小冲杆试验的有限元模拟中GTN模型参数的确定

On the Determination of Gurson-Tvergaard-Needleman Model Parameters for Finite Element Simulation in Small Punch Test

GTN模型参数的选择一直是小冲杆模拟中一个至关重要的环节,其正确与否直接影响着模拟得到的载荷-位移曲线的正确性。以16MnR材料作为研究对象,结合拉伸试验与小冲杆试验的实验结果,逐步确定出有限元模拟中的GTN模型参数。本文重点介绍了参数fN,fc,ff的确定方法。结果发现,拟合的载荷位移曲线不具有唯一性。为了验证所用方法的正确性,增加了试样断后减薄率作为另一评判标准。这一做法后来证明是可行的。这说明载荷位移曲线不能作为判断GTN参数正确的唯一准则,而增加的断后减薄率作为另一判断标准,对此方法有很好的辅助作用。上述结果可为小冲杆实验的有限元模拟夯实基础。

Selection of GTN model parameters has been a vital link in small punch simulation, which directly influence the correctness of load-displacement curve obtained from simulation. Taking 16MnR material as study object, combining experimental results from both tensile test and small punch test, GTN model parameters in finite element simulation were determined step by step. This paper focuses on the determination of parameters fN, fc, and f f . Results show that the fitted load-displacement curve is not unique. In order to verify the reliability of this method, the thinning rate of specimen after fracture was introduced as another judgment criterion. This measure is proved to be feasible later. Above result indicates that load-displacement curves cannot serve as the only criterion to verify the C-TN parameters. Introduction of specimen＇s thinning rate after fracture as another judgment criterion provides a good assistant role for original method. Above results may place a solid foundation for finite element simulation in small punch test.