INFLUENCE OF HEAD MASS ON THE ACCELERATION OF THE HEAD AND NECK COMPLEX IN AUTOMOBILE REAR-END COLLISIONS USING A THREE-DIMENSIONAL FINITE ELEMENT METHOD

This study evaluated the influence of head mass on the acceleration of the head and neck complex in automobile rear-end collisions using a three-dimensional finite element method. The geometry of the finite element model is based on a cervical (C2–7) motion segment of a 20-year-old man that was obtained by computed tomography. Four types of models were prepared by changing the parameters of mass for an examination of the effects of head mass. Simulated loads were applied at the lower end of the C7 vertebra, with the axial direction constrained. Each model was loaded, and the head acceleration and distribution of von Mises stress were analyzed. Stress was observed to concentrate on the C2/3, C5/6 and C6/7 intervertebral discs. With a large head mass, the delay of the initial rise of the acceleration curve was large and the value of acceleration was small. On the contrary, when the head mass was small, the acceleration curve started to rise earlier. The acceleration curve of the model with the head mass of 1.0 kg was the closest to that of the experiments by Severy. Head mass is an important factor which influences the dynamic response of the head in rear-end collisions.