pointed out the hysteresis damping in the L-N force model is effective only for high coefficients of restitution .
The damping force is related to relative penetration velocity and damping coefficient D, which was widely expressed as a product of a hysteresis damping factor and an exponential item of penetration.
(1998a) assumed that the secondary shear modulus decreases and the hysteresis damping
ratio increases with shear displacements, on the basis of Ishibashi and Zhang (1993).
The calculated [beta] was then converted into the hysteresis damping curve.
According to the theory of free vibration, the vibration isolation of materials can be evaluated from the damping constant and the hysteresis damping characteristics .