Mesh Performance Simulation And Fatigue Analysis Of Beveloid Helical Gears In Gearbox With Small Shaft Angle

Beveloid helical gears are adopted in marine gearbox with small shaft angle, themain characteristic of this gear is its modification coefficient varies along the axes, theneed of intersecting and crossed axes transmission in marine gearbox can be well metby this feature. This paper uses the spatial gears meshing theory, fatigue life evaluationtheory and dynamic contact analysis method comprehensively, carries out researchabout gear tooth surface generation of involute and non involute beveloid gears,contrastive analysis the meshing performance and fatigue life of the gear pairs withdifferent profile. Correlational research will be of great theoretical significance andengineering application valuation in choosing the appropriate beveloid gears’ parameter,improving the bearing capacity and extending the service life.The research work in this thesis can be summarized as follows:(1) Using the normal tooth profile equations of counterpart rack, the transversetooth profile equations are established, the coordinate transformation matrix of imitatingmachining involute beveloid gear is derived based on the transverse tooth profile. Thenthe tooth surface equations of involute beveloid helical gear can be built up. Accordingto the spatial bevel gear meshing theory, the assembly relation of involute beveloidhelical gear pair can be determined, the assemble model of this gear pair is constructedby UG software.(2) Taking the involute beveloid helical gear as the imaginary cutter, mesh equationof involute and non involute beveloid helical gears is established; and then their toothsurface equation can be obtained, after that the solid model of non involute beveloidhelical gear can be built up. On the bases of assemble relation with the involutebeveloid helical gear, the assemble model of non involute beveloid helical gear pair canbe constructed.(3) With the help of ANSYS/LS-DYNA, the solid models of the two kinds ofbeveloid gear pairs are discretized, and then the contact finite element model can becreated. Through the dynamic contact finite elements simulation, the tooth surface stresscontour, tooth resultant force and the max von Mises stress curve can be obtained, theeffect that tooth profile impact on the mesh performance is analyzed contrastively.(4) Taking up the dynamic contact force of gear pairs during rotation as the loadspectrum，calculating the S-N curve of gear material based on GL standard, combining the stress strain result from static simulation of gears, fatigue life analysis can beconducted to the two kinds of beveloid helical gear pairs by ANSYS/FE-SAFE, thenthe logarithmic fatigue life and the fatigue safety factors of beveloid helical gears withdifferent profile can be obtained.