We often encounter situations where the bolt connection is not tight enough, that is, the strength of the connection is not enough. 

      So, what can we do to improve? Today I will introduce several methods to you.

1. Improve load distribution between threads

2. Avoid or reduce additional stress

3. Reduce stress concentration

4. Reduce stress amplitude

Measures to reduce the stiffness of the bolt include: appropriately increasing the length of the bolt; partially reducing the diameter of the bolt or making it into a hollow structure, that is, a flexible bolt. Installing elastic elements under the nut can also function as a flexible bolt. When the flexible bolt is stressed, the deformation is large, the energy absorption is strong, and it is also suitable for withstanding impact and vibration.

5. Improve manufacturing process

      The manufacturing process has a great influence on the fatigue strength of the bolt. For high-strength steel bolts, it is even more significant.            When rolling thread is used, due to the effect of cold work hardening, the surface layer has residual compressive stress, the metal streamline          is  reasonable, and the bolt fatigue strength is higher than that of turning. Carbonitriding, nitriding, and shot peening can improve the fatigue          strength of bolts.