strain, and stress) accumulated inelastic strain appears to be the best gage of the amount of damage in the material. Since the fracture strain may be a ...
NASA Website
inelastic strainrate as a function of inelastic strain. .... strain i s accumulated so that recovery becomes the dominant cause of straining. ...
tertiary creep response for small values of accumulated inelastic strain and the long term fatigue response corresponding to large values of accumulated ...
... represent the accumulation of inelastic strains as a function of the strain increments applied to the element. The intrinsitive incremnts were assurred ...
DTIC Science & Technology
gradual accumulation of inelastic strain lead to deviation of the stress�strain curve from the initial not account for the inelastic accumulated strain during the whole cycle (e.g. Hamiel et al. 2004a-related inelastic defor- ...
E-print Network
... ponse that is fully elastic since inelastic strains would be present ... the total d. at 4% strain. ... W and other quantities such as accumulated plastic strain ...
established for any type of inelastic strain cycle. Continuous strain ..... and creep strains are accumulated at continuously varying temperatures ...
have used the total inelastic strain energy or other strain energies as the basis for fatigue models. In general, the cyclic .... accumulated test data and experience. ...
failures associated with gradual accumulation of inelastic strain and brittle instability, respectively and positive damage evo- lution, a gradual irreversible (inelastic) strain accumulates before C 2006 gradual inelastic strain ...
for the effective inelastic strain are de- rived. A detailed study on the choice of the pore shape is performed. . . . . . . . . . . . 134 46 Components of the macroscopic inelastic strain as a function of the loading (both plastic between the experimental results and the model simulation.156 60 Plastic ...
... and rules for crack growth and damage accumulation in metals ... 4] has shown that Neuber's hypothesis can incorrectly estimate the inelastic strain. ...
with no inelastic strain occurring in the stress-free virgin state. Small strains ..... The effect of a slowly accumulated propagat- ing error is found in the Runge- Kutta ...
... motions of a strain-softening, inelastic material. ... in the temperature and strain rate of the ... Experience accumulated through studies of initial value ...
Strain Hardening Illustration. The incremental test, the cyclic increasing load steps result accumulation of inelastic strain during cyclic increasing load ...
which indicates that each component of the inelastic strain increment is pro- ..... is usually taken as a function of some measure of accumulated plastic strain ...
macroscopic failure, the model incorporates a gradual accumulation of inelastic strain, i ij, given by (Hamiel the damage rate coefficient to be Cd102 s-1 . Accounting for the gradual accumulation of inelastic strain (7 the deviatoric stress to the rate of gradual ...
that accumulates slip by sequentially increasing the number of dis- crete bands linearly with the inelastic strain to equation 3, kmatrix = kcexp[�I( � c)] > c, (4) where I = IVc is the inelastic strain sensitivity define an inelastic strain, x = ...
has been accumulated, the material cannot sustain additional inelastic strain without initiating microcracks. The time taken to arrive at this condition is a function ...
Previous experimental results were very encouraging; the accumulated data ... large amount of inelastic strain (up to 400%) may be recovered by heating. ...
Previous experimental results were very encouraging; the accumulated data ... elastic modulus E above and below the Tg. A large amount of inelastic strain (up ...
An inelastic analysis procedure to establish structural adequacy of an elevated temperature piping system is presented in this paper. The analytical method is incidental to the procedure used to comply with Code Case N-47 inelastic strain accumulation and creep-fatigue damage criteria.
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Energy Citations Database
On the basis of analyzing available results for studying features of inelastic strain and fatigue damage of various materials the possibility is considered of determining the end of the stage of dispersed fatigue damage or fatigue crack generation from the overall accumulated inelastic strain, ...
as an analytically rigid surface. Figure 9 shows the FE-predicted accumulated equivalent plastic strain at the end the dwell time at 900�C. Figure 10 shows the predicted local 11 stress versus inelastic strain, in 11 to occur for this combination of stress-strain components, which essentially ...
of the presence of inelastic processes due to accumulation of phase and interface damage; �R(), �L, and �M () and () () for = . Microscopically nonlocal inelastic strains, �(), and microscopically nonlocal phase damage variable, () ph between the experimental observations of a certain quantity of interest ...
