平面应力状态断裂强度的椭圆准则分析

Fracture Strength Analysis of the Plane-Stress State by the Ellipse Criterion

简要分析了近年来提出的一个断裂准则——椭圆准则的基本特征,导出了它在主应力坐标系下的基本方程.根据所导出的基本方程,获得了平面应力条件下椭圆准则理论断裂强度曲线的完整描述关系,并分析讨论了破坏发生的方位及断裂形式与材料本征力学性质参数之间的联系.与既有理论结果及实验现象的对比解释了椭圆准则在材料相关参数确定方面的局限性.当应力状态相关材料特征参数在拉伸区和压缩区均作为常数时,获得了铸铁和混凝土平面应力状态下的断裂强度曲线.与相关实验数据的对比表明,它们在拉伸区能较好地吻合,但压缩区的差异十分显著,进一步证实了材料特征参数随应力状态变化规律对椭圆准则发展的必要性.

The features of the ellipse criterion for fracture mechanics was briefly analyzed,and the general equation of the criterion was derived in the principal stress coordinate system.According to this general equation,a complete description of the theoretical fracture loci was proposed for the fracture under the plane stress state,then a discussion by this criterion was presented about the relationship between the failure plane direction,the fracture pattern and the material intrinsic parameters of mechanical properties.The comparison with previous theoretical results and experimental phenomena explains the limitation of the ellipse criterion in the determination of material parameters.With material characteristic parameters associated with the stress state as 2 constants in the tension and the compression zones,the theoretical fracture loci were obtained for the cast iron and the concrete.The theoretical results coincide well with the related experimental data in the tension zone,but vastly differ in the compression zone.The work illustrates the necessity to reveal the relation between the material intrinsic parameters and the stress state for the development of the ellipse criterion.