Using piezoelectrically excited transverse vibrations for bolt tension estimation

Recent work suggests using transverse natural frequencies of a bolt as a measure for bolt tension. Until now, hammer impacts have been suggested as the tool for obtaining the desired natural frequencies. In this work, as a continuation, we suggest using piezoelectric excitation instead. A piezoelectric actuator permits control of the input force. A COMSOL model of a beam with a piezoelectric actuator is used to test simple hypotheses for obtaining the best amplitude response in a beam. Experimental testing of the hypothesizes on a real bolt, clamped in a structure, reveals that significant acceleration response amplitude can be obtained without substantial effort, lending confidence in this as a tool for exciting frequencies for bolt tension estimation. A piezoelectric actuator excites higher natural frequencies better compared to hammer impacting results, but it is less effective at low frequency and requires careful mounting. Despite these disadvantages, piezoelectric excitation has application potential, especially for shorter bolts and higher frequencies.