动态扩展裂纹的热-弹塑性耦合分析

 以弹塑性扩展裂纹的裂尖参数为研究对象,对快速扩展的裂纹问题进行了细致的分析。首先建立了经验的应变率以及热 -弹塑性耦合的材料本构关系,完善了增量路径无关积分参数 T*的数值计算。通过与 J积分的比较,给出了两种积分参数在不同扩展速度、是否考虑热和应变率影响等情况下的变化规律,说明了T*积分用于快速扩展裂纹的合理性和优越性。在裂尖场的讨论中,重点分析了裂尖应力、应变、应力三轴度和塑性区的演化发展过程,发现了快速扩展裂纹塑性区发展非单调的有趣现象,并且获得了应力三轴度可以作为裂纹扩展过程控制参数的基本结论。

STUDY OF THE CRACK-TIP PARAMETER IN HIGH SPEED CRACK GROWTH

Based on the study of the crack tip parameter in elastic plastic crack growth, further discussions on the high speed crack growth are given. A thermal elastic plastic coupled material model and an advanced method for calculating the incremental path independent integral are introduced. The characteristics of the crack tip integrals under different crack growth speeds and different situations, whether considering temperature and strain rate or not, are described. The distributions of stresses and strains in front of the crack tip and the development of plastic zone are also given. It is interesting to find that the expansion of the plastic zone during dynamic crack growth is non monotony. And it is concluded that the triaxiality stress parameter may control both steady crack growth and dynamic crack growth.