A Seminar IIIOn

“Flight Dynamics and Numerical Analysis of an Unmanned Aerial Vehicle (UAV)”

ByMs. Harshada A Gurav

GuideProf. A. R. Suryavanshi

Department of Mechanical EngineeringZeal Education Society’s

Zeal College of Engineering and Research, Pune.Savitribai Phule, Pune University

[2015-16]

CONTENT

Abstract Introduction Seminar II Review Case Study Summary References

ABSTRACTRecent applications of an UAV requires good sustainability and

performance. Various types of mathematical simulation methods can be

adopted for analysis of UAV before actual production. The simulation

method can reduce the flight period, cost and risk. The case studies are

done for structural, vibration, fluid and landing analysis for structural

safety and performance. Maximum possible loads are applied to

observe and study extreme conditions. A total of 10 modal frequencies

are obtained for finding the resonant condition. The landing analysis

study kept limited to the stresses and deformation calculations and

fluid analysis is done to analyse the effect of air on UAV in case of drag

and pressure.

INTRODUCTION An unmanned aerial vehicle (UAV), commonly known as

a drone, is an aircraft without a human  pilot on board. Its flight is either controlled autonomously by computers in the vehicle, or under the remote control of a pilot on the ground or in another vehicle. [1]

Review of Seminar II

Flight Dynamics

LiftWeight

Drag

ThrustBlade

Flapping

Pitch

Roll

Yaw

Blade Flapping [9] UAV Movements [5,6] Forces acting on UAV [7,8]

Components of UAV [2] Flight Dynamics [4]

Review of Seminar II

TYPES

Size

Range

Altitude

No. of rotors

Analysis

Static

Dynamic

Aerodyna-mic

Crash and Impact

Frequency

Types of UAV [3] Types of Analysis [10,11,12]

LITERATURE REVIEWSr. No.

Title of Paper Author Summary

1 Structural Analysis of a Composite Target-drone [1]

Yong-Bin Park et al. [13]

Structural static and dynamic analysis of a wing and landing gear

2 Design and Structural Analysis for an Autonomous UAV System Consisting of Slave MAVs with Obstacle Detection Capability Guided by a Master UAV Using Swarm Control [2]

Lakshmi Narashiman Aswin et al. [14]

Master and slave frame structural analysis.

3 Low Velocity Impact Analysis Of A Composite Mini Unmanned Air Vehicle During Belly Landing [3]

Serhan Yüksel [3]

Studied impact stresses induced during belly landing

4 Design and aerodynamic analysis of a flapping-wing micro aerial vehicle [4]

Bor-Jang Tsai et al. [15]

Aerodynamic study during different AOA and K.

5 Design And Analysis of Engine Mounting Frame of an UAV [5]

Santhosh N et al. [16]

Frequency analysis of frame.

CASE STUDY STRUCTURAL ANALYSIS

Material - T7075-T6 (Aluminium Alloy)

Density -2850 kg/m3, Yield Strength - 490 N/mm2 Allowable Stress - 392 N/mm2

Landing Gear Loads Lift Load = 1000 N Drag load = 450 N Side load = 260 N Torsion Load = 20000 N-mm [17]

Fig: CAD model of landing gear

Stresses and Deflection due to self weight

Maximum von-mises stress of around 3.44 MPa is observed due to self weight. This stress is much less the yield stress of the structure. Also maximum deflection of 1mm due to self weight of the landing gear is analysed at the wheel end.

Fig: Von-Mises stresses and deflection of landing gear under load

Stresses and Deflection due to loads

Maximum von-mises stress is around 353 N/mm2 is observed in the landing gear. The stress is less than the yield stress of the material. Maximum displacement is around 22 mm (0.022 m). Maximum displacement is taking place at the loading region.

Fig: Von-Mises stresses and deflection of landing gear due to self-weight

Set 1 2 3 4 5

Frequency (Hz) 15.6 98.3 104.5 130.2 177

Set 6 7 8 9 10

Frequency (Hz) 240 258 260 429 447

VIBRATION ANALYSIS:

The frequency analysis is done for the same model used for structural analysis. The modal frequencies are extracted for 10 frequencies. The modal frequencies are required to calculate the resultant effect of modal spectrum vibration. The initial frequency of 15.6 Hz is corresponding to a speed of 936 rpm. This speed indicates resonance condition if the structure is excited with 936 rpm of the air craft. [17]

FLUID ANALYSIS

Blended Wing Body (BWB) aircraft is a concept where fuselage is merged with wing and tail to become a single entity [18].

Simulation is done for Mach number 0.1 and 0.3 corresponding to Reynolds number equals to 4.66 × 106 and 1.4 × 107 respectively.

It is observed that the value of CLmax increases as the air velocity i.e. Reynolds number

Fig: CLmax versus Reynolds number for wind tunnel experiments

CAD model of UiTM BWB-UAV

When the angle of attack increases, the upper surface will αcreate a lower pressure coefficient, CP . For = 0º, the high-αintensity blue area located on the upper surface suggests high lift is generated with 7.4% force directed backward creating drag. For = 35º, BWB-UAV is still capable of generating lift, αhowever about 1/3 of the total force is directed backward (drag).

Fig: Pressure coefficient contours at = 0º, M=0.3 and at = 35º, M=0.3α α

LANDING ANALYSIS

The landing analysis for Emperical Eagle Mini UAV for belly landing is done to analyze the impact loads on the composite sub-structures [19].

Composite material used is carbon and Kevlar fabric.

The force equilibrium is assumed to be quasistatic in this case for the impact velocity between 2 m/s to 10 m/s.

