Research On Shafting Alignment Technology Affected By Dynamic Factors

Rational alignment method is usually used in shafting alignment in China, it hasn't considered dynamic factors, but it has been researching in overseas. In this dissertation, finite element method and shafting alignment software have been used to give the calculation method of some dynamic factors, including the wave force,marine vibration exciting force,bearing stiffness and so on, which could have an effect on the shafting alignment. Meantime, a shafting alignment calculation model is built and calculated, which rationally gives a theoretical basis and calculation method of the ship shafting alignment in consideration of the dynamic factors. The main contents of this dissertation are given as follows:(1) Model building. A bulk ship is built in the finite element software PATRAN by a ratio of 1:1, which laid a good foundation for future studies.(2) The influence calculation of the wave force. In this program, different phases and different head sea angles Ariy wave forces is exerted on the FE model of the ship hull in the form of PCL (Patran command language) to figure out the influence degree of the wave to the ship hull deformation, among which, the wave parameters is in accordance with the billow of the National Standard (GB). Besides of this, the compiled PCL is applicable to the other ship hull FE model, it could be used to load different draft,phase,inclination angle and period wave force, the method is effective and convenient.(3) Diesel engine vibration exciting force. Summarized the calculation method of the diesel engine exciting forces and found the order of engine's biggest external moment,X-moment and H-moment, meanwhile those external forces have been loaded to the FE model of the diesel engine, which was used to calculate the influence degree of those forces to shafting alignment.(4) Bearing dynamic stiffness. Analyzed the sliding bearing theory, and calculated the before and after stern tube bearings, intermediate bearing oil film stiffness when diesel engine in rated conditions by MATLAB software; and then, finite element method was used to calculate the dynamic stiffness of the hull at these places such as the before and after the stern tube bearings,intermediate bearings; Built the intermediate bearing model and calculated its dynamic stiffness and finally got the composite stiffness.(5) Hydrodynamic performance of propeller. Made an in-depth studied of Hydrodynamic performance of propeller, and specially introduced the steady surface panel method of bearing forces calculation when the propeller under the influence of hydrodynamic. The characteristic of bearing forces has been analyzed in different speed and load, which provided important reference for the affection researching of the shafting alignment.(6) Shafting alignment calculation. Built a bulk ship model in dynamic shafting alignment software EnDyn, Wave influence has been taken as an example for the shafting alignment calculation, and assessed the influence of wave to shafting alignment in stopped,hot-stopped and hot-running conditions, finally proposed the improvement scheme for alignment.