小冲杆试验参数的有限元分析

FEM ANALYSIS OF EXPERIMENTAL PARAMETERS OF THE SMALL PUNCH TEST

小冲杆试验 (smallpunchtest,SPT)技术作为一种新型微试样试验技术近年来发展很快 ,通过极少量试样材料进行试验就可以得出材料的诸多性能。由于小冲杆试验过程很复杂 ,如果想直接用分析的办法得到令人满意的解析解很难 ,早期的一些研究也多重于经验公式的推导。随着计算机技术的发展 ,有限元方法 (FEM )作为一种模拟分析工具逐渐应用到小冲杆试验研究中 ,文中通过ABAQUS有限元分析软件模拟小冲杆试验过程 ,并对试验中的钢珠直径d、下夹头直径D和试样厚度t以及摩擦因数 μ的变化对试验结果的影响进行考察分析 ,发现试验结果对t的微小精度差异相当敏感 ,因此在圆片试样制备中要特别注意试样厚度t的尺寸精度。此外因为目前小冲杆试验参数D和d还不是很统一 ,因此对D、d不同而引起的载荷—位移曲线变化趋势的讨论将有助于分析比较不同研究者的试验结果。

As a new test method, small punch test (SPT) provides a practical possibility in determination of material properties by using small specimen. However, due to the complexity of the test procedure, a satisfying analytical solution is too difficult to be found. With the development of the numerical simulation, FEM has been applied into the SPT research. In present study, a SPT FE model was established by ABAQUS code, the test process was simulated and the effects of the changes of some experimental parameters were investigated. The effects of the parameters such as ball diameter d, lower die diameter D and specimen thickness t as well as friction coefficient factor on test result were evaluated. It was found that the test result was influenced significantly by the thickness t of the specimen preparations. Due to the SPT parameters, D and d, are still not consistent, so the analysis of the effects of different D and d is of necessity in comparison and cross-checking of the test result made by different researchers.