Numerical modeling of acoustic emission in laminated tensile test specimens

Acoustic emission from transverse matrix cracks and fiber fracture in typical laminated tensile test specimens is modeled. The acoustic sources are described as time dependent displacement discontinuities which subsequently are translated to volume forces. The transient waves are computed using a finite element model of the specimen's cross-section. The finite element modeling leads to a system of differential equations in the axial coordinate and time. The differential equations are solved using Fourier transforms and eigenmode superposition followed by inversion of the transforms through residue calculus and FFT. Computed time histories for matrix cracking and fiber fracture are presented. The highest frequency content in these signals corresponds typically to 300 kHz. A method to measure the average matrix crack propagation velocity is suggested. (C) 2001 Elsevier Science Ltd. All rights reserved.