Digital image processing and thermo-mechanical response of neat epoxy and different laminate orientations of fiber reinforced polymer composites for vibration isolation applications

In this study, tensile tests are performed under quasi-static loading on neat epoxy and for different laminate configurations [(0/90), (0/90/30/–60), (0/90/45/–45) and (30/–60/60/–30)] of glass/epoxy, carbon/epoxy and cross ply interply hybrid (glass/carbon/epoxy) composites. A camera-based advanced image processing technique called as digital image correlation is employed to obtain the full-field strain fields and identify the direction of failure of the matrix and composites as a function of fiber orientation angle. Further, the viscoelastic properties (storage modulus, loss modulus and loss factor) are measured over the temperature range from 20 °C–140 °C for five different frequencies (1, 10, 20, 33 and 50 Hz) using the dynamic mechanical analyzer. The glass transition temperature (Tg) is found out from temperatures corresponding to the loss modulus and loss factor peak values. The results revealed that as the temperature increases, the storage and loss moduli decrease attributed to the softening of the material because of free molecular movements. The cross ply laminates of GFRP and CFRP exhibit higher storage and loss moduli at all frequencies due to strong fiber network as compared to the other laminate configurations. The hybrid composites possess higher storage and loss moduli than GFRP and neat epoxy. The neat epoxy has higher loss factor values than composites. As the frequency increases, the Tg shifts to higher values. Loss modulus Tg values are found to be lower than that of loss factor Tg values.