Novel insert design for thick single lap bolted composite joints

Abstract

Mechanical fastening is a popular choice in joining composites because of the ability to transfer high loads and the ease of assembly and disassembly. However, drilling operations expose the fibers to environmental factors, and the high contact stresses between the bolt and the hole lead to localized delaminations, decreasing the joint strength. A new insert design, proposed here, seals the joint and increases the contact area between the bolt and the hole. This design is also low-cost and compatible with current machining techniques. With the novel design, a phase changing liquid is injected into the empty region between the bolt and the hole. The liquid is then allowed to cure. The tests then performed are on non-reinforced joints and joints reinforced with both machined isotropic inserts and the novel design. Initial tests in the elastic range are analyzed by using Digital Image Correlation. The joints are also tested to ultimate failure to determine any trends. From these tests and other preliminary considerations, it can be concluded that the novel design has tremendous potential for applications involving thick composite joints. ©2010 Society for Experimental Mechanics Inc.