Contact analysis of thin films bonded to graded coatings
Contact analysis of thin films bonded to graded coatings
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DOI：
10.1016/j.ijmecsci.2011.12.003
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发表时间：
2012-02
影响因子：
7.3
通讯作者：
M. A. Guler;Y. F. Gülver;E. Nart
中科院分区：
文献类型：
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作者：
M. A. Guler;Y. F. Gülver;E. Nart
本文对薄膜与梯度涂层的接触力学进行了分析和数值研究。在这些问题中，应力的产生可能是由于均匀温度变化和温度漂移、远场机械载荷以及薄膜加工或制造过程中产生的残余应力。本研究的主要兴趣是检查薄膜末端附近的应力集中或奇点。潜在的力学问题是通过假设薄膜作为“膜”而梯度涂层作为功能梯度材料（FGM）来制定的。在解析式中，通过渐近展开将问题化为未知界面剪应力的奇异积分方程，然后采用合适的配置技术进行数值求解。在计算研究中采用了有限元法。计算结果包括膜与梯度涂层之间的界面剪切应力、膜端应力奇异强度和膜内的轴向法向应力。研究表明，系统的力学参数和几何参数以及加载类型对膜端应力分布和剪应力奇异强度有很大影响。调整这些参数并选择适当的分级类型将减少这些可能对涂层失效产生影响的应力。
In this study, the contact mechanics of thin films bonded to graded coatings is investigated both analytically and numerically. In these problems, the stresses may be arisen due to uniform temperature changes and temperature excursions, far field mechanical loading, and residual stresses resulting from film processing or manufacturing process of the graded coatings. The primary interest in this study is the examination of the stress concentrations or singularities near the film ends. The underlying mechanics problem is formulated by assuming the film acts as a “membrane” and the graded coating as a functionally graded material (FGM). In the analytical formulation, the problem is reduced to a singular integral equation for the unknown interfacial shear stresses through an asymptotic expansion and then solved numerically using a suitable collocation technique. Finite Element Method (FEM) is utilized in the computational studies. The calculated results include interfacial shear stress between the film and the graded coating, strength of stress singularity at the film ends and the axial normal stress in the film. This study reveals that both mechanical and geometrical parameters of the system as well as the loading type have a great effect on the stress distribution and the strength of shear stress singularity at the film ends. Adjusting these parameters and selecting the appropriate type of grading will reduce these stresses that may have a bearing on the failure of the coating.