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本文采用大变形弹塑性有限元法对金属板条在柱形模中的压弯成形过程进行了数值模拟,并与实验进行了比较,首先给出了纠正的拉格朗日有限元公式和基于弹塑性乘法分解的超弹性塑性本构关系。对接触摩擦问题的处理采用了罚函数法。通过对数值结果的分析得出了些对弯曲工艺的设计有指导价值的结论。 相似文献
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边界元法与其它数值方法相比,由于具有应力和面力计算精度高的特点,非常适合于接触问题的分析,本文建立了考虑摩擦三维弹塑性接触问题的边界元法,采用此方法对板带轧制这一典型的弹塑性接触问题进行了分析,证明本文人出的方法是有效的。 相似文献
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岩石弹塑性破裂过程的数值模拟研究 总被引:6,自引:0,他引:6
分析了对于非均质、非连续且材料参数分布具有分散性和随机性的岩体介质,采用传统有限元法解决其工程问题的局限性.阐述了用岩石力学性质的分布特性来描述岩石材料不均匀性,并用蒙特卡洛模拟方法,将符合Weibull分布规律的材料参数赋予岩体结构中的各个单元体,进而用计算机进行数值模拟的研究方法.应用了在Windows95环境下利用FORTRAN Power Station4.0平台开发的具有可视性的“岩石弹塑性破裂过程分析”软件——REPFPA软件,对典型的岩石试样和巷道模型的弹塑性破裂过程进行数值模拟研究,得到了有价值的实验结果.证明把材料参数随机赋值方法引入到岩土类材料的弹塑性破裂过程分析中去,并用计算机进行数值模拟是研究岩石弹塑性破裂过程的一种有效方法。 相似文献
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非均质材料弹塑性破裂过程的数值模拟研究 总被引:7,自引:0,他引:7
阐述了岩土类材料的非均质特性,根据这种特性提出了对材料参数进行随机赋值的方法。为了对非匀质类材料的弹塑性破裂过程进行数值模拟研究,必须在有限元计算中实现材料的参数随机赋值。还给出了实例--平面应力状态下试样的弹塑性破裂过程的数值模拟分析。 相似文献
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R. Kreißig U. Benedix U.-J. Görke 《Archive of Applied Mechanics (Ingenieur Archiv)》2001,71(2-3):123-134
Summary The presented method to identify material parameters for inelastic deformation laws is based on the numerical analysis of
inhomogeneous stress and strain fields received from suitable experiments. Tensile and bending tests were carried out to obtain
elastic and hardening parameters. The deformation law for small elasto-plastic strains is presented as a system of nonlinear
differential and algebraic equations (DAE) consisting of the stress–strain relation, evolution equations for the internal
variables and the yield condition. Different rules for the evolution equations of isotropic, kinematic and distorsional hardening
are proposed. The DAE are discretized using an implicit Euler method, and the resulting system of nonlinear algebraic equations
is solved using the Newton method. Deterministic optimization procedures are preferred to identify material parameters from
a least-squares functional of numerical and measured comparative quantities. The gradient of the objective function was calculated
using a semianalytical sensitivity analysis. Due to measurement errors, the optimal sets of material parameters are non unique.
The approximate estimation of confidence regions and the calculation of correlation coefficients is presented.
The results of several optimization processes for material parameters of elasto-plastic deformation laws show a good agreement
between measured and calculated values, but they show also problems which may occur if systematic errors will not be recognized
and deleted.
Received 30 September 1999; accepted for publication 8 March 2000 相似文献
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Ultra High Speed DIC and Virtual Fields Method Analysis of a Three Point Bending Impact Test on an Aluminium Bar 总被引:1,自引:0,他引:1
This paper deals with the analysis of an aluminium beam impacted in a three point bending configuration using a Hopkinson
bar device. Full-field deformation measurements were performed using Digital Image Correlation on images captured with an
ultra high speed camera (16 frames at a time resolution of 10 μs). The performance of the deformation and strain measurements were evaluated and the data were then used quantitatively to
analyse the very complex dynamic behaviour of the beam. It was shown that the deformation of the beam was controlled by the
interaction between the striker and the flexural bending wave triggered by the initial impact. The principle of virtual work
was used to reconstruct the impact force from the shear strains and to analyze how this impact force relates to the acceleration
of the specimen (inertia forces) and the development of the bending stresses. The results are in good agreement with expectations.
This opens up new perspectives in the quantitative use of full-field measurements to extract elasto-plastic constitutive parameters
from such impact tests. 相似文献
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This paper deals with the identification of elasto-plastic constitutive parameters from deformation fields measured over the
surface of thin flat specimens with the grid method. The approach for recovering the constitutive parameters is the virtual
fields method. A dedicated algorithm is used for deriving the distribution of the 2D stress components from the measured deformation
fields. A state of plane stress is assumed. Guesses of the constitutive parameters are input in the algorithm and updated
until the stresses satisfy the principle of virtual work in the least squares sense. The advantage of this approach is that
it can handle very heterogeneous plastic flows and it is much faster than classical finite element model updating approaches.
