Study of Vehicle Dynamics and Occupant Response in Side Impact Crash Tests
Side impact crash is a leading cause of fatalities on the roadways of the industrialized world. In the mid 1990's NHTSA implemented a new car assessment program testing the lateral crashworthiness of vehicles entering the market with a moving deformable barrier. Previous work has been done in an attempt to distill these tests into finite element simulations using specific vehicle test results; however there has not been a comprehensive study attempting to develop a model that includes a large number of tests to evaluate trends in vehicle kinematics and how they affect the occupants coupled with finite element simulations. To this end, a study of side NCAP tests was performed on all sedan cars based on the test results reported in the NHTSA Vehicle Crash Test Database since the introduction of the 2005 model year. This data was used to evaluate typical motion of the target vehicle during a regulatory crash test, and the corresponding occupant response. This sample consisted of new models entering the market and nameplates with major redesigns with a sample size of 72 vehicles. From these tests a series of velocity profiles were developed including time versus average velocity plots for vehicle center of gravity, door sill, driver's seat and driver door. These parameters have been shown to be important in occupant response and injury. There was significant variability in the response at several accelerometer locations. It was also found that rotation of the vehicle did not become significant until after 100 ms, after the maximum injury was predicted by the dummy. A parametric finite element analysis was performed using the both the USSID and ES-2re models to study the response of a restrained occupant during a typical crash test. These simulations showed that the velocity of the intruding door had a large effect on the thoracic injury predicted by the side impact dummy models. The full text of this paper may be found at: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv21/09-0016.pdf For the covering abstract see ITRD E145407.
OBSERVATIONS DURING VALIDATION OF SIDE IMPACT DUMMY MODELS - CONSEQUENCES FOR THE DEVELOPMENT OF THE FAT ES-2 MODEL
Detailed finite element side impact dummy models of the USSID and EUROSID have been developed in cooperation with the German Association for Automotive Research (FAT) during the last 5 years. Both models are validated using tests at material and component levels as well as fully assembled models. The development of the LS-DYNA dummy models has been performed by the authors. Both models are used by nearly all car manufacturers worldwide which use LS-DYNA for occupant safety simulations. EuroNCAP (European New Car Assessment Program) announced recently a modified testing protocol for side impact assessment using the ES-2 dummy instead of the EUROSID-1 dummy. The ES-2 dummy is identical in many parts with the EUROSID-1 dummy but shows different behavior in experiments. Hence, the development of a model for the ES-2 dummy is of great interest for the automotive engineers working in the field of passive safety. The FAT has launched a project similar to the previous one to develop an ES-2 model. Due to urgent need of the model in the industry a tight schedule is given for the development. The first release of the model is already available. DYNAmore GmbH is responsible for the developing the LS-DYNA models. This paper summarizes experiences gained during the validation of the EUROSID-1 and USSID model and describes the tests performed to validate the ES-2 model. Finally, the performance of the first version of the ES-2 model a nd the schedule for the project is presented.
Representation of systems disturbed by wide band noise
In this paper, a method of handling and working with wide band noise is developed. We represent wide band noise as a distributed delay of white noise and use it to reduce a nonlinear system disturbed by wide band noise to a nonlinear system disturbed by white noise. An application of this reduction to a nonlinear filtering problem under a wide band noise disturbance is discussed.