Kishore, M. Suresh Kumar
June 11, 2013
Two flat glass/epoxy test pieces were adhesively bonded to varying degree along the common width face starting from either ends to yield a set of samples i.e., sparsely bonded, moderately bonded and fully bonded ones. The samples thus prepared were subjected to low velocity impacts. Impact data show total energy and peak load registering low values for the sparsely bonded case and the value increasing as the bond area increases. Further, the stiffness parameter also showed a gradual increasing value with an enhancement in the level of interfacially introduced bond area. However, as regards the deflection, a discernible trend reversal was noticed in that it was high for the sparsely bonded case and low for fully bonded ones. Fractographic analysis showed that fully bonded ones displayed the through thickness crack propagation, tensile outward fiber failure and protrusion feature on one face while the sparsely bonded ones displayed debonding of the end region, a split and a wide opening of one of the two debonded end region with hardly any tensile outward fiber fracture features. Moderately bonded, on the other hand, showed hybrid characteristics encompassing both the outward protrusions of fibers on the tension side as well as the debonding, a feature also corroborated by the scanning electron microscopic (SEM) observations. These fracture features were analyzed and an effort made to correlate them with the impact test data.