Study On Semi-actve Shock Control Technique Of Tow-Stage Isolation System Using Electromagnetism Absorber

Research about mechanical equipment against shock is reviewed in this thesis; the importance and necessity of investigation into anti-shock performance of two-stage isolation system are illustrated. The shortages in the previous studies are analyzed. The semi-active control method of using tuned vibration absorber in two-stage isolation system is proposed. Some theoretical and experimental studies are carried out to validate its feasibility, and the semi-active shock control is implemented on a two stage vibration isolation system.The dynamic model of two-stage isolation system under shock excitation is developed. Newmark approach is adopted for the calculation program written and the system shock response is derived from the program. The validity of the results from the calculation program is verified by comparison with those calculated by using ANSYS software.The dynamic model of two-stage isolation system with vibration absorber is established. The effects of different parameters of semi-active vibration absorber on the performance of system anti-shock are analyzed numerically, the numerical results is validated by some experiments. It is shown from the numerical results that placing the vibration absorber on mass block of upper stage can achive a better anti-shock compared with other location, and there exists a set of optimal absorber parameters achieving the optimal anti-shock performance. When the parameters of vibration absorber are optimal, the amplitude of shock excitation has no effect on the anti-shock performance of system which is however affected by the time and wave forms of shockexcitation.A semi-active vibration reduction and shock resisting control system is designed including electromagnetism semi-active vibration absorber, DSP controller and constant current source. Some experimental studies on the control effectiveness and response time of such system are conducted on the two stage vibration isolation setup. It is demonstrated by the results that: such system can work well in two working status, i.e. vibration reduction and shock resisting; these two status can transiently switch, and then the design target of "absorbing vibration in the peacetime, and resisting shock in the wartime" is realized.