COMPARISON OF SINGLE- AND MULTILAYER MATERIALS USED AS DAMPENING ELEMENTS IN KNEE-PROTECTORS

Abstract

The purpose of this study was to identify characteristics of protectors and materials used to assemble protectors, which can be used to create a ranking and proof that a protector has the effects wanted. Single layer neoprene of increasing material strength (n=7) was compared to prototype multilayer materials (n=18) and different commercially available knee protectors (n=18). The test object was attached to a realistic knee dummy, and a fall to the floor was recorded, both kinematically and kinetically. Maximum acceleration and pressure on a single sensor was calculated at the time of the impact, as well as the height of the first rebounce after impact. For single layer materials, results showed a linear correlation of material strength and all three measured parameters. While max. acceleration and pressure both decreased with growing material strength, bounce height increased. This behaviour cannot be observed in multilayer systems. For our test materials as well as fully assembled protectors, pressure values were almost identical, while bounce height varied in a wide range. Different protectors showed great difference in their effectiveness to reduce maximum acceleration.