The Optimal Design Of Forearm Of Bucket-wheel Stacker Reclaimer Considering Uncertainties

Bucket-wheel stacker-reclaimer is an indispensable equipment for bulk material handling.The forearm is the transitional connection part between the bucket wheel and the car body in the bucket-wheel stacker reclaimer,as well as the carrier of material transportation and the structure that stacking and reclaiming position.It is a key part of the bucket-wheel stacker reclaimer.Therefore,the stability of the forearm must be ensured during the design process.However,while blindly ensuring the stability of the forearm,the forearm will be a structure with excessive weight,resulting in waste of steel,increased energy consumption and increased weight of the whole machine.In response to this problem,this paper conducts the weight reduction optimization of the forearm under the condition of the structural stability.During the optimization,there are the following problems and difficulties.First,the forearm studied in this paper has dozens of design variables,which means that the optimization problem in this paper is a high-dimensional problem,with a large number of optimization iterations and low efficiency.Secondly,the physical quantities in the optimization problem are calculated by finite element analysis.However,the optimization with the finite element model can cause overwhelming computational cost and reduce the optimization efficiency.Finally,due to the complex structure and working conditions of the forearm and errors in manufacturing,multiple uncertainties exist in practical applications and affect the reliability of a design.In view of the above problems and difficulties,this paper constructs a parametric finite element model for the forearm of the bucket-wheel stacker reclaimer,screens the main factors with the sensitivity analysis,constructs Kriging models of the physical quantities instead of the finite model for the optimization,establishes mathematic models for multiple uncertainties,and performs reliability-based analysis and optimization on the forearm considering uncertainties.The main work of this paper is as follows:(1)Establishment of parametric finite element model and finite element analysis of the forearm.According to the structural characteristics and actual working conditions,the parameter analysis and force analysis of the forearm are carried out,and the parametric finite element model is constructed with the ANSYS APDL command flow.The finite element analysis of the forearm is carried out under different pitch angles to determine the specific location where the forearm is most likely to fail.(2)Sensitivity analysis and main factor screening for the forearm.The Morris method is used to analyze the influence the design variables of the forearm on the weight,maximum stress,maximum displacement and nature frequencies.According to the results,the design variables with significant influence on the optimization problem is selected as the main factors so that the reduction of dimension is fully achieved and the optimization efficiency is improved.(3)Construction of surrogate models of the forearm with high precision.Kriging models of the forearm's weight,maximum stress,maximum displacement and nature frequencies are constructed and those with poor accuracy are improved with the multi-point infill criterion to obtain highly precise Kriging models.(4)Analysis and modelling of the uncertainties and reliability-based analysis and optimization of the forearm.In order to improve the optimization efficiency further,before the weight reduction optimization of the forearm considering uncertainties,the deterministic optimization is performed firstly.Then,mathematic models are constructed according the characteristics.Based in the uncertainty models,the reliability-based analysis and optimization are performed on the deterministically optimal design.A lightweight and highly reliable design is obtained.