What effect does a rivet head not being flush have on assembly?

When a rivet head is not flush with the surface where it is installed, it can indeed lead to structural issues. Rivets are designed to create a secure and tight joint between materials, which is essential for maintaining the integrity of the assembly. If a rivet head protrudes, it can create points of stress concentration which may weaken the joint over time, especially under conditions of vibration or thermal expansion and contraction.

Additionally, a non-flush rivet head can introduce aerodynamic drag, which is particularly critical in aerospace applications where efficiency and performance are paramount. In extreme cases, improper rivet installation can lead to fatigue cracks or failure of the joint, compromising the overall safety and functionality of the assembly. Therefore, ensuring that rivet heads are flush is crucial for maintaining both structural integrity and performance in aerospace assemblies.