What is a bolt's "proof load"?

A bolt's "proof load" refers to the maximum load that a bolt can withstand without experiencing permanent deformation. This is an important concept in mechanical design and engineering because it ensures that the bolt will perform effectively under normal service conditions without being compromised.

Understanding proof load is essential for engineers who must select the appropriate bolts for specific applications, ensuring reliability and safety. The proof load serves as a benchmark to evaluate the bolt's performance under stress, distinguishing it from other loads such as the ultimate load, which is associated with the point of failure. By utilizing the proof load, designers can ensure that bolts function properly within their intended limits, thus preventing mechanical failures in structures or machinery where they are employed.

In comparison, other options do not correctly capture the definition of proof load, as they either misrepresent the bolt's performance metrics or stray from the technical context of assessing a bolt's capacity.