Testing method of bolt load distribution in carbon fiber/resin composite multi-bolt joints

A calculation model based on uncertainty theory for relative uncertainty of bolt load distribution in carbon fiber X850/resin composite multi-bolt joints was proposed for the existing problem of indeterminate testing deviation of bolt load distribution. This problem was caused because of the different testing methods and bolt load distributions of composite joints in different testing processes, so both the widely used strain gauge method and the latest instrumented bolt method were investigated. The research shows that the bolt load distribution in single-lap joints cannot be tested by the strain gauge method, and the relative uncertainty of double-lap joints is more than 2.8% in usual and will increase with the increasing of the number of bolts and the sticking deviation angle of strain gauges. The relative uncertainty of both single-lap and double-lap joints is no more than 1.5% with arbitrary number of bolts in the instrumented bolt method.