Effect of manufacturing tolerance on strength scatter of composite bolted joint structure

The manufacturing tolerance, which leads to different fit clearances between bolts and composite plate holes, is ineluctable in the manufacture process. Thus diversified pin load distribution of composite bolted joint is present and further results in the strength scatter of the joints. Taking a double-lap four-bolt composite joint with high locked bolts as an example, the influence of the fit clearance on the pin load distribution was investigated by a clearance-based direct stiffness method. Furthermore, the strength scatters of the four-bolt joint stemmed from the manufacturing tolerance have been predicted by a modified characteristic curve method, a modified strength envelope method and a progressive damage model with the dispersion intervals being [-3.87%, 2.16%], [-4.01%, 3.95%] and [-3.16%, 5.14%], respectively, which shows the effect range of the manufacturing tolerance on the strength of the joint is less than 6%, if the fasteners and holes both meet the manufacturing criterion.