Topology Optimization Of Aft Fuselage Based On Variable-density Method

Drones are a high-tech industry that has been developing rapidly in recent years.With the popularity of drone applications and the development of related industries,the use environment has put more and more stringent requirements on the stiffness and weight of the overall structure of the drone.In order to meet the increasing structural requirements,it is imperative to optimize the structure of the UAV.Structure optimization can be divided into three levels: size optimization,shape optimization,and topology optimization.These three design difficulties increase in turn.Weight reduction has always been one of the most important design requirements for aircraft.In UAV lightweight design,in addition to using lighter materials,topology optimization is the most effective method,and it is also the most widely used and cutting-edge technology in this field.Compared with the former methods,topology optimization has more design variables,the process of optimization is more complicated,and the realization of optimization results is more difficult,too.This thesis takes the back fuselage of “ETS10”(a drone of the Intelligent UAV Laboratory of SUSTech)as the research object.According to the result of test flight,the actual working conditions of the back fuselage of the drone are obtained.Topology optimization of the skin reinforcement ribs of the back fuselage of the drone is applied.This thesis analyzes the actual working conditions and ultimate load conditions of the UAV’s rear fuselage based on the actual flight environment and flight attitude of the UAV.The rear fuselage load is the largest at full speed and the horizontal tail is fully deviated.The stress and displacement of the pure skin structure and truss structure of the rear fuselage under these two boundary conditions are analyzed.Based on the SIMP interpolation model of variable density method,the minimum flexibility is used as the objective function,a mathematical model of topology optimization with volume fraction as constraint is established,and the model is solved using OC criterion method and sensitivity filtering.Then 2D and 3D beam structures are taken as examples.The examples show the impact of the penalty factor and the sensitivity filtering radius on the topology optimization results in the topology optimization,and the influence of the boundary conditions on the optimization results.Then,to meet the structural rigidity and lightweight goals,the topology of the rear fuselage reinforcement of the drone is topologically optimized,including pre-processing and statistic analysis of optimization results,and the internal reinforcement of the fuselage is re-modeled according to the optimization results,and the final optimization results are compared with the mechanical properties of ordinary pure skin structure and truss-type fuselage structure,including the simulation and experiment.It is determined that the final optimized structure achieves a lightweight design while greatly improvingthe bending stiffness and torsional stiffness of the rear fuselage.Topology optimization has practical engineering significance.