The common ways of failure of mechanical parts can be divided into three types: failure of excessive deformation, failure of fracture, and failure of surface damage. This is called failure：

1. Excessive deformation failure: Failure of the part due to excessive deformation beyond the allowable range. It mainly includes failure modes such as excessive elastic deformation, plastic deformation, and creep at high temperatures.

2.Failure: a phenomenon of two or more parts that are separated into each other because of the excessive load or fatigue damage of the parts.Fracture is

the most severe form of failure, including the failure of ductile fracture, brittle failure of low temperature, failure of fatigue fracture, failure of creep rupture and failure of environmental rupture.

3.Failure of surface damage: failure due to surface relative friction or corrosion of environmental media caused by damage or dimensional change on the part surface.It mainly includes surface wear failure, corrosion failure, surface fatigue failure and other forms.

It needs to be pointed out that the same mechanical parts are often not only a failure mode in the work.However, it is always a way to play a leading role in the failure of parts.The core problem of failure analysis is to find out the main failure mode.