脆性断裂的微观机理和非平衡统计特性

Ⅰ.引言如何才能将断裂的微观机理与宏观特性结合起来,把断裂理论建立于微裂纹演化的微观动力学基础上,从而统一导出所有重要的宏观力学量并以某些更基本的物理量表示之?这是人们为实现材料的强度和韧性设计必需解决的一个重要理论课题。就脆性断裂来说,尽管现有几个主要代表性的理论如断裂力学理论、位错理论和统计理论都各取得一定成就,但就其理论框架来说,由于明显的局限性,却难以发展成可供指导设计的理论。因此,人们在探索微观与宏观相结合的断裂理论。最近的工作表明:从微裂纹演

THE MICROSCOPIC MECHANISM AND NONEQUILIBRIUM STATISTICAL NATURE OF BRITTLE FRACTURE

A nonequilibrium statistical theory of the brittle fracture of metals, connecting macroscopic process with a microscopic mechanism has been constructed. The microcrack evolution equation is given. The growth speed of crack, the distribution function and the fracture probability arcobtainrd in connection with the dislocation mechanism. Mechanical properties such as elongation, fracture strength, plastic Work, crack-extension force, fracture toughness and their statistical distribution functions have been derived in a unified theory.