Design and evaluation of composite car-front subframe rails in a sedan and its corresponding occupant crash injury response
Today occupant safety is of a prime concern to every car manufacturer. New standards are being set for the safety of the occupant in different crash scenarios like frontal head on collision, angle impacts, side impacts, rear impacts and rollover. Among these standards, frontal impact is one of the fatal crash scenarios that lead to death of scores of people in the United States and across the globe. The automotive mid-rail is the main load carrying/energy-absorbing component in a event of frontal vehicle crash. In the contemporary world, fuel consumption also poses a serious issue that has to be considered. With these constraints in consideration, a lighter and stronger composite material is used in car front rail than steel. Using this material would help in reducing the fuel efficiency without sacrificing the safety of the vehicle. In this research, section modeling of rails is designed to replace the present rail model and the injury sustained by the occupant is recorded. An attempt is made to use Carbon fiber/Epoxy and Glass fiber/epoxy composite materials for the rails. In addition, parametric study is carried out on the rail to find out the maximum possible energy absorbing parameters. It was found that carbon/epoxy rail with a pertinent orientation and thickness was absorbing more energy than the present steel rail. Energy absorption, displacement and the acceleration of the original and section model is compared and discussed in detail. The Ford Taurus model is first validated using the LS-DYNA finite element software package and then dynamic analysis is performed on the original model and the section model according to the Federal Motor Vehicle Safety Standard (FMVSS) 208, the New Car Assessment Program (NCAP) and the Insurance Institute for Highway Safety (IIHS) regulations. The vehicle displacements, Energy absorption and deceleration levels are compared for the steel, carbon-fiber epoxy and glass-fiber epoxy model. The occupant injuries are then evaluated for the full width rigid barrier test at 30 mph and 35 mph using the MADYMO, occupant modeling software package. With the new composite model and the section model the injury levels including, the head, neck and chest injuries are evaluated and compared. It is demonstrated that the new composite rail with carbon/epoxy is more effective than the present steel rail.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
Includes bibliographic references (leaves 108-110)