基于优化算法及压痕形貌的金属塑性力学参数表征

CHARACTERIZATION OF METAL PLASTIC MECHANICAL PARAMETERS BASED ON OPTIMIZATION ALGORITHM AND INDENTATION MORPHOLOGY

相比于需要特定形状尺寸试样的传统力学测试手段,压入法具有试样加工方便及可实现原位测试等优点,针对现有压入表征法对所采集压入载荷-深度曲线的依赖性,通过作为压入后材料塑性力学性能直观响应的残余压痕形貌有效获取金属塑性力学参数可提供一种新的压入表征方法;本研究通过Instron万能材料试验机开展了紫铜/镁合金的球形压入测试,基于轮廓形态系统对压入测试后的残余压痕形貌进行扫描并将所得形貌特征作为后续研究的数据基础;将压入数值模拟与实验测试所得残余压痕形貌的对比结果作为拟合优度,对传统Nelder-Mead算法在参数筛除、预处理、重复性判断及收敛条件方面进行改进,以保证进入数值计算的材料参数的合理性并提高计算效率,基于Abaqus二次开发结合改进的Nelder-Mead算法进行参数寻优以得到紫铜/镁合金的相关塑性参数;将由Instron万能材料试验机拉伸测试表征所得紫铜/镁合金的相关塑性参数值作为对照标准,给出了算法寻优结果的相对误差,并验证了所提出基于优化算法及残余压痕形貌获取金属塑性参数方法的有效性,相关研究提供了一种新的有效表征金属力学性能参数的方法.

Compared with the traditional mechanical testing method requiring samples of specific shape and size,indentation method has the advantages of simple manufacturing of samples and in-situ testing.The existing indentation characterization methods mainly relies on indentation load–depth curve,while the residual indentation morphology is an intuitive response to material plastic mechanical properties.Effective acquisition of metal plastic parameters by residual indentation morphology can provide a new characterization method for metal plastic mechanical properties.In this study,spherical indentation tests of Cu/Mg have been carried out by the Instron universal material testing machine,the residual indentation morphology of Cu/Mg was scanned by the contour morphology system and the obtained morphology feature will be used as the data basis for subsequent studies.The comparison result of residual indentation morphology from indentation numerical simulation and experimental test was taken as the goodness of fit.In order to discard the data less than zero,determine the initial value range of the optimization parameters and improve the efficiency of optimization calculation,related improvements of parameter screening,preprocessing,repeatability judgment and convergence conditions were carried out on the traditional Nelder-Mead algorithm.Based on the secondary development of Abaqus software and the improved Nelder-Mead algorithm,the optimization process was performed to obtain the plastic mechanical parameters of Cu/Mg.Also,the related plastic mechanical parameters of Cu/Mg was acquired through the conventional uniaxial tensile test and characterization based on the Instron universal material testing machine.By comparing the optimization results from algorithm and the tensile test characterization results,the relative errors of related plastic mechanical parameters of Cu/Mg obtained from optimization algorithm were identified,and the effectiveness of the proposed method for obtaining metal plastic parameters based on optimization algorithm and residual indentation morphology was verified.Relevant research provides a new and effective method for characterizing the mechanical properties parameter of metals.