磁流變液(Magnetorheological Fluid)簡稱MRF是由可極化的固體顆粒分散在絕緣溶劑中形成的懸浮液。在外加磁場的作用下，其內部結構和黏滯性質會發生顯著的變化。由於該過程迅速(毫秒量級)、可逆、易於控制且連續可調，因而在工業、科技和國防等領域有廣泛的應用前景。本文即利用磁流變阻尼器阻尼係數可藉磁場改變調整的特性，將其應用於汽車前端的保險桿內，並透過主動調整阻尼比來達到低速碰撞時，車體等減速度前進，減低車體損害及降低車內乘員因為碰撞而造成的損傷。數值模擬分析的結果顯示，具磁流變液阻尼器的保險桿確實能夠有效降低碰撞時的最大減速度。在雙自由度CRASH碰撞模式下，裝有10cm緩衝行程的磁流變液保險桿（MR Bumper）可將車體不變形的最大碰撞初速由8 Km/h提升至12.5 Km/h，約改良56%，本文並就雙自由度SMAC碰撞模式之五大參數，即車體自然頻率、保險桿阻尼比、車體與保險桿剛性比、阻尼器有效衝程及車體碰撞初速做分析討論，提供設計準則。

Magnetorheological Fluid (MRF) is a suspension fluid formed by scattering polarizable solid granule in isolated solvents. Under the influence of outside magnetic field, its inner structure and viscosity properties have a remarkable change. As the process is dramatically speedy (in the measurement of milliseconds), reversible, easily controllable and continuously adjustable, its applications in comprehensive fields such as industry, high technology and military defense have a very bright outlook. Since the damping coefficient of MRF damper can be changed and adjusted through magnetic field, this property can be utilized in the car’s front end bumper and when the damping ratio is adjusted in an active way so that the car body would decelerate to progress after low-speed collision to reduce damage to the car body and injury to the passenger. Results of numeric simulation analyses show the bumper with MRF damper can indeed effectively decrease the maximum deceleration during collision. Under the two-degree-of-freedom CRASH collision model, MR bumper having a buffer distance of 10cm could boost the initial maximum collision speed which makes the car body undistorted from 8 Km/h to 12.5 Km/h, or roughly improving 56%. This thesis also discusses and analyzes five main parameters of the two-degree-of-freedom SMAC collision model：car body natural frequency, bumper damping ratio, stiffness ratio of car body and bumper, effective damper stroke and initial car body collision velocity , to provide the design criteria for a MRF bumper.

第一章 緒論1
1.1 前言1
1.2 磁流便流體簡介 1
1.3 汽車保險桿設計沿革7
1.4 文獻回顧15
1.5 研究動機19
1.6 本文簡介20
第二章 汽車碰撞運動分析22
2.1 汽車碰撞運動類型22
2.2 車損與人傷間的關聯26
2.3 汽車碰撞模擬軟體CRASH與SMAC理論分析35
2.4 單自由度車體模型41
2.5 雙自由度車體模型47
第三章 結果與討論54
3.1 單自由度車體碰撞模型數值分析54
3.2 雙自由度車體碰撞模型數值分析81
第四章 結論與建議89
4.1 結論89
4.2 未來展望90
參考文獻91

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