Hill-type muscle model for analysis of mechanical effect of muscle tension on the human body response in a car collision using an explicit finite element code

A string of series-connected Hill-type bars is proposed for modeling the effect of muscle tension on human body kinematics in a car collision. The preliminary results indicated that such strings exhibit oscillations and instabilities when subjected to a large and transient stretch. A new algorithm for calculation of the force-velocity of the deformation relationship and the concept of the Hill-type multi-bar muscle element are introduced as countermeasures against these instabilities. In the Hill-type multi-bar muscle element, muscle force is computed from the sum of the deformations and the velocities of deformation of all the series-connected bars applied to model a given muscle. When the Hill-type multi-bar muscle element was applied to model experiments on fast stretching of an activated muscle, the calculated force well corresponded with the results published in the literature. Moreover, the current approach to muscle modeling yielded results consistent with the literature data on volunteers subjected to transient acceleration when it was utilized in simulations of the effect of muscle tension on the head-neck kinematics in a frontal car collision.