Computer Simulations of R‐Curve Behavior in Microcracking Materials
Computer Simulations of R‐Curve Behavior in Microcracking Materials
复制标题
微裂材料 R 曲线行为的计算机模拟
DOI：
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发表时间：
1987
期刊：
影响因子：
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通讯作者：
R. Hoagland
中科院分区：
文献类型：
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作者：
Gregory D. Bowling;K. Faber;R. Hoagland
本文编制了一个模拟两相陶瓷材料微裂纹形成过程的计算机程序。该模拟提供了一种研究扩展裂纹与其周围残余应力颗粒之间复杂相互作用的方法。当第二相夹杂物附近的残余应力通过微裂纹的形成而释放时，在主裂纹周围形成了一个过程区，部分地屏蔽了主裂纹。由此产生的抗裂性曲线或R曲线与裂纹屏蔽机制相关。用微裂纹密度（fs）、与微裂纹相关联的应变（θ）和微裂纹的取向（θ）三个变量来确定它们对断裂韧性的影响。的稳态韧性被发现增加与第二相颗粒的添加，增加的塑性应变，并形成平行于所施加的应力的方向的微裂纹。然而，在这些模拟中获得的增韧幅度一般低于连续模型预测。这种差异归因于微裂纹之间的相互作用产生了导致正Δk的前沿区，因此，稳态韧性较低。当微裂纹与主裂纹连接以促进进一步扩展时，这种行为得到增强。
A computer program has been developed which simulates the process of microcracking in two-phase ceramic materials. This simulation provides a method of examining the complex interactions which occur between a propagating crack and the residually stressed particles around it. As the residual stresses near second-phase inclusions are relieved by microcrack formation, a process zone forms around the main crack, partially shielding it. The resulting crack resistance curves, or R curves, associated with crack shielding mechanisms are generated by the program. Three variables— the microcrack density (f_s), the dilatant strain associated with each microcracked particle (θ), and the orientation of the microcracks (Ψ)— were used to determine their influence on fracture toughness. The steady-state toughness was found to increase with second-phase particle additions, increased dilatant strain, and the formation of microcracks parallel to the direction of applied stress. However, the magnitude of toughening increase attained in these-simulations was generally lower than that predicted by continuum models. This discrepancy is attributed to the fact that interactions between microcracks produce frontal zones which result in a positive Δk, and hence, a lower steady-state toughness. This behavior is enhanced when microcracks link with the main crack to promote further extension.