Journal ofScience & Technology 100 (2014) 020-025 Problem of Elastic Deformation for Aircraft Wings with the Variation of Velocity and Incidence Angle Hoang ThiBich Ngoc^*, Dinh Van Phong', Nguyen JManh Hung', Nguyen Hong Son''^ 'Hanoi Umversity ofScience and Technology, No I, Dai Co Viel Str Hai Ba Trung, Ha Noi, Viet Nam -Hanoi University of Industry Received: Februaiy 28, 2014; accepted: April 22 2014 I Abstract | The structure of aircraft wing is a closed tube affected by aerodynamic forces Aerodynamic forces distnbuted on the upper side and lower side of wing are determined by a 3D numerical method which are external forces and considered as known input parameters The problem of elastic deformation for the wing is solved with a 3D degenerate model, discretized and approximated by finite element method The built program allows calculating and determining the location and value of the most dangerous stress on the wings which depends on the value and direction of the free flow velocity with a certain structure of wing, from that it allows determining the limit of elastic deformation for wings depending on the velocity anil the incidence angle of the free flow Keywords; 3D wing, Numerical methods, Aerodynamic forces, Elastic deformahon Introduction The structure of aircraft wing has the shape of aerodynamic profile followed the velocity direction and it is a closed tube, so the shell thickness is very small compared lo the rest of the field size This is the basis for the choice of degenerate 3D models in structural calculations Aerodynamic load on the wing is very large, larger than the weight of the entire aircraft Aerodynamic load distnbution is caused by the pressure difference between the upper side and the lower side of wing With a defined structure, distributed load varies due to the velocity and the direction of motion (angle of incidence) If aerodynamic problem allows us to identify threedimensional load distribution on the wing, the elastic deformation problem will facilitate the development of the model on the three-dimensional structure In the limited framework of this article, only the method solving the elastic deformation of the wing is introduced Details of the method determining the 3D aerodynamic forces are refened to [1] Results of aerodynamic pressure distribution on the wing are extemal force given to solve elastic deformation Results of elastic deformation problems are worked on analysis of aspects related to limitation of elastic deformation of the wing, Method of Calculation 2.1 Calculation of aerodynamic of wing and length of the finite wing span needed to be done by a numerical method to determine the pressure distribution on the upper side and the lower side of each specific field Hereby, calculations are carried by the combined doublet and source singularity distiibution method (Fig, 1), Fig For determining aerodynamic forces on 3D wing by using doublet - source singularities Velocity potentials at a point P(x,y,z) induced from sources of constant strength O and doublets of constant strength |J ananged on the discrete elements of the upper side and the lower side are as followed; dS (Ps{x,y,z)^-—\ 4.T J {^(x-x,f+(y-y^y+z' zdS '\^{x-x,)-+{y-y^)'+z'T forces The determination of the forces on the 3D aerodynamic profile wing considering the thickness • Corresponding author: Tel: (+S4) 912.313 350 Email: ngoc.hoangthibich@hust.edu.vn (1) The velocity components (u,v,w) at a pomt are determined from the derivatives of velocity f '"'-'