Reduction of welding residual stress using ultrasonic vibration load (Effects of material properties on reduction rate)

Welding is used as a joining method in the construction of many structures. Residual stress is generated near the bead because of locally given heat. It is well known that it degrades fatigue strength. Especially, it is a cause of stress corrosion cracks in stainless steel. Since reduction methods, stress-relief annealing and shot peening are widely used, reduction methods of residual stress have been studied. However, these methods require special equipment and are time-consuming. The authors have proposed a method using vibrations during welding and shown the effectiveness of the method in rolled steel for general structures. On the other hand, the authors have also investigated the effectiveness of the method on stainless steel which is used for important structures. However, the experimental conditions were not the same. In this paper, the reduction of residual stress on build-up welded SUS304 and SS400 specimens were compared in the same experimental conditions and the effects of material properties on the method were investigated. The experiment is conducted for different amplitudes of the ultrasonic vibration load and without vibration load. It is concluded that the reduction rate for SUS304 is greater than that for SS400 and that the greater the amplitude of the ultrasonic vibration load, the greater the reduction rate. Statistical values of residual stress were obtained and there were significant differences in the mean values between each amplitude of ultrasonic vibration load. Additionally, the effectiveness of the method has also been verified. The experimental results were examined by the simulation method using a model considering plastic deformation caused by ultrasonic vibration load. It is found that residual stress is reduced using ultrasonic vibration load during welding

A human capital development model in higher engineering professions

This paper describes a novel model of education program and curricula in higher engineering to be employed in ASEANs and its related countries. Our investigation and research program consists of 10 universities including University of Brunei Darussalam, Institute of Technology at Cambodia, Institute of Technology at Bandung, National University of Laos, University of Technology in Malaysia, Yangon Technological University, De La Salle University at Philippines, Nanyang Technological University, Vietnam National university, and Advanced Institute of Industrial Technology in Japan. Our team made an MOU to conduct investigation to create a standard model of higher education program for engineering professions between 2015 to 2017. In this paper, we propose and introduce our invented education program and curricula, example of course in information technology and mechanical engineering, evaluation through questionnaires in external organizations. The proposed program consists 9 years program through high school to graduate school, but students can join in each school based on their needs. The contribution of this paper includes these three points; the proposed model is related with a human capitals development model to complement the existing engineering professional education; schools provide professional education program to execute effective learning; and the proposed model enables to be employed in current various schools easily. © 2017 IEEE