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首页> 外文期刊>Engineering analysis with boundary elements >Evolution of subsurface radial cracks in bi-material structures undergoing indentation loading
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Evolution of subsurface radial cracks in bi-material structures undergoing indentation loading

机译：压痕载荷作用下双材料结构地下径向裂纹的演变

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Mathematical modelling is used to study the evolution of damage caused by indentation loading on curved bilayers consisting of brittle shells filled with polymer support material. Such loads are pertinent to all-ceramic crown structures on tooth dentin in occlusal function. The aim is to develop tools to assist in the design of such structures to ensure both high damage resistance and high damage tolerance. Specifically, the initiation and propagation of a radial crack emanating from the interface is studied using the boundary element method (BEM) in three dimensions. The system that is analysed consists of a spherical indenter and both flat and convex bi-material samples. A semi-circular intrinsic flaw/crack is assumed to lie on the axis of indentation at the interface of the two materials, in the coating. Upon application of an indentation load, the mode I stress intensity factor distribution along the crack front is determined and the crack front is propagated using a small increment. By repeating this process, the critical load for propagation of the crack is obtained as a function of crack size. The results compare well with experimental crack propagation studies in bi-materials, as well as observed damage in porcelain crowns that have been used to repair teeth. The convex models show that radial cracks can exist in the brittle coating, without leading to catastrophic failure, up to a critical crack length. An increase in the applied load, causing the crack to grow beyond this length, causes the coating to fail in an unstable way. The results show that there is an optimum combination of design parameters for maximising the damage resistance. It is shown that larger convex radii of curvature lead to higher damage tolerance. (C) 2006 Elsevier Ltd. All rights reserved.
机译：数学模型用于研究由弯曲双层压痕载荷引起的损伤的演变，该双层由填充有聚合物支撑材料的脆性壳组成。这样的负荷与咬合功能中的牙本质上的全瓷冠结构有关。目的是开发工具以帮助设计此类结构，以确保高抗损伤性和高抗损伤性。具体而言，使用边界元方法（BEM）在三个维度上研究了从界面发出的径向裂纹的萌生和扩展。被分析的系统包括一个球形压头以及平坦的和凸起的双材料样品。假定在涂层中两种材料的界面处的压痕轴上存在半圆形的固有缺陷/裂纹。施加压痕载荷后，确定沿裂纹前沿的I型应力强度因子分布，并以较小的增量传播裂纹前沿。通过重复该过程，获得了裂纹扩展的临界载荷，该临界载荷是裂纹尺寸的函数。该结果与双材料中的实验裂纹扩展研究以及用于修复牙齿的瓷冠中观察到的损坏进行了比较。凸模型表明，脆性涂层中可能存在径向裂纹，而不会导致灾难性的破坏，直至临界裂纹长度。施加载荷的增加会导致裂纹扩展到超过此长度，从而导致涂层以不稳定的方式失效。结果表明，存在设计参数的最佳组合，以最大程度地提高抗破坏性。结果表明，较大的曲率凸半径导致较高的损伤容限。 （C）2006 Elsevier Ltd.保留所有权利。

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