Acoustic Emission Characterization of a Glass-Matrix Composite

Abstract

Acoustic emission (AE) analyses have been performed on a high compliance, high failure strain randomly oriented carbon reinforced glass matrix composite. The composite exhibits a unique nonlinear stress-strain behavior with high failure strain during both uniaxial tensile and flexural testing. The extensive matrix cracking of this material during loading provides an excellent opportunity to study the fracture mechanism..In this study, two types of composites using similar constituents but different processing procedures resulting in different mechanical behavior, were studied. One composite showed a very pronounced non-linear stress-strain behavior during tensile testing. The curve consists of an initial linear portion, followed by a deviation from linearity and a large amount of longitudinal strain is produced with very little increase in the stress. The second composite did not show similar behavior with the slope of the stress-strain decreases continuously. The apparent different mechanical behavior of the two composites provided an excellent opportunity to use the AE characterization to distinguish two different fracture processes.This study concentrates on monitoring damage initiation and damage progression during tensile and flexural testing using acoustic emission sensors. Detailed examination of AE characterization, including cumulative AE events, event occurrence and its rate as a function of load, and amplitude distribution histograms of events at different load levels, reveals a different emission activities during tensile and flexural loading conditions, indicating different fracture patterns. The examination of amplitude distributions at various loads revealed that the method is sensitive enough to distinguish various fracture processes.

Non-destructive inspection of initial defects of PA6.6-GF50/aluminum self-piercing riveted joints and damage monitoring under mechanical static loading

“…Overall, it is also observed for both samples that most of the acoustic events are recorded after F MAX that is to say during the slow decrease of the force and its final quicker drop. Moreover, the average amplitudes of the acoustic peaks are found around 60 dB, which typically corresponds to matrix cracking and delamination (Chen et al, 1992); events of higher energy (from 80 to 100 dB), which should be the signatures of fiber breaking damage, are also detected but in a much lower proportion.…”

An experimental criterion to detect onset of delamination in real time

“…This technique has already been used by many authors. 25–31 To differentiate various damage mechanisms, some authors tried to relate each damage mechanism to one range of frequencies 30,31 or amplitudes of AE signals. 26–28 Nevertheless, the correspondence between frequency range and damage mechanisms is not the same for all the authors and seems to be dependent on sample size, type of sensor (Micro 30 s piezoelectric sensors for this study), wave propagation and other parameters.…”

Acoustic emission based deep learning technique to predict adhesive bond strength of laser processed CFRP composites

“…Other researchers classified few amplitude ranges in between and associated it with corresponding failure mechanism [19][20][21][22]. Gong et al [23] stated five failure types and distinguished it separately. Many studies were published using the combination of AE parameters with soft computing technique.…”