Damage detection in a bolted lap joint using guided waves

Abstract The paper presents the experimental investigation of guided waves application to the condition assessment of prestressed bolted connections and a concept of new quantitative indicator. The main goal of the research was the analysis of the influence of the contact conditions changes to the characteristics of a propagating disturbance. The experimental tests were carried out for a single bolted lap joint. The excitation and acquisition of elastic waves were performed using piezoelectric plate transducers. The measurements were performed for the gradually increased value of the bolt load, which was controlled by the force washer transducer. The results of tests show the occurrence of relationship between the recorded signals amplitudes or the phase shifts and bolt load values only in initial time period. Therefore, the quantitative analysis of recorded waveforms was performed in the frequency domain based on the power spectral moment theory. Additionally the concept of the modified power spectral moment taking into account the guided wave frequency characteristic has been introduced. The results indicated the possibility of the use of higher order modified power spectral moments for evaluation of the bolted joint condition.