断裂力学判据的评述

从Inglis和Griffith的著名论文到Irwin和Rice等的奠基性贡献,对断裂力学中的线弹性断裂力学的K判据,界面断裂力学的G判据,和弹塑性断裂力学的J判据作了扼要的综述.介绍了在界面断裂力学G判据的基础上提出的界面断裂力学的K判据,以说明断裂力学的判据存在改进的可能性.在综述中归纳出断裂力学判据中目前还没有较好解决的几个问题.在总结以往断裂力学研究经验的基础上,指出裂纹端应力奇异性的源是对断裂力学判据存在的问题作进一步研究的切入点.探讨了裂纹端应变间断的奇点是裂纹端应力奇异性的源的问题,从而对裂纹端应力强度因子的物理意义进行了讨论.最后,阐述了进行可靠的裂纹端应力场的弹塑性分析是改进弹塑性断裂力学判据的关键,而进行可靠的裂纹端应力场的弹塑性分析的前提是要通过裂纹端应力奇异性的源的研究来获得作用在裂纹端的造成裂纹端应变间断的有限值应力.

A CRITICAL REVIEW ON CRITERIA OF FRACTURE MECHANICS

In this paper, the K criterion for linear fracture mechanics, the G criterion for interfacial fracture mechanics, and the J criterion for elastoplastic fracture mechanics has been briefly reviewed, from the preliminary works of Inglis and Griffith to the foundation contributions of Irwin and Rice. Recently, on the basis of the G criterion for interfacial fracture mechanics, the K criterion for interfacial fracture mechanics was derived. This shows that the criteria of fracture mechanics need to be further improved. Thereupon, some debatable issues in the criteria of fracture mechanics are raised. Then, the strain discontinuity at the crack tip is assumed as the source of the stress singularity at a crack tip, and the physical meaning of the stress intensity factor is discussed. At the end, it is concluded that an improved and reliable analysis for the elastoplastic stress field near a crack tip is the key for the establishment of a criterion of elastoplastic fracture mechanics, and an improved and reliable analysis for the elastoplastic stress field near a crack tip depends on the determination of the magnitude of the stress at the crack tip, which caused the strain discontinuity at the crack tip.