Ⅰ型动态扩展裂纹尖端的弹粘-理想塑性场

Perfect Elastic-Viscoplastic Field at Mode Ⅰ Dynamic Propagating Crack-Tip

由于材料在扩展裂纹尖端的粘性效应的存在,考虑粘性效应并假设粘性系数与塑性等效应变率的幂次成反比,对理想塑性材料中平面应变扩展裂纹尖端场进行了弹粘塑性渐近分析,得到了不含间断的连续解,并讨论了Ⅰ型裂纹数值解的性质随各参数的变化规律.分析表明,应力和应变均具有幂奇异性,通过分析使尖端场的弹、粘、塑性可以合理匹配.对于Ⅰ型裂纹,裂尖场不含弹性卸载区.趋于极限情况时,裂纹尖端处于一种超粘性状态,并积聚了大量的能量,在各个受压应力状态下裂纹扩展.

The viscosity of material is considered at propagating crack-tip. Under the assumption that the artificial viscosity coefficient is in inverse proportion to power law of the plastic strain rate, an elastic-viscoplastic asymptotic analysis was carried out for moving crack-tip fields in power-hardening materials under plane-sWain condition. A continuons solution was obtained containing no discontinuities. The variations of numerical solution were discussed for mode Ⅰ crack according to each parameter. It is shown that stress and strain both possess exponential singularity. The elasticity, plasticity and viscosity of material at crack-tip only can be matched reasonably under linear-hardening condition. And the tip field contains no elastic unloading zone for mode Ⅰ crack. It approaches the limiting case, crack-tip is under ultra-viscose situation and energy accumulates, crack-tip begins to propagate under different compression situations.