汽車座椅結構強度設計之有限元素法分析

本論文係針對汽車座椅利用有限元素軟體進行電腦輔助工程(CAE)分析，分別依據四種汽車座椅法規內容進行模擬分析。針對汽車座椅法規內容之模擬可分為靜態分析與動態分析，靜態分析為安全帶固定點強度試驗；而動態分析則為荷室隔壁強度試驗以及前向、後向衝擊試驗。本論文首先將複雜之座椅結構進行CAE分析模型之簡化，移除對強度無影響之部件，並根據試驗需求保留關鍵結構件。在安全帶固定點試驗模擬中，滑軌滾珠簡化之設定方式會影響座椅骨架變形量模擬之結果；利用簡易模型驗證出分析軟體ABAQUS當中若兩部件以MPC link設定連接，則其中一部件受力可由MPC link將力量傳至另一部件。荷室隔壁強度試驗模擬中發現汽車後座椅骨架正中間之部件所使用之coupling設定以及衝擊物塊重量對模擬出來之結果變形量造成相當程度之影響，衝擊物塊和平台之間摩擦係數經過模擬比較後，對衝擊物塊撞擊到座椅骨架時之能量影響不大。前向衝擊試驗模擬中則正確建立出安全帶之簡化，使座椅骨架模擬變形量和實際結果更為接近；假人HP點位移量經過各種不同織帶捆綁的條件之下其結果為假人腳踝有織帶捆綁之模擬最為合理，並且探討安全帶預縮器觸發時間以及安全帶預縮器張力對假人HP點位移量造成之影響。後向衝擊試驗的部份則探討加入了座椅後背彈簧以及假人腳踝無織帶兩項模擬和初始模擬結果之差異。本論文探討各種座椅骨架模型以及模擬參數對模擬結果之影響，可供未來進行相關研究之參考。

關鍵字

汽車座椅；安全帶固定點強度試驗；荷室隔壁強度試驗；前向衝擊試驗；後向衝擊試驗

並列摘要

This study adopted an infinite element application to carry out a CAE analysis on car seats. A simulation analysis was performed according to 4 situations in car seat regulations. The simulation was divided into Static Analysis and Dynamic Analysis. Static Analysis was a safety belt anchorage strength test. Dynamic Analysis included a load cell wall strength test and a forward impact test and a backward impact test. First, this study simplified the complicated seat structure into a CAE analysis model by removing parts which had no effect on strength. Then, key structural parts were reserved as needed by the test. In the safety belt anchorage test simulation, how the guideway ball simplification was set would influence the result of the amount of deformation in the seat framework in the simulation. A simplified model was applied to verify ABAQUS: if two parts were connected by setting the MPC link, then when one of the two parts received a force, the force could be transferred to another part through the MPC link. In the load cell wall strength simulation test, it was found that the effect of the coupling setting used by the part located right in the middle of the rear seat framework and the weight of the impact block on the amount of deformation resulted from the simulation was significant. A simulation comparing the coefficient of friction between the impact block and the platform found that the effect on the energy when the impact block stroke the seat framework was insignificant. In the forward impact test simulation, a safety belt simplification was correctly built, which brought the amount of deformation in the seat framework simulation closer to the practical result. Through different conditions of strap fastening with the displacement of the dummy HP point, the result found that the simulation with the dummy’s ankles fastened by the strap was most reasonable. Moreover, the effect of the time of triggering the belt tensioner on the dummy HP point displacement was also discussed. In the backward impact test, we discussed the difference between the two simulations – adding a seat back spring and no strap on the dummy’s ankles – and the initial simulation result. This study discussed the effect of different seat framework models and simulation parameters on simulation results and the results can be provided for reference of related researches in the future.