Acoustic Emission from a Porous Non-Woven Fiberglass Material

Abstract

Acoustic emission (AE) signals are studied for a porous non-woven glass fiber material subjected to both static and cyclic compression. An experimental set-up for the measurement of acoustic signals emitted from the porous solid during mechanical loading is described, and the interpretation of AE signal data is established in the context of scaling laws originally developed for the description of earthquakes. The analysis of micro-CT images before and after loading quantifies that fiber fracture is a predominantly associated with fiber fracture. Several prior studies have established the use of the Gutenberg-Richter and Omori scaling laws for the analysis of AE signals under static loading, but it is unknown if and how such approaches can be extended to cyclic loading. First, static fatigue experiments establish a baseline response of the porous glass fiber material. It is demonstrated that the Gutenberg-Richter and Omori scaling laws can be used to describe AE for the present material. Subsequently, it is shown that the Gutenberg-Richter law still holds under cyclic compression loading. However, the Omori law needs to be replaced. A new scaling law is proposed here which relates the density change in compression to the AE signal. Finally, a relationship between the AE signal statistics and the mechanical damage rate is established for the material at hand.