Effect of velocity on compression and energy absorption sensitivity of coir fiber

Coir fiber, a natural plant fiber material, is known for its excellent shock absorption ability and potential to improve the performance of composite materials. This paper investigates the compression and energy absorption of coir fibers arranged horizontally and vertically at different speeds to determine their velocity sensitivity. A quasi-static compression speed test was conducted on coir fiber blocks using a universal testing machine. Load displacement changes were observed at speeds of 1 mm/Min, 2 mm/Min, 4 mm/Min, and 50 mm/Min, and Dynamic Increase Factor (DIF) was introduced to evaluate speed sensitivity. The microstructure of the fibers was evaluated using a scanning electron microscope (SEM). According to the results, vertical fibers have better energy absorption characteristics than horizontal fibers, resulting in an increased energy absorption effect ranging from 25.7 % to 45.38 %. On the other hand, horizontal fibers exhibit high sensitivity under low-speed compression, with a significant increase in energy-absorbing effect as speed increases. However, this sensitivity is significantly reduced when compression occurs at high speed. The energy-absorbing effect of horizontal fibers increases from 6.96 % to 33.58 %. Vertically placed fibers, on the other hand, exhibit low sensitivity under low-speed compression but greater sensitivity as speed increases. As speed increases, the energy absorption effect becomes more apparent, resulting in an increase in the energy absorption of vertical fibers from 12.88 % to 17.99 %. This paper presents a methodology for evaluating the compression properties of coir fibers, which can be used as a reference for studying the impact resistance of natural fibers.