A gradual accumulation of inelastic strain can be most conveniently described in terms of the so-called intrinsic time, whose increment depends on the time increment as well as the strain increments. This approach, which gives a particularly simple description of irreversibility of strain at ...
ing) that accumulates over several cycles under cyclic stressing occurs i sotropical ... i n which E i j denotes the components of inelastic strain-rate, u is a material ...
of the linear distribution of strain along the section (Figure 1). He relates the accumulated tensile strain. Therefore the displacement capacity of walls are controlled by concrete and steel strain. The inelastic of the sections, concrete strain concentration, and low ...
inelastic deformation rate; � is the total accumulated S. Nemat-Nasser, J. Zhang / International Journal granular mass is deformed in shear, and includes the coupling between shearing and volumetric straining (or-Nasser, 1993a, b), Nemat-Nasser (2000) shows that the inelastic deformation rate tensor, Dp , for the ...
The structure of island arcs is formed as the result of the cumulative process of inelastic deformation over a long time. There is no doubt but the essential cause of crustal deformation is in the subduction of oceanic plates. Plate subduction certainly produces elastic deformation in the Earth�s crust, but it remains unsolved how the elastic deformation is transformed into ...
NASA Astrophysics Data System (ADS)
measured by LVDT1 and LVDT2 that can be attributed to accumulation of inelastic deformation in the bridge) are included in a cement matrix to produce a material that strain hardens under tension. Exhibiting high damage tolerance and tensile strain capacity on the order of 1 to 3%, HPFRCC materials can be used to ...
The kinetics of dislocations is studied with computer simulation at loadings of different intensity. It is established that the dislocations have a few different structural states. The dislocations "with the micropore" play important role in the formation of large curved boundaries, and, as a consequence, in the formation of fine grains. Alternation of elastic and inelastic ...
A preliminary inelastic analysis of a dissimilar metallic transition joint was made based on the piping design specification for CRBRP applications. The transition joint was analyzed to satisfy the elevated temperature ASME Code requirements. The transition joint analyzed is a tri-metallic joint composed of 316 stainless steel, alloy 800H, and 2-1/4 Cr-1Mo steel sections. The ...
The exact solution to the quasi-static, inelastic response of a cantilever beam of rectangular cross
NASA Technical Reports Server (NTRS)
In the analysis of the inelastic deformation of the polymer matrix, the definitions of the effective stress and effective inelastic strain have been ...
The influence of inelastic material models on computed stress-strain states, and therefore predicted
The elastic stress range over a complete load cycle is routinely used to formulate simplified rules regarding the inelastic behavior of structures operating at elevated temperature. For example, a 300 series stainless steel structure operating at elevated temperature, in all probability, would satisfy the ASME Boiler and Pressure Vessel Code criteria if the linearized elastic ...
... Accession Number : ADA195667. Title : Nonlinear Stress-Strain and Inelastic Rebound with Exponential Stiffness. Descriptive Note : Technical rept., ...
... Accession Number : ADD129176. Title : Cyclic Response and Inelastic Strain Energy in Low Cycle Fatigue,. Corporate Author : ...
This paper focuses on the low cycle fatigue (LCF) behaviour of reduced activation ferritic/martensitic steels irradiated to a displacement damage dose of up to 70 dpa at 330�337 �C in the BOR 60 reactor within the ARBOR 2 irradiation programme. The influence of neutron irradiation on the fatigue behaviour was determined for the as-received EUROFER97, pre-irradiation heat-treated EUROFER97 HT ...
Several complex pipelines of the Fast Flux Test Facility (FFTF) were evaluated using detailed inelastic analysis because they did not satisfactorily comply with the ASME elastic analysis rules. The purpose of the inelastic analysis is to demonstrate that the piping systems, which operate at elevated temperatures, comly with ASME Code requirements under the ...
The conventional view of plate boundary strain during the seismic cycle in subduction zones portrays the accretionary margin and upper-plate wedge as the primary site of intra-seismic strain accumulation and co-seismic strain release. This textbook model provides a mechanism for tsunamigenesis, and the ...
The conventional view of plate boundary strain during the seismic cycle in subduction zones portrays the accretionary margin and upper-plate wedge as the primary site of intra-seismic strain accumulation and co-seismic strain release. This textbook model provides a mechanism for tsunamigenesis and the ...
