D . \ 8tX QD $\ XɕD T\ ©( xX 0e 8 ȩX, xǴtX \͌T| <\ Xt h, \ptD ̹qXՔ ǩ\ \t| D . t\ X ȩD t H\ )X 1 ǩ1D ɅX.; Crashworthiness is the issue that we should consider when designing a passenger vehicle or an aeroplane for occupants safety in a vehicle accident. The governments of countries in the world and insurance companies suggest conditions considering passengers safety in designing vehicles, and regulations in which many of the conditions are reflected have been enacted. The suggested regulations reflect the crashworthiness of structures in order to consider the passengers safety. Therefore, these conditions should be used as objective functions or constraints when designing a vehicle structure. However, it is difficult to apply gradient based optimization methods to a crash optimization problem because of large nonlinearities of the problems which should be considered in time domain. The nonlinearilties and oscillation of the responses make difficult to calculate the sensitivity information. Therefore, it is needed to develop a design method regarding the crash optimization problem. The present study suggests a crashworthiness design optimization using equivalent static loads (CDOESL) that could reduce the number of nonlinear analyses considering characteristics of the crash problem. Crash prblem is mainly the issue of nonlinearities in time domain and should be taken into consideration in the three nonlinearities, which are material, geometric and contact nonlinearities. Thus, equivalent static loads for applying the crash problem should be considered contact force, deformation shape on a contact boundaries and material nonlinearity and geometric nonlinearity in the process of the linear static response optimization. Crash problem should consider crashworthiness of the vehicles. That is, design problem should be solved regarding crash energy conveyed from the outside and injuries of the human body. In this research, it is proposed the crashworthiness design optimization method using equivalent static loads that could consider the strain energy and injuries of the human body in order to apply to crash problem. CDOESL is verified in terms of accuracy and efficiency by applying it to some small examples. For verifying the crashworthiness design optimization, traditioanl optimization methods such as finite difference method a<nd response surface method are used. An optimum solution gained through the crashworthiness design optimization shows a better result in terms of the number of crash analyses comparing with the traditional optimization methods. The suggested crashworthiness design optimization methods using equivalen static loads are applied to practical engineering problems. An optimum solution satisfying the crashworthiness constraints could be found with a small number of crash analyses by applying it to automobile parts that would reduce conveyed crash energy into the human body in a car accident such as crash box and knee bolster. Also, the excellence and the usefulness of the suggested crashworthiness design optimization is proven by successfully applying it to the crash problem having intrusion constraint regarding minimizing the injury of human body.;&HQsj&)KLng?aHjQsTver +,- dMbP?_*+%" ,,??U >@ !"#$%&'Root EntryWorkbook0SummaryInformation(DocumentSummaryInformation8