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1.
2.
A computational thermo-metallographic and thermoelastoplastic model for the analysis of the quenching process is developed
and validated. The diffusive transfor-mations are modeled according to the Johnson–Mehl–Avrami–Kolmogorov model and the Scheil’s
additivity rule. Two different models are investigated for the non-diffusive transformation—the Koistinen–Marburger model
and the Yu model. A large displacement formulation is assumed for the deformation analysis, modeling the plastic behavior
of the material according to the Prandtl–Reuss model. Two different bilinear hardening models—the isotropic and the kinematic
hardening model—are used and compared. The model allows to evaluate the transient stress and strain distributions during the
quenching process, the final phases and hardness distributions, and to predict the residual stress and the final deformation
of the processed part. A good agreement between computational results and reference data is found 相似文献
3.
A nonstationary coupled problem of thermoelectrodynamics is formulated for resistance heating of dissimilar ferro- and paramagnetic
bodies by an alternating current. An iterative algorithm for solving this problem by finite-difference methods is proposed.
Temperature and electromagnetic-field distributions are obtained for the processes of direct resistance heating both in air
and in the region of the molding tool.
Perm' State Technical University, Perm' 614000. Translted from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No.
4, pp. 156–164, July–August, 2000. 相似文献
4.
考虑路径相关性的非比例循环塑性本构模型 总被引:2,自引:0,他引:2
根据非比例加载下金属材料响应的延迟特性及加载路径相关性,选取沿应力迹法向的塑性应变的累积量作为非比例加载影响的度量,相应给出反映非比例附加强化的变量,并假设其模量和强化率与加载路径的几何参数相关.为反映由于非比例加载而引起的材料强化的异向效应,在Valanis的塑性内时响应方程中引入与加载路径几何性质有关的应力项,构成非比例循环塑性本构关系.对316和304不锈钢材料在一些典型非比例循环加载路径下的应力响应进行了理论预测,与Benallal等及McDowell的实验结果取得了良好的一致. 相似文献
5.
A refined Timoshenko-type model based on the straight-line hypothesis is used to develop an approach to analyzing the stress
state of longitudinally corrugated cylindrical shells with elliptic cross-section. The approach is to reduce the two-dimensional
boundary-value problem that describes the stress–strain state of the shell to a one-dimensional one and to solve it with the
stable numerical discrete-orthogonalization method. The solutions obtained using the straight-line hypothesis and the equations
of three-dimensional elasticity are compared. The dependence of the stress–strain state of the shell on the number and amplitude
of corrugations and the aspect ratio of the cross-section is analyzed 相似文献
6.
Yu. A. Dubravin 《Journal of Applied Mechanics and Technical Physics》1995,36(4):565-574
Perm' State University, Perm' 614600. Translated from Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol.
36, No. 4, pp. 98–109, July–August, 1995. 相似文献
7.
A. F. Nikitenko 《Journal of Applied Mechanics and Technical Physics》1998,39(2):277-281
A relationship between noncoaxial tensors of stress and creep strain rate is established for the case of plane strain or a
plane stress state. The basis is the experimentally substantiated hypothesis on the existence of a creep surface, which is
a set of loading paths in the stress space that, at any time, ensure identical values of the creep intensity for a certain
chosen measure and orthogonality of the creep strain rate vector to this surface. The relation obtained completely corresponds
to available experimental data for complex loading.
Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 2, pp. 135–140, March–April, 1998. 相似文献
8.
Yu. N. Shevchenko R. G. Terekhov N. N. Tormakhov 《International Applied Mechanics》2006,42(4):421-430
Equations relating the components of the stress and strain tensors (constitutive equations) are formulated in terms of Euler
coordinates. The equations describe the finite elastoplastic deformation of an isotropic body along paths of small curvature.
It is assumed that the stress deviator is coaxial with the plastic-strain differential deviator. The relationships between
the first and second invariants of the stress and strain tensors in the case of complex elastoplastic deformation of the body’s
elements are determined from base tests on tubular specimens loaded along rectilinear paths for several values of the stress
mode angle. Methods for specification of these relationships are proposed. The assumptions adopted to derive the constitutive
equations are validated experimentally
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 4, pp. 62–72, April 2006. 相似文献
9.
V. M. Greshnov 《Journal of Applied Mechanics and Technical Physics》2008,49(6):1021-1029
Scalar and tensor models of plastic flow of metals extending plasticity theory are considered over a wide range of temperatures
and strain rates. Equations are derived using the physico-phenomenological approach based on modern concepts and methods of
the physics and mechanics of plastic deformation. For hardening and viscoplastic solids, a new mathematical formulation of
the boundary-value plasticity problem taking into account loading history is obtained. Results of testing of the model are
given. A numerical finite-element algorithm for the solution of applied problems is described.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 159–169, November–December, 2008. 相似文献
10.
