Abstract The mechanical response of a system composed of a DLC coating on a steel substrate under indentation considering real conditions is investigated by using finite element method. The primary consideration is the mechanics of indentation induced coating cracking and interfacial delamination. A bilinear cohesive zone model with prescribed mechanical properties is applied to simulate evolutions of the crack and delamination. The effects of the rough surface and residual stress on the indentation results are evaluated. It is found that the surface roughness can reduce both the initial contact stiffness and maximum indentation load when the indenter is on an asperity peak. The compressive residual stress results in a greater indentation load level for a fixed penetration depth. Under the influence of rough surface and residual stress, the indentation elicited cracking and delamination occur in loading shear stress and unloading tensile stress modes, respectively. Moreover, the phenomenon of pop-in and pop-out on the load-displacement curve during the loading and unloading stages is individually monitored once the crack and delamination initiate. Additionally, the interface delamination is weakened by the coating cracking. Numerical results are also compared with previous studies, and can establish a reference for checking the results of actual indentation experiment.

中文翻译：

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考虑粗糙表面和残余应力的压痕下薄硬涂层的机械响应

摘要 采用有限元方法研究了钢基体上DLC涂层在考虑实际条件下压痕下的力学响应。主要考虑的是压痕引起涂层开裂和界面分层的力学。应用具有规定机械性能的双线性内聚区模型来模拟裂纹和分层的演变。评估了粗糙表面和残余应力对压痕结果的影响。结果表明，当压头处于粗糙峰时，表面粗糙度会降低初始接触刚度和最大压痕载荷。对于固定的穿透深度，压缩残余应力会导致更大的压痕载荷水平。在粗糙表面和残余应力的影响下，压痕引起的开裂和分层分别发生在加载剪切应力和卸载拉伸应力模式中。此外，一旦裂纹和分层开始，加载和卸载阶段载荷-位移曲线上的突然出现和突然出现的现象将被单独监测。此外，涂层开裂削弱了界面分层。数值结果也与以往的研究进行了对比，可为实际压痕实验结果的检验提供参考。此外，涂层开裂削弱了界面分层。数值结果也与以往的研究进行了对比，可为实际压痕实验结果的检验提供参考。此外，涂层开裂削弱了界面分层。数值结果也与以往的研究进行了对比，可为实际压痕实验结果的检验提供参考。