Thermal and ultrasonic analysis of fatigue damaged CFRP samples under traction and bending load

摘要

In this work, damage delamination or plies separation was analyzed and monitored during fatigue tests on two different series of CFRP specimens. The research work includes two cases of work, the first is delamination initiation due to bending loads on cross-section CFRP samples and the second one deals with delamination due to wrinkle defect presence. Preliminary static tests are carried out with aid of digital image correlation technique to evaluate failure static loads and strains field modifications. Fatigue experimental tests were performed with non-destructive thermographic, optical and ultrasonic monitoring. This study includes an analysis of the damage to rupture behavior of the material through the mechanical tensile test and a non-destructive inspection procedure is adopted during HCF load, in order to detect in real time local compliance variations and damage initiation. Thermographic continuous monitoring and occasional ultrasonic analysis are implemented with the purpose to analyze composite anomalies during fatigue life and elaborate a method for the identification of the wrinkle induced failure well before rupture. Thermal and ultrasonic data are processed with MATLAB codes for damage evaluation with compliance data acquired during tests.