Structure Design And Finite Element Analysis Of Multifunctional Child Safety Seat

With the rapid development of China’s economy and the improvement of our consumption level, the number of private cars is increasing so is the traffic accident rate. So the safety problem of child safety seat has drawn attention from all sorts of the society. However, the penetration of child safety seat is still low in China. And the domestic products have certain differences at functions and reliabilities compared with foreign like products. Moreover, relevant laws and regulations are not complete in China. At present, the price of child safety seat is high, the rage of its application is limiting and the usage rate of it is low. It will be kept in the trunk when out of use, which takes lots of space. So the child safety seat needs to be improved to achieve multifunctional, portable and enhance safety.This thesis studies the structure design of multifunctional child safety seat and uses finite element theory to achieve statics analysis, modal analysis and harmonic response analysis on the structure. The thesis mainly contains following parts:(1) The multifunctional structure design of child safety seat. It is designed according to national standard’s requirement on size and with the application of CATIA three-dimensional modeling software. It including entirety structure designs of base, lazyback and headrest and parts designs such as wheels, extend-retract handgrip, recliner, headrest height adjuster, ISOFIX connector and so on. Kinematics simulation analysis is also used on these pats, and the interference situation is tested to improve the design structure.(2) The structure statics analysis of multifunctional child safety seat. The study applies ANSYS Workbench to mesh the three-dimensional model of child safety seat and to achieve finite element analysis. And according to the equivalent stress nephogram provided by simulation, the equivalent stresses of the parts such as recliner, ISOFIX connector, lazyback, base and headrest height adjuster are large. So the appearance, size and material should be paid special attention to during the design. The further studies on these crucial parts indicate that the designed parts meet the requirement of strength.(3) The modal analysis of multifunctional child safety seat. To analysis the comfortable capability of the seat, this thesis uses modal analysis and acquires each modal shape. According to the analysis of first few modes, the rage of the seat’s natural frequency avoids the natural frequency of kids’ organs and different postures.(4) The harmonic response analysis. On the basis of mode analysis the thesis uses mode superposition method to do harmonic response analysis, and obtains the frequency and amplitude which will highly respond to and the engine speeds which the child safety seat will cause resonance. The cars should avoid being driven when engine is moving at these speeds.