Investigation of Bonding Strength of Medium Density Fiberboard by Using Ultrasonic Testing

Abstract

Medium density fiberboard (MDF) is a widely used wood-based material, where the internal bond strength is a crucial mechanical performance index. Currently, the measurement of internal bond strength is achieved through destructive testing, which has the disadvantages of a complex procedure and a long testing time. This article proposes a model for measuring the dynamic compression modulus of elasticity (DCME) based on elastic dynamics. The model involves attaching a piezoelectric ceramic sheet to each side of the board, one for excitation and the other for response. By measuring the resonance frequency based on the response amplitude change, the DCME can be determined using the proposed model. Results indicated that there is a highly linear correlation between DCME and internal bond strength, with an r-squared value above 0.96. As the DCME increases, the internal bond strength improves, and the internal bond strength can be predicted based on the DCME. The article analyzes the model from the perspectives of acoustic transmission and ultrasonic directional analysis and verifies the correctness of the model through acoustic theory.