ULTRASONIC-DETECTION OF DAMAGE IN CFRPS

A good knowledge on damage processes in CFRPs can be given by developi ng non-destructive testing. In order to improve ultrasonic capabilitie s to detect matrix cracking development, a water tank has been mounted directly on a servo-controlled machine and an automatic scanning by p oints has been investigated. More accurate testing procedures have bee n implemented including mechanical improvements, amplitude measurement accuracy, resetting points under loading, comparative evaluation of t he attenuation between undamaged and damaged state. A comparison betwe en X-ray and ultrasonic results has been made. Another aim was to cont rol hidden damage due to impact and especially to measure the size and shape of delaminations at each interply location using an improved pu lse echo method. Hence, conventional equipment has been modified in or der to explore the material by thickness segments. A new procedure has been added to a classical equipment providing in a single scan multip le C-scan images of a coupon with a very limited amount of data. The m ain purpose of this paper is to describe the methods used and to discu ss the original procedures that have been performed. The new capabilit ies of an improved ultrasonic set-up are going to be examined mainly i n relation to crack-density measurement, matrix cracking development u nder tension and ply by ply delamination sizing and location. With the se features, an ultrasonic set-up can find its application in many aer onautical fields: improving composites, moisture influence on damage, detecting of damage resulting from impact, structures lifetime.