Dynamic Structure Optimization And Fatigue Life Analysis Of Bridge Crane Reducer

As manufacturing and handing field turn to indoor workplace slowly, the bridge crane plays a more and more important role in the production and logistics. So the bridge crane must possess high reliability, small vibration, lightweight, and stability character. As the key component of the bridge crane, the reducer determines the overall behavior of the crane. So the research on dynamic response simulation, dynamic optimization, fatigue life prediction and reliability analysis of the reducer has great theoretical significance and practical value for the vibration reduction, and lightweight of the bridge crane.This paper is supported by National Science and Technology Support Program. Using of the theory of vibration analysis, the theory of fatigue damage, the method of optimization design and the finite element simulation technology, the dynamic structure optimization and the fatigue life analysis of bridge crane reducer are carried out. The main research work in this paper can be summarized as follows:① The parametric finite elment model of the bridge crane reducer is established, the natural frequency and the natural mode can be calculated by the Block Lanczos method. On the basis, the dynamic response is studied by mode superposition methd in consideration of excitation including stiffness excitation, error excitation, meshing impact excitation and the variation of input torque. Subsequently, the vibration displacement, velocity and acceleration of bridge crane reducer can be obtained.② Picking the structure wall thickness as design variables, the vibration acceleration of the reducer housing as objective function, and the volume of the box as state variable. the dynamic optimization modal of structure sub-system is established based on parametric finite elment model. The optimal solution of design variable can be got by Zero-order optimization method. Finally, the vibration response is re-evaluated using the optimized parameters.③ The vibration differential equations of transmission system can be derived based on the torsional dynamics model of reducer by lumped parameter method, then the vibration acceleration analytical expressions of each component is obtained by using the harmonic balance method. On the basis, then the dynamic optimization modal of transmission sub-system can be established, taking the modulus, tooth number and the helix angle etc. as design variables, the transmission ratio, the strength, the center distance etc. as constraint variables, the vibration acceleration and mass as the objective function by linear weighting method. The optimal solution of design variable can be got through the multivariable mixed discrete optimization program based on branch-bound algorithm.④ Picking the dynamic contact force as the load spectrum, the corrected S-N curve of gear material is calculated according the GL specification, combined with the static strain and stress which are got by static contact analysis. Then the fatigue life analysis of the gear pair can be conducted based on the nominal stress method by Fe-safe software. The reliability analysis model of the optimized input helical gear pair after optimization can be established, which picked the input speed, the tooth width, the elastic modulus of materials etc. as random variables. Then the reliability and the reliability sensitivity of the gear pair can de analyzed.