Bolts that arrest (or, more precisely, retard) onset of fatigue cracking caused by inelastic strains
... Descriptors : *METALS, *STATIC LOADS, *DEFORMATION, THERMAL PROPERTIES, STRESS STRAIN RELATIONS, IMPACT, THEORY, STRAIN ...
inelastic material constant representing hardening rate of material ...... development, small strain conditions are assumed, and thermal and moisture ...
An experimental study examined the tensile stress-strain behavior of cortical bone during rapid load cycles to high strain amplitudes. Machined bovine and human cortical bone samples were subjected to loading cycles at a nominal load/unload rate of +/- 420 MPa/s. Loads were reversed at pre selected strain levels such that load cycles ...
PubMed
... Title : Inelastic Stress-Responses of an Aluminium Alloy in Non-Proportional ... and effects of strain rate were studied in 5056 aluminum at 200 C ...
... MADE OF STRAIN-HARDENING MATERIALSi TECHNICAL REPORT, ... 4 made of linear strain-hardening materials. He used Tresca's yield criterion. ...
n is the strain-hardening exponent. Creep behavior of the solder is modeled with a Weertman steady state creep law. Thus, the strain rate is assumed to have ...
This report describes the bilinear stress-strain analysis under cyclic loading conditions for the alloy Incoloy 800. Although the method for determining the bilinear stress-strain parameters is based on a procedure proposed in the RDT Standard F9-1 for inelastic analysis of Fast Flux Test Facility (FFTF) components, the accuracy and ...
The paper addresses some important features of the inelastic behavior of 2/sup 1///sub 4/Cr--1Mo steel and indicates a mathematical framework that is capable of representing these types of response. While the constitutive model discussed embraces capabilities beyond those of equations presently used in design analyses; their implementation into practicable analysis methods ...
Simplified and detailed inelastic analyses have been used to assess strain concentrations. Evaluations of beams, cylinders, notched sections, perforated plates, and shells revealed that predictions of inelastic peak strains are sensitive to the choice of yield strength. The extent of sensitivity, however, depends ...
. Phys. Solids 48, 1565�1595. Aifantis, E.C., 1984. On the microstructural origin of certain inelastic necessary dislocation accumulation. J. Mech. Phys. Solids 50, 2403�2424. Fleck, N.A. and Hutchinson, J.W., 1997. Strain gradient plasticity. Adv. Appl. Mech. 33, 295�361. Fleck, N.A., Muller, G.M., Ashby, F
Using spontaneous rupture models with off-fault elastoplastic material response, we investigate the deformation of compliant fault zones induced by nearby earthquake ruptures in a two-dimensional plane-strain framework. We find that dynamic stresses from nearby ruptures can produce inelastic strain along some portions of a fault zone ...
... Title : Effect of Strain Accumulation and Dynamic Recrystallisation on the Flow Stress of HSLA Steels During Flat Rolling. ...
... Title : CYCLIC STRAIN ACCUMULATION UNDER COMPLEX MULTIAXIAL LOADING. ... Abstract : When a tubular specimen of copper is subjected to ...
This document summarizes the work performed by the author and associates at Stanford on a new approach to the analysis and simulation of localization arising in inelastic solids that exhibit strain-softening response. In addition, the document describes n...
National Technical Information Service (NTIS)
Strain redistribution corrections were developed for a simplified inelastic analysis procedure to economically calculate material cyclic response at the critical location of a structure for life prediction proposes. The method was based on the assumption ...
The solder fatigue specimen designed by NASA-Goddard/UNISYS is analyzed in order to obtain the inelastic strain history during two different representative temperature cycles specified by UNISYS. Results are summarized from viscoplastic finite element ana...
The solder fatigue specimen designed by NASA-GSFC/UNISYS is analyzed in order to obtain the inelastic strain history during two different representative temperature cycles specified by UNISYS. In previous reports (dated July 25, 1990, and November 15, 199...
An analogy between inelastic strains caused by temperature and those caused by creep is presented in terms of isotropic elasticity. It is shown how the theoretical aspects can be blended with existing finite-element computer programs to exact a piecewise ...
plasticity that make up the inelastic strain range (ref. 1). It ...... for kinematic or flow-induced anisotropic effects, while the ...
