Search Results

This paper outlines a method for estimating the probablistic nature of airbag crash sensor response and its effect on occupant position. Probability surfaces of airbag fire times are constructed for the impact velocities from 0 to 40 mph. These probability surfaces are obtained by using both frontal offset deformable barrier and frontal rigid barrier crash data. Another probability surface of displacement is constructed to estimate the occupant displacement time history before airbag deployment. This probability surface is constructed by using the initial occupant seating position data and the vehicle impact velocity and deceleration data. In addition, the probability of airbag firing at a given crash velocity is estimated from NASS-CDS, frontal offset and rigid barrier crash data.

This paper presents an energy relationship between vehicle impact pulses and restraint systems and applies the relationship to formulations of response factors for linear and nonlinear restraints. It also applies the relationship to derive optimal impact pulses that minimize occupant response for linear and nonlinear restraints. The relationship offers a new viewpoint to impact pulse optimization and simplifies the process mathematically. In addition, the effects of different vehicle impact pulses on the occupant responses with nonlinear restraints are studied. Finally, concepts of equivalent pulses and equal intensity pulses are presented for nonlinear restraints.

Due to commercial television almost everyone is familiar ‘automotive inflatable restraint system,’ commonly referred to as airbag. Traditionally these bags were made of polyamide fabrics coated with polychloroprene, which made them essentially impermeable. Even though this restraint technology has been in use for more than fifteen years, there remain some features that still need to be improved; i.e., the high cost, the high package volume, the weight and the need for replacement of coated fabrics. In this paper special attention is given to uncoated fabrics. A novel blister-inflation technique was utilized to evaluate the permeability of test fabrics under biaxial stretching conditions. Further, the effect of inflation temperature and internal pressure drop across the fabric on the permeability of the fabrics can be evaluated by this technique.

Safety restraint technology relies on woven fabrics as the principle material of construction. On impact, gases are generated instantaneously to inflate the bag. As the pressure within the bag increases during deployment and later from passenger contact, the airbag fabric stretches in a biaxial-manner. Passenger contact with the slowly deflating airbag accelerates the gaseous outflow through the fabric, airbag seams, and through specially constructed vents. A fraction of the impact energy can also be adsorbed by mechanical biaxial stretching of the fabric's fibers. However, the fabric's permeability and/ or vent system appear to be of primary importance to energy dissipation. A unique blister-inflation technique was developed and used to evaluate the fabric properties necessary for energy dissipation by these four mechanisms. The performance of fabrics woven from two traditional commercial polymeric fibers offered for airbag construction were considered.

Supplemental airbag safety restraint systems are an integral part of today's vehicle package. This inflatable restraint technology relies heavily on woven fabrics and particularly on knowledge pertaining to a fabric's permeability as a function of pressure drop, inflation temperature of the gas and fabric weave. While fabric permeability can be quantified by actual experimental measurements, the number and non-linearity of the variables involved make the experiments time and cost intensive. Moreover, interpolations within a given data set yield questionable results. For these reasons a feed-forward artificial neural network (ANN) technique was utilized to predict fabric permeability. This is an interpretive procedure. An ANN routine must first be trained. During this training the ANN is introduced to actual cause and effect patterns with adjustments being made by changes in weighting factors until the errors in the output variables are minimized.

A comparison of the NHTSA advanced dummy and the Hybrid III is presented in this paper based on their performance in repeated sled tests under 3 different restraint systems. The restraint systems considered are: the airbag alone, the 3-point belt alone, and a combined use of the airbag and the 3-point belt. Various time-histories pertaining to accelerations, angular velocities, deflections and forces have been compared between the two dummies in order to study their repeatability. The Hybrid III appears to be more repeatable than the NHTSA advanced dummy in its response in one case, that of restraint with the 3-point belt alone. The response of the NHTSA advanced dummy in other two restraint modes, the airbag alone and the combination of 3-point belt and airbag, appears to be no less repeatable than that of Hybrid III in this series of tests.