COMSOL modelling of the acoustoelastic effect

Many structural components are subjected to either constant or temporal mechanical loads, such as a suspension bridge bolts and rail tracks. Methods are required to accurately and efficiently measure the stresses experienced by these components to ensure they can continue to operate in an effective and safe manner. Acoustic techniques can be used to monitor the stress in a solid material via the acoustoelastic effect. This is the stress dependence of the acoustic velocity in an elastic media. This work develops a multiphysics computational model to study the acoustoelastic effect in a three point bending system. A simple linear relationship was utilised to represent the stress effect on the acoustic velocity. The simulation results were compared with experimental results and the same general trend was observed. An increase in applied load resulted in a greater difference between the time of flight of two transducers at the top and bottom of a component and perpendicular to the applied load. However, there were quantitative differences between the model and the experiment. The model was used to investigate different ultrasound transducer location and operating frequency, highlighting the benefit of modelling tools for the design of acoustic equipment.