The main purpose of summarizing and analyzing the common failure forms of parts

Date：2022-03-09 15:14:16 Views：2174

The significance of part failure analysis is to reduce and prevent the recurrence of failure of similar mechanical parts, ensure product quality and improve product competitiveness. In order to prevent the failure of parts, it is necessary to analyze the failure of parts, that is, by judging the failure form of parts, determining the failure mechanism and causes of parts, selecting materials pertinently, determining reasonable processing routes, and putting forward failure prevention measures.

Summary of common failure forms of parts: overall fracture, plastic deformation, surface wear, excessive elastic deformation, functional failure, etc.

1. Integral fracture

When the parts are subjected to external loads such as compression, tension, shear, bending and torsion, the fracture occurs because the stress on a dangerous section exceeds the strength limit of the parts, or the fatigue fracture occurs on the dangerous section when the parts are subjected to variable stress. For example, the fracture of bolt, the fracture of gear tooth root, etc.

2. Plastic deformation

Plastic deformation is a kind of deformation that cannot be recovered by itself. Permanent deformation will occur when engineering materials and components are loaded beyond the range of elastic deformation, that is, unrecoverable deformation or residual deformation will occur after removing the load, which is plastic deformation. Not all engineering materials have the ability of plastic deformation.

Metals and plastics have different degrees of plastic deformation ability, so they can be called plastic materials. Brittle materials such as glass, ceramics and graphite have no plastic deformation ability. Obvious plastic deformation is generally not allowed in the design of engineering components, otherwise the components will not maintain the original shape or even fracture.

3. Surface wear

Wear is a basic type of component failure. Generally speaking, wear refers to the reduction of geometric dimension (volume) of parts. The loss of the function specified in the original design of parts is called failure. Failure includes complete loss of original function; If the function is reduced and there is serious damage or hidden danger, the reliability, safety and safety will be lost if it is used continuously.

Surface wear and fretting wear can be divided into surface wear and fretting wear according to the mechanism. The first three are the basic types of wear, and the latter two occur only under certain specific conditions.

4. Excessive elastic deformation

Exceeding the elastic limit is called excessive elastic deformation, which usually causes plastic deformation, commonly known as "permanent deformation"

5. Function failure

The constituent materials of the structure can meet the requirements, and the structure has been completed, but it can not meet the needs of the original design. For example, when a bridge is designed and erected, the clearance under the bridge is too low, so that a considerable number of ships cannot pass under the bridge. This is an example of functional failure.

The structure cannot meet its functional needs. Here, the constituent materials of the structure can meet the requirements, and the structure has been completed, but it can not meet the needs of the original design. For example, when a bridge is designed and erected, the clearance under the bridge is too low, so that a considerable number of ships cannot pass under the bridge. This is an example of functional failure. This kind of failure is the first consideration in any design.

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