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中文核心期刊

各向异性材料中波传播与微结构影响的 近场动力学模拟

Peridynamic Modeling of Wave propagation and the effect of microstructure in anisotropic materials

  • 摘要: 金属的微观结构显著地影响其宏观力学性能,深入理解金属在动态条件下的力学响应具有重要意义。近场动力学是一种新兴的非局部理论,在研究冲击作用下材料的损伤与破坏方面具有天然理论优势。本文以非常规态型近场动力学为理论框架,模拟了波在各向异性材料中的传播过程以及波与微观结构之间的相互作用。为了在非局部模型中准确捕获冲击波,采用非迭代近似黎曼解修正非局部力态中的界面压力,保证了冲击波界面物理量的守恒性与求解稳定性、兼顾了计算效率。基于晶体塑性理论和均匀化理论,将有限变形晶体黏塑性本构引入近场动力学的非局部理论框架。与解析解的对比表明,所提出的模型能够有效消除波阵面后的非物理振荡、准确捕捉弹塑性双波结构。与实验结果对比表明,高效显式晶体黏塑性近场动力学模拟所得的宏观力学响应吻合较好。在此基础上,本文探讨了不同的冲击速度、材料的初始微观结构对冲击响应的各向异性和塑性变形的非均匀性的影响。晶体取向决定了Hugoniot弹性极限和材料的软硬取向,进而影响弹塑性波结构的演化,晶界导致Hugoniot状态下应力分布和累积滑移应变呈现高度非均匀性。

     

    Abstract: The microstructure of metals significantly impacts their macroscopic mechanical properties, and a deep understanding of the mechanical response of metals under dynamic conditions is of great significance. Peridynamics, an emerging nonlocal theory, has a natural theoretical advantage in studying the damage and failure of materials under impact. In this paper, the theory of non-ordinary state-based peridynamics is used as the theoretical framework to simulate the propagation of waves in anisotropic materials and the interaction between waves and microstructures. To accurately capture shock waves in the nonlocal model, the interface pressure in the nonlocal force state is corrected using a non-iterative approximate Riemann solution, ensuring the conservation and solution stability of the physical quantities at the shock wave interface, and taking into account computational efficiency. Based on crystal plasticity theory and homogenization theory, the finite deformation crystal viscoplastic constitutive model is introduced into the nonlocal theoretical framework of peridynamics. Comparisons with analytical solutions show that the proposed model can effectively eliminate non-physical oscillations behind the wavefront and accurately capture the elastoplastic wave structure. Comparisons with experimental results show that the macroscopic mechanical response obtained from the efficient explicit crystal viscoplastic peridynamics simulation is in good agreement. On this basis, the effects of different impact velocities and the initial microstructure of the material on the anisotropy of the impact response and the heterogeneity of plastic deformation are discussed. The crystal orientation determines the Hugoniot elastic limit and also the soft and hard orientations of the material, thereby affecting the evolution of the elastoplastic wave structure. Grain boundaries lead to highly heterogeneous stress distributions and cumulative slip strains in the Hugoniot state.

     

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