Accession Number : AD0679651

Title :   DYNAMIC OPTIMIZATION OF A VISCOELASTIC STRUCTURE: THE SEATBELT.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF THE AEROSPACE AND MECHANICAL ENGINEERING SCIENCES

Personal Author(s) : Nachbar,W. ; Schipmolder,J. B.

Report Date : NOV 1968

Pagination or Media Count : 45

Abstract : Optimization of the parameters of elementary linear viscoelastic models is considered for the design of a lap seatbelt in automobiles. The vehicle is assumed to stop abruptly on impact. The parameters are optimized to allow the speed of the vehicle before impact to have the largest permissible value consistent with constraints imposed for the safety of the user of the belt. The constraints chosen here are: (1) the maximum displacement of the body after impact is equal to or less than a prescribed critical displacement; (2) the forward speed of the body at the critical displacement does not exceed a prescribed maximum value; (3) the force exerted by the belt on the body during the motion following impact does not exceed a prescribed maximum value. It is found that the optimized Kelvin-Voigt viscoelastic model is nearly 40% more effective than the purely elastic material. It is nearly as effective as constant deceleration. An additional and advantageous property is proposed, moreover, for belts of viscoelastic materials. This is that the material should have a relatively low spring rate at relatively small strain rates. The optimized belts for the elementary viscoelastic models are shown to be quite stiff at low strain rates, however. (Author)

Descriptors :   (*VISCOELASTICITY, SAFETY BELTS), (*SAFETY BELTS, OPTIMIZATION), MATHEMATICAL MODELS, IMPACT SHOCK, MASS ENERGY RELATION, PASSENGER VEHICLES, MOMENTUM, STRESSES, INTEGRAL TRANSFORMS, STATISTICAL ANALYSIS

Subject Categories : Safety Engineering
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE