Aircraft Structure Weight Estimation Based On Equivalent Method

During the aircraft design process,the aircraft weight is related to the flight performance and economic applicability of the aircraft,which is one of the important factors that determine the success of the aircraft design.However,due to various limitations,the traditional empirical formula method can not meet the weight estimation of new configuration and new material aircraft.The finite element method is very time consuming.Therefore,in order to quickly and accurately evaluate the aircraft weight,this thesis develops a method of weight estimating based on an equivalent modeling.In this thesis,the Equivalent Plate Method(EPM)is applied to the estimation of the wing structure weight in the overall design stage of the aircraft.The Equivalent Plate Method based on the first-order Shear Deformation Plate is realized by the MATLAB and C language mixed programming technology.Based on the polynomial displacement function,the method analytically describes the shape change of the whole structure under load,and solves the displacement analytical solution of the model through static and dynamic analysis.Then the shell-based equivalent modeling method of the fuselage section is developed and verified,according to the EPM method.This method has a faster calculation speed under the premise of ensuring the accuracy of calculation,and is suitable for new material aircraft.It is a new method between empirical formula and finite element method.The main work of this thesis are as follows:(1)Based on the mixed programming of MATLAB and C language,the equivalent plate modeling of the wing based on the first-order shear deformation theory and the modeling of the equivalent shell fuselage section were realized.(2)The feasibility of the equivalent modeling method is verified by the finite element modeling analysis of the wing box segment and the reinforced shell section of the fuselage.The influence of different Ritz basis functions on the calculation results is investigated,and the selection suggestions are given.(3)Based on the MATLAB program,the iSight optimization software platform is used to establish the weight estimation and optimization process of the wing and fuselage structure,and the optimal weight meeting the stiffness and strength requirements is obtained.