A study on internal bond strength detection model based on vibration mechanics

This study proposed a linear model between internal bond strength and compressive elastic modulus based on Griffith’s fracture theory. The local compressive elastic modulus was determined by non-destructively detecting the inherent frequency of material vibration using a method based on rod longitudinal vibration theory. In the experiment, the inherent vibration frequencies of 10 types of medium-density fiberboard (MDF) were measured through excitation and vibration of piezoelectric ceramics based on longitudinal wave vibration theory. Then, the compressive elastic modulus of each board was calculated. The calculated compressive elastic modulus of MDF and the measured internal bond strength values were fitted into a linear regression model. A high linear correlation between them (r² = 0.972) was found, having a mean square error of \(2.6\times {10}^{-5}\). In addition, the average error between the model prediction value and the measured value was 0.014 MPa, having an average relative error of 1.49%. The maximum error was 0.044 MPa with a maximum relative error of 5.06%, indicating that the developed model was highly consistent with reality and had very small deviations. The results indicated that this proposed method can be used to accurately estimate the internal bond strength by non-destructively detecting the compressive elastic modulus of MDF.