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对偶域常规态基近场动力学弹脆性体稳定性分析

STABILITY ANALYSIS OF ELASTIC-BRITTLE BODIES IN DUAL-HORIZON ORDINARY STATE-BASED PERIDYNAMICS

  • 摘要: 稳定性是固体力学理论的核心问题之一. 作为一种新兴非局部理论, 近场动力学(peridynamics, PD)的稳定性分析方法尚不完善, 尤其是常规态基近场动力学(ordinary state-based peridynamics, OSBPD). 对于复杂场景, 如涉及变近场域、表面效应、损伤断裂、非均质及各向异性问题的弹脆性体稳定性, 仍缺乏严格理论支撑. 为应对这一挑战, 文章旨在为对偶域OSBPD(dual-horizon OSBPD, DH-OSBPD)理论建立一个通用稳定性分析手段. 从线性化DH-OSBPD材料模型的应变能密度函数出发, 利用柯西-施瓦茨不等式, 将基本的材料稳定性定理推广至涵盖任意积分域、弹性体整体稳定性、非均质性、含裂纹损伤以及各向异性等多种情形, 建立复杂情形下的稳定性条件. 在此基础上, 文章推导半正定应变能函数二阶变分为0的充要条件, 从而统一概括所有零能模式的数学形式. 分析表明, 满足定理条件的理想弹性体零能模式仅包含刚体运动; 而对于已断裂的弹脆性体, 则自然地包含各碎片间相互独立的相对刚体运动. 通过典型算例的特征值分析, 验证定理对于半正定性和零能模式个数的预测. 核心贡献在于将稳定性基本定理的适用范围, 从仅适用于理想弹性体内部材料点, 推广至涵盖存在表面效应、弹脆性断裂、各向异性及非均质等情形的系统整体稳定性分析, 为DH-OSBPD模型在广泛问题的数值仿真应用中的鲁棒性奠定了坚实的理论基础.

     

    Abstract: Stability is a fundamental issue in solid mechanics theory. As an emerging non-local theory, peridynamics (PD), particularly ordinary state-based peridynamics (OSBPD), still lacks a comprehensive framework for stability analysis. Rigorous theoretical support is currently missing for the stability of elastic-brittle bodies in complex scenarios involving variable horizons, surface effects, damage and fracture, heterogeneity, and anisotropy. To address this challenge, this paper aims to establish a general stability analysis framework for the dual-horizon OSBPD (DH-OSBPD) theory. Based on the strain energy density function of the linearized DH-OSBPD material model and utilizing the Cauchy-Schwarz inequality, the fundamental material stability theorems are generalized to cover arbitrary integration domains, global stability of elastic bodies, heterogeneity, presence of cracks and damage, and anisotropy. On this basis, the necessary and sufficient conditions for the vanishing second variation of the positive semi-definite strain energy function are derived, thereby unifying the mathematical formulation of all zero-energy modes. The analysis indicates that for an ideal elastic body satisfying the theorem conditions, the zero-energy modes consist solely of rigid body motions. Conversely, for a fractured elastic-brittle body, these modes naturally encompass the independent relative rigid body motions among fragments. Eigenvalue analysis of representative numerical examples validates the theorem's predictions regarding positive semi-definiteness and the number of zero-energy modes. The primary contribution of this work lies in extending the scope of fundamental stability theorems—previously limited to internal material points of ideal elastic bodies—to global stability of complex systems involving surface effects, elastic-brittle fracture, anisotropy, and heterogeneity. This lays a solid theoretical foundation for the robustness of the DH-OSBPD model in numerical simulations across a wide range of applications.

     

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