine, into a parallel code for a vector and/or shared-memory multiprocessor system. Parafrase is not a compiler; it transforms a code and provides information for a vector or concurrent process. Parafrase uses a data dependency to reveal parallelism among instructions. The data dependency test distinguishes between recurrences and statements that can be directly vectorized or parallelized. A number of transformations are required to build a data dependency graph.
TSAN: a package for time series analysis.
Wang, D C; Vagnucci, A H
1980-04-01
Many biomedical data are in the form of time series. Analyses of these data include: (1) search for any biorhythm; (2) test of homogeneity of several time series; (3) assessment of stationarity; (4) test of normality of the time series histogram; (5) evaluation of dependence between data points. In this paper we present a subroutine package called TSAN. It is developed to accomplish these tasks. Computational methods, as well as flowcharts, for these subroutines are described. Two sample runs are demonstrated.
C-statistic fitting routines: User's manual and reference guide
NASA Technical Reports Server (NTRS)
Nousek, John A.; Farwana, Vida
1991-01-01
The computer program is discussed which can read several input files and provide a best set of values for the functions provided by the user, using either C-statistic or the chi(exp 2) statistic method. The program consists of one main routine and several functions and subroutines. Detail descriptions of each function and subroutine is presented. A brief description of the C-statistic and the reason for its application is also presented.
Computerized Life and Reliability Modelling for Turboprop Transmissions.
1988-07-13
analyses with the data in the common block. Con- The log of the reciprocal of Eq. (3) is: figuration specific subroutines are used to pre- pare the...con- ilO) figuration data , perform component force and life S i1l analyses with the help of the generic component property analysis subroutines, fill...9). The slope of a split path power transfer through multiple inter- least squares fit to this data is the negative of mediate gear shafts. These
Design of a Lighter Than Air Vehicle That Achieves Positive Buoyancy in Air Using a Vacuum
2012-06-01
membrane stretched over it was evaluated using v Finite Element Analysis with the frame modeled as clamped, cylindrical beam elements . A W/B=0.57 was...Optimization Sub-Routine: Finite Element Program ...........................................134 A.6 Optimization Sub-Routine: Datcreate (Datcreate.m...axial load on cylinder bearing load centripetal force force due to atmospheric pressure FEA Finite Element Analysis ft feet g
Development of a curved pipe capability for the NASTRAN finite element program
NASA Technical Reports Server (NTRS)
Jeter, J. W., Jr.
1977-01-01
A curved pipe element capability for the NASTRAN structural analysis program is developed using the NASTRAN dummy element feature. A description is given of the theory involved in the subroutines which describe stiffness, mass, thermal and enforced deformation loads, and force and stress recovery for the curved pipe element. Incorporation of these subroutines into NASTRAN is discussed. Test problems are proposed. Instructions on use of the new element capability are provided.
1988-09-01
subroutines. This type of structuring facilitates easy alteration of major program functions by a knowledgeable programmer. However, a compiled version...the ’mainframe" requirement common among most submarine versus submarine simulation programs. . The simulation search scenario is easy to set-up using...the subroutines: FALTR, HSCRN, IN, C LSJ, OUT, FLOSS , POSIT, REFLCT, SRCR, SSDET, TGCR, C TGTR, TRACK, TROR, TRDET, LRNDPC, LNORPC, LGAMPC. C C
XPQ/GCOS-8 SYSOUT INTERFACE SOFTWARE
NASA Technical Reports Server (NTRS)
Flor, F. A.
1994-01-01
This software consists of GCOS-8 operating system modifications. It includes an applications subroutine which permits the XPQ remote print software package as modified by LSOC to access, read, and release data from the GCOS-8 system output (SYSOUT) files. Specifically, it contains a slave subroutine RSYOT, a site unique Master Mode Entry (MME) processor and alters to the GEOT, INIT and System Macro modules for GCOS-8 SR3002/3003. The RSYOT subroutine will allow a slave user program to obtain and transfer SYSOUT records to a remote device. There is no limit to the number of SYSOUT jobs that may be in the process of transferring data simultaneously, but it will be the slave program's responsibility to keep track of the jobs. The operating system modifications allow the RSYOT subroutine to access the system SYSOUT (BLINK) files. This implements all of the privilege logic needed to access SYSOUT jobs. System privileges are not needed for either the user's program or this subroutine. RSYOT was written in GCOS-8 Assembler for execution on a Honeywell DPS-8/70 computer. The subroutine requires 1106 36-bit words of memory. This program was developed in 1987.
CHEMKIN2. General Gas-Phase Chemical Kinetics
Rupley, F.M.
1992-01-24
CHEMKIN is a high-level tool for chemists to use to describe arbitrary gas-phase chemical reaction mechanisms and systems of governing equations. It remains, however, for the user to select and implement a solution method; this is not provided. It consists of two major components: the Interpreter and the Gas-phase Subroutine Library. The Interpreter reads a symbolic description of an arbitrary, user-specified chemical reaction mechanism. A data file is generated which forms a link to the Gas-phase Subroutine Library, a collection of about 200 modular subroutines which may be called to return thermodynamic properties, chemical production rates, derivatives of thermodynamic properties, derivatives of chemical production rates, or sensitivity parameters. Both single and double precision versions of CHEMKIN are included. Also provided is a set of FORTRAN subroutines for evaluating gas-phase transport properties such as thermal conductivities, viscosities, and diffusion coefficients. These properties are an important part of any computational simulation of a chemically reacting flow. The transport properties subroutines are designed to be used in conjunction with the CHEMKIN Subroutine Library. The transport properties depend on the state of the gas and on certain molecular parameters. The parameters considered are the Lennard-Jones potential well depth and collision diameter, the dipole moment, the polarizability, and the rotational relaxation collision number.
LINPACK. Simultaneous Linear Algebraic Equations
Miller, M.A.
1990-05-01
LINPACK is a collection of FORTRAN subroutines which analyze and solve various classes of systems of simultaneous linear algebraic equations. The collection deals with general, banded, symmetric indefinite, symmetric positive definite, triangular, and tridiagonal square matrices, as well as with least squares problems and the QR and singular value decompositions of rectangular matrices. A subroutine-naming convention is employed in which each subroutine name consists of five letters which represent a coded specification (TXXYY) of the computation done by that subroutine. The first letter, T, indicates the matrix data type. Standard FORTRAN allows the use of three such types: S REAL, D DOUBLE PRECISION, and C COMPLEX. In addition, some FORTRAN systems allow a double-precision complex type: Z COMPLEX*16. The second and third letters of the subroutine name, XX, indicate the form of the matrix or its decomposition: GE General, GB General band, PO Positive definite, PP Positive definite packed, PB Positive definite band, SI Symmetric indefinite, SP Symmetric indefinite packed, HI Hermitian indefinite, HP Hermitian indefinite packed, TR Triangular, GT General tridiagonal, PT Positive definite tridiagonal, CH Cholesky decomposition, QR Orthogonal-triangular decomposition, SV Singular value decomposition. The final two letters, YY, indicate the computation done by the particular subroutine: FA Factor, CO Factor and estimate condition, SL Solve, DI Determinant and/or inverse and/or inertia, DC Decompose, UD Update, DD Downdate, EX Exchange. The LINPACK package also includes a set of routines to perform basic vector operations called the Basic Linear Algebra Subprograms (BLAS).
LINPACK. Simultaneous Linear Algebraic Equations
Dongarra, J.J.
1982-05-02
LINPACK is a collection of FORTRAN subroutines which analyze and solve various classes of systems of simultaneous linear algebraic equations. The collection deals with general, banded, symmetric indefinite, symmetric positive definite, triangular, and tridiagonal square matrices, as well as with least squares problems and the QR and singular value decompositions of rectangular matrices. A subroutine-naming convention is employed in which each subroutine name consists of five letters which represent a coded specification (TXXYY) of the computation done by that subroutine. The first letter, T, indicates the matrix data type. Standard FORTRAN allows the use of three such types: S REAL, D DOUBLE PRECISION, and C COMPLEX. In addition, some FORTRAN systems allow a double-precision complex type: Z COMPLEX*16. The second and third letters of the subroutine name, XX, indicate the form of the matrix or its decomposition: GE General, GB General band, PO Positive definite, PP Positive definite packed, PB Positive definite band, SI Symmetric indefinite, SP Symmetric indefinite packed, HI Hermitian indefinite, HP Hermitian indefinite packed, TR Triangular, GT General tridiagonal, PT Positive definite tridiagonal, CH Cholesky decomposition, QR Orthogonal-triangular decomposition, SV Singular value decomposition. The final two letters, YY, indicate the computation done by the particular subroutine: FA Factor, CO Factor and estimate condition, SL Solve, DI Determinant and/or inverse and/or inertia, DC Decompose, UD Update, DD Downdate, EX Exchange. The LINPACK package also includes a set of routines to perform basic vector operations called the Basic Linear Algebra Subprograms (BLAS).
Mathematics and Physics Studies - Multi-Project Support
1989-09-02
by video recorders on the Orbiter. Current information from Johnson Space Center has identified the recorders on board the Orbiter as TEAC IOOOABD...models with 4 MHz bandwidth and using 30 minute 3/4" U-matic tapes. These may be upgraded to TEAC 100ABF 41 recorders with 4.5 MHz bandwidth and using 72...William (1989) The Current Crop, Byte, Vol 14, No 2, p 235-245. Norton, Peter (1986) Inside the IBM PC, Simon and Schuster, New York, pp. 387. Poor
XPS Study of Sulfonated Polyaniline.
1991-08-07
WORK UMaT Arlington, VA 22203-17 14 ELEMENT NO. INO. NO. CCESSION No 11. TITLE (tinclude Security Clisification) "XPS STUDY OF SULFONATED POLYANILINE ...by block nvjmhet) FlIELD GROUP $u-GOP sulfonated polyaniline , x-ray photoelectron spectroscopy O(IPS) 19. ABSTRACT (Continue on reverse if nvessary...STUDY OF SULFONATED POLYANiLINE " by J. Yue, AJ. Epstein and A.G. MacDiarrnid Published in PMSE Preprints, (In Press 1991) University of Pennsylvania
Josephson Junction Digital Waveform Generation for Very Wideband Radars
1992-01-31
designs available from TRW’s microcell library. The cell design will be optimized as necessary for operation at 4 GHz and higher clock rates. 1-BIT FULL...sourcesI 41 " , c . (04- I 4’lteon of~ mtor - on Send comments relJardirg (hi’s burden ,%umate or .,)ny ,(her olpect of iha, s rd 1 ’ .,I 3thon H4,-aau4...This operation is accomplished by adding the input word to the accumulated output word each clock cycle. The sine- ROM converts this phase word into
NASA Technical Reports Server (NTRS)
Krueger, Ronald; Goetze, Dirk; Ransom, Jonathon (Technical Monitor)
2006-01-01
Strain energy release rates were computed along straight delamination fronts of Double Cantilever Beam, End-Notched Flexure and Single Leg Bending specimens using the Virtual Crack Closure Technique (VCCT). Th e results were based on finite element analyses using ABAQUS# and ANSYS# and were calculated from the finite element results using the same post-processing routine to assure a consistent procedure. Mixed-mode strain energy release rates obtained from post-processing finite elem ent results were in good agreement for all element types used and all specimens modeled. Compared to previous studies, the models made of s olid twenty-node hexahedral elements and solid eight-node incompatible mode elements yielded excellent results. For both codes, models made of standard brick elements and elements with reduced integration did not correctly capture the distribution of the energy release rate acr oss the width of the specimens for the models chosen. The results suggested that element types with similar formulation yield matching results independent of the finite element software used. For comparison, m ixed-mode strain energy release rates were also calculated within ABAQUS#/Standard using the VCCT for ABAQUS# add on. For all specimens mod eled, mixed-mode strain energy release rates obtained from ABAQUS# finite element results using post-processing were almost identical to re sults calculated using the VCCT for ABAQUS# add on.
Associations between the big five personality factors and multiple mini-interviews.
