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arXiv 2103.11938cond-mat.mtrl-sci
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由实测运动场确定弹塑性应力-应变特性的偏微分方程

Partial differential equations to determine elasto-plastic stress-strain behavior from measured kinematic fields

Benjamin C. Cameron, Cem Tasan

摘要:

当控制塑性形变的流动规则未知时,推导了一组偏微分方程(PDE),由观测的运动学场计算全场应力。这些方程推广了以前提出的假设没有弹性的纯塑性行为的方程。本文还提出了一种数值求解这些方程的方法。除了力的平衡,方程推导出的变形梯度的弹塑性分解,假设各向同性,并假设映射的弹性应变应力的函数是已知的。方程组可以直接应用于复杂的几何形状,有限变形,非线性弹性和塑性,可压缩材料,率相关材料,和各种硬化规律。这个系统的偏微分方程是非线性和时间依赖性。此外,它克服了一个重要的限制:它可以直接应用于身体的一些区域弹性变形,而其他区域弹塑性变形的情况。一个二维的单轴拉伸试样的颈缩的情况下,研究来说明和验证的方法。使用从有限元模拟输出的应变场对控制方程进行数值求解,并针对显示准确结果的相同模拟进行验证。

英文摘要:

A system of partial differential equations (PDEs) is derived to compute the full-field stress from an observed kinematic field when the flow rule governing the plastic deformation is unknown. These equations generalize previously proposed equations that assume pure plastic behavior without elasticity. A method to numerically solve these equations is also presented. In addition to force balance, the equations are derived from the elastic-plastic decomposition of the deformation gradient, the assumption of isotropy, and the assumption that the function mapping the elastic strain to stress is known. The system of equations can be directly applied to complex geometries, finite deformation, non-linear elasticity and plasticity, compressible materials, rate dependent materials, and a variety of hardening laws. This system of PDEs is non-linear and time dependent. Furthermore, it overcomes an important prior limitation: it can be directly applied to cases where some regions of a body are elastically deforming while others are elasto-plastically deforming. A two-dimensional case study of necking in a uniaxial tensile specimen is investigated to illustrate and validate the method. The governing equations are numerically solved using strain fields output from a finite element simulation and validated against this same simulation showing accurate results.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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