Bolted Connections in Solar Installations: Fatigue

The third consideration for bolted connections in solar installations is the possibility of fatigue and its effects on the integrity of the assembly.

Dynamic and alternating service loads will cause a bolt to fracture at a load less than its static tensile strength. That Fatigue Strength is the maximum tensile load a material can support before fracturing prior to a given number of loading cycles. As load is reduced, the number of loading cycles that a bolt can endure increases until a level known as the Endurance Limit Δ is reached, at which a bolt will function with immunity against fatigue.

Here are some guidelines to preventing fatigue:

• High preloads protect bolts against failure.

• When the portion of the fluctuating service load is less than the bolt’s endurance limit, the fatigue life is essentially infinite.

If you’re looking for help preventing fatigue in bolted connections for your solar panel installation, contact Mudge to get the assistance you need.

Two fatigue cracks have developed. The central area is the last to fail. Examination of the threads confirmed the bolt was loose.