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This paper discusses a computer modeling system being developed by Springwater Micro Data Systems. The system, SIFEM, simulates normal and oblique, vehicle-to-vehicle side impacts. The system is being developed as a practical, user friendly, design and evaluation tool for the practicing design and test engineer. Side impact computer models most commonly used in the industry today generally fall into two main groups. One group involves overly simplified one and two dimensional spring-mass models to represent the vehicle and its occupants. The second group takes the other extreme, using advanced analytical methods to develop 3-dimensional linked mass and finite element models. These advanced models generally require large, expensive computing systems to operate. Both groups of models impose severe restrictions, limiting their usefulness as a practical design and test evaluation tool. The SIFEM system, discussed in this paper, is a compromise between these two modeling groups.

This paper discusses a simplified analytical/experimental method for evaluating and designing large buses and motor coaches for rollover protection. The proposed method makes use of the work-energy principle in analyzing the energy-absorbing capacity of the roof and sidewall structure of the vehicle. The basic structural unit is treated as a nonlinear, elastoplastic, 4-bar linkage, with the links connected at hinge points. During rollover, the deformation of the structure is focused at these hinge points and energy absorption is achieved through plastic bending and rotation of the hinge material. The proposed method allows the evaluation and design of these plastic hinges to achieve the energy-absorbing requirements for the vehicle. This paper demonstrates the proposed methodology by evaluating an exemplar large bus design against the European ECE-R.66 rollover design standard.

The recent real-world experience with the frontal airbags and their sometimes unfortunate interaction with small size adults and children led to the analytical efforts and the results reported in this paper. The focus of this paper is an analytical study investigating the side impact protection performance of side airbags in interaction with, out-of-position occupants. The study evaluates interaction of the two extreme size occupants including a 3 year old child, and a small 5th percentile adult female. The objective is to identify any potential problems with the side impact airbags in real world scenarios. To date, a considerable amount of research has been invested in developing and evaluating occupant protection systems for both frontal and side impacts. However, the majority of this research has focused on the 50th percentile adult male occupant size, who is properly seated in his seat.

This paper discusses the side impact computer model,SIFEM (Side Impact Finite Element Model). The SIFEM model is being developed for use as an analytical design and evaluation tool for vehicle-to-vehicle side impacts. The SIFEM model uses two (2)two-dimensional, linked, rigid body models to represent the three dimensional movement of the occupant and a two-dimensional spring -mass model to represent the impacting vehicles. The model makes use of the elasto-plastic,finite element method to calculate the force-displacement characteristics of various spring elements in the model. This paper discusses the technical features of the model and the theoretical basis from which the model was derived.

This paper describes a computer modeling system and its application in evaluating several vehicle designs for side impact protection of children and small adults.