基于细观力学的多孔材料断裂特性分析

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• 英文论文题名：A Micromechanical Analysis of the Fracture Properties of Porous Materials
• 论文作者：刘明超 ; 陈常青
• 英文论文作者：Mingchao Liu ; Changqing Chen ; Department of Engineering Mechanics & CNMM ; Tsinghua University
• 年：2016
• 作者机构：清华大学工程力学系&微纳米力学中心;
• 论文关键词：多孔材料 ; 断裂特性 ; 应力强度因子 ; 断裂韧性 ; 细观力学
• 英文论文关键词：Porous materials ; Fracture properties ; Stress intensity factor ; Fracture toughness ; Micromechanics
• 会议召开时间：2016-11-25
• 会议录名称：2016年航空科学与技术全国博士生学术论坛摘要集
• 语种：中文
• 分类号：TB383.4
• 学会代码：XBHH
• 会议名称：2016年航空科学与技术全国博士生学术论坛
• 会议地点：中国陕西西安
• 主办单位：西北工业大学研究生院、中国高校航空学院院长联席会
• 学会名称：西北工业大学航空学院
• 页数：1
• 文件大小：472k
• 原文格式：D
• 会议级别：全国

摘要

多孔材料在自然界和现代工业中广泛存在,如天然存在的蜂窝、木材,以及人工制备的泡沫铝和金属点阵材料等。由于具有相对密度低、比强度高等优点,多孔材料广泛应用于航空航天、机械、建筑和医药等领域。多孔材料的微观结构通常由联通的固体骨架和相互贯通或封闭的孔洞构成,孔洞等微观结构的存在会对其断裂特性产生显著的影响。本文首先通过二维细观力学模型研究了线弹性介质中裂纹尖端存在微孔洞的情况,给出了预测孔边最大应力的半解析公式,并通过与有限元结果的对比验证的该公式的准确性。基于关于单孔的分析结果,我们进一步分析了具有周期排布孔洞多孔材料的断裂特性。从细观结构出发给出了多孔材料应力强度因子的解析表达式,并基于固体骨架的抗拉强度准则提出了脆性和韧性破坏两种模式,得到了相应的断裂韧性。对于实际的多孔材料,其破坏模式通常介于脆性和韧性之间,因此该断裂韧性的理论预测结果给出了相应的上下限。最后,基于上述结果建立了多孔材料的断裂准则,该准则可以用于分析各种具有孔隙结构的材料的断裂问题,对于多孔材料在工程结构中的应用具有很强的指导意义。
Porous materials, such as natural honeycomb, wood, manmade Aluminium foam and metal lattice materials, are widely available in nature and modern industry. Due to their low relative density and high relative strength, porous materials are widely used in a broad range of applications including aeronautics and astronautics, mechanical engineering, construction, and pharmaceutical industry. Their microstructures usually contain both a solid skeleton and interconnected or closed pores. The existing of micro- structures, such as micro-pores at crack tip, has significant effect on the fracture properties. In this paper, key-hole-notched components are investigated based on a 2D micromechanical model. A semi-analytical formula is developed for predicting the maximum notchtip-stress, good agreement with finite element simulation results are found. Based on the analysis of the one-hole case, the fracture behaviour of porous materials is investigated by employing a micromechanical model consisting of elastic matrix and square arrays of holes. Theoretical expressions for the stress intensity factor is derived based on the microstructure. Furthermore, adopting the tensile strength criterion and assuming either brittle or ductile failure of the constituent solid skeleton of the porous media, lower and upper bounds of the fracture toughness are obtained for real materials. Based on the analysis, the fracture criterion of porous media is established. It can be applied to analysis the fracture problem of a large class of materials with porous structure and, has strong guiding significance for the applications of porous materials in engineering structures.

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