| Multilayer bonding structure has been widely used in the aerospace,machinery manufacturing and other related fields due to its high specific strength,high specific modulus and excellent vibration damping performance.From the storage and use of multilayer bonding structure components at home and abroad,nearly 1/3 of the accidents are caused by the debonding of multilayer bonding interface.It can be said that the bonding structure interface is one of the weakest links in the reliability of multilayer structure.In order to improve the ultrasonic testing accuracy of bonding quality in multilayer structure,the following work is mainly done in this paper:Firstly,the propagation characteristics of ultrasonic in multilayer bonding structure are studied based on the wave equation and spring model.The mathematical model of ultrasonic in multilayer bonding structure is established.The changes of bonding interface quality and ultrasonic reflection / transmission characteristics in the multilayer bonding structure are analyzed.Then,the propagation characteristics of ultrasonic in multi-layer bonding structure are simulated and analyzed by COMSOL finite element simulation software.The finite element simulation models of ultrasonic in single-layer plate,double-layer and three-layer bonding structure are established.The relationship between different incident frequencies and ultrasonic attenuation characteristics of ultrasonic in single-layer plate is studied.The effects of different bonding quality on ultrasonic propagation characteristics in doublelayer bonding structure are analyzed.Under the condition of intact bonding,the reflection characteristics of ultrasonic with different incident frequencies and thickness in three-layer bonding structure are simulated.Finally,the ultrasonic reflection/transmission experiments were performed through an ultrasonic detection device.The experimental results show that,when the ultrasonic incident vertically to the single plate,the ultrasonic attenuation increases with the incident frequency increasing.As the increase of pressure,the transmission coefficient increases for the double-layer bonding structure.However,when the pressure exceeds 15 MPa,the transmission coefficient approaches constant.As the medium thickness of the second layer medium increases gradually,the ultrasonic attenuation coefficient in the three-layer bond structure increases gradually.The above experimental results are in good agreement with the finite element simulation results and the numerical simulation results. |
PDF Full Text Request