Paper number 501

ACOUSTIC EMISSION IN LAMINATED BEAMS DUE TO FIBER FRACTURES

Mats Åberg and Peter Gudmundson

Department of Solid Mechanics, Royal Institute of Technology, KTH
100 44 Stockholm, Sweden

Summary

A model for excitation and propagation of waves resulting from fiber fracture in laminated beams is presented. The fiber fracture was described as a time dependent displace-ment discontinuity and wave propagation was modeled by a higher order beam theory. The equations of motion defined by the beam model were then formally solved by employing integral transforms. Asymptotically valid solutions were subsequently found using residue calcu-lus and the stationary phase method. In particular displacement velocities at different points in a [90/0 2 /90] beam with a width to thickness ratio of 10 is presented. Based on the results it is concluded that fiber fracture excites several modes of vibration in the specimen, also a criterion for validity range, in frequency, of beam models is suggested.

Keywords

wave propagation, fiber fracture, acoustic emission, laminated beams.