Lightweight Design Of Seedling Box Of Rice Transplanter Based On Ensemble Approximate Model

The lightweight of mechanical equipment can not only save the raw materials,but also reduce the cost and environmental pollution.So it has significant social,environmental and economic benefits,which can promote the construction of a conservation minded society.The lightweight of mechanical equipment component has a greater development space with the rapid development of industry and manufacturing industry and the urgent need for energy saving and emission reduction.At the same time,it is also facing a huge challenge.The lightweight design is a complex optimization problem,it isn't only to lighten weight,but also to ensure that the performance can stay the same or even be improved.The approximate method is applied in this paper to the lightweight design of rice transplanted seedling box,in order to improve the computational efficiency and speed up the optimization process,while the reliability of the optimization results can be ensured.Firstly,the simplified geometric model of the seedling box is established,and the finite element model is built in ANSYS.The static performance which is the bending stiffness and torsional conditions under the three conditions and the dynamic performance of the first eight natural modes are carried out to obtain the initial performance,and to provide the foundation for the subsequent optimization.The analysis results show that the values of bending stiffness EI₁ and torsional stiffness GJ are bigger than actual needed,and there is a further optimization space.At the same time,it is necessary to ensure that the bending stiffness EI₂ and the first order natural frequency f₁ are large enough.Then,the key technologies related to the approximation method are studied thorough,which includes the design of the experiment,the construction of the approximate model,the evaluation index of the model precision and the calculation method of the weight coefficient of the ensemble approximate model.The responses approximate models for structural response of mass?M?,bending stiffness?EI₁ and EI₂?,torsional stiffness GJ and the first order natural frequency f₁ were built in this paper by using the optimal Latin hypercube experiment method.It is identified that using the polynomial response surface method to build the mass approximate models,using the polynomial response surface,the radial basis function and the Kriging to build the ensemble model of other responses after computing weight coefficient with the minimize mean square error method.The results show that,the precision of the ensemble model is higher than single model.The mathematical model of the lightweight is built,nine dimensions including thickness and sizes of some parts are taken as the design variables while the minimum mass is taken as the objective function,the bending stiffness?EI1 and EI2?,the torsional stiffness?GJ?and the first order natural frequency?F1?are taken as constraints.An optimization platform integrated optimization and approximate model components is built and the optimization is solved by particle swarm optimization in Isight.The results show that the optimized value can meet the design requirements in general except the bending stiffness EI₁.So,the structural improvement of the model is put forward,and the scheme is determined.The simulation analysis shows that the scheme is feasible as all the performances can meet the design requirements.