Structural Optimization Design Of Key Components Of Engine Based On Substructure Method

In recent years,with the rapid development of computer hardware and software,CAE technology has made great progress.Accordingly,the application of CAE technology is more extensive,and the computing scale is even larger.The rapid development of modern society has also put forward higher requirements for researchers to improve the computing efficiency.In this golden age,how to simulate and calculate the results of components faster and more accurate is particularly important.As the key parts of the engine,the piston and connecting rod bearing actual working conditions in the complex.It's necessary to extract a work cycle of dynamic load of engine for simulating the real working environment of the transient structural strength better and enhancing the precision of calculation.On the other hand,the structure optimization design with minimum volume as objective function can not only reduce the amount of material used in the batch manufacturing process,but also reduce the reciprocating inertia force of piston rod during high-speed motion.However,it has a high requirement for computer hardware configuration and large amount of time to simulate millions of elements and nodes.So it is very hard to imagine directly optimizing the design of such components under dynamic load.Aiming at the existing problems,this paper introduced "sub structure method" into the engine piston connecting rod group structure optimization design process.Transforming dynamic load into static load with the sub structure method and equivalent static load method break through the bottleneck of the time-consuming of engine piston structure optimization design program.The full text analysis process as follows:(1)The equivalent static transformation of the dynamic load of the piston.Analysis andcalculation of transient dynamic loads on the engine piston,solving the maximum equivalent stress and maximum equivalent displacement moment,in the moment of the piston stress and displacement data as the basis,using the equivalent static load method for dynamic load on the static state transformation.(2)The generation of the piston static substructure model and the comparison and analysis of the result verification.The substructure of the piston is divided and the node's attenuation is calculated and a super element is generated in the area which is not important for analysis results.The part of the piston structure which needs to be optimized is parameterized and reorganized for the common element and the super element.Finally,the calculation results of the stress and displacement of the substructure model are compared with the original model,and the accuracy of the substructure model is verified.(3)The structural optimization design calculation and comparison analysis of the structure under the static substructure condensation of the piston.The structure optimization of the substructure model is calculated,and the accuracy and efficiency of the substructure method are demonstrated by comparison with the traditional calculation results.(4)The simulation calculation of free vibration of the rod body without damping.The sixteen order free modal calculation of the connecting rod is carried out,and the vibration frequency is used as the contrast data to verify the accuracy of the modal calculation results of the substructure model.(5)The choice of the main degrees of freedom of the bar structure model and the reconstruction of the link structure model.The sub structure division,generation,reorganization and result analysis of the connecting rod body are carried out to verify the feasibility of the substructure method in structural modal analysis and calculation.(6)Topology optimization design of connecting rod small head structure model.By using the link rod structure model to optimize the structure topology,the potential of the optimization of the connecting rod small head structure is explored through the analysis of the calculation results.(7)The idea of the design of the method GUI for the selection of the principal degree of freedom of the substructure of the super element is put forward.The master degree of freedom method to select the embedded ANSYS software platform,designed a GUI dialog,calculated to help choosing the suitable structure of the super element of master degree of freedom user convergence through the built-in optimization mathematical model.Through the application of substructure method in optimization design of piston connecting rod structure,the accuracy and efficiency of substructure method in structural optimization design are demonstrated.It extends the application scope of substructure method,and provides reference for other complex structures.So the substructure method has certain practical value of promotion.