Energy Analysis Approach for Detecting Bolt Loosening

Abstract Bolt connections are integral to civil infrastructure and mechanical assemblies, where bolt loosening poses risks of structural instability and safety issues, potentially causing injuries and financial losses. Monitoring the loosening of bolts can mitigate accident risks, enhance safety, and prevent disasters. Consequently, understanding and identifying bolt connection integrity is a critical aspect of structural research. This study introduces a quantitative approach for detecting bolt loosening through controlled small-ball impacts. By adjusting the bolt torque within a defined range to simulate varying levels of tightness or looseness, a small ball is released from a consistent height to strike the bolt. PZT sensors, mounted on the back of the flange, capture the impact signals, with multiple measurements taken across bolts. Experimental and simulation outcomes show that, under specific conditions, the vibration energy captured increases with higher bolt torque. This method of small-ball impact combined with signal analysis effectively and accurately identifies bolt loosening. The approach provides straightforward data processing, making it well-suited for complex structures with low energy requirements. It is compatible with single or multiple sensors, cost-efficient, fast, and accessible to operators with minimal experience, enabling rapid and extensive detection within confined spaces. This technique, therefore, holds substantial research potential.