COMPARATIVE STUDY OF NON-DESTRUCTIVE DAMAGE EVALUATION METHODOLOGIES FOR CFRP LOW VELOCITY IMPACT DAMAGE

摘要

Damage evaluation for fiber-reinforced polymer composites has been a topic of interest for morernthan 30 years, and for good reason. With damage modes significantly different than monolithicrnalloys, engineers have had to design composite structures to tolerate delamination, fiberbreakage,rnmatrix cracking, and fiber-matrix debonding. Accomplishment of this goal hasrnrequired understanding how and why these damage modes manifest themselves and grow torncritical levels, even when the damage is barely visible from the surface. To this end, many nondestructivernevaluation techniques have been developed, each with their advantages andrndisadvantages to characterize these damage forms. In this study, a series of non-destructivernevaluation techniques are performed and evaluated on a set of damaged carbon fiber reinforcedrnplastic (CFRP) specimens that have been subjected to varying levels of incident kinetic energyrnfrom low velocity impact (LVI). Specifically, 3-D x-ray computed tomography (CT), activernthermography, electrical impedance tomography (EIT), and vibrothermography have beenrnsystematically utilized for evaluation of the specimens. The advantages and disadvantages arernthoroughly explored and reported for each method in order to gain insight into the limitation ofrneach of the damage detection methods and the damage morphology resulting from LVI.