Study On Static And Dynamic Multi-objective Optimization Of Gantry Machine Beam Structure

The structure characteristics of milling machine beam directly affect the machining precision and working stability. The structural optimization design of large gantry milling machine beam is studied by conceptual modeling, finite element analysis, sensitivity analysis and goal-driven optimization design method based on response surface.According to characteristic that the beam of gantry milling machine belongs to thin-walled structure, the plate and shell unit is employed in the beam structure modeling. In the scheme design, three forms of beams structure have been set up.In the scheme comparison process, the finite element numerical calculation simulated is applied to study the static and dynamic properties of beam structures. The static characteristics such as the maximum displacements, equivalent stress distribution maps and the dynamic characteristics such as the first eight order natural frequency, amplitude of beam structures proved that the static and dynamic characteristics of O beam is better than the other two kinds of structure beam.To establish the beam structure optimization model, the sensitivity coefficient of mass of structure, equivalent stress, three directions of displacement and natural frequency with the beam structure parameters were analyzed. In order to improve the optimization efficiency, reduce the amount of calculation time, the mass of beam structure, the maximum displacement of Y direction and first-order natural frequency were selected as the main target to determine effective design variables by the screening method of sensitivity ratio.In order to reduce weight, the goal driven optimization design is performed based on response surface method to solve the optimal values of design variables in static and dynamic multi-objective optimization process, and the result of the optimized structure is verified and analyzed, it shows that the aim of beam structure lightweight design is obtained.The modeling method, research process and conclusions of this paper have certain reference significance for the structure optimization design with the characteristics of thin shell, such as vehicles, ships and plane.