OPTIMAL DESIGN OF THE IMPACT DAMPER IN FREE VIBRATIONS OF SDOF SYSTEM USING ICACO

The impact damper is a passive method for controlling vibrations of dynamic systems. It is designed by placing one or several masses in a container, which is installed on the structure. Damping performance is affected by many parameters, such as the mass ratio of the primary structure, size, number, and material of the particles, friction and restitution coefficients of the particles and gap distance. Impact damper is effective, economical, and practical and its functionality can be further enhanced by an optimal design. In this paper, first, the mathematical modeling of a rigid impact damper used in free vibration reduction of a single degree of freedom (SDOF) system is performed. The results on this step are validated with those results of previous studies, and a good agreement is achieved. Next, the robust hybrid optimization method that is called Imperialist Competitive Ant Colony Optimization (ICACO) is introduced. After that, the damper function is optimized using ICACO, and the optimum values of the effective parameters for maximizing damping effectiveness are obtained. Comparing the results of the optimized and the basic designs shows that the optimization method is robust and the optimal results are practical. The optimum design of damper parameters using ICACO method can damp more than %94 of the system’s initial energy in a short time.