A three-part study was conducted to further define comfort requirements for seat belt systems with respect to shoulder belt fit, shoulder belt contact pressure, and 3-point restraint system pullout forces. Objective of the belt-fit portion of the study was to determine how much an originally-proposed shoulder belt crossing specification could be modified (to make it less restrictive on the vehicle designer) if a somewhat smaller segment of the user population was accepted as the criterion for design. As a result, a new compliance envelope was developed and is herein proposed. The objective of the shoulder belt pressure portion of the study was to verify (or modify) the upper pressure criterion limit derived in the original study, using a larger sample of test subjects. The results essentially confirmed those of the original study. Purpose of the shoulder belt pullout force portion of the study was to develop a criterion value for inclusion in the new comfort rulings if this appeared desirable. The value found proved to be essentially the same as one developed in an earlier study of active belt system comfort, "Sources and Remedies For Restraint System Discomfort and Inconveniences", DOT-HS-230-3-674, Final Report dated October 1974).
Abstract