基于球形压入法提取材料的塑性力学参数

A NEW SPHERICAL INDENTATION-BASED METHOD TO EXTRACT PLASTIC MATERIAL PARAMETERS

基于球形压入的工作方式,重点研究材料塑性力学参数的表征方法.首先,通过对球压入可测量的综合评价,选取能量比(可释放功和压入总功之比)作为主要分析参数;其次,利用孔洞模型、量纲分析和数值模拟等工具,定义特定的代表性应变,建立起能量比和材料塑性力学参数之间的关系式,由此,提出一种能提取材料屈服应力和硬化指数的力学表征方法,该方法避免了对接触半径的测量,确保了方法的可操作性,并通过参数重组提高其稳定性;最后,选用45号钢和6061铝合金进行压入试验,与拉伸试验结果比对显示:该方法识别的塑性力学参数能满足工程测试需要.

This paper presents a new spherical indentation-based method to extract plastic properties of materials. With the specific evaluation on the response parameters in indentation tests, the energy ratio （the ratio of releasable work to total work） was chose and investigated in order to avoid the estimation of contact radius. Based on expanding cavity models, finite element computations and dimensional analysis, the relationships between energy ratio and plastic parameters are established. With these relationships, the plastic properties of materials can be consequently solved from instrumented spherical indentation test data. Furthermore, the stability of the method has been improved by reorganization of parameters. Finally, the veracity and simplicity of this method is checked by using two typical materials （Steel 45C and A1 6061）, which have known true stress-true strain curves.