The caustic approach to Rayleigh-waves and their interaction with surface irregularities

Abstract

During the past 25 years the method of caustics has matured to the stage where it offers a highly potential tool for qualitative as well as quantitative solutions of engineering problems in many fields. In conjunction with high-speed recording techniques such as high-speed cinematography, the method of caustics serves as a means for visualizing the highly complex interaction processes that occur when elastic stress waves interact with material inhomogeneities or discontinuities such as inclusions, surface or embedded cracks and contacting surfaces during impact. In this contribution, the method of caustics is applied to a number of dynamic problems all of which are associated with the propagation and interaction of Rayleigh-waves: • the pseudo-caustic of a Rayleigh-wave; • Rayleigh-wave generation during dynamic impact of two elastic bodies; • Rayleigh-wave interaction with a shallow embedded crack; • Rayleigh-wave interaction with various configurations of sets of surface cracks. Sequences of high-speed cinematographic recordings of the evolution of a dynamic process provide the raw data for data and image analysis for the determination of stress intensity factors, contact forces, load-time traces or other quantities of physical interest. The paper also discusses some of the advantages and disadvantages of the method of caustics over other methods currently used in photomechanics such as dynamic photoelasticity. Data reduction and analysis aspects will also be highlighted.