NON-DESTRUCTIVE ANALYSIS IN COMPOSITES PLATES SUBMITTED TO LOW VELOCITY IMPACT

摘要

In this work different techniques of non-destructive testing have been used to analyse laminated composites containing defects caused by low velocity impact. It is well known that laminated composite plates are easily damaged by impacts. Two kind of composite laminated plates were fabricated (carbon-epoxy) with the following stacking sequence of plies: [0,90,0,90]_(2s) and [0,90]_8. Low velocity impact test was conducted using an instrumented drop-weight test rig. The plates were impact with 1.5 J, 2 J, 2.5 J and 3 J of energy. Impact velocities regulated by selected drop heights varied between 0.9 m/s and 1.2 m/s. The impactor has to 20 mm in diameter and is captured after rebound to prevent repeated impact. An ultrasonic technique, C-SCAN, was used to analyse the damage in the plates in order to predict the area and location of the damages. Another two non-destructive techniques, based in laser interferometry, ESPI (Electronic Speckle Pattern Interferometry) and SHEAROGRAPHY, were also used to the same goal. This study has permitted to analyse the influence of the stacking sequence of plies and the impact energies in the evolution of defects.