On the lamb solution and Rayleigh-wave-induced cracking

This paper examines the extension of surface microcracks induced by a surface or Rayleigh wave (R-wave). This problem is examined both theoretically and experimentally. The theoretical approach involves a full-field reappraisal of the Lamb solution for a surface wave propagating in a homogeneous, isotropic, elastic, two-dimensional material for the cases of plane strain and plane stress. Using the Griffith-Irwin energy-release-rate fracture criterion for cracks under combined Mode I and Mode II loading, a prediction is made of the path and final length of the surface microcrack extension produced by the R-wave. Predictions of the crack-extension direction are also obtained using the maximum normal-stress fracture criterion. The experimental approach uses dynamic photoelasticity to observe the isochromatic patterns associated with an R-wave propagating along the narrow edge of a transparent birefringent plate, examining in detail the process of crack extension. When the theoretically and experimentally obtained results are compared, reasonable agreement is obtained.