机器另件或工模具(以下简称机件)在使用过程中,可能因为变形、断裂、或表面状态尺寸变化(磨损、腐蚀、辐照)而失去原设计的使用效能,我们称它为“失效”。在各种失效方式中,断裂是最常见的,所造成的危害也是最严重的。在设计机件时,根据机件的服役条件和失效特点,对其在整个服役期限内的安全与可靠性已经进行了充分的老虑,照理机件在整个服役过程中就不会发生断裂了。但是,实践证明,机件的断裂仍然不断发生,而且常常造成灾难性的后果,这是因为在设计机件时有许多 Machine parts or tooling (hereinafter referred to as mechanical parts) may lose the original design performance due to deformation, fracture, or dimensional changes of the surface state (wear, corrosion, radiation) during use. We call it “invalid ”. Fracture is the most common type of failure, and the damage done is the most serious. In the design of mechanical parts, according to mechanical service conditions and failure characteristics of its service throughout the period of the safety and reliability have been fully affirmative, mechanical parts will not be in service throughout the fracture . However, it has been proven that the breakage of mechanical parts continues to occur and often leads to catastrophic consequences because there are many