Research On Related Dynamics About The Power Transmission System Of Special Ships

Marine power transmission system is to realize the energy transfer of Marine engine and propeller, at the same time, will generate axial thrust of the propeller rotation through the shafting to the hull to push ship forward system, ship power plant is the indispensable important component in the system. As a special military uses of underwater ship propulsion shafting in the process of navigation will encounter more complex hydrological environment and stress state. Also may be subjected to contact explosion and non-contact underwater explosion, natural weapon launch the recoil force of the effect of impact load, will inevitably produce vibration. Destructive vibration will affect the life and the working reliability of the machinery, can even directly cause the moving parts or the whole machine seriously damaged. Vibration caused by noise can reduce the concealment of the ships, often constitute the enemy communications equipment in wartime search object, lead to attack the enemy weapons. Therefore, to the study of the dynamics characteristic of shaft system is particularly important. But the literature shows that after the dynamics characteristics of underwater ship whole power transmission system of the research is relatively less.This research mainly based on a military underwater ship power transmission device for the model of actual examples, the drive shaft and the related dynamic characteristics research and analysis of the important components. Aimed at the structure characteristics of each part of the device, select the dynamics of the most typical and the most effective method, selected the typical system dynamics properties, outstanding impact on the system of several major parts:the main transmission shaft, high-pressure pump, main diesel engine crankshaft, change gear box of the related properties were studied. Combined with concrete example has carried on the theory of computation and simulation analysis, the main research work is as follows:(1) Main transmission shaft of the underwater ship structure is relatively complex, is more than a quality of the elastic vibration system. From the piston connecting rod crank mechanism, transmission gear, the back of the clutch, main motor and propeller between multiple attachments. The vibration characteristics of the concealment of the hull, noise, stability and reliability of the power system operation plays an important influence. Is the basis of studying the characteristics of power transmission system dynamics. In this paper, the main shaft system according to its specific structure, using transfer matrix method, the lumped mass model, to solve the inherent frequency and vibration mode. By the rotor system of discrete equivalent principle of quality, focus on the equivalent formula of moment of inertia and shaft stiffness. Based on discrete equivalent lumped mass model, this paper discusses hybrid bearing transfer method, in the calculation of hybrid bearing special treatment, and the multi span child with general transfer matrix of hybrid bearing shafting. And the frequency equation is solved by using MATLAB software, the critical Angle speed and get the order critical speed, and on the basis of rotor each order modal are obtained.(2) Scavenge pump as an important auxiliary body of underwater ship’s main diesel engine, in the practical work is one of the high failure rate of equipment. Characterized by high speed, big noise and strong vibration conditions. In this paper, in order to improve the study of generality, will simplify the system dynamics modeling for rolling bearing-bias rotor system, give full consideration to the disc offset, gyroscopic moment, rubbing, and the influence factors of nonlinear rolling bearing force, dynamics modeling and nonlinear response analysis. According to the second Lagrange equation established a more complete rolling bearing-offset single disc rotor 8 degrees of freedom dynamic equations, and use the numerical method to solve it, by analyzing the model of the dynamic characteristic, the rotational speed, disk eccentricity, bearing clearance, contact stiffness, disc roller offset and damping effect the nonlinear response of the system.(3) For main diesel engine crankshaft torsional vibration characteristics of the research mainly considers the piston, connecting rod with variable moment of inertia of factors effect on the torsional vibration of diesel engine shafting system problems are studied, considered in the calculation of the nonlinear dry friction between the piston and cylinder and nonlinear elastic restoring force the influence of the torsional vibration of shafting, some conclusions are drawn. On this basis, the diesel engine was established based on Lagrange equation coupled nonlinear dynamic model of shafting bending and twisting, respectively, analytical method and numerical integral method is applied to nonlinear dynamics characteristic of shaft system are simulated. The results show that eccentric mass, variable moment of inertia and nonlinear dry friction between the piston and cylinder to nonlinear vibration of shaft system behavior has a different degree of influence. Conclusion to improve the system dynamic characteristics, to ensure the safe and stable operation of internal combustion engine provides a theoretical basis.(4) Marine gearbox dynamic finite element analysis. Large Marine helical gear tooth geometry model is complex, its mechanics analysis is very difficult. With the development of computer technology, in the study of gear is widely used to calculate the stress and strain finite element method.Using finite element software Abaqus finite element analysis model of gear transmission system was established first, each bearing supporting stiffness spring stiffness to simulation of the binding between the gear (tie) constraints, thus solving nonlinear contact mode, simplified as a linear modal solution, to solve the dynamic characteristics of transmission system and drive system of excitation frequency, map Campbell, combining with the system vibration model, amplitude and phase of the energy, for the whole transmission system resonance analysis. Using Lanczos method to solve the inherent characteristics of the system. Based on stress wave at the same time to analyze the dynamic meshing gear stress, using Abaqus software module, display in the dynamics of involute cylindrical gear pair turned a few 3 d entity of gear dynamic contact problem are simulated, also analyzed the transient contact stress distribution and stress of gear tooth transmission case, get a good contact form.