What are the ways to improve the fatigue life of parts?

1) Designed to reduce stress concentration.

Avoid sharp angle connection at the adapter;

2) Reduce the surface roughness of parts.

3) Strengthen the surface, cause residual compressive stress on the surface of the part, offset part of the tensile stress, reduce the peak value of the actual tensile stress on the surface of the part, so as to improve the fatigue strength of the part.

The reinforcing surface can be rolled or shot peened, or heat treated.

The fatigue strength of parts can be improved by the following hidden spring sleepiness style:

1. Choose the corresponding material.

2. If it is high-carbon steel, quenching and tempering treatment can also improve the strength of Mingsen Xinxian.

3. The mechanical design should be reasonable and there should be no shape mutation. The sharp corners of the steps should have smooth transition arcs. The surface roughness of the whole body should be low.

4. Shot peening (sand) on the surface of the part can also improve some strength by hardening the surface.

1. Choose anti-fatigue materials, such as alloy steel.

2. Adopt forging process.

3. Adopt heat treatment process.

4. Avoid and slow down the stress concentration of parts. Deburring, edge chamfering, and corner transition are effective methods to reduce stress concentration.

5. Preset stress.

6. Note that the fiber direction of rolled and forged materials should be consistent with the main force direction, because the bearing strength will decrease by about 20% in the vertical fiber direction.

7. Load reduction, cooling and lubrication design.

8. Adopt a symmetrical structure as much as possible to avoid eccentric structures, and pay attention to local bending caused by asymmetry.

of stress. 9. Pay attention to the corrosion resistance of the material.

10. The opening of the structural parts should be reduced as much as possible, especially on the tensile surface.

11. Reduce or eliminate the initial cracks that may occur on the surface of the parts as much as possible. For important parts, strict inspection methods and requirements should be specified in the design drawings.

Through surface heat treatment, surface shot peening, improve the structure, and select good fatigue-resistant materials!! You can refer to Higher Education Press's Mechanical Design, thank you.

1.Use fatigue-resistant materials such as alloy steel. Like manganese steel and the like.

2.The blank is made by forging and hammering. 3.

Heat treatment methods are used to improve fatigue strength, such as quenching and tempering. 4.Eliminate the stress concentration point of the part, such as the corner of the corner with the corner transition, the hole edge to make the corner.

There are many factors that affect the fatigue life of the workpiece, including stress concentration, part size, surface condition, environmental medium, loading sequence and frequency, among which the first three are the most important.

1.Influence of stress concentration: When the part is loaded, at the sudden change of geometric shape, such as fillets, holes, grooves, etc., stress concentration should be generated, and the sensitivity to stress concentration is also related to the material.

The higher the force-crossing limit of the material, the more sensitive it is to stress concentration. If there are several sources of concentration on the same cross-section, the maximum effective stress concentration coefficient should be used for calculation.

2.Effect of size: The influence of the size of the part on the fatigue strength can be expressed by the size factor (you can refer to the relevant manual).

All other things being equal, the larger the size, the more significant the effect on the fatigue strength of the part. The reason is that the material has a coarser grain and a high probability of defects, and at the same time, the cold work hardening layer on the surface (which is beneficial for fatigue strength) is relatively thin after machining.

3.Effect of surface condition: The effect of the surface quality of the part on the fatigue strength can be expressed by the surface state coefficient (you can refer to the relevant manual).

Cast iron is very insensitive to the surface state after processing, and the strength limit of the steel can be extremely high, the rougher the surface, the lower the surface state coefficient, so the parts made of high-strength alloy steel, in order to improve the fatigue strength, its surface should have a higher processing quality. In addition, the following measures can be taken to improve the surface.

In addition to the material itself, it is also necessary to pay attention to the smooth surface of the part without scratches, and the compressive stress is increased by shot peening.