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首页> 外文学位 >Stress Intensity Factors and Effective Spring Stiffness for Interfaces with Two and Three Dimensional Cracks at the Interface between Two Dissimilar Materials.
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Stress Intensity Factors and Effective Spring Stiffness for Interfaces with Two and Three Dimensional Cracks at the Interface between Two Dissimilar Materials.

机译：两种异种材料之间的界面处具有二维和三维裂纹的界面的应力强度因子和有效弹簧刚度。

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摘要

Stress intensity factors and effective spring stiffnesses for two-dimensional and three-dimensional cracks at the interface between dissimilar solids are investigated. First explicit analytical expressions are obtained for the longitudinal and transverse effective spring stiffnesses of a planar periodic array of collinear cracks at the interface between two dissimilar isotropic materials; they are shown to be identical in a general case of elastic dissimilarity (the well-known open interface crack model is employed for the solution). The effects of elastic dissimilarity, crack density and crack interaction on the effective spring stiffness are clearly represented in the solution. It is shown that in general the crack interaction weakly depends on material dissimilarity and, for most practical cases, the crack interaction is nearly the same as that for crack arrays between identical solids. This allows approximate factorization of the effective spring stiffness for an array of cracks between dissimilar materials in terms of an elastic dissimilarity factor and two factors obtained for cracks in a homogeneous material: the effective spring stiffness for non-interacting (independent) cracks and the crack interaction factor.;Second, the longitudinal and transverse effective spring stiffnesses of non-interacting penny-shaped cracks at the interface between two dissimilar, isotropic, linearly elastic materials is obtained based on classical fracture mechanics. Special care is taken to avoid crack surface interpenetration for transverse loading, and the valid loading range is obtained to assure negligibility of crack surface interpenetration for all possible ranges of isotropic, linearly elastic material combinations. For linear ultrasound applications, it is shown that the expression obtained for transverse springs can be used for most isotropic, linearly elastic material combinations, if the initial maximum crack opening displacement is more than 10-6 of the crack radius.;Third, based on Kachanov's approximate method for crack interaction problems, the stress intensity factors for a periodic array of coplanar penny-shaped cracks are obtained as a function of angle around the crack circumference and crack density for square and hexagonal crack configurations. Crack interactions in the hexagonal configuration are shown to be more than those in the square configuration. Numerical errors and errors due to the approximate nature of the method are estimated, and obtained results are shown to be valid within 8% error for crack density up to 95%.;Fourth, following the approximate factorization of the effective spring stiffness for an array of cracks between dissimilar materials, approximate expressions for the longitudinal and transverse effective spring stiffnesses of co-planar penny-shaped cracks with square or hexagonal configurations at the interface between two dissimilar isotropic materials are proposed.;They are based on elastic dissimilarity factors and two factors obtained for cracks in a homogeneous material: the effective spring stiffnesses for non-interacting (independent) cracks and the crack interaction factor. The crack interactions as a function of crack density for square and hexagonal configuration are obtained by comparing the effective spring stiffnesses for coplanar penny shaped cracks and those for non-interacting cracks. By comparing expressions of the effective spring stiffnesses for non-interacting penny shaped cracks at the interface between two dissimilar materials and those in a homogeneous material, the effect of material dissimilarity on the equivalent spring stiffnesses are expressed in terms of material dissimilarity functions. Since the interfacial spring stiffnesses can be experimentally determined from ultrasound reflection and transmission analysis, the obtained expressions can be useful in estimating the percentage of disbond area between two dissimilar materials, which is directly related to the residual strength of the interface.
机译：研究了异种固体之间界面处二维和三维裂纹的应力强度因子和有效弹簧刚度。对于两种不同的各向同性材料之间的界面处的共线裂纹的平面周期性阵列的纵向和横向有效弹簧刚度，首先获得了明确的解析表达式。在弹性不相似的一般情况下，它们被证明是相同的（解决方案采用了众所周知的开放界面裂纹模型）。解决方案中清楚地显示了弹性相异性，裂纹密度和裂纹相互作用对有效弹簧刚度的影响。结果表明，一般而言，裂纹相互作用几乎取决于材料的不相似性，并且在大多数实际情况下，裂纹相互作用与相同实体之间的裂纹阵列几乎相同。这样就可以根据弹性不相似因子和为均质材料中的裂纹获得的两个因素，对异种材料之间的一系列裂纹的有效弹簧刚度进行近似分解：非相互作用（独立）裂纹的有效弹簧刚度和裂纹其次，基于经典的断裂力学，获得了两种互不相同的各向同性线性弹性材料之间的界面处的非相互作用便士形裂纹的纵向和横向有效弹簧刚度。要特别注意避免在横向载荷下裂纹表面互穿，并且获得有效载荷范围以确保对于各向同性，线性弹性材料组合的所有可能范围，裂纹面互穿可以忽略不计。对于线性超声应用，已表明，如果初始最大裂纹开口位移大于裂纹半径的10-6，则对于大多数各向同性，线性弹性材料组合，可以使用横向弹簧获得的表达式。对于裂纹相互作用问题，采用Kachanov的近似方法，共面便士形裂纹的周期性阵列的应力强度因子作为围绕裂纹周长的角度和正方形和六角形裂纹构型的裂纹密度的函数来获得。六边形构造中的裂纹相互作用显示出比方形构造中的裂纹相互作用更大。估计了数值误差和由于该方法的近似性质而引起的误差，对于裂纹密度高达95％的情况，所获得的结果表明在8％的误差内有效。第四，对阵列的有效弹簧刚度进行近似分解对于不同材料之间的裂纹，提出了两种不同各向同性材料之间界面处具有正方形或六边形构型的共面便士形裂纹的纵向和横向有效弹簧刚度的近似表达式。均质材料中裂纹获得的因素：非相互作用（独立）裂纹的有效弹簧刚度和裂纹相互作用因子。通过比较共面便士形裂纹和非相互作用裂纹的有效弹簧刚度，可以得到正方形和六角形裂纹作为裂纹密度的函数。通过比较两种互不相同的材料和均质材料之间的界面处的非相互作用便士形裂纹的有效弹簧刚度的表达式，材料异质性对等效弹簧刚度的影响用材料异质性函数表示。由于可以从超声反射和透射分析中通过实验确定界面弹簧刚度，因此所获得的表达式可用于估算两种不同材料之间的粘结面积百分比，这直接与界面的残余强度有关。

著录项

  • 作者

    Lekesiz, Huseyin.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 291 p.
  • 总页数 291
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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