Griffin, B; Wilson, I
2012-08-01
Given the accumulating evidence that performance in medical school and beyond is related to personality, it is important for research to consider how personality assessment can be included as part of the process of selecting medical students. Interviews are one way of measuring personality and this study extends prior research investigating whether the multiple mini interview (MMI) is related to the five factor model of personality. In contrast to prior results (Kulasegaram et al. in Adv Health Sci Edu 15:415-423, 2010), examination of MMI scores for 868 applicants to an Australian medical school over 3 years showed significant uncorrected correlations every year with extraversion (.19, .19, .30) and conscientiousness (.20, .22, .25) and with agreeableness in 2 years (.17, .19). Investigation of personality at a facet-level revealed differing relationships with the MMI within the five factors of personality. MMI scores were also correlated in 2 years (.17, .22) with a situational judgment test of interpersonal understanding (UMAT Section 2) but were unrelated to tests of logical reasoning ability (UMAT Section 1), non-verbal reasoning (Section 3), or past academic performance (Higher School Certificate results).
PSHFT - COMPUTERIZED LIFE AND RELIABILITY MODELLING FOR TURBOPROP TRANSMISSIONS
NASA Technical Reports Server (NTRS)
Savage, M.
1994-01-01
The computer program PSHFT calculates the life of a variety of aircraft transmissions. A generalized life and reliability model is presented for turboprop and parallel shaft geared prop-fan aircraft transmissions. The transmission life and reliability model is a combination of the individual reliability models for all the bearings and gears in the main load paths. The bearing and gear reliability models are based on the statistical two parameter Weibull failure distribution method and classical fatigue theories. The computer program developed to calculate the transmission model is modular. In its present form, the program can analyze five different transmissions arrangements. Moreover, the program can be easily modified to include additional transmission arrangements. PSHFT uses the properties of a common block two-dimensional array to separate the component and transmission property values from the analysis subroutines. The rows correspond to specific components with the first row containing the values for the entire transmission. Columns contain the values for specific properties. Since the subroutines (which determine the transmission life and dynamic capacity) interface solely with this property array, they are separated from any specific transmission configuration. The system analysis subroutines work in an identical manner for all transmission configurations considered. Thus, other configurations can be added to the program by simply adding component property determination subroutines. PSHFT consists of a main program, a series of configuration specific subroutines, generic component property analysis subroutines, systems analysis subroutines, and a common block. The main program selects the routines to be used in the analysis and sequences their operation. The series of configuration specific subroutines input the configuration data, perform the component force and life analyses (with the help of the generic component property analysis subroutines), fill the
Beach, R.C.
1992-01-01
This document describes a number of subroutines that can be useful in GKS graphic applications programmed in FORTRAN-77. The algorithms described here include subroutines to do the following: (1) Draw text characters in a more flexible manner than is possible with basic GKS. (2) Project two-dimensional and three-dimensional space onto two-dimensional space. (3) Draw smooth curves. (4) Draw two-dimensional projections of complex three-dimensional objects. FORTRAN-77 is described in American National Standard, Programming Language, FORTRAN. GKS is described in American National Standard for Information Systems: Computer Graphics -- Graphical Kernel System (GKS) Functional Description and the FORTRAN-77 interface is described in American National Standard for Information Systems: Computer Graphics -- Graphical Kernel System (GKS) FORTRAN Binding. All of the subroutine names and additional enumeration types that will be described in this document begin with the letters GZ.'' Since GKS itself does not have any subroutine names or enumeration types that begin with these letters, no confusion between the usual GKS subroutines and the ones described here should occur. Many concepts will have to be defined in the following chapters. When a concept is first encountered, it will be given in italics. The information around the italicized word or phrase may be taken as its definition.
Beach, R.C.
1992-01-01
This document describes a number of subroutines that can be useful in GKS graphic applications programmed in FORTRAN-77. The algorithms described here include subroutines to do the following: (1) Draw text characters in a more flexible manner than is possible with basic GKS. (2) Project two-dimensional and three-dimensional space onto two-dimensional space. (3) Draw smooth curves. (4) Draw two-dimensional projections of complex three-dimensional objects. FORTRAN-77 is described in American National Standard, Programming Language, FORTRAN. GKS is described in American National Standard for Information Systems: Computer Graphics -- Graphical Kernel System (GKS) Functional Description and the FORTRAN-77 interface is described in American National Standard for Information Systems: Computer Graphics -- Graphical Kernel System (GKS) FORTRAN Binding. All of the subroutine names and additional enumeration types that will be described in this document begin with the letters ``GZ.`` Since GKS itself does not have any subroutine names or enumeration types that begin with these letters, no confusion between the usual GKS subroutines and the ones described here should occur. Many concepts will have to be defined in the following chapters. When a concept is first encountered, it will be given in italics. The information around the italicized word or phrase may be taken as its definition.
Optimization of KINETICS Chemical Computation Code
NASA Technical Reports Server (NTRS)
Donastorg, Cristina
2012-01-01
NASA JPL has been creating a code in FORTRAN called KINETICS to model the chemistry of planetary atmospheres. Recently there has been an effort to introduce Message Passing Interface (MPI) into the code so as to cut down the run time of the program. There has been some implementation of MPI into KINETICS; however, the code could still be more efficient than it currently is. One way to increase efficiency is to send only certain variables to all the processes when an MPI subroutine is called and to gather only certain variables when the subroutine is finished. Therefore, all the variables that are used in three of the main subroutines needed to be investigated. Because of the sheer amount of code that there is to comb through this task was given as a ten-week project. I have been able to create flowcharts outlining the subroutines, common blocks, and functions used within the three main subroutines. From these flowcharts I created tables outlining the variables used in each block and important information about each. All this information will be used to determine how to run MPI in KINETICS in the most efficient way possible.
The use of three-parameter rating table lookup programs, RDRAT and PARM3, in hydraulic flow models
Sanders, C.L.
1995-01-01
Subroutines RDRAT and PARM3 enable computer programs such as the BRANCH open-channel unsteady-flow model to route flows through or over combinations of critical-flow sections, culverts, bridges, road- overflow sections, fixed spillways, and(or) dams. The subroutines also obstruct upstream flow to simulate operation of flapper-type tide gates. A multiplier can be applied by date and time to simulate varying numbers of tide gates being open or alternative construction scenarios for multiple culverts. The subroutines use three-parameter (headwater, tailwater, and discharge) rating table lookup methods. These tables may be manually prepared using other programs that do step-backwater computations or compute flow through bridges and culverts or over dams. The subroutine, therefore, precludes the necessity of incorporating considerable hydraulic computational code into the client program, and provides complete flexibility for users of the model for routing flow through almost any affixed structure or combination of structures. The subroutines are written in Fortran 77 language, and have minimal exchange of information with the BRANCH model or other possible client programs. The report documents the interpolation methodology, data input requirements, and software.
Portable FORTRAN contour-plotting subprogram
Haskell, K.H.
1983-07-01
In this report we discuss a contour plotting Fortran subprogram. While contour plotting subroutines are available in many commercial plotting packages, this routine has the following advantages: (1) since it uses the Weasel and VDI plot routines developed at Sandia, it occupies little storage and can be used on most of the Sandia time-sharing systems as part of a larger program. In the past, the size of plotting packages often forced a user to perform plotting operations in a completely separate program; (2) the contour computation algorithm is efficient and robust, and computes accurate contours for sets of data with low resolution; and (3) the subprogram is easy to use. A simple contour plot can be produced with a minimum of information provided by a user in one Fortran subroutine call. Through the use of a wide variety of subroutine options, many additional features can be used. These include such items as plot titles, grid lines, placement of text on the page, etc. The subroutine is written in portable Fortran 77, and is designed to run on any system which supports the Weasel and VDI plot packages. It also uses routines from the SLATEC mathematical subroutine library.
A Stress Factor Method for Perforated Muzzle Brake Design
1994-02-01
unlimited documents, destroy when the report is no longer needed. Do not return it to the originator. Sion lowý pile 2A& *Val) 1.tltVifU anu Fom AoWovod...obtained. The finite plot correspond to brake entrance Mach numbers of 1.0 element structural analysis code ABAQUS was used for both and ..5. The higher...confined to the 14,000 second-order tetrahedron elements ( ABAQUS upstream wall. as shown in Figure 3b. The pressure level C3D1O) were used, each
Research Into Improving the Durability of the Hot Section in the Aircraft Turbine Engine
1991-12-01
ability. A trial problem is being run to determine whether the more readily available packages (ANsys, ABAQUS ) are suitable. MARC is used in USA and...expensive) or run offshore (unwieldy). * If tests prove that ANSYs or ABAQUS is suitable, computer time could be bought at an Australian installation or the...Technical Memorandum 473 41 415F 21. CONPTER PROGRAMS USED 22. EsrABJISuwET PILE 1IW.9 2S. A OflORAL fOOfl’OW " RQUfREDI
Patra, Anirban; Tome, Carlos
2016-03-23
This Milestone report shows good progress in interfacing VPSC with the FE codes ABAQUS and MOOSE, to perform component-level simulations of irradiation-induced deformation in Zirconium alloys. In this preliminary application, we have performed an irradiation growth simulation in the quarter geometry of a cladding tube. We have benchmarked VPSC-ABAQUS and VPSC-MOOSE predictions with VPSC-SA predictions to verify the accuracy of the VPSCFE interface. Predictions from the FE simulations are in general agreement with VPSC-SA simulations and also with experimental trends.
The use of XFEM to assess the influence of intra-cortical porosity on crack propagation.
Rodriguez-Florez, Naiara; Carriero, Alessandra; Shefelbine, Sandra J
2017-03-01
This study aimed at using eXtended finite element method (XFEM) to characterize crack growth through bone's intra-cortical pores. Two techniques were compared using Abaqus: (1) void material properties were assigned to pores; (2) multiple enrichment regions with independent crack-growth possibilities were employed. Both were applied to 2D models of transverse images of mouse bone with differing porous structures. Results revealed that assigning multiple enrichment regions allows for multiple cracks to be initiated progressively, which cannot be captured when the voids are filled. Therefore, filling pores with one enrichment region in the model will not create realistic fracture patterns in Abaqus-XFEM.
Application of MCT Failure Criterion using EFM
2010-03-26
ABAQUS. 5 Comparison between HELIUS:MCT™ and EFMMCT Open hole tension ( OHT ) models are analyzed using HELIUS:MCT™ and EFM-MCT codes in ABAQUS in...Figure 5 OHT failure pattern using EFM-MCT with thermal/curing analysis 13 Mesh 1 (168 elements) Mesh 2 (200 elements) Mesh 3 (600...elements) Mesh 4 (864 elements) 45o 0o -45o 90o Figure 6 OHT failure pattern using EFM-MCT without thermal/curing analysis 14
VizieR Online Data Catalog: Advanced fit technique for astrophysical spectra (Bukvic+, 2008)
NASA Astrophysics Data System (ADS)
Bukvic, S.; Spasojevic, Dj.; Zigman, V.
2007-11-01
Simple FORTRAN90 Demo of a complete program that uses DLSFIT routine (Bukvic, Spasojevic, and Zigman) for robust data fitting. The program consists of: 1) main program: DLSFITAADemo 2) subroutine DLSFIT, which performs DSL data fitting, 3) subroutine fit - WLS "working engine" for DLSFIT, 4) copyright protected FORTRAN77 subroutines: mrqmin, mrqcof, lfit, covsrt, gaussj, zbrent from: Numerical Recipes in Fortran 77: The Art of Scientific Computing, by Press, W.H., Teukolsky, S.A., Vetterling, W.T., and Flannery, B.P., Cambridge University Press, Cambridge, 2001, software version 2.10: available on WEB site: http//www.nr.com Tested with Compaq Visual Fortran 6.6 and Intel 9.1 compilers. Should be compiled with REAL(8) as default real kind. (1 data file).
Experiences with Cray multi-tasking
NASA Technical Reports Server (NTRS)
Miya, E. N.
1985-01-01
The issues involved in modifying an existing code for multitasking is explored. They include Cray extensions to FORTRAN, an examination of the application code under study, designing workable modifications, specific code modifications to the VAX and Cray versions, performance, and efficiency results. The finished product is a faster, fully synchronous, parallel version of the original program. A production program is partitioned by hand to run on two CPUs. Loop splitting multitasks three key subroutines. Simply dividing subroutine data and control structure down the middle of a subroutine is not safe. Simple division produces results that are inconsistent with uniprocessor runs. The safest way to partition the code is to transfer one block of loops at a time and check the results of each on a test case. Other issues include debugging and performance. Task startup and maintenance (e.g., synchronization) are potentially expensive.
