Fig. 4
a The disc height variation over 600 s of cyclic compression obtained from the LE, HE, and Biphasic models. The disc had a purely sinusoidal height change in the LE and HE models. However, the disc height variation in the Biphasic model had a decaying sinusoidal oscillation with the amplitude of δ as shown in b about an exponential curve with the equation of ∆ =  − 0.3 exp (0.004t) − 0.37. c Representative force-disc height variation in cycles 2, 3, 50, 100. The dissipated energy (highlighted area) increased with the number of load repetitions. ∆Ei is the dissipated energy at cycle i