This award is for support of a joint research project by Dr. Mohamed A. Seif, Department of Mechanical Engineering, Northern Illinois University (NIU), Dekalb, Illinois, and Dr. Usama Khashaba, Department of Mechanical Design and Production Engineering, and Dr. Gamal Nawara, Research and Graduate Studies, both at Zagazig University, Zagazig, Egypt. With the wide use of composite materials in structural components, it has become necessary to drill holes into laminates to facilitate bolting or riveting to the main load-bearing structures. Stress concentration, delamination and microcracking are the main problems associated with drilled holes, which significantly reduce the composites' performance. The PIs will investigate the effect of the drilling parameters on the mechanical properties of composites. This includes the effect of different cutting conditions (feeds and speeds), machining operations (CNC, laser, and water jet), and the size and shape of the drills. The influence of the quality of the hole on the notched strength, pin bearing strength and bolted joint strength under uniaxial static and fatigue loading conditions will also be examined. Special interest will also be given to study the joint performance under various assembly conditions such as the bolt tightening torque, the washer size, the bolt clearance, and the diameter/width ratio. Optical microscopes, SEM, and laser measurement techniques will be used in this investigation.
Scope: This project will help in establishing a better understanding of the behavior of bolted joints in composite materials. In addition, the development of engineering models will contribute to improve basic studies of composite materials under various operational conditions. The collaboration involves an established and experienced U.S. scientist in the field and two researchers in a relatively small university in Egypt as well as a number of industrial organizations in that country.