Chemkin-II: A Fortran chemical kinetics package for the analysis of gas-phase chemical kinetics
Kee, R.J.; Rupley, F.M.; Miller, J.A.
1989-09-01
This document is the user's manual for the second-generation Chemkin package. Chemkin is a software package for whose purpose is to facilitate the formation, solution, and interpretation of problems involving elementary gas-phase chemical kinetics. It provides an especially flexible and powerful tool for incorporating complex chemical kinetics into simulations of fluid dynamics. The package consists of two major software components: an Interpreter and Gas-Phase Subroutine Library. The Interpreter is a program that reads a symbolic description of an elementary, user-specified chemical reaction mechanism. One output from the Interpreter is a data file that forms a link to the Gas-Phase Subroutine Library. This library is a collection of about 100 highly modular Fortran subroutines that may be called to return information on equation of state, thermodynamic properties, and chemical production rates.
Preliminary design methods for fiber reinforced composite structures employing a personal computer
NASA Technical Reports Server (NTRS)
Eastlake, C. N.
1986-01-01
The objective of this project was to develop a user-friendly interactive computer program to be used as an analytical tool by structural designers. Its intent was to do preliminary, approximate stress analysis to help select or verify sizing choices for composite structural members. The approach to the project was to provide a subroutine which uses classical lamination theory to predict an effective elastic modulus for a laminate of arbitrary material and ply orientation. This effective elastic modulus can then be used in a family of other subroutines which employ the familiar basic structural analysis methods for isotropic materials. This method is simple and convenient to use but only approximate, as is appropriate for a preliminary design tool which will be subsequently verified by more sophisticated analysis. Additional subroutines have been provided to calculate laminate coefficient of thermal expansion and to calculate ply-by-ply strains within a laminate.
NASA Technical Reports Server (NTRS)
1972-01-01
The QL module of the Performance Analysis and Design Synthesis (PADS) computer program is described. Execution of this module is initiated when and if subroutine PADSI calls subroutine GROPE. Subroutine GROPE controls the high level logical flow of the QL module. The purpose of the module is to determine a trajectory that satisfies the necessary variational conditions for optimal performance. The module achieves this by solving a nonlinear multi-point boundary value problem. The numerical method employed is described. It is an iterative technique that converges quadratically when it does converge. The three basic steps of the module are: (1) initialization, (2) iteration, and (3) culmination. For Volume 1 see N73-13199.
Computer programs for plotting curves with various dashed-line sequences
NASA Technical Reports Server (NTRS)
Desmarais, R. N.; Bennett, R. M.
1972-01-01
Two FORTRAN-callable subprograms have been written to draw a smooth curve through a set of input points as a solid line or as a general sequence of long and short dashes. Subroutine LINSEQ draws conventional curves whereas subroutine CONSEQ draws smooth closed curves (contours). The subprograms are based on an approximate calculation of the arc length along the curve and spline interpolation along the arc length. Options are provided for smoothing of the input data and for offsetting the plotted curve from the input data points. The method of calculation of the arc length and the generation of the line sequence are described.Usage descriptions of the main subprograms, sample calling programs illustrating the various features of the subprograms, and sample plots are given. The subroutines should be readily adaptable to almost any computer-driven incremental plotter.
NASA Technical Reports Server (NTRS)
Houston, Johnny L.
1989-01-01
Program EAGLE (Eglin Arbitrary Geometry Implicit Euler) Numerical Grid Generation System is a composite (multi-block) algebraic or elliptic grid generation system designed to discretize the domain in and/or around any arbitrarily shaped three dimensional regions. This system combines a boundary conforming surface generation scheme and includes plotting routines designed to take full advantage of the DISSPLA Graphics Package (Version 9.0). Program EAGLE is written to compile and execute efficiently on any Cray machine with or without solid state disk (SSD) devices. Also, the code uses namelist inputs which are supported by all Cray machines using the FORTRAN compiler CFT77. The namelist inputs makes it easier for the user to understand the inputs and operation of Program EAGLE. EAGLE's numerical grid generator is constructed in the following form: main program, EGG (executive routine); subroutine SURFAC (surface generation routine); subroutine GRID (grid generation routine); and subroutine GRDPLOT (grid plotting routines). The EAGLE code was modified to use on the NASA-LaRC SNS computer (Cray 2S) system. During the modification a conversion program was developed for the output data of EAGLE's subroutine GRID to permit the data to be graphically displayed by IRIS workstations, using Plot3D. The code of program EAGLE was modified to make operational subroutine GRDPLOT (using DI-3000 Graphics Software Packages) on the NASA-LaRC SNS Computer System. How to implement graphically, the output data of subroutine GRID was determined on any NASA-LaRC graphics terminal that has access to the SNS Computer System DI-300 Graphics Software Packages. A Quick Reference User Guide was developed for the use of program EAGLE on the NASA-LaRC SNS Computer System. One or more application program(s) was illustrated using program EAGLE on the NASA LaRC SNS Computer System, with emphasis on graphics illustrations.
Buxbaum, M.E.; Shay, M.R.
1986-11-01
The WASTES Version II (WASTES II) Programmer's Reference Manual was written to document code development activities performed under the Monitored Retrievable Storage (MRS) Program at Pacific Northwest Laboratory (PNL). The manual will also serve as a valuable tool for programmers involved in maintenance of and updates to the WASTES II code. The intended audience for this manual are experienced FORTRAN programmers who have only a limited knowledge of nuclear reactor operation, the nuclear fuel cycle, or nuclear waste management practices. It is assumed that the readers of this manual have previously reviewed the WASTES II Users Guide published as PNL Report 5714. The WASTES II code is written in FORTRAN 77 as an extension to the SLAM commercial simulation package. The model is predominately a FORTRAN based model that makes extensive use of the SLAM file maintenance and time management routines. This manual documents the general manner in which the code is constructed and the interactions between SLAM and the WASTES subroutines. The functionality of each of the major WASTES subroutines is illustrated with ''block flow'' diagrams. The basic function of each of these subroutines, the algorithms used in them, and a discussion of items of particular note in the subroutine are reviewed in this manual. The items of note may include an assumption, a coding practice that particularly applies to a subroutine, or sections of the code that are particularly intricate or whose mastery may be difficult. The appendices to the manual provide extensive detail on the use of arrays, subroutines, included common blocks, parameters, variables, and files.
Torak, L.J.
1993-01-01
A MODular Finite-Element, digital-computer program (MODFE) was developed to simulate steady or unsteady-state, two-dimensional or axisymmetric ground-water-flow. The modular structure of MODFE places the computationally independent tasks that are performed routinely by digital-computer programs simulating ground-water flow into separate subroutines, which are executed from the main program by control statements. Each subroutine consists of complete sets of computations, or modules, which are identified by comment statements, and can be modified by the user without affecting unrelated computations elsewhere in the program. Simulation capabilities can be added or modified by either adding or modifying subroutines that perform specific computational tasks, and the modular-program structure allows the user to create versions of MODFE that contain only the simulation capabilities that pertain to the ground-water problem of interest. MODFE is written in a Fortran programming language that makes it virtually device independent and compatible with desk-top personal computers and large mainframes. MODFE uses computer storage and execution time efficiently by taking advantage of symmetry and sparseness within the coefficient matrices of the finite-element equations. Parts of the matrix coefficients are computed and stored as single-subscripted variables, which are assembled into a complete coefficient just prior to solution. Computer storage is reused during simulation to decrease storage requirements. Descriptions of subroutines that execute the computational steps of the modular-program structure are given in tables that cross reference the subroutines with particular versions of MODFE. Programming details of linear and nonlinear hydrologic terms are provided. Structure diagrams for the main programs show the order in which subroutines are executed for each version and illustrate some of the linear and nonlinear versions of MODFE that are possible. Computational aspects of
Marine Steam Condenser Design Optimization.
1983-12-01
Rerf . 61. !kS 2XLI: Those parametars which the opti heztion proqran ms--faitted to change in order to improre’the esign. Pesin variablis appear oely on...subroutine SEC& LC is called. 5. jZ.~ This subroutine determines all the parameters of each of the sectors in the condenser by row. The first...force the pressure losses to converge to a single value. Once steam flow to the sectors has been adjusted, the sector and row analysis in SEC& LC is
Nutter, C.
1981-04-01
MAG2D is an interactive computer program used for modeling 2-1/2-dimensional magnetic data. A forward algorithm is used to give the theoretical attraction of magnetic intensity at a station due to a perturbing body given by the initial model. The resultant model can then be adjusted for a better fit by a combination of manual adjustment, one-dimensional automatic search, and Marquardt inversion. MAG2D has an interactive data management system for data manipulation and display built around subroutines to do a forward problem, a one-dimensional direct search and an inversion. These subroutines were originally separate batch-mode programs.
Application Portable Parallel Library
NASA Technical Reports Server (NTRS)
Cole, Gary L.; Blech, Richard A.; Quealy, Angela; Townsend, Scott
1995-01-01
Application Portable Parallel Library (APPL) computer program is subroutine-based message-passing software library intended to provide consistent interface to variety of multiprocessor computers on market today. Minimizes effort needed to move application program from one computer to another. User develops application program once and then easily moves application program from parallel computer on which created to another parallel computer. ("Parallel computer" also include heterogeneous collection of networked computers). Written in C language with one FORTRAN 77 subroutine for UNIX-based computers and callable from application programs written in C language or FORTRAN 77.
NASA Technical Reports Server (NTRS)
Fleischer, G. E.
1973-01-01
A new computer subroutine, which solves the attitude equations of motion for any vehicle idealized as a topological tree of hinge-connected rigid bodies, is used to simulate and analyze science instrument pointing control interaction with a flexible Mariner Venus/Mercury (MVM) spacecraft. The subroutine's user options include linearized or partially linearized hinge-connected models whose computational advantages are demonstrated for the MVM problem. Results of the pointing control/flexible vehicle interaction simulations, including imaging experiment pointing accuracy predictions and implications for MVM science sequence planning, are described in detail.
Graphics Programs for the DEC VAX Computer
NASA Technical Reports Server (NTRS)
Long, D.
1986-01-01
Variety of plots available in video or printed form. LONGLIB library of computer programs set of subroutines designed for vector plotting on cathode-ray tubes and dot-matrix printers. LONGLIB subroutines invoked by program calls similar to standard CALCOMP routines. In addition to basic plotting routines, LONGLIB contains extensive set of routines to allow viewport clipping, extended character sets, graphic input, gray-level plots, polar plots, and three-dimensional plotting with or without removal of hidden lines. LONGLIB written in FORTRAN 77 and C for batch execution.
Versatile High Performance Holographic Optical Coatings
1990-12-15
normally obtained from animal skins and bones. Gelatin has the property that it can be cross-linked by certain polyvalent metallic ions when exposed to...row) else3 hnext=4. *h endif endifI do 13 i=1I,n y (i)=y( i)+ytemp( i) *fcor 13 continue 19 return end 3 subroutine rk4(y,dydx,n,x,h, yout ,derivs) c...interval H and return the c incremented variables as YOUT , which need not be a distinct c array from Y. The user supplies the subroutine c DERIVS(X,Y,DYDX
Articulated Total Body Model Enhancements. Volume 1. Modifications
1988-01-01
DRIFT CORRECTION 21 3.1 Technical Discussion 21 3.2 Correction of Drift 24 3.3 Changes to Program 25 4.0 EDGE EFFECT OPTION 27 4.1 New Subroutines 27...other aerodynamic force improvements. Corrections to prevent angular drift in the joints are described in Section Three. The edge effect option in...changed subroutines are in Volume 3 of this report. New or changed lines are labeled with JDRIFT starting in column 73. 26 4.0 EDGE EFFECT OPTION In the
A study of the optimization method used in the NAVY/NASA gas turbine engine computer code
NASA Technical Reports Server (NTRS)
Horsewood, J. L.; Pines, S.
