Experimental investigation of sandwich panel subjected to transverse point load

Abstract

Low velocity impact tests were conducted on carbon fibre reinforced epoxy sandwich panels of 10 ply laminate with configuration of [+45/-45/0/90/0]s in order to investigate the load bearing capabilities and energy absorption characteristics of the sandwich panels and identify quantifiable trends.

Specimens of 100mm by 100mm with core configuration of 6:20, 6:25, 13:20 and 13:25 were fabricated and subjected to impact energies ranging from 0.85J to 35J. The results were then tabulated and graphs of Load versus Time, Load versus Deflection and Load versus Energy were made in order to analyse the results.

Firstly, it was found that with increasing velocity the specimens were able to absorb more load and that the time to reach the maximum load reduced. Secondly, it was found that the kink which signifies debonding of the adhesive occurred at approximately 0.3kN to 0.7kN and at a displacement of approximately 0.25 to 0.6mm. Thirdly, it was observed that as the amount of impact energy increased, the amount of load the specimen was able to take increased until damage occured. After damage had occurred, the load remained constant despite the increasing impact energy thus indicating that the major load drop is independent of impact energy. Lastly it was also found that when damage occurred, the amount of absorbed energy was a constant between 3.44J and 4.8J thus indicating that by knowing the amount of absorbed energy, it is possible to predict the amount of damage in the specimen thus giving a better understanding of the load bearing and energy absorption capabilities of sandwich panels.