Tetsumaro Hiroi

Reduction of Residual Stress of Welded Joint Using Local Plasticity Caused by Ultrasonic Vibration

Welding is widely used for construction of many structures. It is well known that residual stress is measured on welded joint. In this paper, a new method for reduction of residual stress using ultrasonic vibration during welding is proposed. Two thin plates are butt-welded. When ultrasonic vibration is used on one plate, tensile residual stress is reduced at center of the bead. Second, ultrasonic vibrations with different frequencies are applied on both plates. In this case, reduction rate of residual stress increases. Next, reduction of tensile residual stress is demonstrated by simulation method using an analytical model with dynamic characteristics of welded joint.

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.Copyright

A New Method for Reduction of Residual Stress of Welded Joint Using Ultrasonic Vibrational Load

A new method for reduction of residual stress using ultrasonic vibrational load during welding is proposed. The proposed method is examined experimentally. First, in order to simulate butt-welding of thin plates, reduction of residual stress is examined by using a specimen with a groove and specimens supported on the supporting device. Next, in order to simulate repair welding of press die, reduction of residual stress is examined by using a thick plate with a groove. From these experiments, it is found that tensile residual stress near the bead is reduced when the specimen is shaken during welding.