Instrument Panel Assembly Performance Analysis And Optimization

Instrument panel (called IP for short) assembly is one of the most important members of the inner parts of cars, and the most attractive parts in the car. IP assembly must fill to the functional demands, and it should fill to lots of security rules, such as the passenger's impact protection requirements (head impact and knee impact), man-machine engineering requirement, appearance requirement, etc. CAE technology can evaluate the IP's modal performance, rigidness, head impact performance very quickly, to guide the structural design, and then to reduce the development cost.In this assay, based on the IP's basic structure, the static model of the IP is set up. To check up the IP's vibration property, the IP's constrained-free mode is calculated referring to the modal testing requirement of the IP. To check up the IP's total rigidness, the vertical 2g acceleration of gravity is analyzed. According to the result of the sensitivity analysis,21 parts of the IP are selected to be design variables, the minimum of the IP's total mass is the optimize objective, the IP's modal performance and rigid performance are the constraint equation, size optimization is done. In the effective head impact area that decided by the European Regulation ECE 21,10 points are selected to do the head impact simulation. The results show that the IP's first order integrate natural frequency is 35.6Hz, and this is higher than 34Hz regulated by the criterion, so the IP's integrate modal performance is good. The IP's maximum displacement is 0.73mm, and this is far smaller than 2mm of the requirement, so the IP's rigid performance is good. After the optimization, the IP's mass is decreased from 38.14Kg before Optimization) to 35.86Kg, the decreasing percentage is 5.98%. There are two locations that can't fulfill the regulation, and the main reason is local rigidness is too big and the structure should be modified further.Besides, it is declared in this assay that the sensitivity is not the bigger the better, the selection of variables should be good to the objective function and constrained function. And it is indicated that the selection of the variables should be done following the such steps:firstly, to select variables that are most sensitive to objective function. Secondly, to select variables that are profit to weight reduction and constrained function's constringency. Thirdly, to select variables those are not sensitive to constrained function. Fourthly, to select variables that are not good for the constrained function's constringency, and use these variables to remove the variables that selected before. Finally, remove the parts that can't be changed to be variables.Whereas there are not enough national studies for head impact, some problems of head impact are talked over in this assay referring to the regulation about IP's head impact home and abroad. Including the confirmation of the head impact areas, the determine of the exemption areas, the selection of head impact points, the ascertain of the impact points and impact angle. It is confirmed that the European regulation and American regulation are the same relating to the definition of the head impact areas, but are great different relating to the determination of the exemption areas, impact points and impact angles.