A computer program is developed for the purpose of determining the discrete spring constants of supporting material to increase the efficiency of vibration isolation for machines. The vibration isolation system is modelled by FEM to calculate the supporting forces of the isolators and to determine the sensitivity of the isolator deflection to the change of the isolator spring constant. In the optimal design formulation, an object function without constraints is established so that all deflections of isolators converge to a fixed value which is readily computed considering the vibration isolation efficiency. The object function is then minimized using design variables with discrete values of stiffness since the isolators commercially available are restricted to a finite number of models. As an example, the vibration isolation system which has been installed at Joong Ang Daily News is analyzed and optimized. It is found that the optimal vibration isolation designed is more efficient and stable than the system which is currently in use.
