Micromechanical modeling of transient waves from matrix cracking and fiberfracture in laminated beams

A micromechanical model for excitation of waves resulting from fiber fractu re and matrix cracking in laminated beams is presented. The source is descr ibed as a time dependent displacement discontinuity and the wave propagatio n in the beam is modeled by a higher-order beam theory. The equations of mo tion defined by the beam model are then formally solved by employing integr al transforms. Asymptotically valid solutions are subsequently found using residue calculus and the stationary phase method. As an example, a [90/0(2) /90] beam with a width to thickness ratio of 10 is considered. The dispersi on curves resulting from the beam theory and three-dimensional finite eleme nt computations are compared and a maximum frequency for applicability of t he beam theory is determined. The time response from fiber fracture and tra nsverse matrix cracking is presented. The applications of the results to th e analysis of acoustic emission experiments are also discussed. (C) 2000 El sevier Science Ltd. All rights reserved.