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The engine subframe (cradle) is an important contributor to crash energy management in frontal impact for automotive vehicles. Subframe design can enhance vehicle crash performance through energy management. In addition to energy management targets, the subframe must meet stiffness, durability and other vehicle engineering requirements. Various subframe concepts are reviewed. Their design intents and vehicle performance are discussed. A development process of an aluminum subframe is then presented which details the subframe design as an energy absorbing component for frontal impacts. The architecture of the subframe is developed based on overall functionality requirements and package constraints. The geometry of the subframe is first designed to accommodate engine mounts and suspension support locations. The subframe member's shape, orientation, and location are then refined to accommodate the subframe-to-body connection requirements.

Although the crush of composite tubes has been studied extensively in static and dynamic impacts, the mode of collapse and energy absorption data for the next level of automotive components, sub-structure, or structures have been limited. In this study design/analysis were conducted on glass/vinylester CSM and braided composite Ford-Escort front end. The investigation consists of energy assessments; crush strength prediction and mode of collapse for the lower and upper rails structure with apron. Component models for lower and upper rails were evaluated for design iteration using stability code COMPCOLLAPSE to determine the maximum and average crush loads. A sub-structure consisting of both rails and apron with and without foam were analyzed using nonlinear collapsible beam code VCRUSH. The result of the analysis showed good guidelines for design.