Prevention of Delamination during Drilling of Composite Material Using Vibration

Prevention method of delamination at adhesive layer during drilling of composite material using vibration is examined. First, this method is examined experimentally. As vibrational load, relatively low frequency vibration and ultrasonic vibration are used. It is concluded occurrence of delamination is less when vibration is used during drilling. Next, experimental results are examined by analytical method. Adhesive layer is assumed to be damping component. Condition of occurrence of delamination is proposed.

Reduction of Residual Stress of Welded Joint Using Random Vibration

Welding is widely used for construction of many structures. It is well known that residual stress is generated near the bead because of locally given heat. Tensile residual stress on the surface degrades fatigue strength. Some reduction methods such as heat treatment and shot peening are practically used. Authors have proposed a new method for reduction of residual stress using vibrational load during welding. In this paper, random vibration is used as vaibrational load considering noise added to input signal. White noise is used as random vibration. Two thin plates are butt welded and residual stresses near the bead are measured. It is found that tensile residual stresses near the bead are reduced when random vibration is used as vibrational load during welding. The proposed method is examined by simulation method using analytical model of the specimen. From the simulation method, it is demonstrated that tensile residual stresses near the bead are reduced when random vibration is used as vibrational load.