An experimental study on quasi-static indentation, low-velocity impact and damage behaviors of laminated composites at high temperatures

Nowadays, fiber reinforced laminated composites are widely used in many applications due to their high strength/weight ratio. However, these materials are very sensitive to transverse loading. The low-velocity impact test has been widely used by researchers to simulate the transverse loading. However, the low-velocity impact tests are highly toilsome, and this test requires expensive hardware and software systems. To reduce the experimental costs of the low-velocity impact test, it will be more attractive, much simpler, cheaper and more widely available to achieve impact behavior using quasi-static tests. Thus, to compare both tests, in this work the absorbed energy and force-deflection curves obtained by low-velocity impact and quasi-static indentation loading in two different fiber reinforced epoxy composites have been investigated. The Carbon-Kevlar hybrid fabrics and S2 glass fabrics were used as reinforcements. For low-velocity impact tests, a range of energies was used between 20 and 80 J. For quasi-static indentation test, the crosshead speeds were increased gradually from 1 mm/min to 60 mm/min. In addition, tests at 23°C, 40°C, 60°C and 80°C were made to examine the effect of temperature on these tests. As a result of the quasi-static tests performed, the amount of energy required to perforate the samples at a certain test speed is at the same level as the low-velocity impact test. Thus, the required energy amount for the perforation of the materials can be found by performing a quasi-static test at an appropriate speed, rather than the low-velocity impact test.