Robust Performance Optimization Research Of A Forklift Truck Beam System

Forklift truck combine the cargo fork and lifting mechanism,can realize the function of handling,stacking and short distance transport,expanded its adaptability and flexibility,thus effectively improve the work efficiency,reduce labor intensity and safety work concerns.Research for the forklift truck door frame system in this thesis,based on the finite element software to analyze the structure performance and robust optimization study,completed the hoisting handling the door frame system parametric modeling,experiment design and the kriging model,montecarlo sampling and more island six sigma robust optimization design of genetic algorithm integrated research,and has carried on the door frame system dynamic characteristics and design variable parameter sensitivity analysis.This paper completed the initial design of the steel frame system of local dangerous section strength,stiffness,stability analysis,parametric modeling and static mechanics analysis by using APDL language,which siginificantly improve design efficiency.Through the analysis of the static results,we can quickly get the results of the stiffness for the structural system,and find out the weak part,which is conducive to the follow-up analysis.On this basis,the modal analysis of free state,constraint state,load state and prestress state is carried out on the door frame system,and the dynamic stiffness of the system is checked.Based on the working conditions of the hoisting truck,the resonance analysis based on the excitation vibration of the road excitation is completed,which provides a reference for avoiding the resonance in the practical working conditions.Harmonic response analysis using modal superposition method is completed,most likely to find out the structure resonance occur under the external excitation frequency range,so as not to arouse resonance caused by structural failure or fatigue.Combine GRA(Gray relational degree)algorithm,pearson algorithm model and integrated use of correlation degree analysis to the design variables,then draw the pareto diagram,Identified 7 final design variables in a wide range of design variables in the primary,reduce the uncertainty in the process of design that design parameter's wave effects on optimization results.With the optimal latin hypercube experiment design method to generate test matrix,using Kriging agent model fitting out of the door frame system structure precise approximation model,instead of the original implicit nonlinear structural model optimization iteration in order to improve the efficiency of optimization,saves the computing cost.The monte carlo method,descriptive sampling was used to analyze the deterministic optimization results,and the six sigma robust optimization design was carried out in combination with the multi-island genetic algorithm.The six sigma robust optimization design for steel frame system,make the quality to reduce 11.24%,the structure size distribution more reasonable,realize the lightweight as well as the reliability levels increase to 8 sigma,reliability increased to nearly 100%,greatly improving the robustness of the optimization results.