考虑接触的斜裂纹动态应力强度因子分析

Analysis of dynamic stress intensity factors for inclined cracks considering contact interaction

为了研究含中心穿透斜裂纹的有限板在拉伸冲击载荷下裂纹尖端的动态应力强度因子,本文采用有限元方法建立模型进行系列分析。裂尖的应力奇异性通过1/4节点奇异单元来模拟,应用相互作用积分法计算动态应力强度因子,考虑了裂纹面接触作用、冲击载荷形式、裂纹长度、裂纹角度及裂纹位置等参数的影响,并给出了接触应力随时间的变化曲线。数值结果表明:裂纹面的接触作用可消除负的Ⅰ型动态应力强度因子,接触刚度比摩擦系数的影响明显,载荷形式在总冲量不变的情况下对动态应力强度因子的影响也非常大,而裂纹长度等裂纹参数对Ⅰ型动态应力强度因子的影响比Ⅱ型显著。

A series of models was analyzed by using the finite element method to investigate the dynamic stress intensity factors(DSIFs) at the crack tip of a centrally cracked finite plate under tension impact loading. The stress singularity at the crack tip was simulated by quarter-point singular elements. DSIFs were obtained through the interaction integral method. The influences of crack contact, impact load style, crack length, crack angle, and crack location were discussed. The time history curves of contact stresses were also presented. Numerical results showed that the negative DSIFs for mode Ⅰ can be eliminated if the contact between crack faces was considered. The influence of contact stiffness on DSIFs was more pronounced than that of the friction coefficient, and the influence of load style was significant even if the total impulse remained constant. The effect of crack parameters, such as crack length, on the DSIFs for mode Ⅰ was more significant than that on the DSIFs for mode Ⅱ.