... PROPERTIES, NUMERICAL ANALYSIS, ELASTIC PROPERTIES, THEOREMS, RESIDUAL STRESS, UNLOADING, REPRINTS, STRESSES. ...
... Thus, in (2) 1 and m denote the elastic stiffness of the inhomogeneity ... IThe composite inelastic strain is typically obtained from an elastic unloading. ...
Development of a simplified method for estimating structural inelastic stress and strain response to
... because it combines creep and plastic strains as inelastic strains, the constitutive model for unreinforced al2xxx-t4 is also a unified model. ...
onset of a shear fault imparts to the solid an apparent plastic behavior with strain hardening. In this behavior the inelastic strain that results ...
May 31, 2011 ... To account for the tension/compression asymmetry in the material, the effective stress and effective inelastic strain definitions have been ...
In this paper, the representation of the kinematics of inelastic flow problems involving finite strains and rotations is discussed. The concept of multiplicatively decomposing the deformation gradient into elastic and plastic components is utilized, where...
... Descriptors : *GUN BARRELS, SHEAR MODULUS, STRAIN HARDENING, PLASTIC PROPERTIES. Subject Categories : GUNS MECHANICS. ...
... strain hardening factor OL is found from the un ... C trcuq the computation of effective stress-effective strain. ... ences between the two factors were small. ...
... The Bodner-Partom form of unified theory satisfactorily describes the 821S stress-strain response for a range of temperatures from 230C to 81 50C ...
... The Bodner-Partom form of unified theory satisfactorily describes the Timetal 21S stress-strain response for a range of temperatures from 23 deg C ...
... The Bodner-Partom form of unified theory satisfactorily describes the B21S stress-strain response for a range of temperatures from 23 deg C and ...
Previously, strain rate dependent inelastic constitu- tive equations developed to model the polymer matrix were incorporated into a mechanics of materials ...
... Title : A New Methodology for the Numerical Simulation of Strain Softening in Inelastic Solids. Descriptive Note : Final rept. Oct 92-Sep 94,. ...
The zero-to-tension ratchetting behavior was investigated under uniaxial loading at room temperature and at 550, 600 and 650/degree/ C. In History I the maximum stress level of ratchetting was equal to the stress reached in a tensile test at one percent strain. For History II the maximum stress level was established as the stress reached after a 2100 s relaxation at one ...
Procedures are presented for expressing the Strainrange Partitioning (SRP) method for creep fatigue life prediction in terms of total strain range. Inelastic and elastic strain-range - life relations are summed to give total strain-range - life relations....
A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. Strain rate dependent inelastic constitutive equations have been deve...
This paper presents results for a detailed inelastic finite element analysis for a part of the Clinch River Breeder Reactor Control Rod Drive Mechanism. The analysis results indicate that plastic strain concentration factors may in fact be less than corresponding elastic strain concentration factors for nominal ...
A review of the accumulated data from deep inelastic lepton scattering which has studied the EMC effect is given. Analysis of the data in terms of QCD confinement and the standard meson exchange model is given. (AIP)
A new pressure-shear recovery experiment for investigating out-of-plane dynamic shear resistance of composites has been developed. The technique was used to investigate failure mechanisms during dynamic multiaxial loading of an S-2 glass fiber woven composite with 60% fiber volume fraction. Velocity profiles of the target surface were measured with a Variable Sensitivity Displacement ...
A continuum model is proposed as a theoretical foundation for the inelastic state variable theory of Hart. The model is based on the existence of a free energy function and the assumption that a strained material element recalls two other local configurat...
The report describes an approach for the analysis of beams using a tangent stiffness finite element incremental method applied to a layered element. Each layer has its own modified Ramberg-Osgood type stress strain curve and may have inelastic, cracking a...
In plasticity and creep theory it is generally assumed that inelastic deformations are volume preserving. Available tensile and creep tests were evaluated to see whether the experiments confirm the constant volume assumption. None of the experiments which...
The objective of this research project was to quantify the response of shocked ceramics, including strength in the shocked state, to understand the mechanisms governing inelastic deformation at high stresses and high strain- rates in these materials. In-s...
