Numerical simulation on seismic behavior of mechanical structure for electronic equipment with bolted joints

Abstract

To stably operate electronic equipment such as computers and networking devices is essential to the current information society. They should be stably operated even when they are being subjected to seismic excitations. The computers and other devices are often mounted to a framework called a rack by using some screws when they are operated. In this research, we developed an effective numerical code to analyze the seismic behaviors of mechanical structure with bolted joints such as the rack. The numerical code was developed based upon the adaptively shifted integration (ASI) - Gauss technique, which is a finite element scheme that provides higher computational efficiency than the conventional code. Loosening mechanism of bolted joint was considered by employing a bearing-surface slip frequency dependent model. We carried out a seismic vibration test of a rack on a shake-table and simulated with three types of numerical simulation models. The screw elements were not considered in the first numerical model. The screw elements were considered in the second numerical model; however, the loosening mechanism of bolted joint was not considered. In the third numerical model, both the screw elements and the loosening mechanism were considered. Each numerical result was validated by comparing with the shake-table test result. Consequently, the numerical result of the third model agreed best with the test result. These results suggest that it is necessary to consider the loosening mechanism of bolted joint when analyzing the seismic behaviors of mechanical structure with screws.

Keywords

• rack
• seismic excitation
• asi-gauss technique
• finite element method
• screw
• bolted joint