1977-01-01
Sources of numerical noise affecting the convergence properties of the Powell's Principal Axis Method of Optimization in the NAVY/NASA gas turbine engine computer code were investigated. The principal noise source discovered resulted from loose input tolerances used in terminating iterations performed in subroutine CALCFX to satisfy specified control functions. A minor source of noise was found to be introduced by an insufficient number of digits in stored coefficients used by subroutine THERM in polynomial expressions of thermodynamic properties. Tabular results of several computer runs are presented to show the effects on program performance of selective corrective actions taken to reduce noise.
SOFT TREE: Fault Tree Technique as Applied to Software. Revision.
1983-10-01
MCINTEE 01 OCT 83 UNCLRSS IF I E FG /2 N EhEEonsoonh ELEEE hh--Ah ’S .~ 45 LL -, Glln 12.2 0t MWMA LA11 1.8 MICROCOPY RESOLUTION TEST CHART NATIONAL...memory location in RAM ms - millisecond OBD - Instruction to output Bd register to D register OSD - office of the Secretary of Defense PAF - Piston...continue with the Soft Tree, we find that the OBD instruction that charges the PAF capacitor is in the PAF CHG subroutine. The PAF/CHG subroutine, used for
CHORDS: A New Temperature or Sound Speed Profile Thinning Algorithm.
1984-05-01
applications while reducing the number of profile points by a factor of 10. A zero value of the tolerance limit will force the subroutine to halt the...subroutine, a zero value will be returned for the number of output points (NR). 11LANK 11. DETAILED FUNCTIONAL DESCRIPTION In the following...REAL INTERP 0043 DIMENSION DIFF(MPNTS),NUM(MPNTS) 0044 DATA DIFFLT/-999V9./ 0045 NOLINuMPNTS-1 0046 C 0047 C ZERO ARRAYS 0048 C 0049 DO 9999 J=.,MPNTS
NASA Technical Reports Server (NTRS)
Haas, L. A., Sr.
1976-01-01
The Fail-Safe Abort System TEMPerature Analysis Program, (FASTEMP), user's manual is presented. This program was used to analyze fail-safe abort systems for an actively cooled hypersonic aircraft. FASTEMP analyzes the steady state or transient temperature response of a thermal model defined in rectangular, cylindrical, conical and/or spherical coordinate system. FASTEMP provides the user with a large selection of subroutines for heat transfer calculations. The various modes of heat transfer available from these subroutines are: heat storage, conduction, radiation, heat addition or generation, convection, and fluid flow.
1980-10-01
SOLRED 53. C NFGSW =1 DAM PROBLEM 54. C =2 PROBLEM (5.3),(5.4). 55. C 56. C 57. C NINTSW =1 INJECTION. SUBROUTINE INTADD -77- ==.... APPX-C-PFMG 58. C =2...ARRAY Q SIZE SHOULD BE AT LEAST =1, 110) 256. STOP 257. 92 CONTINUE 258. C 259. C 260. CALL SOLRED 261. C 262. C INITIALIZE 263. WU=0 264. CALL...CONTINUE 996. PRINT *,(QTEM(LL),LL=1,L) 997. 20 CONTINUE 998. CALL URTIMS(TIME) 999. RETURN 1000. END 1001. C 1002. C 1003. C 1004. SUBROUTINE SOLRED
Crew appliance computer program manual, volume 1
NASA Technical Reports Server (NTRS)
Russell, D. J.
1975-01-01
Trade studies of numerous appliance concepts for advanced spacecraft galley, personal hygiene, housekeeping, and other areas were made to determine which best satisfy the space shuttle orbiter and modular space station mission requirements. Analytical models of selected appliance concepts not currently included in the G-189A Generalized Environmental/Thermal Control and Life Support Systems (ETCLSS) Computer Program subroutine library were developed. The new appliance subroutines are given along with complete analytical model descriptions, solution methods, user's input instructions, and validation run results. The appliance components modeled were integrated with G-189A ETCLSS models for shuttle orbiter and modular space station, and results from computer runs of these systems are presented.
1978-04-15
ENTMOD as there are modules. Con- fusion is avoided by executing the correct overlay link. Subroutine discussion, then, is initiated with ENTMOD whose...corresponding to the Nth time-uf-arrival bin. 278ILK | ,, F IMU (N,.J) is the sumation of UP(G,J) for all weapons arriving at the target through the Nth...56. Part VII: Local Subroutine CALSG 295 CSTART Initialize Read Columnn (NRD) To Lo aHrs Comnent Durment U end oluin beI a Estimate) By OnU, And
Implementation of a PETN failure model using ARIA's general chemistry framework
Hobbs, Michael L.
2017-01-01
We previously developed a PETN thermal decomposition model that accurately predicts thermal ignition and detonator failure [1]. This model was originally developed for CALORE [2] and required several complex user subroutines. Recently, a simplified version of the PETN decomposition model was implemented into ARIA [3] using a general chemistry framework without need for user subroutines. Detonator failure was also predicted with this new model using ENCORE. The model was simplified by 1) basing the model on moles rather than mass, 2) simplifying the thermal conductivity model, and 3) implementing ARIA’s new phase change model. This memo briefly describes the model, implementation, and validation.
Development of a Microprocessor-Based Instrument for Static Testing Small Rocket Engines.
1979-09-01
program jumped to the ADC12 A/D conversion subroutine before returning from the interrupt. Otherwise it returned from interrupt directly at this point...bytes into one and a half consecutive bytes. All of the A/D software was contained in one subroutine entitled ADC12 , which occupied 131 bytes and required...required by the DAC before sending them out, then changing the final result back to the straight binary used in the rest of the system. ADC12 could be
NASA Technical Reports Server (NTRS)
1971-01-01
Appendixes are presented that provide model input requirements, a sample case, flow charts, and a program listing. At the beginning of each appendix, descriptive details and technical comments are provided to indicate any special instructions applicable to the use of that appendix. In addition, the program listing includes comment cards that state the purpose of each subroutine in the complete program and describe operations performed within that subroutine. The input requirements includes details on the many options that adapt the program to the specific needs of the analyst for a particular problem.
Users manual for the Variable dimension Automatic Synthesis Program (VASP)
NASA Technical Reports Server (NTRS)
White, J. S.; Lee, H. Q.
1971-01-01
A dictionary and some problems for the Variable Automatic Synthesis Program VASP are submitted. The dictionary contains a description of each subroutine and instructions on its use. The example problems give the user a better perspective on the use of VASP for solving problems in modern control theory. These example problems include dynamic response, optimal control gain, solution of the sampled data matrix Ricatti equation, matrix decomposition, and pseudo inverse of a matrix. Listings of all subroutines are also included. The VASP program has been adapted to run in the conversational mode on the Ames 360/67 computer.
1985-09-01
In this case the interior quadrature points should be chosen as P if Yx=I isgivn, r pa, +l) . if Y(x) is given, or P , if Y(x=0) is given. The Radau ...Subroutines JCOBI computes the zeros of p (aP) and the i*o.’ n first derivatives of the Jacobi polynomial; Subroutine RADAU determines the integration weights...RECIPIENT’S CATALOG NUMBER Technical Report HL-82-15 A~ l P A5 _I 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED THE ATCHAFALAYA RIVER DELTA; Report
NASA Technical Reports Server (NTRS)
Seidel, R. C.
1974-01-01
FORTRAN computer subroutines stemming from requirements to process state variable system equations for systems of high order are presented. They find the characteristic equation of a matrix using the method of Danilevsky, the number of roots with positive real parts using the Routh-Horwitz alternate formulation, convert a state variable system description to a Laplace transfer function using the method of Bollinger, and evaluate that transfer function and obtain its frequency response. A sample problem is presented to demonstrate use of the subroutines.
Orbital Mechanics: A Learning Tool on the Main Frame
1989-09-01
IJK COORDINATES TO Pqw COORDINATES 0R504590 0R304600 DOUBLE PRECISION INC, I,J,K,PQWoR11 ,Rl2tRl3,R2lR22,R23, ORB04610 + R31l,R32,R33, LANAP ORB04620...ORB11030 ORB11040 ORB11050 SUBROUTINE TLON( LANAP ,TA,TL) ORB11060 THIS SUBROUTINE CALCULATES THE TRUE LONGITUDE AT EPOCH ORB11070 ORB11080 DOUBLE PRECISION... LANAP ,TA,TL ORB11090 ORB11100 TL = AP + LAN + TA ORB11110 RETURN ORB11120 END ORB11130 45 ORDIII40 ORS1 1150 ORB 11160 * ’TH.LZS SlETIN T . PERIOD
Frequency Domain Identification Toolbox
NASA Technical Reports Server (NTRS)
Horta, Lucas G.; Juang, Jer-Nan; Chen, Chung-Wen
1996-01-01
This report documents software written in MATLAB programming language for performing identification of systems from frequency response functions. MATLAB is a commercial software environment which allows easy manipulation of data matrices and provides other intrinsic matrix functions capabilities. Algorithms programmed in this collection of subroutines have been documented elsewhere but all references are provided in this document. A main feature of this software is the use of matrix fraction descriptions and system realization theory to identify state space models directly from test data. All subroutines have templates for the user to use as guidelines.
A program and data base for evaluating SMMR algorithms
NASA Technical Reports Server (NTRS)
1979-01-01
A program (PARAM) is described which enables a user to compare the values of meteorological parameters derived from data obtained by the scanning multichannel microwave radiometer (SMMR) instrument on NIMBUS 7 with surface observations made over the ocean. The input to this program is a data base, also described, which contains the surface observations and coincident SMMR data. The evaluation of meteorological parameters using SMMR data is done by a user supplied subroutine. Instruments are given for executing the program and writing the subroutine.
NASA Technical Reports Server (NTRS)
1979-01-01
The quasi-one dimensional flow program was modified in two ways. The Runge-Kutta subroutine was replaced with a subroutine which used a modified divided difference form of the Adams Pece method and the matrix inversion routine was replaced with a pseudo inverse routine. Calculations were run using both the original and modified programs. Comparison of the calculations showed that the original Runge-Kutta routine could not detect singularity near the throat and was integrating across it. The modified version was able to detect the singularity and therefore gave more valid calculations.
Thermal APU/hydraulics analysis program. User's guide and programmer's manual
NASA Technical Reports Server (NTRS)
Deluna, T. A.
1976-01-01
The User's Guide information plus program description necessary to run and have a general understanding of the Thermal APU/Hydraulics Analysis Program (TAHAP) is described. This information consists of general descriptions of the APU/hydraulic system and the TAHAP model, input and output data descriptions, and specific subroutine requirements. Deck setups and input data formats are included and other necessary and/or helpful information for using TAHAP is given. The math model descriptions for the driver program and each of its supporting subroutines are outlined.
Operational manual for two-dimensional transonic code TSFOIL
NASA Technical Reports Server (NTRS)
Stahara, S. S.
1978-01-01
This code solves the two-dimensional, transonic, small-disturbance equations for flow past lifting airfoils in both free air and various wind-tunnel environments by using a variant of the finite-difference method. A description of the theoretical and numerical basis of the code is provided, together with complete operating instructions and sample cases for the general user. In addition, a programmer's manual is also presented to assist the user interested in modifying the code. Included in the programmer's manual are a dictionary of subroutine variables in common and a detailed description of each subroutine.
PASLIB programmer's guide for the finite element machine, revision 2.1-A
NASA Technical Reports Server (NTRS)
Crockett, T. W.
1984-01-01
PASLIB is a library of Pascal callable subroutines designed to give application programs access to the unique architectural features of the Finite Element Machine and to the software support services provided by the Nodal Exec operating system which runs on it. The PASLIB subroutines are documented and the procedures needed to write Pascal programs for execution on the Finite Element Machine are defined. Considerations for obtaining optimum hardware and software performance are given. A brief overview of debugging and performance analysis capabilities available to the programmer is presented.
1983-09-01
the ti and t2 directions on the source patch. 3. METHOD : The electric field at a segment observation point due to the source patch j is given by 1-- lnA...PURPOSE: Tocalculate the magnetic field due to a unit current in the tj and t2 directions on the patch source. 3. METHOD : The magnetic field is...WLKBCK (GTD, INPUT, MOM, OUTPUT) 2. PURPOSE: To accumulate the walkback table information. 3. METHOD : The subroutine accumulates a table of the subroutine
The conical scanner evaluation system design
NASA Technical Reports Server (NTRS)
Cumella, K. E.; Bilanow, S.; Kulikov, I. B.