A theory and a numerical procedure are presented for the determination of the inelastic axisymmetric buckling pressure of a clamped shallow spherical shell made of work hardening materials. A modified incremental theory of plasticity on the stress-strain ...
The inelastic buckling of eccentrically loaded simply supported columns of rectangular and circular cross sections is analyzed. The material of the column is assumed to satisfy Ramberg-Osgood's stress-strain relation. The load-carrying-capacity of the col...
The results of an experimental and analytical program to develop stress-strain relations for a granular medium are presented. Explicit three-dimensional relations are given which represent the inelastic deformation of the medium. A simple version of the f...
This report develops a general procedure for modeling the inelastic stress-strain response of structural metals subjected to complex irregular cyclic loadings. The model is ideally suited for programming on a digital computer and uses 'cyclic' material pa...
We consider a body to have an initial stress field. When the body is loaded beyond the elastic range, a plastic strain occurs in some part of the body. If the body is then unloaded, the plastic strain remains and causes a residual stress field. Now consid...
. - The essentials of phenomenological modeling of metal deformation behavior at small strain are introduced together - sometimes called (path dependent) hardening. This term does not refer to the positive slope of a stress-strain (the elastic regions), the inelastic strain rate is extremely small and negligible. ...
Fatigue behaviour is essentially dependent on the real strain range, but the current practice is the use of elastic analysis. In low cycle fatigue conditions where inelastic strains predominate, elastic analysis never gives the real value of the strain ra...
May 31, 2011 ... One life-limiting structural response for this application is creep; creep deformation is the accumulation of time-dependent inelastic ...
Thermal and inelastic analyses were performed on two tubesheet configurations proposed for the support of ceramic filters in a flue gas cleanup vessel. A duty cycle specified for a Pressurized Fluidized Bed Combustor (PFBC) was incorporated into the analyses. Lower transients stresses and strains were calculated for a V-support design than for a shelf ...
Control of secondary stresses is important for long-term reliability of components, particularly at elevated temperatures where substantial creep damage can occur and result in cracking. When secondary stresses are considered in the design of elevated temperature components, these are often addressed by the criteria contained in Nuclear Code Case N-47 for use with elastic or ...
An investigation was made on the strain-controlled low-cycle fatigue (LCF) of K40S cobalt-base superalloy at 900 �C in ambient atmosphere. The results show that K40S alloy possesses high LCF resistance in comparison with X-40 alloy. Under the testing conditions in this study, K40S alloy exhibits a cyclic stress response of initial hardening followed by softening. The cyclic ...
To describe the time-dependent nonlinear tensile behavior observed in experimental studies of cortical bone, a damage model was developed using two internal state variables (ISV's). One ISV is a damage parameter that represents the loss of stiffness. A rule for the evolution of this ISV was defined based on previously observed creep behavior. The second ISV represents the ...
Simulations with many modern aerospace materials require realistic mechanical response models for use in isothermal and non-isothermal applications. One such model is a unified inelastic-strain theory which has been applied to capture the strain-rate sens...
Jan 22, 2011 ... Title: Statusof GPS/Acoustic Measurements of Seafloor Strain Accumulation Across the Cascadia Subduction Zone. Authors: Purcell, G. Jr. ...
Interseismic Strain Accumulation Across Metropolitan Los Angeles: The Slip ... and the San Andreas Fault and the Effect of the Los Angeles Sedimentary Basin ...
Interseismic Strain Accumulation Across Metropolitan Los Angeles: The Slip Rates Along the Puente Hills Thrust and the San Andreas Fault and the Effect of ...
energy for the rupture. The rates at which tectonic plates move and accumulate strain at their boundaries for the rupture. The rates of strain accumulation at the boundaries of tectonic plates are approximately uniform
... Title : Accumulation of Elastic Strain Energy during Cyclic Loading,. Corporate Author : NORTHWESTERN UNIV EVANSTON IL. ...
... Softening occurred by both recovery and recrystallization with the amount increasing with temperature, strain rate, pass strain, and accumulated ...
... The inelastic strain of samples of pyrolyzing PAA, phenolic, and polyfurfural alcohol during heat ... IF (CODE EQ 1) or (code eq 4) TEEN BEGIN Y=(Y ...
