Tasarım ve çamaşır makinesi titreşim kontrolü için magnetorheological damperi analizi

Magnetorheological (MR) dampers are state of the art adaptive devices that can change damping capability within milliseconds to control undesired vibrations in the dynamic systems. A novel magnetorheological friction damper has been developed to control the vibration of washing machine drum. A 2-D axis symmetric model of MR damper has been developed in finite element analysis software for magnetic analysis and parameter optimization. This analysis will help designers to design an efficient electromagnet capable of delivering maximum magnetic flux and force with less electrical energy and compact geometry. The hardware design of MR damper has been developed based on magnetic analysis, force and stroke requirements in the washing machine. Experimental modal analysis was performed to determine the dynamic characteristics of MR damper. An experimental test setup was developed to test and validate the performance such as force-velocity and force-displacement relationships. Off-state friction characteristics were studied to determine the behavior of damper without applied current. On-state damping characteristics have been studied using hysteretic model. Damper mathematical model parameters such as damping coefficient, stiffness and hysteresis are identified using mathematical and experimental data. Parameter optimization techniques like least square fit, fmincon, and fminuncon and multistart methods were applied to obtain the trends of damping coefficient and stiffness against various excitation amplitudes of displacement, velocities and frequencies. The displacement and speed of washing machine drum has been analyzed using sensors at full range of drum speeds. The data was recorded first with conventional passive dampers installed in washing machine. Then passive dampers were replaced by MR dampers and the data is recorded again to compare the performance of both types of dampers. The damping force is adjusted by changing the current through look-up controller. The current is adjusted on the basis of displacement and speed of the drum. Finally a performance comparison was presented that justifies that MR damper can control the vibration of washing machine far better than conventional passive dampers.