Abstract Summary
Bolted connections are crucial components in mechanical systems with the purpose of assembling different components. However, the tension of bolts may decrease due to recursive loading and environmental conditions. Therefore, monitoring the tension of bolted connection can help prevent failures and reduced fatigue life of structures. Vibration-based estimation has shown to be a reliable and attractive method for bolt untightening identification. Previous studies have shown that there is a correlation between the change in tension and the bending mode frequency of the protruding thread part of the bolted connection. The literature has shown it is possible to model bolted connections using Euler-Bernoulli beams to some success. However, the protruding thread part is usually ignored and not accounted for. This calls for a theoretical model that would successfully model a bolted connection including the contributing bending mode frequencies from the protruding thread end of a bolt. This work explores the feasibility of an extended model of the pre-stressed Euler-Bernoulli beam with different boundary conditions to account for the protruding end. A comparison is also made between the calculated natural frequencies of the extended models. This model has many potential applications and can be complemented for physics-based modeling and Vibration-based Structural Health Monitoring (VSHM) to inform data from measurements.
