Detecting Damage in Carbon Fibre Composites using Numerical Analysis and Vibration Measurements

IN THIS WORK, CARBON FIBRE REINFORCED POLYMER (CFRP) PLATES HAVE BEEN TESTED UNDER FREE IMPACT VIBRATION TESTS PRISTINE AND DAMAGED CONFIGURATIONS. EACH PLATE INVOLVED ONE CRACK OF SPECIFIC ORIENTATION (HORIZONTAL, VERTICAL, DIAGONAL). THE WERE SUSPENDED AS CANTILEVERS VIBRATED USING AN HAMMER. TWO ACCELEROMETERS MICROPHONE USED TO OBTAIN RESPONSE DATA SIGNALS FROM PLATES, FREQUENCY FUNCTION (FRF) WAS PLOTTED. CFRP ALSO SUBJECTED A TENSILE TEST SCANNING ELECTRON MICROSCOPY (SEM), THEREBY ESTIMATING THEIR MECHANICAL PROPERTIES EVALUATING MICROSTRUCTURES. CURRENT TECHNIQUE FOCUSED ON DETECTED SIGNAL MORE THAN SENSOR ENSURE MEASUREMENT'S ACCURACY. COMPARISONS BETWEEN EXPERIMENTAL FINITE ELEMENT ANALYSIS (FEA) SIMULATION SHOWED THAT RESULTS AGREED. DAMAGE SIGNIFICANTLY AFFECTED COMPOSITES’ DYNAMICPROPERTIES. FRF MEASURES COMPOSITES LOWEST EIGENVALUES FOR EXCITED MODE SHAPES' RESONANT FREQUENCIES. 0/90 LAYUP LAMINATE COMPOSITE EXHIBITED GREATER FLUCTUATIONS FREQUENCIES ACROSS VARIOUS SHAPES DID QUASI-ISOTROPIC LAMINATES. REACHED 2.85% DIFFERENCE COMPARED COMPOSITES.