Understanding the damage mechanisms in 3D layer-to-layer woven composites from thermal and acoustic measurements

Abstract

This article deals with an interlock woven composite and aims at providing a better understanding of the dissipative mechanisms activated under cyclic loadings and describing the damage scenario characteristic of heat build-up experiments. Since the ultimate objective of heat build-up experiment analyses is usually fatigue life predictions that are based on constitutive modelling, the correct interpretation of experimental results is essential. Three different loading protocols are proposed. The instrumentation of these experiments includes infrared thermometry and acoustic emission monitoring. The results show that the coupling of these two techniques provides useful information in order to identify the most important dissipation sources: viscoelasticity, damage and friction. Furthermore, by analysing different loading sequences, it is possible to elaborate the dissipation evolution scenario as well as the damage evolution scenario occurring during heat build-up experiments.

Estimating fatigue life of carbon/epoxy composites: A rapid method coupling thermo‐mechanical analysis and residual strength

“…As the specimen moves while the camera is fixed, it is necessary to transpose each pixel in a reference configuration. This has been done using the same approach used by Navrátil et al, 22 which has been implemented in an in‐house software called Celenos 23 . The evolution of the temperature as a function of time is determined at each pixel ( ).…”

“…The heat build-up protocol consists of subjecting the specimen to a sequence of cyclic loading steps defined by a fixed stress ratio and an increasing peak stress value (see Figure 2). This type of protocol has been applied to various composite materials (short fiber composite with thermoplastic matrix, 20,21 woven composite with carbon fibers and epoxy matrix 22 ), and its aim is to determine the relationship between the cyclic energy dissipated and the applied stress.…”