Acoustoelastic effect

Summary

The acoustoelastic effect is the change of the speeds of elastic waves in a solid when the solid is under static stress. Linear elasticity predicts speeds that do not depend on stress. So the effect comes from the nonlinear part of the elastic response, through the third-order elastic constants. For moderate stress the change of speed is proportional to the stress. Measuring it with ultrasound gives a non-destructive way to estimate residual and applied stresses in structures.