Transformation of Nine-Accelerometer-Package (NAP) Data for Replicating HeadpartKinematics and Dynamic Loading

摘要

This report describes a procedure and associated software package fortransforming time-varying kinematic quantities computed in a rotating-decelerating reference frame, to a fixed coordinate system. Time-varying kinematic quantities are computed, based on accelerometer measurements made with a 3-2-2-2 nine accelerometer package (NAP) located in the headpart of an anthropometric test device, and transformed to fixed coordinates in the form of generalized six-degree-of-freedom velocity time histories at the headpart center of gravity. An algorithm is also included to compensate for cross products angular velocity and centripetal accelerations arising from the non-coplanar geometry of the NAP. Angular and translational velocity components are then applied as velocity boundary conditions, to the center of gravity of finite-element representation of a rigid skull-headpart component of an anatomic brain model in order to replicate the generalized six-degree-of-freedom kinematics, and corresponding inertial loads produced by these kinematics. These efforts are part of a larger program to develop tools and methods aimed at providing an improved head injury criteria for use in automobile crash testing.