SEDL / STP / STP1077-EB / STP19112S

Detection of Impact Damage in Composite Bi-Axial Test Specimens by Use of Thermally-Activated Acoustic Emission

Whittaker, JW
Oak Ridge Y-12 PlantMartin Marietta Energy Systems, Inc., Oak Ridge, TN

Brosey, WD
Oak Ridge Y-12 PlantMartin Marietta Energy Systems, Inc., Oak Ridge, TN

Pages: 11    Published: Jan 1991

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Abstract

Acoustic emission (AE) produced during thermo-mechanical loading of composite materials is known as thermo-acoustic emission (thermo-AE). When thermally cycled, coupons of various composite materials have been shown to produce quantities of AE which are directly proportional to the damage level. This work demonstrates the applicability of thermo-AE monitoring to an engineering structure.

Impact-damaged bi-axial composite test specimens were thermally cycled and their AE response recorded. An undamaged specimen produced little AE while damaged ones generated widely varying amounts. For damaged specimens, the thermo-AE was found to originate primarily in the damaged regions. Damaged specimens produced AE as a function of increasing and decreasing temperature but the effect was not repeatable. More severely damaged specimens produced copious amounts of AE. It was not possible to determine the source(s) of the emission.