The objective of this research was to develop, experimentally validate, and exercise head/neck injury models designed to sim ulate head and com pression-related cervical spine injuries resulting from direct head impacts. The ultimate goal of this endeavor was to provide a rational too l for the optimum design of safety headgear. The achievement of this objective and ultimate goal involved the following work:​

1. An extensive literature search
2. Parametric studies of those linear and quasi-linear viscoelastic models which were considered for depicting actual neck and helmet responses. These studies investigated:​
   1. the effects of frequency variations on the complex modulus and the constant velocity load~deflection responses of the linear elastic, viscous, and two- and three-param eter viscoelastic models
   2. the effects of frequency variations on the reduced complex modulus of the quasi-linear viscoelasticmodel
   3. the effects of frequency, displacement amplitude, and displacement rate variations on the constant velocity load-deflection responses of the quasi-linear viscoelastic model
   4. the effect of varying the reduced relaxation function constants on the relaxation and constant velocity load-deflection responses of the quasi-linear viscoelasticmodel
3. Measurement of the time-dependent responses of the cervical spine and a variety of helmet types to dynamic compression loading
4. Comparison of measured neck and helmet responses to those predicted by the Calspan numerical algorithm, the linear elastic, viscous, viscoelastic, and quasi-linear viscoelasticmodels
5. Development of a simple one-dimensional head/neck injury model
6. Modification of the Calspan three-dim ensional Crash Victim Simulation program to incorporate a more realistic neck and helmet
7. Experimental validation of the head/neck injury models
8. Param etric one-dimensional head/neck injury model studies varying helmet and contact surface characteristics, effective torso mass, and impact velocities in order to estimate head and neck injury potential, evaluate the potential dangers of the aforementioned rebound phenomena and phasing problems re ce ntly associated with head/neck trauma, and ascertain optimum helmet characteristics in various impact situations.
9. The models developed as a result of this work showed good predictive potential. The validation studies showed a reasonable match between experimental and predicted results for the drop, pendulum, and dummy tests. However, the model predictions were strongly influenced by the neck and helmet responses. The simpler linear viscoelasticmodels (Kelvin, Maxwell, and standard three-parameter solid) were inadequate representations of these structures. A thorough study of linear and quasi-linear viscoelasticmodels based on relaxation, cyclic, and constant velocity tests was required. Experimental protocols were developed and tests performed to provide the basic data for modeling the human neck and a variety of helmet types.