The main failure mode of mechanical parts – Reynolds

The top failure modes of mechanical parts:

Failure: The mechanical part cannot complete its normal function within the planning and booking period and under the regular conditions.

Ways in which mechanical parts fail: overall cracking, plastic deformation, corrosion, abrasion, gluing, and touch exhaustion

General criteria for planning mechanical parts: static strength, exhaustion strength, conflict wear

1. Static strength failure

When mechanical parts are subjected to external loads such as tension, compression, bending, torsion, etc., cracking or damage occurs because the static stress on a certain risk section exceeds the strength limit of the part. For example, bolts that are pulled off after being pulled and keys or pins that are sheared or crushed are all classified as such failures.

In addition, when the stress acting on the part exceeds the yield limit of the data, the part will be plastically deformed. Plastic deformation will lead to a decrease in accuracy or positioning forbidden, etc., which will seriously affect the normal operation of the part, so it will also be considered failure.

The main failure mode of mechanical parts – Reynolds

The main failure mode of mechanical parts – Reynolds

2. Exhaustion intensity failure

Most of the mechanical parts are operated under the condition of variable stress, and the effect of variable stress can cause the parts to be tired and damaged and lead to failure.

In addition, cracks or particles may fall off when the surface of the part is subjected to the effect of touching and changing stress for a long time. Fatigue damage is a failure mode that occurs gradually with the continuous operation time, and is an important cause of failure of mechanical parts. For example, cracking due to exhaustion crack propagation after loading on the shaft, fatigue fracture and pitting of tooth roots, and fatigue cracking of the chain are typical fatigue damages. The static strength failure of mechanical parts is because the static force exceeds the yield limit and often shows great deformation before cracking occurs, so the static strength failure is often discoverable and predictable.

Exhaustion intensity failure is progressive, but difficult to predict in advance, so it is more damaging.

3. Conflict science failure

Clash failures are primarily corrosion, abrasion, slipping, gluing, and touch exhaustion.

Corrosion is an electrochemical or chemical corrosion phenomenon that occurs on the surface of metal, and the result will be that the appearance of the part will be corroded and the fatigue resistance of the part can be reduced.

Abrasion is the phenomenon of loss or handling of material on the surface in the process of relative motion of two touch surfaces.

Gluing is because the oil film between the two opposing moving surfaces is damaged, and under the working conditions of high speed and heavy load, local adhesion occurs, and when the parts of the two surfaces are relatively sliding and bonded are torn and form a groove along the relative movement direction on the surface, it is called gluing.

Touch fatigue is a phenomenon in which cracks or particles fall off on the surface that has been subjected to the effect of touch stress for a long time.

Some parts can only work normally if they are satisfied with certain operating conditions. For example, the sliding bearing with liquid conflict can only work normally when the surface of the part is coated with a smooth oil film, otherwise the sliding bearing will fail in the form of overheating, gluing, wear, etc., and it will be classified as conflict failure.

For example, the slippage of the belt drive and the fretting wear of the thread are also examples of conflict failure.

4. Other invalidations

In addition to the primary failure modes indicated above, there are also some other failure modes for mechanical parts, such as stiffness failure with excessive deformation, unstable failure, and so on.

In addition, the specific failure mode of a mechanical part depends on a variety of factors such as the operating conditions, material, load condition and stress nature of the part. Even the same part, due to different operating conditions and mechanical requirements, may present multiple failure methods. For example, gear transmission may exhibit failure methods such as tooth breakage, wear, tooth surface exhaustion, pitting, gluing, or plastic deformation.

The main failure mode of mechanical parts – Reynolds

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