On the response time of a new permanent magnet based magnetorheological damper: experimental investigation

Most recently, a novel concept of tunable magneto-rheological (MR) dampers has been proposed which can be operated by only permanent magnet (PM) movement instead of an electromagnetic coil. The damping force variation of the PM based MR damper (PMMR damper) is realized by the variation of the magnetization area or magnet flux dispersion, not by the magnitude of the input current. Thus, the input variable of PMMR damper is totally different from conventional MR damper (CMR damper). In this work, in order to evaluate the feasibility of PMMR damper on real field applications, the investigation on the response time of PMMR damper is empirically undertaken by considering several factors such as magnetic material which can influence on the response time. In order to achieve this goal, PMMR damper is modified to realize damping force variation, and CMR damper whose size is similar to PMMR damper is manufactured for the reasonable comparison. Experimental tests to measure the response time of the dampers are undertaken by considering three influence factors; materials of the magnetic circuit, the magnitude of damping force variation, and the excited frequency of the piston. Then, it is shown that the response time of PMMR damper can be shortened faster than CMR damper.