The Study Of Effect Of Manufacturing Characteristics On The Stress State Of The Components In LFG

As one of the key instrument of inertial navigation system, Liquid Floated Gyroscope(LFG) plays an important role in the defence of the country. In the assembly ofprecision/ultra-precision mechanical systems, such as LFG, there is a usual phenomenon,that is, the accuracy stability is not good even with qualified parts, resulting in lowassembly yield. Therefore, system performance cannot meet the design requirements. Themain cause of this phenomenon is the deficiency of effective and quantitative method toanalyze the relationship between manufacturing features of parts and system accuracystability, which is influenced by the stress state of the parts after assembly in a large extent.In consequence, this thesis investigated the relationship between the manufacturing featuresand the stress state of parts, while taking a LFG as example.At the start, the purpose and meaning of the study on the effect of manufacturingfeatures on the stress state was discussed. Then the research trends, methods andapplication results in related fields domestic and abroad were summrized. Based upon theproblems in the research of LFG system accuracy stabilily, the main contents of this thesiswere put forward as follows:1. The surface shape error modeling studies were carried out, while taking the matingsurfaces of a typical LFG as research object. Feature extraction was carried out based onthe shape error measurement data, to establish a planar shape error model based on thelinear additivity of a primary function. The reconstruction accuracy can be greatlyimproved, if the error data was processed by spline interpolation. Then the experimentalstudy was carried out, based on using the method of modeling shape error, to verify thecorrectness of the model.2. Under the consideration of the surface shape error, the effect of the surface shapeerror on the contact state of parts, during the assembly process, was studied theoreticallyand experimentally. Numerical simulation and experimental validation were carried out tovalidate the effectiveness of the proposed method.3. The effect of manufacturing characteristics on the stress state of the floater in LFGwas studied. The kinematic equation of the fluid was established based on the theory ofFluid Mechanics and Fluid-Structure Interaction Dynamics. And thus the forces applied onthe floater and rotor surface were deduced. Then numerical simulations on the fluid motion and floater stress were carrid out through FVM based on CFD. And experimental study wascarried out to validate the numerical analysis.4. The impact of manufacturing characteristics on the temperature field and the stressstate of the components in LFG was studied. Based on the theory of Heat Transfer andThermal-Structural Coupling, the temperature distribution and thermal stress of LFGanalyzed through numerical simulation method. While taking the manufacturingcharacteristics of LFG into consideration, the influence of the temperature field on thestress and deformation of the key components in LFG was analyed.5. The effect of manufacturing characteristics on the stress state of LFG duringassembly process was studied numerically. The numerical study on the effect of the shapeerror, the relative position, and the preload were carried out by FEM, respectively, whiletaking five different LFGs as research objects. And the sensitivity of stress and deformationwere analyzed qualitatively based on the single factor method, to obtain the effects ofmanufacturing characteristics on the stress state of LFG.