1982-01-01
The software design for the conical scanner evaluation system is presented. The purpose of this system is to support the performance analysis of the LANDSAT-D conical scanners, which are infrared horizon detection attitude sensors designed for improved accuracy. The system consists of six functionally independent subsystems and five interface data bases. The system structure and interfaces of each of the subsystems is described and the content, format, and file structure of each of the data bases is specified. For each subsystem, the functional logic, the control parameters, the baseline structure, and each of the subroutines are described. The subroutine descriptions include a procedure definition and the input and output parameters.
Image Alignment and Correlation System.
1980-07-01
THRESHOLD VS. THRESHOLD SET THRESHOLD TO GIVE NPT POINTS SEARCH FOR PROMINENT SPATIAL FREOENCIES ANDCOMPUTE S1U, SlV , SIUV VARIABLES FORENTER N LEAST...SIU, SlV , S1UV VARIABUS FOR LEAST SQUARES Y Figurell Flow Diagram for Subroutine MEASRE -54- CCIPUrE SlUP *SIVP VARIABLES FR LEASTr SJARES Lm . -55...table to the position of maximum correlation. Subroutine SUMPAR computes UU, UV, VV, UP and VP from the partial products SIU, SlV , SlUV, SlUP and S1VP
Progressive Failure Analysis of Advanced Composites
2008-07-25
subroutine SUBROUTINE UVARM(UVAR,DIRECT,T,TIME,DTIME,CMNAME,ORNAME, 1 NUVARM,NOEL,NPT,LAYER,KSPT,KSTEP,KINC,NDI,NSHR,COORD, 2 JMAC ,JMATYP,MATLAYO,LACCFLA...CHARACTER dmkname*255, FNAMEX*80 DIMENSION UVAR(*),DIRECT(3,3),T(3,3),TIME(2) DIMENSION ARRAY(15),JARRAY(15), JMAC (*),JMATYP(*),COORD(*) C DIMENSION stress(6...CALL GETVRM(’S’,ARRAY,JARRAY,FLGRAY,JRCD, JMAC ,JMATYP,MATLAYO, 1 LACCFLA) C 48 if(klarc.eq.3) then ! LaRC03 failure criteria stress(1) = array(1
1981-02-01
Hence a likely candidate for double precision is array GAMMA in subroutine DUBLIN (and its dummy version A in subroutine MATINV). A more complete list of...23) RHW a,.d W yne II. Hathaway, "Reduction of Yaw Sonde aiid Position ’rime Radar Data by Numerical Integration," 1E Report No. 7%APB506, January...1972. (24) RHW ond Ray C. Houghton, "Reduction of Range and Yaw Sonde Dat. Using Numerical Integration Techniques," GE Report No, 72APB539, September
NASA Technical Reports Server (NTRS)
1973-01-01
A description of each of the software modules of the Image Data Processing System (IDAPS) is presented. The changes in the software modules are the result of additions to the application software of the system and an upgrade of the IBM 7094 Mod(1) computer to a 1301 disk storage configuration. Necessary information about IDAPS sofware is supplied to the computer programmer who desires to make changes in the software system or who desires to use portions of the software outside of the IDAPS system. Each software module is documented with: module name, purpose, usage, common block(s) description, method (algorithm of subroutine) flow diagram (if needed), subroutines called, and storage requirements.
2006-08-08
taking into account the effects of polycrystalline microstructures, elastic anisotropy of the crystals, and material damages due to microplasticity and...anisotropic crystal elasticity, intragranular microplasticity and intergranular microfracture have been developed and implemented into the ABAQUS codes...Zhang, K. S., Wu, M. S., and Feng, R. (2005). Simulation of microplasticity -induced deformation in uniaxially strained ceramics by 3-D Voronoi
Estimation of Ocean and Seabed Parameters and Processes Using Low Frequency Acoustic Signals
2011-09-01
propagation within short ranges. He is investigating the possibility of using commercial software Abaqus to model interface waves. APPROACH The PIs...J. H., “Modeling of Pile driving noise radiation and propagation,” SIMULIA East Regional Users Meeting 2011, Providence, RI, September 22-23, 2011
2009-04-01
anisotropic crystal plasticity FEM model was implemented using the commercial FEM program ABAQUS , in order to better understand the effect of the test...a local pile -up of dislocations at the surface. The magnitude of this disorientation is less than 0.5°. Also note the lack of activity on other
Through-Thickness Texture Gradients in Rolled Polycrystalline Alloys
1997-10-01
code ABAQUS (Hibbit, Karlsson, and Sorensen 1988) and have carried out simulations of simple deformation processes such as simple shear and plane-strain...account for both dislocation pile up and recovery due to cross slip. Further, this model can account for the rate sensitivity of both the yield stress
Tadepalli, Srinivas C; Erdemir, Ahmet; Cavanagh, Peter R
2011-08-11
Finite element analysis has been widely used in the field of foot and footwear biomechanics to determine plantar pressures as well as stresses and strains within soft tissue and footwear materials. When dealing with anatomical structures such as the foot, hexahedral mesh generation accounts for most of the model development time due to geometric complexities imposed by branching and embedded structures. Tetrahedral meshing, which can be more easily automated, has been the approach of choice to date in foot and footwear biomechanics. Here we use the nonlinear finite element program Abaqus (Simulia, Providence, RI) to examine the advantages and disadvantages of tetrahedral and hexahedral elements under compression and shear loading, material incompressibility, and frictional contact conditions, which are commonly seen in foot and footwear biomechanics. This study demonstrated that for a range of simulation conditions, hybrid hexahedral elements (Abaqus C3D8H) consistently performed well while hybrid linear tetrahedral elements (Abaqus C3D4H) performed poorly. On the other hand, enhanced quadratic tetrahedral elements with improved stress visualization (Abaqus C3D10I) performed as well as the hybrid hexahedral elements in terms of contact pressure and contact shear stress predictions. Although the enhanced quadratic tetrahedral element simulations were computationally expensive compared to hexahedral element simulations in both barefoot and footwear conditions, the enhanced quadratic tetrahedral element formulation seems to be very promising for foot and footwear applications as a result of decreased labor and expedited model development, all related to facilitated mesh generation.
Development of an Efficient Micro-Heat Exchanger: The Integration of Design Processing and Testing
2005-11-01
residual stress is contour method if the sample can be cleanly broken (brittle). We could possibly ABAQUS Python scripting interface to mesh actual part...powders during compaction. Among many fugitive phases used (many grades of polymers , papers and graphite), graphite is the only fugitive material that
Engineering Property Prediction Tools for Tailored Polymer Composite Structures (49465)
Nguyen, Ba Nghiep; Kunc, Vlastimil
2009-12-29
Process and constitutive models as well as characterization tools and testing methods were developed to determine stress-strain responses, damage development, strengths and creep of long-fiber thermoplastics (LFTs). The developed models were implemented in Moldflow and ABAQUS and have been validated against LFT data obtained experimentally.
FFATA: Mechine Augmented Composites for Structures with High Damping with High Stiffness
2012-12-05
49 Element 2—Shear Thinning Fluid Computational research of HG...with shear thinning fluids .......................................... 59 Element 3 – Shear Thickening Fluid...163 FINITE ‐ ELEMENT MODEL (ABAQUS
NASA Astrophysics Data System (ADS)
Sawadogo, Teguewinde
. Stability tests were conducted in the second stage of the project to validate the theoretical model. The two phase damping, the added mass and the critical velocity for fluidelastic instability were measured in two-phase flow. A viscoelastic damper was designed to vary the damping of the flexible tube and thus measure the critical velocity for a certain range of the mass-damping parameter. A new formulation of the added mass as a function of the void fraction was proposed. This formulation has a better agreement with the experimental results because it takes into account the reduction of the void fraction in the vicinity of the tubes in a rotated triangular tube array. The experimental data were used to validate the theoretical results of the quasi-steady model. The validity of the quasi-steady model for two-phase flow was confirmed by the good agreement between its results and the experimental data. The time delay parameter determined in the first stage of the project has improved significantly the theoretical results, especially for high void fractions (90%). However, the model could not be verified for void fractions lower or equal to 50% because of the limitation of the water pump capability. Further studies are consequently required to clarify this point. However, this model can be used to simulate the flow induced vibrations in steam generators' tube bundles as their most critical parts operate at high void fractions (≥ 60%). Having verified the quasi-steady model for high void fractions in two-phase flow, the third and final stage of the project was devoted to the development of a computer code for simulating flow induced vibrations of a steam generator tube subjected to fluidelastic and turbulence forces. This code was based on the ABAQUS finite elements code for solving the equation of motion of the fluid-structure system, and a development of a subroutine in which the fluid forces are calculated and applied to the tube. (Abstract shortened by UMI.)
NASA Astrophysics Data System (ADS)
Peters, Max; Poulet, Thomas; Karrech, Ali; Regenauer-Lieb, Klaus; Herwegh, Marco
2014-05-01
Layered rocks deformed under viscous deformation conditions frequently show boudinage, a phenomenon that results from differences in effective viscosity between the involved layers. In the case of continuous necking of a mechanically stiffer layer embedded in a weaker matrix, symmetric boudins are interpreted as the result of dominant visco-plastic deformation (Goscombe et al., 2004). However, information on the physical conditions, material properties and deformation processes are yet unknown. Natural samples deformed under low-grade (T<350°C) metamorphic conditions were studied in detail in the Dent de Morcles and Doldenhorn nappes of the Helvetic Alps in order to accurately simulate their deformation styles by numerical models. In these samples, monomineralic calcite (Cc) veins were repeatedly boudinaged on cm- to µm-scale. Remnants of incompletely recrystallized original vein Cc grains in the swells indicate a sequence of deformation twinning, followed by progressive dynamic recrystallization along former twin planes up to complete recrystallization in the pinches (Schmalholz and Maeder, 2012). This sequence suggests dislocation creep to be active as important deformation mechanism. In contrast to the pinch-and-swell structures, the grain size of the Cc in the surrounding matrix is much finer-grained due to pinning by secondary particles, forcing the matrix to deform under viscous granular creep, i.e. by diffusion accommodated grain boundary sliding. The deformation processes observed in the natural samples were incorporated into a numerical model in order to evaluate the rheology of both layer and matrix, using an extension to a user material subroutine (Karrech et al., 2011a) for the finite element solver ABAQUS. We implemented thermo-mechanical coupling allowing elastic, viscous and plastic deformation of Cc (Herwegh et al., in press). We simulate a pure-shear box using finite elements, each representing a grain size distribution, which undergo layer
NASA Astrophysics Data System (ADS)
Zhang, Nan
constructed by calculating the theoretical M-K model with Newton method and backtracking algorithm. The obtained FLDs are found to be instructive and will be applied in the post-processing of FE simulation for stamping so as to identify the critical area of failure. The developed constitutive model and modified yield function are implemented in the form of user defined subroutine (VUMAT) in ABAQUS/Explicit. An explicit stress integration algorithm has been selected for the stress integration with rate-depend viscoplasticity model at temperature higher than 150°. In the low temperature range, the Newton method and cutting plane algorithm are utilized to update the stress tensor with a classic elastoplastic constitutive model. To validate the VUMAT, a non-isothermal tensile testing has been performed with aids of infrared thermal camera and DIC. The heat transfer coefficients in FE model are calibrated with captured thermal images. With appropriate selection of mesh size and mass scaling factor, the punch load vs. displacement curve obtained from the simulation perfectly correlates the experimental result.
Video equipment recommendations for slit lamp videography.
Hammack, G G
1991-08-01
Current developments in video technology have made videotaping through a slit lamp a useful capability available at a more reasonable cost. The technical basis of equipment needed to select or design an apparatus for slit lamp videography is reviewed. As an overview, the optimum slit lamp video apparatus would have the following criteria; the slit lamp should have zoom optics and rheostat illumination, the beam splitter should be a mirror or 70/30 type, the camera should have maximal light sensitivity (101ux) with reasonable resolution (greater than 300 lines). The recorder should be SP-Umatic or Super VHS for documentation, or consumer VHS for patient education, and the monitor should be a professional 13- or 15-inch monitor.
