MODEL FOR CRACK INITIATION IN ELASTIC-PLASTIC INDENTATION FIELDS
MODEL FOR CRACK INITIATION IN ELASTIC-PLASTIC INDENTATION FIELDS
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DOI：
10.1007/bf00552240
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发表时间：
1977-01-01
影响因子：
4.5
通讯作者：
EVANS, AG
中科院分区：
文献类型：
--
作者：
LAWN, BR;EVANS, AG
提出了一个尖锐压头下微裂纹萌生的模型。使用一个简单的近似的拉伸应力分布在弹性/塑性压痕领域，结合几何相似性的原则，断裂力学程序被施加到确定的临界条件，从次表面缺陷的硬币状的“中值裂纹”的增长。分析提供了一个功能之间的关系的临界缺陷和压痕载荷的大小，使该缺陷扩展。只有当临界缺陷位于一定的尺寸范围内时，启动才是明确的（不稳定的）;在此范围外，大缺陷可以稳定延伸，但小缺陷根本不能延伸。在特征最小载荷以下，没有缺陷可以延伸，在该载荷下的压痕变量的值相应地提供有用的阈值参数。这些量涉及内在的变形/断裂参数，硬度和韧性，在一个基本的方式，从而建立了材料选择的基础上，在材料敏感的应用。
A model is proposed for the initiation of microfracture beneath sharp indenters. Using a simple approximation for the tensile stress distribution in the elastic/plastic indentation field, in conjunction with the principle of geometrical similarity, fracture mechanics procedures are applied to determine critical conditions for the growth of penny-like “median cracks” from sub-surface flaws. The analysis provides a functional relationship between the size of the critical flaw and the indentation load necessary to make this flaw extend. Initiation is well defined (unstable) only if the critical flaw lies within a certain size range; outside this range, large flaws can extend stably but small flaws can not extend at all. No flaws can extend below a characteristic minimum load, values of the indentation variables at this load accordingly providing useful threshold parameters. These quantities involve the intrinsic deformation/fracture parameters, hardness and toughness, in a fundamental way, thereby establishing a basis for materials selection in fracture-sensitive applications.