Reliability Optimal Design Of Passenger Car In Side Impact

In recent years, with the rapid economic growth, the vehicle becomes an important transportation tool for more and more normal families. The car ownership increases year by year in China. The increase of car ownership facilitates people’s lives, but brings a series of social problems such as traffic saf ety, air pollution and energy shortage. The traffic accident has become a serious public security issue. One of the high frequency traffic accidents is side impact. The number of side impact accidents and death toll is second from the frontal collision. The traditional deterministic optimal design is mostly based on meeting regulatory requirements specified in impact standards, without taking the randomness of the impact velocity and angle at the real world situation into consideration. Because the actual collision angle and velocity in real-world traffic accidents are different from the test conditions as specified in regulations. It is less that do study on side impact with considering the actual collision angle and velocity.Based on C-NCAP and US-NCAP side impact test regulations, this study applied the reliability theory to optimize the side impact for improving vehicle safety performance in side impacts according to traffic accident investigation statistics and related researches with taking the randomness of the impact velocity and angle at the real world situation into consideration. The main content of this dissertation are shown as following:1. On the basis of reading and researching many papers and used methods about automobile side impact safety to build a moving deformable barrier finite element model and a full-vehicle finite element model similarly,2. Select the key components of side wall as design variables and the impact angle and impact velocity from real-world traffic accident conditions are taken as the random variable inputs. It is obtained that 100 groups of crash simulation data by experimental design to analyze the effect of parameters on the output response. Set up the polynomial response surface model and complete the accuracy validation of response surface model.3. Using a combination of the multi-objective optimization algorithms and reliability theory, a vehicle side wall was constructed based on the polynomial response surface model. It was done by the deterministic optimization and reliability optimization respectively, and both results were analyzed. The reliability optimization results were rounded and verified its feasibility of the project. It will provide a reference basis for structural parameters of vehicle side impact.It is indicated that when compared with the initial design, deterministic optimization makes the mass minimum by reducing 14.64%. But the deterministic optimization results cannot meet the requirement of the reliability. When compared with the initial design, the reliability optimizations with 90% and 95% reliability yield 11.04% and 8.96% lower than the initial mass of vehicle, respectively. And the reliability optimization results all can meet the requirements of reliability. The higher the reliability target, the farther away the ultimate mean from the constraint boundary.