Multidisciplinary Collaborative Design Optimization Of Passenger Restraint System Safety And Comfort

With the continuous warming of the automotive industry, constant innovation in automotive technology, and the rapid rise in car ownership in China, people in the car made more stringent requirements: For the occupant restraint system, the comfort is being increasingly concerned and gradually thought to be an economic indicator for high-end cars, while the traditional safety rules are continuously improved at same time.Under such technical background, this paper carries out studies on multi-disciplinary collaborative design optimization for the safety and comfort of the occupant restraint system, and improves the comprehensive performance of occupant restraint system in the dual-disciplinary collaborative design optimization point of view.Firstly, the occupant restraint system composition and main components are described in detail, and the technical points of current stage for the assembly which has significant influence on occupant restraint system is analyzed, then the main problems and key techniques of the study is proposed;Secondly, the assessment systems for the safety and comfort are described respectively. Considering the relative maturity of the safety assessment systems, those existing are summarized and compared, while corresponding simulation and testing approach are introduced. For the comfort issue, the objective comfort concept is proposed with quantitative assessment from body pressure distribution stand,jointly considering degrees of limbs diastolic for the integrated assessment of comfort degrees.Also, MADYMO and LS-DYNA models for safety and comfort targeting synchronous simulations are established, with emphasis on the description of comfort assessment modeling,including dummy model with human details,the seat model with hyperelastic nonlinear foam material,the hybrid seatbelt model with anisotropic fabric material and the hybrid airbag model. The procedure and key technical points are presented.Furthermore, the multi-disciplinary optimization problem is introduced and analyzed,the realization and features of various optimization strategies are presented, which leads to the multi-level optimization strategy for collaboration optimization design, as well as the primary technology roadmap. On the basis of disciplinary decomposition and optimization strategy finalization, the optimal Latin hypercube sampling and Kriging unbiased estimation are used to establish the agent model, where the adaptive supplementary sampling strategy with El and MP dual addition criteria is proposed to improve Kriging agent model accuracy. The low complexity FEA model with mesh adaptive is proposed to improve computing efficiency, and applied for the establishment of comfort agent model, while it's validated with high complexity FEA model. On the optimization algorithm stand, the mathematical basis of multi-objective optimization problem and typical solutions methods are introduced, the development history of these algorithms and difference between each are described, which leads to particle swarm algorithm. Accordingly, the Parallel computation based multi-level sub-population Collaborative Particle Swarm Optimization algorithm (PCPSO) is proposed. It decomposes the population for multiple objectives,assign to different CPU for optimal solution, and collaboratively interacts. Then the improvement of PCPSO is validated via typical ZDT test function, the global search capability is expanded while keeping computational efficiency, overcoming the deficiencies that easy to fall into local optimal solution and slow convergence.Finally, the experiment design frame for vehicle test and sled test is presented,focusing on sled test setup and main factors. The dual-disciplinary simulation model proposed in the study is validated through testing, and the model accuracy meets requirements. On the basis, the design optimization solution for 50KPH frontal crash is obtained, applying dual-disciplinary collaborative optimization. It shows the relative lower weight of comfort and the coordination with safety under the high speed crash condition. Then the 40KPH straight line braking condition test is designed,the vehicle attitude test is used as an example to apply the dual-disciplinary collaborative optimization. It's demonstrated that the comfort weight increases. Therefore, it's necessary to add and improve more design conditions to completely understand the relation between safety and comfort and obtain fully integrated design solutions.