Code Usage Analysis System (CUAS)
NASA Technical Reports Server (NTRS)
Horsley, P. H.; Oliver, J. D.
1976-01-01
A set of computer programs is offered to aid a user in evaluating performance of an application program. The system provides reports of subroutine usage, program errors, and segment loading which occurred during the execution of an application program. It is presented in support of the development and validation of the space vehicle dynamics project.
HICOV - Newton-Raphson calculus of variation with automatic transversalities
NASA Technical Reports Server (NTRS)
Heintschel, T. J.
1968-01-01
Computer program generates trajectories that are optimum with respect to payload placed in an earth orbit. It uses a subroutine package which produces the terminal and transversality conditions and their partial derivatives. This program is written in FORTRAN 4 and FORMAC for the IBM 7094 computer.
Progressive failure analysis of fibrous composite materials and structures
NASA Technical Reports Server (NTRS)
Bahei-El-din, Yehia A.
1990-01-01
A brief description is given of the modifications implemented in the PAFAC finite element program for the simulation of progressive failure in fibrous composite materials and structures. Details of the memory allocation, input data, and the new subroutines are given. Also, built-in failure criteria for homogeneous and fibrous composite materials are described.
Computational Investigation of an Improved Cowl Concept for Hypersonic Propulsive Nozzles
1994-06-01
profile for the parailelized code. CPU usage is broken down for the four processors used on the Silicon Graphics 4D1240 machine. Processor number 1: Profile...Parallelization of Subroutine Lf .......................... 143 Appendix C: Pressure and Mach Number Contours ..................... 145 V ita...Schematic of Over and Underexpanded Exhaust at Supersonic Freestream Mach Number (1) ................................ 63 Figure 4-2 Grid Resolution Effects
SDL: A Surface Description Language
NASA Technical Reports Server (NTRS)
Maple, Raymond C.
1992-01-01
A new interpreted language specifically designed for surface grid generation is introduced. Many unique aspects of the language are discussed, including the farray, vector, curve, and surface data types and the operators used to manipulate them. Custom subroutine libraries written in the language are used to easily build surface grids for generic missile shapes.
Calculation of Ray Paths in the Ionosphere Using an Analytic Raytracing Technique
1986-07-01
could have been intercented, the delay time DLAY is stored in the array ADLAY (ITHET. 1FREQ) which it; subse- quently plotted in the subroutine DLAYPL...870 and all rays whose final height XX(MAXR) is within 10 km of the satellite height SXAT are accepted and stored in ADLAY for plotting. Wm mm mm
NASA Technical Reports Server (NTRS)
Davidson, Frederic M.; Sun, Xiaoli; Field, Christopher T.
1994-01-01
This interim report consists of two reports: 'Space Radiation Effects on Si APDs for GLAS' and 'Computer Simulation of Avalanche Photodiode and Preamplifier Output for Laser Altimeters.' The former contains a detailed description of our proton radiation test of Si APD's performed at the Brookhaven National Laboratory. The latter documents the computer program subroutines which were written for the upgrade of NASA's GLAS simulator.
Glasgow, B.B.; Meier, W.R.
1987-01-12
Analytical models for scaling the cost and performance of inertial confinement fusion (ICF) electric-power plants have been developed and incorporated into the SAFIRE code. SAFIRE denotes systems analysis for ICF reactor economics. This volume, Volume 2, describes the subroutines, COMMON blocks, file handling, and input and output variables of the code. (WRF)
FIO/RIO -- FORTRAN file I/O routines
NASA Astrophysics Data System (ADS)
Allan, P. M.; Chipperfield, A. J.
FIO/RIO is a subroutine package that allows a FORTRAN programmer to access sequential and direct access data files in a machine independent manner. The package consists of stand alone FIO and RIO routines, which can be used independently of the Starlink software environment, plus routines to interface to the Starlink parameter system.
Erosion in radial inflow turbines. Volume 5: Computer programs for tracing particle trajectories
NASA Technical Reports Server (NTRS)
Clevenger, W. B., Jr.; Tabakoff, W.
1975-01-01
Computer programs used to study the trajectories of particles in the radial inflow turbines are presented. The general technique of each program is described. A set of subroutines developed during the study are described. Descriptions, listings, and typical examples of each of the main programs are included.
Computer program developed for flowsheet calculations and process data reduction
NASA Technical Reports Server (NTRS)
Alfredson, P. G.; Anastasia, L. J.; Knudsen, I. E.; Koppel, L. B.; Vogel, G. J.
1969-01-01
Computer program PACER-65, is used for flowsheet calculations and easily adapted to process data reduction. Each unit, vessel, meter, and processing operation in the overall flowsheet is represented by a separate subroutine, which the program calls in the order required to complete an overall flowsheet calculation.
Tip vortex computer code SRATIP. User's guide
NASA Technical Reports Server (NTRS)
Levy, R.; Lin, S. J.
1985-01-01
This User's Guide applies to the three dimensional viscous flow forward marching analysis, PEPSIG, as used for the calculation of the helicopter tip vortex flow field. The guide presents a discussion of the program flow and subroutines, as well as a list of sample input and output.
ERIC Educational Resources Information Center
Anderson, Lougenia; Gales, Larry
This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. FFORM is a portable format-free input subroutine package written in ANSI Fortran IV…
A detailed description of the sequential probability ratio test for 2-IMU FDI
NASA Technical Reports Server (NTRS)
Rich, T. M.
1976-01-01
The sequential probability ratio test (SPRT) for 2-IMU FDI (inertial measuring unit failure detection/isolation) is described. The SPRT is a statistical technique for detecting and isolating soft IMU failures originally developed for the strapdown inertial reference unit. The flowchart of a subroutine incorporating the 2-IMU SPRT is included.
SSME structural computer program development: BOPACE programmer manual
NASA Technical Reports Server (NTRS)
1975-01-01
The programming manual for the two-dimensional Boeing Plastic Analysis Capability for Engines (BOPACE) program written in FORTRAN IV is presented. The BOPACE flow logic is summarized along with subroutines and input/output files. Emphasis is placed on linear equation solver routines written as an independent package.
DORCA 2 computer program. Volume 2: Programmer's manual
NASA Technical Reports Server (NTRS)
Gold, B. J.
1972-01-01
A guide for coding the Dynamic Operational Requirements and Cost Analysis Program (DORCA 2) is presented. The manual provides a detailed operation of every subroutine, the layout in core of the major matrices and arrays, and the meaning of all program values. Flow charts are included.
NASA Technical Reports Server (NTRS)
Lennington, R. K.; Rassbach, M. E.
1979-01-01
Discussed in this report is the clustering algorithm CLASSY, including detailed descriptions of its general structure and mathematical background and of the various major subroutines. The report provides a development of the logic and equations used with specific reference to program variables. Some comments on timing and proposed optimization techniques are included.
Program Fighter: An Evaluation.
ERIC Educational Resources Information Center
Hull, David G.; Fowler, Wallace T.
A computer program for the sizing of subsonic and supersonic fighter planes was adapted for use in an aerospace engineering course at the University of Texas at Austin. FIGHTER uses classroom notation and separate subroutines for different disciplines to implement the conceptual design process. Input consists of a set of design variables and a set…
Comment: a schema for the interactions between motor programs and sensory input.
Tatton, W G; Bruce, I C
1981-07-01
In this overview we utilize and extend a model, originally developed for "command interneuron" control of the generation of motor programs, to discuss the roles sensory inputs play in movement control. To provide a conceptual framework, we present a modular schematic of the motor control and sensory processing apparatus of an hypothetical nervous system. In the schematic, "subroutines" (basic units of motor programs) are seen as "playing out" through switching and sequencing networks to "driver neurons." The "driver neurons" then activate motoneurons to execute the programmed movements. Five modes of interaction between motor programs and sensory input are considered using examples from invertebrate and vertebrate neuronal circuitry. These modes of interaction occur at the following locations: (1) the "program selector," to initiate a motor program; (2) the "motor subroutine directory," advancing the program to the next subroutine; (3) the "driver neurons" and motoneurons, where the "gain" of subroutine instructions can be modulated; (4) the "motor programmer," which monitors programs in progress and provides for program development and updating; and (5) the "driver neurons" themselves, which control sensory processing by "selecting" the appropriate sensory inputs for the program in progress. Mode 5 is illustrated in more detail through a consideration of the modification of stretch receptor input by "extensor" and "flexor" command interneurones in the circuitry controlling postural movements of the crayfish abdomen.
Heat pipe cooled heat rejection subsystem modelling for nuclear electric propulsion
NASA Technical Reports Server (NTRS)
Moriarty, Michael P.
1993-01-01
NASA LeRC is currently developing a FORTRAN based computer model of a complete nuclear electric propulsion (NEP) vehicle that can be used for piloted and cargo missions to the Moon or Mars. Proposed designs feature either a Brayton or a K-Rankine power conversion cycle to drive a turbine coupled with rotary alternators. Both ion and magnetoplasmodynamic (MPD) thrusters will be considered in the model. In support of the NEP model, Rocketdyne is developing power conversion, heat rejection, and power management and distribution (PMAD) subroutines. The subroutines will be incorporated into the NEP vehicle model which will be written by NASA LeRC. The purpose is to document the heat pipe cooled heat rejection subsystem model and its supporting subroutines. The heat pipe cooled heat rejection subsystem model is designed to provide estimate of the mass and performance of the equipment used to reject heat from Brayton and Rankine cycle power conversion systems. The subroutine models the ductwork and heat pipe cooled manifold for a gas cooled Brayton; the heat sink heat exchanger, liquid loop piping, expansion compensator, pump and manifold for a liquid loop cooled Brayton; and a shear flow condenser for a K-Rankine system. In each case, the final heat rejection is made by way of a heat pipe radiator. The radiator is sized to reject the amount of heat necessary.
The Development of a Computerized Curriculum Monitoring System To Ensure Student Success.
ERIC Educational Resources Information Center
Heard, Frank B.
A computerized curriculum monitoring system (CMS) was developed at Shelby State Community College (SSCC) in Tennessee to restrict student registration to courses for which they have completed the prerequisites and corequisites. The CMS is a subroutine of the on-line registration program, which matches students' course selections against their…
Monte Carlo Simulation of Plumes Spectral Emission
2005-06-07
Henyey − Greenstein scattering indicatrix SUBROUTINE Calculation of spectral (group) phase function of Monte - Carlo Simulation of Plumes...calculations; b) Computing code SRT-RTMC-NSM intended for narrow band Spectral Radiation Transfer Ray Tracing Simulation by the Monte - Carlo method with...project) Computing codes for random ( Monte - Carlo ) simulation of molecular lines with reference to a problem of radiation transfer
The three-dimensional Event-Driven Graphics Environment (3D-EDGE)
NASA Technical Reports Server (NTRS)
Freedman, Jeffrey; Hahn, Roger; Schwartz, David M.
1993-01-01
Stanford Telecom developed the Three-Dimensional Event-Driven Graphics Environment (3D-EDGE) for NASA GSFC's (GSFC) Communications Link Analysis and Simulation System (CLASS). 3D-EDGE consists of a library of object-oriented subroutines which allow engineers with little or no computer graphics experience to programmatically manipulate, render, animate, and access complex three-dimensional objects.
Coltrin, M.E.; Kee, R.J.; Rupley, F.M.; Meeks, E.
1996-05-01
This document is the user`s manual for the SURFACE CHEMKIN-III package. Together with CHEMKIN-III, this software facilitates the formation, solution, and interpretation of problems involving elementary heterogeneous and gas-phase chemical kinetics in the presence of a solid surface. The package consists of two major software components: an Interpreter and a Surface Subroutine Library. The Interpreter is a program that reads a symbolic description of a user-specified chemical reaction mechanism. One output from the Interpreter is a data file that forms a link to the Surface Subroutine Library, which is a collection of about seventy modular Fortran subroutines that may be called from a user`s application code to return information on chemical production rates and thermodynamic properties. This version of SURFACE CHEMKIN-III includes many modifications to allow treatment of multi-fluid plasma systems, for example modeling the reactions of highly energetic ionic species with a surface. Optional rate expressions allow reaction rates to depend upon ion energy rather than a single thermodynamic temperature. In addition, subroutines treat temperature as an array, allowing an application code to define a different temperature for each species. This version of SURFACE CHEMKIN-III allows use of real (non-integer) stoichiometric coefficients; the reaction order with respect to species concentrations can also be specified independent of the reaction`s stoichiometric coefficients. Several different reaction mechanisms can be specified in the Interpreter input file through the new construct of multiple materials.
