This research focuses on the effects of operational variables of Free Motion Head-Form machine, as well as, the manufacturing process of vehicle's upper interior trim panels on dummy head impact, based on Federal Motor Vehicle Safety Standard 201 (FMVSS 201), regulated by the National Highway Traffic Safety Administration (NHTSA). The compliance test is conducted following the requirements of NHTSA's Office of Vehicle Safety compliance (laboratory Test Procedure TP201U-1). Design of Experiments (DOE) is utilized to develop a mathematical model of the Head Injury Criterion (HIC) as a function of seven significant variables. These independent variables include five manufacturing process variables and two operational variables: Free Motion Head-Form Approach Angle and dummy Head-Form Drop Calibration. An incomplete block design is utilized in order to significantly reduce the number of experiments.

This research evaluates the response difference between a new dummy head THORNT (Test device for Human Occupant Restrain) and the current dummy head (Hybrid III) that is commonly used in automotive environment. Head Injury Criterion (HIC) is computed. The results describe the response surface of both dummy heads. The data concludes that THORNT dummy head needs further development if it is to be used to replace Hybrid III dummy head in FMVSS 201 compliance procedure. The variation effects of the five manufacturing process variables are evaluated in affecting HIC. A mathematical model is developed to optimize the response as a function of the significant variables.