Simply put, you want your fasteners to hold up under many situations including conditions of changing load. However, some fasteners cannot hold up to the challenge. One of the most common forms of fastener failure is fatigue. That is why fatigue resistance and strength is something to look for in your fasteners.
A fastener can experience fatigue for a variety of reasons including assembly parameters, fastener material, geometry, and stress on the fastener. Fatigue often occurs in the first load-bearing part of the thread, and it can be detrimental to your project. This means your design must allow for screws to increase its fatigue strength. However, the fatigue strength of fine threads decreases with increased rigidity and fineness of thread, so there are some things to keep in mind with fatigue strength in your fasteners.
There are ways to increase the fatigue strength of your screws. These would include measures that reduce the effective peak stresses or prevent combined loading.
Check out some options for increasing your fatigue strength:
- Use longer screws rather than shorter screws
- Use screws with waisted shanks
- Use pins or fitted shoulder screws to absorb lateral forces
- Adequate and controlled pre-stressing of the screws
Reach out to us at ProvenProductivity@bossard.com to learn more about fatigue resistance and to find the fastener with the perfect fatigue strength for you.