Some novel discriminating multiaxial cyclic strain paths with incremental and random sequences were used to investigate cyclic deformation behavior of materials with low and high sensitivity to non-proportional loadings. Tubular specimens made of 1050 QT steel with no non-proportional hardening and 304L stainless steel with significant non-proportional hardening were used. 1050 QT steel was found to exhibit very similar behavior under various multiaxial loading paths, whereas significant effects of loading sequence were observed for 304L stainless steel. In-phase cycles with a random sequence of axial-torsion cycles on an equivalent strain circle were found to cause cyclic hardening levels similar to 90° out-of-phase loading of 304L stainless steel. In contrast, straining with a small increment of axial-torsion on an equivalent strain circle results in higher stress than for in-phase loading of 304L stainless steel, but the level of hardening is lower than for 90° out-of-phase loading. Tanaka’s non-proportionality parameter coupled with a Armstrong–Fredrick incremental plasticity model, and Kanazawa et al.’s empirical formulation as a representative of such empirical models were used to predict the stabilized stress response of the two materials under variable amplitude axial-torsion strain paths. Consistent results between experimental observations and predictions were obtained by employing the Tanaka’s non-proportionality parameter. In contrast, the empirical model resulted in significant over-prediction of stresses for 304L stainless steel. 相似文献
11.
《International Journal of Plasticity》2005,21(2):353-379
Motivated by the distribution of non-linear relaxation (DNLR) approach, a phenomenological model is proposed in order to describe the cyclic plasticity behavior of metals under proportional and non-proportional loading paths with strain-controlled conditions. Such a model is based on the generalization of the Gibbs's relationship outside the equilibrium of uniform system and the use of the fluctuation theory to analyze the material dissipation due to its internal reorganization. The non-linear cyclic stress–strain behavior of metals notably under complex loading is of particular interest in this study. Since the hardening effects are described appropriately and implicitly by the model, thus, a host of inelastic behavior of metals under uniaxial and multiaxial cyclic loading paths are successfully predicted such as, Bauschinger, strain memory effects as well as additional hardening. After calibrating the model parameters for two metallic materials, the model has demonstrated obviously its ability to describe the cyclic elastic-inelastic behavior of the nickel base alloy Waspaloy and the stainless steel 316L. The model is then implemented in a commercial finite element code simulating the cyclic stress–strain response of a thin-walled tube specimen. The numerical responses are in good agreement with experimental results. 相似文献
12.
The paper outlines a procedure for the numerical analysis of the thermoelastoplastic stress–strain state of thin compound
shells of revolution under axisymmetric nonisothermal loading. The constitutive equations describing the thermoelastoplastic
deformation of isotropic materials along paths of small curvature and incorporating the third invariant of the stress deviator
are used. A numerical example is presented 相似文献
13.
V. Tarigopula O. S. Hopperstad M. Langseth A. H. Clausen F. Hild O.-G. Lademo M. Eriksson 《Experimental Mechanics》2008,48(2):181-196
Large plastic deformation in sheets made of dual phase steel DP800 is studied experimentally and numerically. Shear testing
is applied to obtain large plastic strains in sheet metals without strain localisation. In the experiments, full-field displacement
measurements are carried out by means of digital image correlation, and based on these measurements the strain field of the
deformed specimen is calculated. In the numerical analyses, an elastoplastic constitutive model with isotropic hardening and
the Cockcroft–Latham fracture criterion is adopted to predict the observed behaviour. The strain hardening parameters are
obtained from a standard uniaxial tensile test for small and moderate strains, while the shear test is used to determine the
strain hardening for large strains and to calibrate the fracture criterion. Finite Element (FE) calculations with shell and
brick elements are performed using the non-linear FE code LS–DYNA. The local strains in the shear zone and the nominal shear
stress-elongation characteristics obtained by experiments and FE simulations are compared, and, in general, good agreement
is obtained. It is demonstrated how the strain hardening at large strains and the Cockcroft–Latham fracture criterion can
be calibrated from the in-plane shear test with the aid of non-linear FE analyses.
An erratum to this article can be found at 相似文献
14.
High-rate decremental-strain-rate test 总被引:1,自引:0,他引:1
A modified torsional split-Hopkinson bar is intoduced and used to study material response associated with a sudden reduction
of stain rate during high-rate plastic deformation. In tests on 1100-0 aluminum iniial deformation at a strain rate of approximately
2400 s−1 is reduced by a factor of 15 after 200 μs of high-rate deformation. After the reduction, the deformation continues at the
low rate for additional 550 μs. The change in the strain rate is obtained by using a stepped input bar. The results for 1100-0
aluminum show a decrease in the flow stress following the reduction in the strain rate. A short delay exists between the beginning
of the strain-rate reduction and the response of the stress. The magnitude of the drop in the stress agrees with the difference
in flow stress expected in constant-strain-rate tests in the corresponding high- and low-strain rates. Following the stress
reduction. The stress remains essentially constant with no hardening during the subsequent deformation at the low rate. 相似文献
15.
