Parameter Optimization And Structure Design Of Lever-type Dynamic Vibration Absorber

Dynamic vibration absorber?DVA?is widely used in engineering field.Its control performance is closely related to the additional mass and structure.Generally speaking,DVA is hardly to get satisfying control performance when the additional mass is too small.Moreover DVA's control performance will deteriorate obviously when system parameters change in small mass case.It can increase the effective mass to apply force amplifier in some control device,which is beneficial to improve the control performance and hopeful to realize light weight design.Therefore,the force amplifier will be introduced in the DVA,and its optimum parameters,performance and structure design will be studied.In addition,the global optimum parameter will not be obtained by using fixed-point theory to optimize grounded type DVAs.Thus grounded three-element DVA will be further studied for its optimum parameter and performance.The main contents of this paper include:?1?Lever is introduced in Voigt DVA,and its optimum parameters and control performance are studied in detail.The optimum parameters under H_?and H₂optimization criterion are obtained by using fixed-point theory and optimization performance index.The relationship between optimum parameters and performance indexes and system parameters are analyzed.Theoretically,the higher the magnification ratio?ratio of lever power arm to lever resistance arm?,the better the control performance of lever Voigt type DVA will be.Further the lever Voigt type DVA is compared with several other type DVAs.It is show that the control performance of lever Voigt type DVA is best.?2?Lever is introduced in grounded DVA,and its optimum parameters and control performance are studied.The optimum parameters are obtained based on H_?and H₂criterion.The change of performance of grounded DVA is analyzed after the lever is introduced,and the comparison is made between lever grounded type DVA and several other type DVAs.The results show that the control performance of lever grounded DVA is best,and the performance of lever grounded DVA is declining,not changing or promoting respectively when the magnification ratio is less 1,equal to 1or greater than 1.The lever grounded type DVA can achieve excellent control performance at small mass ratio case by adjusting the magnification ratio.?3?The optimum parameters and control performance of grounded three-element DVA are studied.The amplitude of the fixed point can basically represent the minimum maximum amplitude of the primary system when system parameters are selected.Thus expressions of fixed point coordinates are derived.For more precise,the relation between the maximum amplitude of the primary system and the system parameters is obtained by using numerical algorithm to optimize parameter.It is found that there are only local optimum parameters and no global optimum parameters in the grounded three-element DVA.The performance and optimum parameters of the grounded three-element and grounded DVA are analyzed by numerical algorithm.It is found that the local optimum parameters of the two DVAs are the same,and the performance of the grounded three-element DVA is better at a low frequency ratio?the ratio of the natural frequency of the DVA to the natural frequency of the primary system?.?4?In addition to lever,many other mechanisms also have the function of force amplification.The design principle of DVA with force amplifier is analyzed.A ball screw type DVA is designed by combining ball screw with Voigt DVA.It is found that the dimensionless optimum parameters of the two DVAs are the same.Compared with the lever type DVA,the stiffness of the ball screw type DVA is higher,and its structure is more compact.It may be more suitable for practical applications.Finally,the content of this paper is summarized,and the future research directions are prospected.