الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Vehicle suspension is used to attenuate unwanted vibrations from different road conditions. So far, three types of suspension system have been proposed and successfully implemented; passive, active and semiactive. Even though the passive suspension system featuring oil damper provides design simplicity and costeffectiveness, performance limitations are inevitable due to the lack of damping force controllability. On the other hand, the active suspension system can provides high control performance in high frequency range. However, this type may require high power sources, The semiactive suspension system offers a profitable performance generally enhanced in the active mode without requiring large power sources and expensive hardware. In recent years, One of very attractive and effective semiactive vehicle suspension systems is to utilize magnetorheological (MR) fluid technology which has received much attraction and consequently has shown much improvement. Its adaptable nature has led to rapid growth in a such varied engineering applications as the base isolation of vehicle suspensions, civil structures, and several bio-engineering mechanisms through its implementation in different MR fluid base devices, particularly in MR dampers. The MR damper is a sophisticated application of a semi-active device which performs effectively in vibration reduction due to its control ability in both on and off states. The MR damper has the capacity to generate a large damping force, with comparatively low power consumption, rapid and flexible response. This study presents a plain quarter car model with the two degrees of freedom and compares it with MR damper by applying the mathematical modeling for both and on various road profiles and diffenrent car speed, the advantages of these semi-active (MR dampers) systems over passive system can be gained. The major advantage of MR damper is determined as a fast and flexibilty suspension response.