An experimental criterion to detect onset of delamination in real time

Abstract

This study about the detection of delamination initiation is integrated into a wider project on the definition of a criterion of delamination on composite materials. It must therefore provide experimental data on the behavior of material to allow the formulation of a criterion of edge delamination as accurate as possible. Reliable experimental methods were used to identify the intrinsic parameters of the studied material. One of the most important procedures of this study consists in determining the onset of delamination in real time in order to determine stress level of delamination. Acoustic emission was used for detection of real-time damage initiation, using a location algorithm and specific pattern recognition. After correlation between experimental results and data processing, an acoustic emission signature of a delamination initiation was defined. Almost all experiments can be stopped before failure, in order to characterize damage. Extensive experimental work enabled us to verify the validity, the accuracy and the reliability of real-time delamination acoustic emission criterion.

Two-Dimensional Finite Element Method for Modeling Edge Effects in Cross-Ply Laminates

“…Several authors have investigated the free-edge effect in symmetrically laminated composite plates under uniform one-dimensional stretch. They have used different approaches in their analysis; some used experimental procedures [5][6][7][8][9] and others used analytical analysis, in order to define the stress distribution. Some have succeeded in establishing approximate analytical solutions using the perturbation technique [10], and some have used numerical procedures such as the finite difference method [11][12][13] and the FE [1,2,[14][15][16][17][18][19][20][21][22][23] method.…”

A stress-relaxation approach to determine onset of delamination in angle ply laminates

“…As a result, use of this type of specimens for characterization of delamination resistance requires either idealization of stress state to extract the delamination criteria, 6,7 or delicate instrumentation to obtain ancillary signals to identify the occurrence of delamination. 8,9 Both approaches are limited to the use of small coupon specimens for the testing, and thus not suitable for large FRP structures of various geometry and dimensions.…”

Cluster analysis of acoustic emission signals and tensile properties of carbon/glass fiber–reinforced hybrid composites

“…As an efficient non-contact optical testing technique, digital image correlation (DIC) method has been developed to obtain the full-field extension and strain information of the composites. [22][23][24] Therefore, a complementary technique that combined AE and DIC method is beneficial for understanding the extension and damage evolution of the composites under the applied loading. Andrew et al 25 summarized the amplitude distribution about different damages in the literature and demonstrated the practicality of integrating AE and DIC in comparing the effects of different types of fiber reinforcements on residual compression properties of repaired glass/epoxy composite laminates.…”