SPAR improved structure-fluid dynamic analysis capability, phase 2
NASA Technical Reports Server (NTRS)
Pearson, M. L.
1984-01-01
An efficient and general method of analyzing a coupled dynamic system of fluid flow and elastic structures is investigated. The improvement of Structural Performance Analysis and Redesign (SPAR) code is summarized. All error codes are documented and the SPAR processor/subroutine cross reference is included.
1980-04-30
CSOTH(2) Number of targets assigned to weapons with a given alert status DEFCOM RATM Highest return rate from DEFALOC ISALFX(250) Storage for fixed...PARAMETERS: IOPT - Print option number COMMON BLOCKS: C30, DEFCOM , DEFRES SUBROUTINES CALLED: None CALLED BY: PRNTNOW Method: The formal parameter
RAYS: a geometrical optics code for EBT
Batchelor, D.B.; Goldfinger, R.C.
1982-04-01
The theory, structure, and operation of the code are described. Mathematical details of equilibrium subroutiones for slab, bumpy torus, and tokamak plasma geometry are presented. Wave dispersion and absorption subroutines are presented for frequencies ranging from ion cyclotron frequency to electron cyclotron frequency. Graphics postprocessors for RAYS output data are also described.
A Numerical Study of High-Speed Missile Configurations Using a Block- Structured Parallel Algorithm
1993-12-01
Transformation Calculation Subroutine ....................... 97 iv List of Figures Figure Page 1. Current and Projected Computational Requirements...B.3. Project Block Structure and Associated Block Table ......................... 68 B.4. Computational-to-Block Coordinate Transformation ...J, & unit vectors aligned along Cartesian xyz axes R position vector AdS surface vector U vector of conserved variables Kronecker Delta function J
Heat pipe cooled heat rejection subsystem modelling for nuclear electric propulsion
NASA Astrophysics Data System (ADS)
Moriarty, Michael P.
1993-11-01
NASA LeRC is currently developing a FORTRAN based computer model of a complete nuclear electric propulsion (NEP) vehicle that can be used for piloted and cargo missions to the Moon or Mars. Proposed designs feature either a Brayton or a K-Rankine power conversion cycle to drive a turbine coupled with rotary alternators. Both ion and magnetoplasmodynamic (MPD) thrusters will be considered in the model. In support of the NEP model, Rocketdyne is developing power conversion, heat rejection, and power management and distribution (PMAD) subroutines. The subroutines will be incorporated into the NEP vehicle model which will be written by NASA LeRC. The purpose is to document the heat pipe cooled heat rejection subsystem model and its supporting subroutines. The heat pipe cooled heat rejection subsystem model is designed to provide estimate of the mass and performance of the equipment used to reject heat from Brayton and Rankine cycle power conversion systems. The subroutine models the ductwork and heat pipe cooled manifold for a gas cooled Brayton; the heat sink heat exchanger, liquid loop piping, expansion compensator, pump and manifold for a liquid loop cooled Brayton; and a shear flow condenser for a K-Rankine system. In each case, the final heat rejection is made by way of a heat pipe radiator. The radiator is sized to reject the amount of heat necessary.
NASA Technical Reports Server (NTRS)
Daly, J. K.
1974-01-01
The programming techniques used to implement the equations and mathematical techniques of the Houston Operations Predictor/Estimator (HOPE) orbit determination program on the UNIVAC 1108 computer are described. Detailed descriptions are given of the program structure, the internal program structure, the internal program tables and program COMMON, modification and maintainence techniques, and individual subroutine documentation.
CNP. Cervical Neoplasia Probe Control
Vargo, T.
1995-05-17
This software, which consists of a main executive and several subroutines, performs control of the optics, image acquisition, and Digital Signal Processing (DSP) of this image, of an optical based medical instrument that performs fluoresence detection of precancerous lesions (neoplasia) of the human cervix. The hardware portion of this medical instrument is known by the same name Cervical Neoplasia Probe (CNP)
A Maximal Flow Approach to Dynamic Routing in Communication Networks,
1980-05-01
of nodes. In Appendix B we provide a computer program in Fortran for finding the maximal flow in these networks, based on the algorithm of Edmons and... Edmons and Karp is implemented by a Fortran Subroutine called MAXFL. The algorithm finds the shortest path between source and destination on which an
NASA Technical Reports Server (NTRS)
Dash, S. M.; Pergament, H. S.
1978-01-01
The basic code structure is discussed, including the overall program flow and a brief description of all subroutines. Instructions on the preparation of input data, definitions of key FORTRAN variables, sample input and output, and a complete listing of the code are presented.
Optimization guide for programs compiled under IBM FORTRAN H (OPT=2)
NASA Technical Reports Server (NTRS)
Smith, D. M.; Dobyns, A. H.; Marsh, H. M.
1977-01-01
Guidelines are given to provide the programmer with various techniques for optimizing programs when the FORTRAN IV H compiler is used with OPT=2. Subroutines and programs are described in the appendices along with a timing summary of all the examples given in the manual.
Manual for Getdata Version 3.1: a FORTRAN Utility Program for Time History Data
NASA Technical Reports Server (NTRS)
Maine, Richard E.
1987-01-01
This report documents version 3.1 of the GetData computer program. GetData is a utility program for manipulating files of time history data, i.e., data giving the values of parameters as functions of time. The most fundamental capability of GetData is extracting selected signals and time segments from an input file and writing the selected data to an output file. Other capabilities include converting file formats, merging data from several input files, time skewing, interpolating to common output times, and generating calculated output signals as functions of the input signals. This report also documents the interface standards for the subroutines used by GetData to read and write the time history files. All interface to the data files is through these subroutines, keeping the main body of GetData independent of the precise details of the file formats. Different file formats can be supported by changes restricted to these subroutines. Other computer programs conforming to the interface standards can call the same subroutines to read and write files in compatible formats.
Potential for hydropower development at existing dams in New England. Volume 2: User's manual
NASA Astrophysics Data System (ADS)
1980-01-01
The computer program HYELEC and its subroutines HYDPOT and ECOPOT is presented. HYELEC stores information relating to the hydropower potential of dams and can perform screening and ranking operations on these dams according to selected criteria pertaining to engineering practicability and economic feasibility. The computer language, the use of program control variables, and the sequence of events required for program operation are described.
New optical and radio frequency angular tropospheric refraction models for deep space applications
NASA Technical Reports Server (NTRS)
Berman, A. L.; Rockwell, S. T.
1976-01-01
The development of angular tropospheric refraction models for optical and radio frequency usage is presented. The models are compact analytic functions, finite over the entire domain of elevation angle, and accurate over large ranges of pressure, temperature, and relative humidity. Additionally, FORTRAN subroutines for each of the models are included.
As-built design specification of the data order processor ORDHDT
NASA Technical Reports Server (NTRS)
Rios, A.
1980-01-01
A description and subroutine documentation of the data order processor, ORHDT is given. As part of the LANDSAT imagery verification and extraction system, ORDHT creates a computer tape containing the AgRISTARS requirements for LANDSAT data to be ordered from Goddard Space Flight Center. A brief description of hardware requirements is also included.
Application of LANDSAT-2 to the management of Delaware's marine and wetland resources
NASA Technical Reports Server (NTRS)
Klemas, V. (Principal Investigator); Bartlett, D.; Philpot, W.; Davis, G.
1976-01-01
The author has identified the following significant results. Imagery from LANDSAT 1 and 2 was analyzed to determine the location, type, and extent of fronts and boundaries in Delaware Bay as a function of tidal conditions. This information is being used to set up a subroutine for an oil slick movement prediction model.
Computing relative plate velocities: a primer
Bevis, M.
1987-08-01
Standard models of present-day plate motions are framed in terms of rates and poles of rotation, in accordance with the well-known theorem due to Euler. This article shows how computation of relative plate velocities from such models can be viewed as a simple problem in spherical trigonometry. A FORTRAN subroutine is provided to perform the necessary computations.
A General-Purpose Graphic Plotting Package.
ERIC Educational Resources Information Center
Freese, David H., Jr.
1983-01-01
Describes subroutines in a group of assembly-level programs (program listings included) which provide the interface between a Basic, Pascal/Z, or JRT Pascal program and the BASE2/IDS-560 graphics printer. The interface can be easily modified for other printers and other languages. (JN)
Rudd, R. E.
2012-08-01
Interatomic force and energy calculation subroutine to be used with the molecular dynamics simulation code LAMMPS (Ref a.). The code evaluated the total energy and atomic forces (energy gradient) according to a cubic spline-based variant (Ref b.) of the Modified Embedded Atom Method (MEAM) with a additional Stillinger-Weber (SW) contribution.
NASA Technical Reports Server (NTRS)
Gallagher, R. R.
1974-01-01
The respiratory control system, functioning as an independent system, is presented with modifications of the exercise subroutine. These modifications illustrate an improved control of ventilation rates and arterial and compartmental gas tensions. A very elementary approach to describing the interactions of the respiratory and circulatory system is presented.
MCAID--A Generalized Text Driver.
ERIC Educational Resources Information Center
Ahmed, K.; Dickinson, C. J.
MCAID is a relatively machine-independent technique for writing computer-aided instructional material consisting of descriptive text, multiple choice questions, and the ability to call compiled subroutines to perform extensive calculations. It was specially developed to incorporate test-authoring around complex mathematical models to explore a…
Basic elements of power spectral analysis
NASA Technical Reports Server (NTRS)
Sentman, D. D.
1974-01-01
The basic elements of power spectral analysis with emphasis on the Blackman-Tukey method are presented. Short discussions are included on the topics of pre-whitening, frequency and spectral windows, and statistical reliability. Examples are included whenever possible, and a FORTRAN subroutine for calculating a power spectrum is presented.
SENSIT.FOR: A program for sensitometric reduction
NASA Astrophysics Data System (ADS)
Maury, A.; Marchal, J.
1984-09-01
A FORTRAN program for sensitometric evaluation of processes involved in hypering astronomical plates was written. It contains subroutines for full or quick description of the operation being done; choice of type of sensitogram; creation of 16 subfiles in the scan; density filtering; correction for area; specular PDS to diffuse ISO density calibration; and fog correction.
SAR-Related Stress Variability in the Marine Atmospheric Boundry Layer
1992-09-30
and temperature profiles typically observed to occur within the surface layer. Dave Ledvina has written a subroutine that uses standard similarity...Shirer and George S. Young Postdoctoral associate: Dr. Harry W. Henderson Research Associates: Dave Ledvina , Julie Schramm Graduate Students: Peter
Interim user's manual for boundary layer integral matrix procedure, version J
NASA Technical Reports Server (NTRS)
Evans, R. M.; Morse, H. L.
1974-01-01
A computer program for analyzing two dimensional and axisymmetric nozzle performance with a variety of wall boundary conditions is described. The program has been developed for application to rocket nozzle problems. Several aids to usage of the program and two auxiliary subroutines are provided. Some features of the output are described and three sample cases are included.
NASA Technical Reports Server (NTRS)
Deffenbaugh, F. D.; Vitz, J. F.
1979-01-01
The users manual for the Discrete Vortex Cross flow Evaluator (DIVORCE) computer program is presented. DIVORCE was developed in FORTRAN 4 for the DCD 6600 and CDC 7600 machines. Optimal calls to a NASA vector subroutine package are provided for use with the CDC 7600.
Estimating plant available water for general crop simulations in ALMANAC/APEX/EPIC/SWAT
Technology Transfer Automated Retrieval System (TEKTRAN)
Process-based simulation models ALMANAC/APEX/EPIC/SWAT contain generalized plant growth subroutines to predict biomass and crop yield. Environmental constraints typically restrict plant growth and yield. Water stress is often an important limiting factor; it is calculated as the sum of water use f...
NASA Technical Reports Server (NTRS)
Chang, H.
