Comprehensive, three-dimensional head-neck model for impact and high-acceleration studies.

A three-dimensional, 54-degree-of-freedom computer model of the head/neck system is presented and discussed. The model consists of nine rigid bodies representing the head and vertebrae together with a series of nonlinear springs and dampers modelling the soft tissue. The soft tissue modelling involves the discs, muscles, and ligaments. The discs are modelled as two-parameter viscoelastic solids; the muscles are also modelled as two-parameter viscoelastic solids, but only able to exert force in tension; and the ligaments are modelled as nonlinear elastic bands exerting force only in tension. Equations of motion are written for this model by using Lagrange's form of d'Alembert's principle, a virtual work type principle. Computer algorithms are written to efficiently compute the numerical coefficients of these equations. The equations are integrated numerically for a number of specific cases where experimental data are available. Results show excellent agreement between the model and the experiments.