As the diameter of the fastener increases, what happens to the amount of allowable gap?

When considering fasteners in aerospace applications, it's important to recognize how the physical dimensions of a fastener, particularly diameter, influence various mechanical properties and tolerances, including the allowable gap. As the diameter of the fastener increases, the surface area in contact with the mating parts also increases. This larger surface area can distribute loads more evenly and can accommodate more significant tolerances.

Allowable gaps can generally increase with the size of the fastener due to the improved load distribution characteristics. Larger fasteners are often designed to handle greater forces, which means they can tolerate greater misalignment or variation in the mating surfaces without compromising structural integrity. With an increase in diameter, the fastener can better handle minor imperfections or gaps between components, resulting in a greater allowable gap compared to smaller fasteners.

Factors such as material properties, the type of joint, and application specifics also play a role, but the fundamental relationship between fastener diameter and allowable gap is that larger diameter fasteners generally provide greater leeway in terms of the fitting of parts.