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There are a number of benefits from Ford Motor Company's participation in motorsports. This paper will describe how an engineering team developed a CAE process to assist in the design of a race car to meet impact requirements, with the technology transfer benefit of improved impact performance of composite structures in passenger cars. In 1997/98, a CAE process was developed and applied in the design and test of Formula One race car composite impact structures. For this particular engineering effort, a Ford proprietary software program, COMP-COLLAPSE, was the primary analysis tool that was utilized to successfully predict impact performance. As a result, COMP-COLLAPSE was used extensively in the design of race car composite impact structures. There were two beneficiaries from this effort: Race Vehicles: Improved vehicle impact performance as well as design improvement in crush efficiency, packaging, weight, and manufacturing.

This paper discusses the challenges, a crash engineer is faced with, when designing for offset crash and the more severe intrusion constraints to be satisfied in offset crash when compared with full frontal crash. Excessive intrusion and higher risk of injuries are some of the tougher constraints to be satisfied when designing for offset crash. Structural reinforcement has been used to control intrusion in a soft offset impact without raising any concern of exceeding passenger compartment pulse requirement. However, the same reinforcement can stiffen the structure, limit the crash distance, and possibly exceed the desired occupant G-values when designing for full frontal crash. These constraints make it more challenging to seek an optimal design that maximizes the energy absorbing capability of the crash zones, minimizes intrusion, and keeps occupant G-values within desired limits. Results of a computer model for a front end structure under 40% offset crash are presented.

The study has been conducted to analyze the effect of interlaminar stresses on the crush behavior of laminated composite structures. Several sets of test data of columns under axial crush load were analyzed. Modes of collapse were identified. Interlaminar stresses due to in-plane axial crush load were calculated and compared with interlaminar strengths. The analysis showed that when laminates have no significant cracks or voids, the interlaminar stresses have no effect on crush mode up to the maximum load, and a thin-walled composite column fails in local buckling mode. When the laminates have initial imperfections, cracks or voids create interlaminar stress concentration and cause the delamination failure. In this case the column walls are split through the thickness into two portions, one crushed inward and the other crushed outward. The study also indicated that fiber orientation is important in initiating interlaminar stresses.

A need exists for a reliable and economical analytical aid for designing vehicle structures for controlled crash energy management. Several of the crash simulation methods, currently available to the designer in the evaluation and development of vehicle structures for crash, are reviewed with respect to their capabilities and shortcomings as design aids. An analytical technique is presented, structured along the lines of a design aid and based on a finite element beam model concept. The functions of the various elements of the code are discussed in the context of typical crash events one needs to consider in the design of a structure composed of beam- and column-type elements. The heart of the proposed system code VRUSH is a component code SECOLLAPSE which monitors and predicts crush responses of thin wall structural components and which controls the input into the system code. Also presented are models generated by SECOIXAPSE for typical loading cases.

In the interest of improved fuel economy, minimum weight design of the car structure has become a main concern for automotive engineers. In the outer surface panel, reducing the weight means reducing the panel thickness or using alternative materials. These changes will affect the dent resistance of the panel. In this study, the correlation between panel geometry, material properties and dent resistance is investigated. The approach is based on the relationship between the stiffness of a shell panel and the energy required to form visible dent. Mathematical formulation and design methods are presented that relate dent resistance to the design parameters of the various panels. The slam area of several deck lids and life gates are investigated and a dent resistance requirement is established.

The study is a combination of finite element method and the basic equations of shallow spherical shell to determine the required stiffness of outer surface panel. One finite element model is run and the required stiffness for different thickness or sweep is achieved from the shell equations by numerical iteration. Thus, the many finite element trials required to evaluate the clay surface can be avoided. Iso-stiffness curves are also presented with a direct conversion of panel thickness from steel to aluminum. A computer program for this method has been developed and applied for hoods, deck lids and roofs of various models. It is found that the stiffness results, in general, are satisfactory. In the case of a panel with outboard character lines the center unsupported area shows more accurate results than the outboard area.