Pile-up现象对材料本构关系反演计算的影响  

Influence of Pile-up on reverse analysis of constitutive relationship of materials

作　　者：王月敏[1] 闫相桥[1] 李垚[1] WANG Yuemin;YAN Xiangqiao;LI Yao(Center for Composite Materials and Structures,Harbin Institute of Technology,Harbin 150080,China)

机构地区：[1]哈尔滨工业大学复合材料与结构研究所,黑龙江哈尔滨150080

出　　处：《哈尔滨工程大学学报》2018年第5期825-830,共6页Journal of Harbin Engineering University

基　　金：国家自然科学基金项目(51572058;91216123)

摘　　要：针对商用纳米压痕测试中忽略凸起(Pile-up)现象的问题,开展了Pile-up现象对材料力学参数和本构反演计算结果影响的研究。推导能量法理论,选取5种不同材料进行了纳米压痕测试,利用商用Oliver-Pharr(O-P)法和能量法分别进行硬度和弹性模量计算,并比较测试误差率。推导极限分析法理论并进行反演计算,得到考虑材料Pile-up现象的应力应变曲线,并根据计算结果对纳米压痕过程进行仿真。结果表明:当纳米压痕测试中压痕残余深度与压入深度比值大于0.7时,Pile-up现象对商用O-P法测试影响明显,弹性模量和硬度值误差率达到20%以上;对发生塑性变形较大材料进行本构关系反演计算时,理论计算值和数值模拟结果均证明了Pile-up现象对应力应变曲线计算有一定的影响。研究结果可为纳米压痕测试本构关系的反演计算方法提供参考。In this study,we investigated the impact of Pile-up behavior on the mechanical parameters of materials and performed an inverse computation of the constitutive relation to determine the effect of neglecting Pile-up in commercial nanoindentation tests. First,we deduced the energy method theory. We selected five different materials for the nanoindentation test,and used the commercial Oliver-Pharr and energy methods to compute the hardness and elastic modulus,respectively. In addition,we compared the test error rates. Next,we deduced the theory underlying the limit analysis approach and performed inverse calculation to obtain a strain-stress curve for the Pile-up of the material. We then simulated the nanoindentation process based on the computation result. The nanoindentation test results show that when the ratio of the residual indentation depth to the indentation depth is greater than0. 7,the impact of Pile-up on the test result is obvious when using the commercial Oliver-Pharr method. In addition,we found the error rates of the elastic modulus and hardness to both be above 20%. The inverse computation was performed to determine the constitutive relation of materials with large plastic deformation,and both the theoretical computation and simulation results confirmed that Pile-up affects the stress-strain curve. These results provide a reference for the inverse computation of the constitutive relation in nanoindentation tests.

关 键 词：能量法 纳米压痕测试 极限分析法 Pile-up现象 反演分析 本构关系 有限元分析 量纲分析 

分 类 号：O341[理学—固体力学]