Biodynamic model of a parachutist.

A three-dimensional, gross-motion, finite-segment model of a parachutist is presented. The model is a modification of the UCIN Crash Victim Simulation Code. It is designed for study and analysis of the effects of opening shock and wind loading on the dynamics of a parachutist. The model consists of 11 rigid bodies linked together to simulate the human figure of a parachutist. Springs and dampers are used to model the joint forces and moments. The parachute forces are modelled by riser forces applied to the torso of the model. The wind loading is modelled as a profile drag force on each body of the model. The governing dynamical equations of motion for the system are coded into a computer program and they are then integrated numerically. Comparison with experimental data on parachutist head acceleration shows good agreement between model and experiment.

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.