Parameter identification of modified Bouc-Wen model and analysis of size effect of magnetorheological dampers

Magnetorheological damper is one of the most promising smart devices for vibration mitigation of structures subjected to dynamic loads. In order to fulfill the value of magnetorheological damping control, a feasible mechanical model of magnetorheological dampers with simplicity and sufficient accuracy is usually required in practice. It comes up, however, with a challenging issue for the modeling of large-size magnetorheological dampers due to physical constraints on the performance test. The large-size magnetorheological damper is typically modeled in up-scaling parameters associated with models of the small-size magnetorheological damper. This treatment remains open since a size effect hinges upon the intrinsic non-linearity inherent in the device. In this article, a dynamic test of a small-size magnetorheological damper is performed first. The relevance of damper force with the input current and excitation frequency is well revealed. The modified Bouc-Wen model is employed to logically represent the dynamic behaviors of magnetorheological dampers. Identification of model parameters in typical loading cases is then proceeded, of which the functional relationship against input current is established. The size effect of magnetorheological dampers is further addressed through investigating the functional relationship relevant to maximum outputs of 200, 10, and 5kN. It is indicated that the small-size magnetorheological damper needs more number of control parameters than the large-size magnetorheological damper. Moreover, a linear current relevance of model parameters appears in the small-size magnetorheological damper, while a quadratic current relevance of model parameters appears in the large-size magnetorheological damper. Size effect of magnetorheological dampers arises to be well-marked in the range of low current and becomes unapparent in the range of high current. Besides, the validation of modified Bouc-Wen model is carried out that reveals the applicability of the model with case-optimized parameters.