Abstract
The objective of this study was to investigate effects on the rebound characteristics for running-specific prostheses of the dynamic behavior of the blade which was obtained using an impact testing apparatus developed in our previous study. The impact load perpendicular to the ground line was measured by a piezoelectric type load cell attached on the impactor, and the load parallel to the ground line was calculated by applying the response of the strain gauge affixed on the blade to the beam theory. A motion of the impactor and blade was taken by two synchronized high-speed video cameras. The deformation of the blade was obtained from the positional coordinate of the blade by tracking markers attached on the surface using the digital image correlation method. The velocity ratio was defined by dividing the rebound velocity by the incidence velocity of the impactor which was calculated using the high-speed images. The deformation behavior for the straight part of the blade has the tendency to be classified into two main types: the deformation in both directions of the planter and dorsal flexion and the deformation in the direction of the dorsal flexion during impact. When the blade is deformed in the direction of the plantar flexion, the velocity ratio tends to correlate with the energy absorption rate. This suggests that it is effective to observe the dynamic behavior of the blade from the directions of perpendicular and parallel to the ground line in order to evaluate the rebound characteristics of the blade.
