High temperature fatigue of carbon/polyimide 8-harness satin woven composites. Part I: Digital Image Correlation and Micro-Computed Tomography damage characterization

This paper focuses on the experimental high temperature fatigue of Carbon/polyimide 8-harness satin woven composite materials. Traction-traction (R = 0.1) fatigue tests at 250 °C are carried out on Carbon/polyimide [45]6 8-harness satin woven composites under three different environments (air, 2 bar N2, 2 bar O2). Part I is specifically devoted to image based damage characterization by employment of Digital Image Correlation (DIC) and Micro-Computed Tomography (µ-CT) techniques. For the used samples, intra tow matrix cracks along fibres on the external plies are the first damage form at the ply-scale. Damage evolution on the sample surface can be followed during the test (in situ) by using 2D DIC. Moreover, fatigue tests are periodically interrupted to perform µ-CT scans to characterize and quantify the damage in the volume of the samples. The obtained results prove that the damage assessment methods presented in this work are suitable for environmentally-assisted fatigue tests on composite materials.