Analysis of acoustic surface waveguide for AE monitoring of concrete beams

The analysis of stress waves in an acoustic surface waveguide is presented. Elastic wave motions in a circular rod propagating through a rigid circula r joint bonded on an elastic half-space were studied. The responses of four different harmonic wave motions-longitudinal, torsional, and two flexural- were investigated. Mode conversion, reflection, transmission, and phase cha nge of these wave motions were observed. This analysis helps in understandi ng the signal transmission ability of a surface waveguide system, which is useful in the application of acoustic emission (AE) monitoring on high atte nuation materials such as concrete. Numerical examples are presented to sho w the transmission and reflection coefficients at different frequencies and to examine the effect of mode conversion. The numerical analysis results w ere implemented into the design of an efficient waveguide system. Results f rom tests of concrete beams show that he AE monitoring range was significan tly increased by using the proposed acoustic surface waveguide. The AE moni toring of a 210-cm concrete beam was accomplished by using only two sensors .