Study On The Vibration Control Of Offshore Platform Diesel Generator Unit And Its Cabin

Vibration of offshore platform diesel generator sets will seriously affect the normal operation of other equipment and the safety performance of platform structure,at the same time,it will also cause acoustic pollution to the platform cabin noise environment.Vibration and noise control level of platform has become an important indicator of platform delivery.Especially,IMO began to implement compulsory amendments to the vibration and noise of ship compartments.Compared with the original standard,the new standard puts forward higher requirements to reduce the noise of living compartments by 5 dB.Therefore,the research on vibration and noise control of platform power plant and cabin has become the focus of attention in the design of new offshore platform.Based on the finite element theory,this paper chooses the vibration frequency response function of the platform as the evaluation index of the vibration reduction effect,and studies the control of the full frequency band vibration of the diesel generator set and its cabin by means of vibration isolation,viscoelastic damping and dynamic vibration absorption technology.The specific research contents are as follows:The finite element model of offshore platform and generator set is established,and the vibration isolation of diesel generator set based on elasticity is studied.Based on equivalent stress,vertical stiffness and torsional stiffness,a reasonable common base structure is designed.On this basis,the single-layer vibration isolation design of the whole unit is studied,and the effects of the installation form,location,stiffness and damping ratio of the isolator on the vibration isolation effect are analyzed.The results show that the centralized installation and symmetrical distribution of the center of gravity of the isolator are the best.The increase of stiffness and damping will reduce the isolation efficiency,but the effect of damping is lower than that of stiffness.In this paper,the viscoelastic damping of platform generator cabin is studied.The influence of damping laying form,number of damping layers,sticking position and thickness of damping layer on vibration reduction effect is analyzed.The results show that the loss factor of the damped structure can be significantly increased by the restraint layer,and the multi-layer laminated composite damping material is better than the single-layer damping at the same damping thickness.In the structure of platform compartment,the influence of the damping and thickness of the rib plate and the bottom plate of the cabin on the vibration characteristics of the platform is greater than that of the bulkhead.On this basis,the combination of vibration mass and viscoelastic damping is applied to optimize the design of the vibration reduction method,so that the vibration response of the platform can be effectively controlled at medium and high frequencies.Aiming at low frequency vibration,the effect of dynamic vibration absorption technology on vibration reduction of diesel generator set is studied.The influence of the installation location,mass and damping ratio of the absorber on the vibration absorption effect is analyzed.The results show that the frequency band of the absorber is widened when the mass and damping ratio of the absorber increase,but at the vibration absorption frequency,the mass increase plays a positive role,while the damping effect is opposite.On the premise that the total mass of the absorber is unchanged,the effect of the combination application of different frequency absorbers on the vibration reduction effect is studied.The results show that this method can widen the frequency band of vibration reduction and effectively reduce the low frequency vibration of the platform.The research methods and results in this paper have important theoretical guiding significance and engineering application value for the study of vibration reduction performance of new offshore platform diesel generating units and their cabins,and also provide reference for the full-band vibration reduction research of complex structures.