... Title : New General and Complementary Energy Theorems, Finite Strain, Rate-Sensitive Inelasticity, and Finite Elements: Some Computational ...
0 coefficient of thermal expansion, m/m K (in/in �F) .... adjusting the coefficient of thermal expansion e for each creeping element. Then, ...
May 31, 2011... which are significant in polymers, the classical J2 plasticity theory definitions of effective stress and effective inelastic strain, ...
... rate sensitivity and time dependent behavior of the titanium alloy Timetal21 S. The Bodner-Partom form of unified theory satisfactorily describes the ...
... In this way p, will still reduce to pe when E ... Figure 4a) which exhibits a continuous stress-strain curve. ... is defined by the intersection of the two curves. ...
Fatigue life at elevated temperature can be predicted by introducing parametric values obtained from
... Elastomers have the ability to stretch to several times ... strain rate jump tests will be performed on ... dot denotes a time derivative and the vertical bars ...
Fatigue (metal); Isothermal fatigue; Bithermal fatigue; Thermomechanical fatigue ; Creep-fatigue; Hysteresis loop; Inelastic strain energy density; ...
local (stress/strain) and global (dynamics, buckling) structural behavior of the three respective components. The methods and the three computer codes, ...
Motivated by recent experiments on metallic glasses, we examine the micromechanisms of strain accommodation including crystallization and void formation during inelastic deformation of glasses by employing molecular statics simulations. Our atomistic simulations with Lennard-Jones-like potentials suggests that a softer short range interaction between atoms ...
Understanding the brain's response to multiple loadings requires knowledge of how straining changes the mechanical response of brain tissue. We studied the inelastic behavior of bovine white matter and found that when this tissue is stretched beyond a critical strain threshold its reloading stiffness drops. An upper bound for this ...
PubMed Central
The design criteria currently used in the design of radioactive material (RAM) transportation containers are taken from the ASME Boiler and Pressure Vessel Code (ASME, 1992). These load-based criteria are ideally suited for pressure vessels where the loading is quasistatic and all stresses are in equilibrium with externally applied loads. For impact events, the use of load-based criteria is less ...
The relaxation of two-dimensional quasicrystalline elastic networks when their constituent bonds are
... of receivers will be used to create maps of strain accumulation along fault lines that will enable ...
NSF Publications Database
The primary objective of the study was to develop an understanding of the stress strain relationship and other related geotechnical properties of cohesive materials such as clays from a microstructural point of view. In the theoretical area, several theor...
A sampling is given of the applications of plasticity theory to structures. Relations between various theories which include or neglect strain hardening and elastic strains are discussed. Applications are given to trusses, beams, frames, and circular plat...
An algorithm developed and incorporated into BOPACE for improving the convergence and accuracy of the inelastic stress-strain calculations is discussed. The implementation of separation of strains in the residual-force iterative procedure is defined. The ...
A new approach to the representation of time dependent inelastic material behavior is described. Realistic properties such as strain hardening, strain rate effects, and anelasticity can be incorporated in this description which is particularly well suited...
Microcontinuum theories for inelastic analysis of rate-independent polycrystals at small strain are investigated. For a macroscopically homogeneous solid, the infinite aggregate model of T. H. Lin is extended to include more general crystal hardening theo...
An improved multiaxial fatigue failure criterion was developed based on the results of combined axial-torsional strain cycling tests of AISI 304 and 2-1/4 Cr-1 Mo steel conducted at 538/sup 0/C (1000/sup 0/F). The formulation of this criterion involves the shear and normal components of inelastic strain range on the planes of maximum ...
An elastic-plastic constitutive model for the simulation of stress-strain response of concrete under any biaxial combination of compressive and/or tensile stresses is developed. An effective tensile stress-strain curve is obtained indirectly from experime...
, we assume that the energy due to mixing is negligible (mix = 0). The stress for a phase is decomposed of the deviatoric strain of that phase (2) where ek, is the plastic strain of kth phase. It is assumed that all ) and inelastic or plastic (dep ) contributions. The increment of total e= = =e = =p = = = = = = RESEARCH
Creep Relaxation Stress q - -1.0 f = 0.50 Hz (30 cpm) Exclusive of Hold. At,. = Total Strain Range = A t + Ati. Ati. = Inelastic Strain Range ...
