Studies On The Anti-shock Analysis Of Propulsion Shafting Of Warship

The warship in commission and the equipments on board are inevitable to encounter shock environment. Then the hull structure's and the equipments' ability to sustain the shock load, induced by the contact or non-contact underwater explosions, is paid most attention by the designers and engineers. The propulsion shafting, including the transmission shafts and other accessories from output end of engine to propeller, is an important part of the power system. Under the shock load, the displacement response and stress response, mainly including the shaft section and bearings, have a direct connection with the vitality of power system. Therefore, the studies on the anti-shock ability of the propulsion shafting are full of practical meaning for navy.Firstly, the theories of anti-shock analysis are investigated systematically, then the calculational model of propulsion shafting of warship for shock analysis is established and some factors of model-buliding are discussed respectively. Based on these, the model-building methods of rotating shafting and the non-linearity problem are futher studied. Secondly, the testing platform to verify the model-building approach is built by using the LMS and the calculation model is verified via modal testing. Finally, on the basis of the previous calculation result and anlysis, the preliminary improvement scheme is proposed for a pratical example. Then the optimization design is implemented based on the genetic arithmetic (GA). In detail, the main research work is as follows:(1) The underwater explosion theory, the fluid-structure interaction theory of ship dynamic response to underwater explosion, the finite element model-building theory of propulsion shafting for shock calculation and the correlative shock response computation methods are expatiated comprehensively. Espescially, the "Large Mass" model, which is suitable for solving the response problem of shafting when the loads at different bearing position are different, is presented.(2) Regarding the propulsion shafting of warship (A) as the research object, the components with great rotation inertia moment, the supporting bearing model and the bearing gap model are explained in theory, then the respective effects on the shockresponse are discussed according to the calculation result.(3) According to the operating practice of shafting, the shafting rotation speed, the propeller thrust and the geometrical non-linear factor are taken into consideration, and the relevant model-building theories are proposed firstly. Subsequently, the relevant finite element models are built and the numerical calculations are carried out for the propulsion shafting of-warship (B). On the basis of which the effect on shock response of different factor is discussed respectively.(4) Considering a real shaft as the testing object, the modal testing is used to measure the systemic dynamic parameters of the real shaft, such as natural frequencies, modes, frequency response functions, and so on. Furhtermore, according to the model-building theory brought forward previously, the finite element model of the real shafting is built and the numerical calculation is implemented, from which the systemic dynamic parameters are gained. Subsequently, based on the modal analysis technique and model amending idea, the calculation results and testing results are compared and the finite element model-building theory is validated.(5) According to the displacement shock response result and the related anlysis of the shafting of warship (B) from Chapter 4, a primary mending project is suggested. Then the strength checking calculation is carried out. In the next place, in the light of the goal of anti-shock design, the maximum potential energy, stored in the bearings during the shock load acting stage, is chosen as the target function. Then the optimum design is put into practice based on the genetic arithmetic (GA).The above investigations perfect the calculational model of propulsion shafting of warship for anti-shock anlysis further, which provides theoretic guide for simulation calculation, shock response evaluation, vibration reduction and shock isolation design, and so on.