Acoustoelastic determination of local surface stresses in polymethylmethacrylate

Acoustoelastic determination of applied and residual stresses plays an important role as a nondestructive tool in current engineering. Rayleigh surface wave, as a special form of ultrasonic waves, makes it possible to probe initial stress at various depths from the surface by changing its frequencies because of its propagation characteristic. In this paper, the propagation of Rayleigh surface wave in isotropic elastic material subjected to a homogeneous stress is studied theoretically in view of elastic wave and finite deformation. Specific surface ultrasonic transducers are constructed to take the measurement of surface stresses and surface cracks in components with very low ultrasonic velocity such as polymethylmethacrylate. The linear dependence of velocity change of Rayleigh ultrasonic wave on the applied static stress is used in determination of local surface stresses in the specimen made of polymethylmethacrylate. Both the acoustoelastic and gauge experiments are synchronously carried out for a specimen with a central hole under uniaxial tensile stress. The results and the experimental errors are shown and analyzed.