On the non-linear dynamic response of the rhesus to impact

A non-linear discrete parameter mathematical model describing the dynamic behavior of a primate (Macaca mulatta) has been developed and programmed for solution on the IBM model 360/91 computer using the Continuous Systems Modeling Program (CSMP). The primate is described by a system of discrete anatomical segments connected by translational and rotational springs representing the inter-segment stiffnesses. For example, the neck is represented by three discrete masses, one translational and four rotational springs. The masses, mass moments of inertia, centers of gravity and the neck axial stiffness, were obtained experimentally. The predicted dynamic behavior of the rhesus monkey to blunt head inpact compares favorably with the observations taken from high-speed films of a cerebral concussion experiment. A study of the effect of the point of application and angle of inclination of the forcing function was conducted. The results show that the important response parameters display the expected sensitivity to the location of the blow but are particularly sensitive to its angle of inclination with respect to the plane containing the foramen magnum.