Vibration Behavior Analysis And Dynamic Optimization For A Medium-speed Mill With Spring Vibration-isolated Foundation

Medium-speed mill is the important auxiliary dynamic equipment of the electric powerplant, spring vibration isolators are adopted to control the vibration of mill and ensure thenormal operation of equipment and guaranty the safety of surrounding buildings. So far,structural engineers always adopt the simple theory of the dynamic characteristic matching todesign the medium-speed with spring vibration-isolated foundation which the majorconsideration is the vibration displacement of top of the foundation, and the phenomenon ofthe equipment vibration is transfinite may be appeared. So the vibration behavior analysis anddynamic optimization for medium-speed mill with spring vibration-isolated foundation is veryimportant.The dynamic performance test of medium-speed mill of five electric power plant havebeen made in this paper, and the3D solid model and the modal analysis of the mill are madeby ANSYS finite element software, and the natural vibration frequency and mode ofmedium-speed mill are obtained. Then the harmonic response analysis has been taken toobtain the dynamical response and frequency-amplitude curve, and the validity has beenproved by comparing the field test and the finite element analysis result. The dynamicresponse is decreased by contrasting the vibration of the mill with spring vibration-isolatedfoundation and without, that concern the vibration response of mill can be decreased by usingspring vibration-isolated foundation. Then the variation of the inherent property of the millhas been analyzed by changing the mass ratio of foundation and equipment, and the numberand stiffness of spring vibration isolator. Finally, the optimality analysis of medium-speedmill has been made by the optimization module of ANSYS. The maximum horizontalvibration displacement of driving point and the volume of foundation are considered as themultiple objective functions, and the design variables and state variables are set reasonably, then the parameter value is obtained.The analysis show that spring vibration isolators always be used to control the vibrationof mill, ensure the good running of equipment and guaranty the safety of surrounding building.The inherent property of the mill has been changed by changing the mass ratio of foundationand equipment, and the number and stiffness of spring vibration isolator. And when thenumber of spring vibration isolator is36,the mass ratio of foundation and equipment shouldbe2.0±0.2, and the vibration of equipment and the mass of foundation is decreasedobviously. Some useful references have been provided for the vibration reduction ofmedium-speed mill with spring vibration-isolated foundation.