1976-01-01
A computer program using Lemke, Salkin and Spielberg's Set Covering Algorithm (SCA) to optimize a traffic model problem in the Scheduling Algorithm for Mission Planning and Logistics Evaluation (SAMPLE) was documented. SCA forms a submodule of SAMPLE and provides for input and output, subroutines, and an interactive feature for performing the optimization and arranging the results in a readily understandable form for output.
A Finite Element Solution of the Transport Equation.
1985-03-01
needed to evaluate the second scattering integral) at each of these points. ANING perfoms the angle integrals, finding matrices LI and NLI. Finally SPING ...w .-- -+ -, . .- - . + , LI, 1 ,50 2 3 * INTEGRATE OVER SPACE (X), ACROSS THE LOCAL TRIANGLE 4 5 SUBROUTINE SPING (DX,TRI,TRIP) 6 7 PARAMETER (MNODE
NEWSUMT: A FORTRAN program for inequality constrained function minimization, users guide
NASA Technical Reports Server (NTRS)
Miura, H.; Schmit, L. A., Jr.
1979-01-01
A computer program written in FORTRAN subroutine form for the solution of linear and nonlinear constrained and unconstrained function minimization problems is presented. The algorithm is the sequence of unconstrained minimizations using the Newton's method for unconstrained function minimizations. The use of NEWSUMT and the definition of all parameters are described.
FGRAAL: Technical documentation
NASA Technical Reports Server (NTRS)
Mesztenyi, C. K.; Breitenlohner, H.; Yeh, J. C.
1972-01-01
Implementation of FGRAAL, a FORTRAN-extended graph algorithmic language for the Univac 1108 is described. The report contains the description of the implemented data structures for sets, lists and graphs. It summarizes the changes made for the RALPH compiler to accommodate the special statements of FGRAAL; gives the calling sequences generated by the changed compiler; and describes the object time subroutine package.
Development of a natural gas systems analysis model (GSAM)
1999-10-01
This report provides an overview of the activities to date and schedule for future testing, validation, and authorized enhancements of Natural Gas Systems Analysis Model (GSAM). The goal of this report is to inform DOE managers of progress in model development and to provide a benchmark for ongoing and future research. Section II of the report provides a detailed discussion on the major GSAM development programs performed and completed during the period of performance, July 1, 1998 to September 30, 1999. Key improvements in the new GSAM version are summarized in Section III. Programmer's guides for GSAM main modules were produced to provide detailed descriptions of all major subroutines and main variables of the computer code. General logical flowcharts of the subroutines are also presented in the guides to provide overall picture of interactions between the subroutines. A standard structure of routine explanation is applied in every programmer's guide. The explanation is started with a brief description or main purpose of the routine, lists of input and output files read and created, and lists of invoked/child and calling/parent routines. In some of the guides, interactions between the routine itself and its parent and child routines are presented in the form of graphical flowchart. The explanation is then proceeded with step by step description of computer code in the subroutine where each step delegates a section of related code. Between steps, if a certain section of code needs further explanation, a Note is inserted with relevant explanation.
Urban storm-runoff modelling; Madison, Wisconsin
Grant, R. Stephen; Goddard, Gerald
1979-01-01
A brief inconclusive evaluation of the water-quality subroutines of the model was made. Close agreement was noted between observed and simulated loads for nitrates, organic nitrogen, total phosphate, and total solids. Ammonia nitrogen and orthophosphate computed by the model ranged 7 to 11 times greater than the observed loads. Observed loads are doubtful because of the sparsity of water-quality data.
Technology Transfer Automated Retrieval System (TEKTRAN)
Streambed sediments have been shown to serve as environmental reservoirs for bacteria, including pathogenic strains. The Soil and Water Assessment Tool (SWAT) has been augmented with bacteria subroutine in 2005. Bacteria die-off is the only in-stream process considered in the current SWAT. The purpo...
Technology Transfer Automated Retrieval System (TEKTRAN)
Streambed sediment has been increasingly attracting attention as the reservoir of bacteria, including pathogenic strains. Soil and Water Assessment Tool (SWAT) has been augmented with bacteria transport subroutine in SWAT2005 in which bacteria die-off is the only in-stream process. The purpose of th...
Technology Transfer Automated Retrieval System (TEKTRAN)
Streambed sediments have been shown to serve as environmental reservoirs for bacteria, including pathogenic strains. Although the Soil and Water Assessment Tool (SWAT), a watershed-scale, physically-based and continuous-time model, has been augmented with bacteria transport subroutine in 2005, the b...
NASA Technical Reports Server (NTRS)
Chang, T. S.
1974-01-01
A numerical scheme using the method of characteristics to calculate the flow properties and pressures behind decaying shock waves for materials under hypervelocity impact is developed. Time-consuming double interpolation subroutines are replaced by a technique based on orthogonal polynomial least square surface fits. Typical calculated results are given and compared with the double interpolation results. The complete computer program is included.
Program to Optimize Simulated Trajectories (POST). Volume 3: Programmer's manual
NASA Technical Reports Server (NTRS)
Brauer, G. L.; Cornick, D. E.; Habeger, A. R.; Petersen, F. M.; Stevenson, R.
1975-01-01
Information pertinent to the programmer and relating to the program to optimize simulated trajectories (POST) is presented. Topics discussed include: program structure and logic, subroutine listings and flow charts, and internal FORTRAN symbols. The POST core requirements are summarized along with program macrologic.
MATHEMATICAL ROUTINES FOR ENGINEERS AND SCIENTISTS
NASA Technical Reports Server (NTRS)
Kantak, A. V.
1994-01-01
The purpose of this package is to provide the scientific and engineering community with a library of programs useful for performing routine mathematical manipulations. This collection of programs will enable scientists to concentrate on their work without having to write their own routines for solving common problems, thus saving considerable amounts of time. This package contains sixteen subroutines. Each is separately documented with descriptions of the invoking subroutine call, its required parameters, and a sample test program. The functions available include: maxima, minima, and sort of vectors; factorials; random number generator (uniform or Gaussian distribution); complimentary error function; fast Fourier Transformation; Simpson's Rule integration; matrix determinate and inversion; Bessel function (J Bessel function for any order, and modified Bessel function for zero order); roots of a polynomial; roots of non-linear equation; and the solution of first order ordinary differential equations using Hamming's predictor-corrector method. There is also a subroutine for using a dot matrix printer to plot a given set of y values for a uniformly increasing x value. This package is written in FORTRAN 77 (Super Soft Small System FORTRAN compiler) for batch execution and has been implemented on the IBM PC computer series under MS-DOS with a central memory requirement of approximately 28K of 8 bit bytes for all subroutines. This program was developed in 1986.
Application of the new modular SWAT code to three watersheds in the United States
Technology Transfer Automated Retrieval System (TEKTRAN)
Due to the integration of new variables and subroutines over the past two decades since the release of the first version of the Soil and Water Assessment Tool (SWAT), the model has become difficult to manipulate and maintain. Therefore, the SWAT code and the input and output file structure have rece...
Cervical Neoplasia Probe Control
Vargo, Timothy D.
1997-01-24
This software, which consists of a main executive and several subroutines, performs control of the optics, image acquisition, and Digital Signal Processing (DSP) of this image, of an optical based medical instrument that performs fluoresence detection of precancerous lesions (neoplasia) of the human cervix. The hardware portion of this medical instrument is known by the same name Cervical Neoplasia Probe (CNP)
NASA Technical Reports Server (NTRS)
Bains, R. W.; Herwig, H. A.; Luedeman, J. K.; Torina, E. M.
1974-01-01
The Shuttle Electric Power System (SEPS) computer program is considered in terms of the program manual, programmer guide, and program utilization. The main objective is to provide the information necessary to interpret and use the routines comprising the SEPS program. Subroutine descriptions including the name, purpose, method, variable definitions, and logic flow are presented.
NASA Technical Reports Server (NTRS)
Chelson, P. O.; Eckstein, R. E.
1971-01-01
The computer program listing for the reliability block diagram computation program described in Reliability Computation From Reliability Block Diagrams is given. The program is written in FORTRAN 4 and is currently running on a Univac 1108. Each subroutine contains a description of its function.
1973-09-01
achieving improved sea and air vehicles. It was formed in March 1967 by merging the David Taylor Model Basin at Carderock, Maryland with the Marine ... DUMO ,ODUM, UM) PRP3 31 END PRP3 32 172 OVERLAY(12,01 AFU2 2 PROGRAM AFU2 AFU2 3 C AFU2 4 C THIS SUBROUTINE DISPLAYS OUTPUT FROM SJBROUTINE IOUPRIN AFU2 5
Airport-Noise Levels and Annoyance Model (ALAMO) system's reference manual
NASA Technical Reports Server (NTRS)
Deloach, R.; Donaldson, J. L.; Johnson, M. J.
1986-01-01
The airport-noise levels and annoyance model (ALAMO) is described in terms of the constituent modules, the execution of ALAMO procedure files, necessary for system execution, and the source code documentation associated with code development at Langley Research Center. The modules constituting ALAMO are presented both in flow graph form, and through a description of the subroutines and functions that comprise them.
NASA Astrophysics Data System (ADS)
Carlini, A.; Hosoya, A.
2001-02-01
Grover's quantum algorithm for an unstructured search problem and the COUNT algorithm by Brassard et al. are generalized to the case when the initial state is arbitrarily and maximally entangled. This ansatz might be relevant with quantum subroutines, when the computational qubits and the environment are coupled, and in general when the control over the quantum system is partial.
A Pilot - An On-Line Library Acquisition System.
ERIC Educational Resources Information Center
Spigai, Frances; And Others
This report presents documentation of files, of file organization, and of 42 of the modular program subroutines used in a pilot project devised by the Oregon State University (OSU) Computer Center to simulate procedures in the Acquisitions Department of the OSU Library. A total of 224 bibliographically verified requests for monographs, 30 vender…
General purpose computer program for interacting supersonic configurations: Programmer's manual
NASA Technical Reports Server (NTRS)
Crill, W.; Dale, B.
1977-01-01
The program ISCON (Interacting Supersonic Configuration) is described. The program is in support of the problem to generate a numerical procedure for determining the unsteady dynamic forces on interacting wings and tails in supersonic flow. Subroutines are presented along with the complete FORTRAN source listing.
Fortran Automatic Code Evaluation System (FACES)
NASA Technical Reports Server (NTRS)
Browne, J. C.; Davis, T.; Haller, A.; Henneman, M.; Kleir, R.; Lasseter, G. L.
1974-01-01
Software package takes as input FORTRAN program which may contain many modules (subroutines and functions). Main parts: (1) FORTRAN front end gathers information about input program and (2) set of routines organized as diagnostic package evaluates information and prints warning messages concerning actual or potential errors.
NASA Technical Reports Server (NTRS)
Artley, J. A. (Principal Investigator)
1981-01-01
The Hodges-Artley spring small grains planting date distribution model was coded in FORTRAN. The PLDRVR program, which implements the model, is described and a copy of the code is provided. The purpose, calling procedure, local variables, and input/output devices for each subroutine are explained to supplement the user's guide.
NASA Technical Reports Server (NTRS)
Keith, J. S.; Ferguson, D. R.; Heck, P. H.
1973-01-01
The computer program listing of Streamtube Curvature Analysis is presented. The listing includes explanatory statements and titles so that the program flow is readily discernable. The computer program listing is in CDC FORTRAN 2.3 source language form, except for three subroutines, GETIX, GETRLX, and SAVIX, which are in COMPOSE 1.1 language.
HALS Post Processing Software Design.
1982-09-01
spikes Read In NAVAID data Apply correction values to NAVAID data Compute geographic position I Convert degrees, minutes and seconds to radians Perform...iterative solution on NAVAID arguments Compute distance and sine and cosine of azimuth between positions SConvert geographic posltlcn to Universal... geographic position via subroutine FITS. The parameters include spheroid axes, flattening, eccentricity, transmitter station coordinates, antenna height
Optimal Regulator Algorithms For The Control Of Linear Systems (ORACLS)
NASA Technical Reports Server (NTRS)
Frisch, Harold P.
1990-01-01
Control theory design package offers engineer full range of subroutines to manipulate and solve Linear-Quadratic-Gaussian types of problems. ORACLS is rigorous tool, intended for multi-input and multi-output dynamic systems in both continuous and discrete form. Written in FORTRAN.