C. M. Sands H. W. Chandler I. A. Guz Y. A. Zhuk 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(2):161-173
This paper demonstrates that, at extreme levels of kinematic hardening, the traditional formulation of the Bodner–Partom model
can produce anomalous results. The reasons for this anomalous behaviour are explained, and a reformulated version of the model
is presented. This reformulation extends the range of the model to include levels of kinematic hardening that may be problematic
in the traditional formulation. The formulation of the model is adjusted so as to retain the rate dependency of the original
Bodner–Partom model; and to permit the values of the material parameters used with the traditional formulation to be re-used
with the extended model—with the exception only of the hardening coefficients which become dimensionless constants holding
different numerical values. This revised formulation also imposes associated flow, thereby ensuring phase consistency between
stress and plastic strain during non-proportional loading. In this way, the anomalies are removed, the range and stability
of the model is increased, and all the advantages and important features of the Bodner–Partom model are retained. 相似文献
16.
对316L不锈钢的非比例循环粘塑性本构描述 总被引:1,自引:0,他引:1
对循环硬化的316L不锈钢提出了一个考虑非比例循环加载下流动和硬化特性的粘塑性本构模型。模型中,通过随动硬化的背应力演化以各向同性阻力演化非比例循环路径及其历史的依赖关系来表征材料的非比例循环附加硬化和非比例循环流动特性,将模型用于预测316L不锈钢的圆形,正菱形应变路径的复杂循环变形行为,其预言结果与实验结果吻合很好。 相似文献
17.
I. S. Chernyshenko E. A. Storozhuk I. B. Rudenko 《International Applied Mechanics》2008,44(12):1397-1404
The elastoplastic state of a thin spherical shell weakened by an elliptic hole is analyzed. Finite deflections are considered.
The hole is reinforced with a thin ring. The shell is made of an isotropic homogeneous material. The load is internal pressure.
A relevant problem is formulated and solved numerically with allowance for physical and geometrical nonlinearities. The distribution
of stresses, strains, and displacements along the elliptic boundary and in the zone of their concentration is studied. The
stress–strain state of the shell near the hole is analyzed
Translated from Prikladnaya Mekhanika, Vol. 44, No. 12, pp. 93–101, December 2008. 相似文献
18.
Local strain data obtained throughout the entire weld region encompassing both the weld nugget and heat affected zones (HAZs)
are processed using two methodologies, uniform stress and virtual fields, to estimate specific heterogeneous material properties
throughout the weld zone. Results indicate that (a) the heterogeneous stress–strain behavior obtained by using a relatively
simple virtual fields model offers a theoretically sound approach for modeling stress–strain behavior in heterogeneous materials,
(b) the local stress–strain results obtained using both a uniform stress assumption and a simplified uniaxial virtual fields
model are in good agreement for strains ɛ
xx < 0.025, (c) the weld nugget region has a higher hardening coefficient, higher initial yield stress and a higher hardening
exponent, consistent with the fact that the steel weld is overmatched and (d) for ɛ
xx > 0.025, strain localization occurs in the HAZ region of the specimen, resulting in necking and structural effects that complicate
the extraction of local stress strain behavior using either of the relatively simple models.
相似文献
S. M. AdeebEmail: |
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20.
《International Journal of Plasticity》2001,17(9):1245-1265
Following our recent studies of the influence of mechanical twinning on the strain hardening of low SFE FCC metals deformed by simple compression, the investigation was extended to two different deformation modes. These were plane strain compression and simple shear carried out on 70/30 brass, which exhibits only strain hardening, and on MP35N, a Co–Ni based alloy that also shows secondary hardening by deformation promoted precipitation. It was found that the magnitude of the primary strain hardening in both alloys, and the secondary hardening in MP35N, was dramatically reduced under simple shear compared to the other deformation paths. This reduced hardening in simple shear appears to be a consequence of the bulk of the deformation twins, and also the secondary hardening precipitates, forming on planes that were parallel to the primary {111} slip planes in this deformation path. These hypotheses are supported by deformation path change tests in which the shear samples that show low flow stress under continued shear, when subjected to simple compression showed a significant increase (jump) in the flow stress, reaching values that are similar to those of the alloy continuously compressed to the same equivalent strain. That is, the reduced strain hardening in shear deformation is due not to reduced twinning, but to the twins produced by shear providing only limited barriers to continued strain by simple shear. Shear banding was found to be more marked in plane strain compression than in simple compression after cold working, and particularly after the additional secondary hardening in MP35N. 相似文献