Dynamic Analysis And Structure Optimization Of An Engine Connecting Rod

The connecting rod is one of the core components of the engine.During the engine operation it bears the alternating load generated by the gas pressure and the reciprocating inertial force.The connecting rod is responsible for transferring the force received by the piston to the engine crankshaft and converting it into torque.The state of the connecting rod directly affects the stability and reliability of the engine.For special engines for drones,in addition to ensuring the reliability of each component,it is also necessary to lighten each component.The main research content of this paper is the connecting rod of the UAV special engine,and carries out three-dimensional modeling of each part of the connecting rod group.The finite element model of the connecting rod group was established by Hyper Mesh,and its accuracy was verified by modal analysis.The results of modal analysis can confirm that the mesh error of the connecting rod finite element model is within a reasonable range and can be used for subsequent analysis.According to the requirements of multi-body dynamics simulation calculation,the finite element model of the connecting rod is modally reduced,and the multi-body dynamic model of the connecting rod is built according to the actual engine parameters.After verifying the multi-body dynamics model,the dynamic load distribution of the connecting rod at any time in the engine working cycle is obtained.And it is output as the load boundary condition of the connecting rod finite element analysis.The dynamic stress distribution of the connecting rod is obtained by using the ABAQUS software to analyze the dynamic load of the connecting rod.Based on the dynamic analysis and dynamic stress results of the connecting rod,it is determined that the connecting rod has a certain lightweight design space.Therefore,topology optimization and size optimization of the connecting rod were carried out,and the topology optimization pointed out the direction for the subsequent size optimization.Subsequently,ISIGHT multidisciplinary design optimization software was used to integrate multiple finite element analysis software to optimize the connecting rod structure under constrained stress and strain conditions.An approximate model was constructed through DOE sampling,and the approximate model was optimized through multi-island genetic algorithm.The obtained design value is substituted into the finite element model for analysis.The simulation results are compared with the response surface prediction results to ensure the accuracy of the approximate model optimization results.The mass of the connecting rod after structural optimization was reduced by 59 grams.The fatigue strength analysis and bench test of the optimized connecting rod proved the safety and reliability of the optimized connecting rod.