Estimation of bolt tension using transverse natural frequencies of the shank and protruding end

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. Monitoring the tension of bolted connections can help prevent failures and identify damage at an early stage. Vibration-based techniques have shown promising results for evaluating the tension present in a bolted connection. However, previous studies have neglected the effect of the protruding end, which can significantly affect the dynamic response of the bolted connection. In this study, a novel extended model based on an Euler-Bernoulli beam is proposed that accurately captures the effects of the protruding end on the estimation of the transverse natural frequency of the bolt. The proposed technique incorporating the transversal natural frequencies associated with the protruding end of the bolted connection provides a more representative frequency response of the bolted connection. The results show that there is a significant shift in the natural frequencies at higher modes which are associated with the protruding end. The findings have important implications for the monitoring of bolted connections and provide a basis for more accurate and reliable health and performance assessments. Further research could focus on the validation of the proposed model using experimental data and its application in practical settings.