A Study into the Effects of Temperature on the Performance of Footwear Foams under Quasi-static Compression Loading and Their Hyperfoam Characterization

The human foot is a multifunctional system that serves as the primary physical interaction between the body and the environment during gait. Footwear foam components maintain efficient foot function which is essential for daily living and provide cushioning by acting as a protective layer between the foot and the ground that attenuates the shock of impact. Footwear foam materials have high temperature dependency mechanical characteristics. The lower the temperature, the less elastic the material becomes. Consequently, it would seem reasonable to expect different mechanical and cushioning characteristics for the same shoe under different temperature conditions. The insole and midsole are two of essential footwear components which play important roles in lowering foot stresses, and also in the correction of any biomechanical irregularities.

The current study investigates effect of temperature on the mechanical and shock absorption behavior of four different types of foams, which are commonly used as insole and midsole, under quasi-static compression loading. To fulfill the objective of this study, a testing method is introduced to subject the footwear foams to quasi-static compressive loading at varying temperatures ranging from 10

o

C to 40

o

C. The stress-strain curves for the foams were produced in each case. Then the non-linear hyperfoam material coefficients using Ogden energy relationship were obtained for each case. The shock absorption efficiency for the foams was computed using trapezium numerical integration method from the individual data and their variations versus temperature were produced.