An experimental application is provided to demonstrate it. Six mild steel double-notched specimens have been tested in a configuration
combining tension and in-plane bending. The identified parameters are in good agreement with their reference counterparts.
Stress fields are eventually reconstructed across the specimen all along the test for analyzing the evolution of the plastic
flow. 相似文献
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本文根据我国南海海底输油气铺管的要求系统分析了海底管道在弯曲与外水压力共同作用下的弹塑性稳定性和屈曲传播.研究了管道的极值型屈曲和分枝型屈曲.在考虑管道的初始非圆度和材料的物理非线性的情况下提出了临界屈曲载荷的计算方法.综述和评论了屈曲传播现象的本质和各种计算方法.介绍了我们所进行的全尺寸管道实验.在分析理论结果时与现行的有关设计规程进行了比较和评论. 相似文献
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Based on the elasto-plastic theory, considering the effect of spherical stress tensor on the elasto-plastic deformation and using the slicing treatment to deal with the plasticity of functionally graded coatings, the elasto-plastic increment constitutive equations of the sandwich plates with functionally graded metal-metal face sheets can be derived. Applying the weak bonded theory to the interfacial constitutive relation and taking into account the geometric nonlinearity, the nonlinear increment differential equilibrium equations of the sandwich plates with functionally graded metal-metal face sheets are obtained by the minimum potential energy principle. The finite difference method and the iterative method are used to obtain the post-buckling path. When the effect of geometrical nonlinearity of the plate is ignored, the elasto-plastic critical buckling load of the sandwich plates with functionally graded metal-metal face sheets can be solved by the Galerkin method and the iterative method. In the numerical examples, the effects of the interface damages, the induced load ratio, the functionally graded index, and the geometry parameters on the elasto-plastic post-buckling path and the elasto-plastic critical buckling load are investigated. 相似文献
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An efficient finite element formulation is presented for geometrical nonlinear elasto-plastic analyses of tensegrity systems based on the co-rotational method. Large displacement of a space rod element is decomposed into a rigid body motion in the global coordinate system and a pure small deformation in the local coordinate system. A new form of tangent stiffness matrix, including elastic and elasto-plastic stages is derived based on the proposed approach. An incremental-iterative solution strategy in conjunction with the Newton-Raphson method is employed to obtain the geometrical nonlinear elasto-plastic behavior of tensegrities. Several numerical examples are given to illustrate the validity and efficiency of the proposed algorithm for geometrical nonlinear elasto-plastic analyses of tensegrity structures. 相似文献
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提出了圆板弹塑性弯曲的简单样条积分方程法.以径向转角作为未知量建立积分方程并结合B样条函数进行求解.这一方法具有域积分容易处理、精度高和计算简单的优点.计算结果表明本文解与文[2]解吻合良好. 相似文献
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The incremental hole-drilling method is widely used in residual stress depth distribution analysis. However, two specific difficulties with the generalization of the incremental method exist, including the consideration of the sample thickness and residual stress states close to the local material’s yield strength. The stress concentration effect of the hole can lead to plastic deformation in the vicinity of the hole, which results in an overestimation of residual stresses. Typically, the effect of the component’s thickness and the plasticity effects are analyzed separately and correction approaches are proposed. In the current paper, we analyze the combined effects of plasticity and thickness on residual stress analysis using the incremental hole-drilling method. A systematic study was performed on steel samples with (i) isotropic and (ii) anisotropic elastic and elasto-plastic material behavior with varying thicknesses ranging between 1 mm and 4 mm. Electronic speckle pattern interferometry (ESPI) hole-drilling experiments were conducted on beam samples loaded using a 4-point bending fixture. Finite element simulations were conducted to gain insight into the effects of incremental hole-drilling. The results indicate that reducing the component’s thickness increases the plastic deformation in the vicinity of the hole and results in significant stress deviations. Thin components bend during hole-drilling as a result of the loss of stiffness, which amplifies the plasticity effect. 相似文献
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In this work, the finite element analysis of the elasto-plastic plate bending problems is carried out using transition rectangular plate elements. The shape functions of the transition plate elements are derived based on a practical rule. The transition plate elements are all quadrilateral and can be used to obtain efficient finite element models using minimum number of elements. The mesh convergence rates of the models including the transition elements are compared with the regular element models. To verify the developed elements, simple tests are demonstrated and various elasto-plastic problems are solved. Their results are compared with ANSYS results.The English text was polished by Keren Wang. 相似文献