Numerical modeling of acoustic emission in laminated tensile test specimens

Acoustic emission from transverse matrix cracks and fiber fracture in typic al laminated tensile test specimens is modeled. The acoustic sources are de scribed as time dependent displacement discontinuities which subsequently a re translated to volume forces. The transient waves are computed using a fi nite element model of the specimen's cross-section. The finite element mode ling leads to a system of differential equations in the axial coordinate an d time. The differential equations are solved using Fourier transforms and eigenmode superposition followed by inversion of the transforms through res idue calculus and FFT. Computed time histories for matrix cracking and fibe r fracture are presented. The highest frequency content in these signals co rresponds typically to 300 kHz. A method to measure the average matrix crac k propagation velocity is suggested. (C) 2001 Elsevier Science Ltd. All rig hts reserved.