三点弯曲试样动态冲击特性的有限元分析

Dynamic behaviour of three point bending specimen under impact loading by using finite element method

本文使用动态有限元技术，对于两种不同几何尺寸，两种不同材料的三点弯曲试样在三类七种不同冲击载荷作用下的动态响应进行了分析，求得了动态应力强度因子随时间的变化规律。并与准静态应力强度因子进行了比较。计算结果表明：将冲击载荷历史代入静态公式确定动态应力强度因子的做法是不正确的，要求得动态应力强度因子，必须对试样进行完全的动态分析。当材料的Ｅ／ρ值相同时，动态应力强度因子的响应曲线完全相同。而动态应力强度因子分别与加载点的位移及裂纹的张开位移之间存在着与准静态情况下各自相同的线性关系。这与资料［５］［６］中的结论完全相同。

In this paper,the dynamic behaviour of three point bending specimen for two kind ofmaterials are analysed by using dynamic finite element technique under seven kind of impactloadings.The dynamic stress intensity factor is solved and compared with quasi-static stressintensity factor. The results show that the method for determining the dynamic stress inten-sity factor by substituting the dynamic loading history into quasi-static formula is not cor-rect.The full dynamic analysis is necessary to determine dvnamic stress intensity factor forthe specimen. The response curves of dynamic stress intensity factor are the same if the val-ues of E/ρ of materials are the same. The linear relationship between dynamic stress intensi-ty factor and the displacements of crack mouth and loading point respectively are the same asthat under quasi-static loading which agrees with that in reference[5][6].