DefinePK

Abstract

Bolt joints are commonly used when joining two or more components together in mechanical structures due to its easiness to be assembled and disassembled for maintenance. However, self-loosening is one of the most frequently found as a cause of failure in dynamically loaded bolted connections. This paper discusses a simple way to observe the dynamics characteristic of a fixed-free beam that consists of two beams that connected by a single and double bolt. The tightening torque of the bolt is varied from loosening condition, 2.5 Nm, 5 Nm, 7.5 Nm, and 10 Nm. The dynamics characteristics of the beam are obtained by modal impact testing. The frequency response functions of the beam are observed to analyze the effect of looseness and tightening torque of the bolts to the dynamics characteristic of the beam. It is found that the loosening condition or lower tightening torque will shift the natural frequency of the structure. Significant change will be observed at higher frequency. Moreover, the damping characteristic is also affected by changing the tightening torque. Especially, when loosening condition, the damping ratio becomes much higher than the tightening one. By this condition, the impact testing measurement could be applied as a simple way to monitor or detect the condition of bolted joint in a structure.