ANALYSIS, DESIGN AND EXPERIMENTAL VALIDATION OF A SIMPLIFIED COMPOSITE STRUCTURE FOR A BOX WING AND A METHOD FOR ITS PRODUCTION

Transcription

1 ANALYSIS, DESIGN AND EXPERIMENTAL VALIDATION OF A SIMPLIFIED COMPOSITE STRUCTURE FOR A BOX WING AND A METHOD FOR ITS PRODUCTION ISCM 2012 Stade, Germany Plamen Roglev Technical University Sofia Branch Plovdiv plroglev@mail.bg

2 Design objective simple and efficient composite wing structure for an experimental UAV Take-off weight Maximum speed 7 kg 50m/s Design load factor +6/-4 Span 1,8 m Overall surface of wings 0,5 m 2 Sweep of front wing 30 о Sweep of rear wing -20,5 о Dehidral of front wing 17 о

3 The joined-wing / box-wing promises many structural, aerodynamic and aeroelastic advantages

4 Joined-wing configurations have been proposed since the earliest days of aviation Bleriot III Lee-Richards

5 Wolkovitch first investigated the joined-wing in more detail

6 There are many possible variants

7 Numerical analysis Spanwise aerodynamic load distribution Vortex Lattice Method Program -VLMpc

8 Section lift coefficient along the span

9 Approximation of the distribution of the lift coefficient along the span APPROXIMATION OF THE DISTRIBUTION OF C L ALONG THE SPAN OF THE WINGS 0,5 CL 0,4 0,3 0,2 0,1 y = -0,6121x 2 + 0,4436x + 0,3464 y = -0,3932x 2-0,0245x + 0,4178 CL(z)front CL(z)rear Poly. (CL(z)rear) Poly. (CL(z)front) 0 0 0,2 0,4 0,6 0,8 1 z,m

10 Structural behaviour investigation Von Mises Stress distribution for an isotropic shell Condition III- I- Positive Low Angle of Attack Condition IV- I - Negative Low Angle of Attack

11 Influence of the type of joint: models studied

12 Von Mises Stress distribution of Model 1 rear wing with no dihedral

13 Von Mises Stress distribution of Model 2

14 Von Mises Stress distribution of Model 3

15 Von Mises Stress distribution of Model 4

16 Condition III simulation results Max von Mises Stresses at the Roots of the Wings Front Wing Rear Wing 250 МРа Cantilever Model 1 Model 1' Model 2 Model 3 Model 4

17 Max twist of the wing 0,04 0,02 0-0,02 rad -0,04-0,06-0,08 Cantilever Model 1 Model 1' Model 2 Model 3 Model 4-0,1-0,12-0,14-0,16-0,18 The joined wing type proposed by WOLKOVITCH(Model 3) leads to divergency and should be avoided

18 Influence of the distribution of the load carrying material in the section of the wing: variants studied

19 FEA results Max displacement mm EVEN WOLKOVITCH TRADITIONAL Distribution of Material Scheme

20 Max von Mises Stresses at the Roots of the Wings МРа EVEN WOLKOVITCH TRADITIONAL Distribution of Material Scheme FRONT WING REAR WING

21 EXPERIMENTAL COMPARISON WINGS WITH MATERIAL DISTRIBUTION ACCORDING TO WOLKOWITCH AT LOAD FACTOR 3 WINGS WITH EVEN MATERIAL DISTRIBUTION AT LOAD FACTOR 4

22 Experimental results The specimen with Wolkovitch type distribution failed at a load factor 3.2 The specimen with even distribution failed at a load factor 4.7 The failure occurred first at the middle of the rear wing and than at its root The type of failure was of local buckling of the compressed skin Load factor 5 4,5 4 3,5 3 2,5 2 1,5 1 0, Displacement, mm The best variant for the material distribution in the section of the wings for a simplified construction is the even distribution. Wolkovitch Even

23 Technological scheme SKIN PRODUCTION SKIN AND CORE BONDING CONTROL SURFACES CUTTING FRONT AND REAR WINGS JOINING CORE SHAPING PAINTING

24 Production method advantages High-temperature cure resin can be used which produces laminate more resistant to compression No finishing sanding and filling A lighter and stronger laminate is achieved Short cycle time of production

25 Acknowledgments I would like to thank Dr. Dimo Zafirof As. Professor at Technical University Sofia Branch Plovdiv and Dr. Hristian Panayotov for the precious assistance they provided during this study

26 References 1. Gay D., Hoa S., Tsai S. - Composite Materials Design And Applications, CRC Gallman J., Smith S., Kroo I. - Optimization of Joined-Wing Aircraft, JOURNAL OF AIRRCRAFT RCRAFT Vol. 30, No. 6, Nov.-Dec Kroo I. - Nonplanar Wing Concepts for Increased Aircraft Efficiency, Wolkovitch J. - The Joined Wing an Overview, AIAA, Zafirov D. I. Joined Wing UAV with Ducted Fan. UAV World Conference, Frankfurt/Main Zafirov, D., Joined Wings Thrust Vectored UAV Flight Envelope. AIAA Papers, AIAA , AIAA Atmospheric Flight Mechanics Conference, Toronto, Панайотов, Х., Д. Зафиров Изследване на аеродинамични характеристики на съчленено крило по метода на дискретните вихри ЮНС 10 години катедра Въздушен транспорт октомври 2003