Fig: Belly landing Approach in Emperial Eagle MINI UAV

Fig: Wing tip displacement wrt. time in inclined drop In inclined drop analysis,

the wing displacement is larger in initial time steps then it decreases with respect to time.

Fig: Maximum stress plot Vs time in inclined drop The maximum von-

Mises stress is observed up to 118 MPa.

CONCLUSIONThe study quadrotor dynamics, the review of literature for various analyses is done. It can be said from the literature that, it is essential to undergo through all types of analysis possible before actual manufacturing of product. These all types of analysis are studied including various case studies for structural analysis, vibration analysis, fluid analysis and landing analysis. From these case studies, it can be observed that, the stresses are produced and it results in deflections which are negligible. Also from fluid analysis it can be concluded that the given type of BWB can fly at very high angle of attack. The resonance condition is found at 936 rpm with 15.6 Hz. and maximum stress of 118 MPa is observed in landing analysis.

References1. Louisa Brooke-Holland, “Overview of military drones used by the UK armed

forces”, House of Commons Library, Number 06493, 8 Oct. 2015, pp. 1-542. J. Leishman, “Principles of Helicopter Aerodynamics”, Cambridge University

Press, New York, 2006. 3. Serhan Yüksel, “Low Velocity Impact Analysis of a Composite Mini

Unmanned Air Vehicle During Belly Landing”, Master Thesis, May2009, Middle East Technical University.

4. Tommaso Bresciani, “Modelling, Identification and Control of a Quadrotor Helicopter”, Master thesis, 2008, Lund University.

5. Guowei Cai, Ben M. Chen, Tong Heng Lee, “Unmanned Rotorcraft Systems”, Advances in Industrial Control, Springer-Verlag London Limited, 2011.

6. Ira H. Abbott, Albert E. Von Doenhoff, “Theory Of Wing Sections Including A Summary of Airfoil Data”, Dover Publications, 1959.

7. Workbook, Naval Air Training Command, CNATRA P-401, 20138. Hoffman G. M., Huang H.; Waslander S. L; Tomlin C. J. "Quadrotor Helicopter

Flight Dynamics and Control: Theory and Experiment", In the Conference of the American Institute of Aeronautics and Astronautics, 2007, pp: 1-20.

9. Richard L. Burden, J. Douglas Faires, “Numerical Analysis”, Ninth Edition, 2011, Brooks/Cole, Cengage Learning.

10. Edward L. Wilson, “Three-Dimensional Static and Dynamic Analysis of Structures”, Computers and Structures, Inc., Third Edition, January 2002

11. P. Yamuna, K. Sambasivarao, “Vibration Analysis of Beam With Varying Crack Location”, International Journal of Engineering Research and General Science, Volume 2, Issue 6, October-November 2014

12. Yong-Bin Park, Khanh-Hung Nguyen, Jin-HweKweon, Jin-Ho Choi, Jong-Su Han, “Structural Analysis of a Composite Target-drone”, International Journal of Aeronautical & Space Science, Vol. 12(1), 2011, pp. 84–91.

13. Lakshmi Narashiman Aswin, Prasanth Rajasekaran, Santhosh Kumar Radhakrishnan, K. Shivarama Krishnan, “Design and Structural Analysis for an Autonomous UAV System Consisting of Slave MAVs with Obstacle Detection Capability Guided by a Master UAV Using Swarm Control”, IOSR Journal of Electronics and Communication Engineering, 2013, Volume 6, Issue 2, PP 01-10.

14. Bor-Jang Tsai, Yu-Chun Fu, “Design and aerodynamic analysis of a flapping-wing micro aerial vehicle”, Aerospace Science and Technology, Vol. 13, 2009, pp: 383–392.

15. Santhosh N, Dr N D Shivakumar, Chetan D M, Pooja Kumari, Sahana B C, Mahalya R, “Design And Analysis Of Engine Mounting Frame Of An Unmanned Aerial Vehicle”, International Journal Of Research In Aeronautical And Mechanical Engineering, Vol.2 Issue.5, 2014, pp: 27-35.

16. Mohammed Imran, Shabbir Ahmed. R. M, Dr. Mohamed Haneef, “Static and Dynamic Response Analysis for Landing Gear of Test Air Crafts”, International Journal of Innovative Research in Science, Engineering and Technology, Vol. 3, Issue 5, May 2014, pp- 1-8

17. Wirachman Wisnoe, Rizal Effendy Mohd Nasir, Wahyu Kuntjoro, Aman Mohd Ihsan Mamat, “Wind Tunnel Experiments and CFD Analysis of Blended Wing Body (BWB) Unmanned Aerial Vehicle (UAV) at Mach 0.1 and Mach 0.3”, 13th International Conference on Aerospace Sciences & Aviation Technology, May 26 – 28, 2009.

18. Akhilesh Kumar Jha, S. Sathyamoorthy, Bharath Kumar, Laxminarayank., “Impact Analysis of Mini UAV during Belly Landing”, DRDO Aeronautical development establishment- Simulation Driven Innovation, 2012.

THANK YOU!!!

1. Structural Analysis of a Composite Target-drone by Yong-Bin Park et al. (2011) [10]

H612 and WR580A glass fabric material is used for wing and Carbon fabric WSN3K is used for

landing gear.

Loadcondition

Max. von-misesstress (MPa)

Max. Deflection (mm)

Max. Tsai-Wu failure index

Bucklingload (N)

5g (2452 N) 168 82 0.930 2,380

-1.5g (736 N) 45 47 0.304 2,200

Tsai-Wu failure index for the main wing.

The tip displacement deviation between the analysis and experimental results were 17%.

Deflections at wing tip

Landing angle(deg)

Vertical landingvelocity (m/s)

Max. shear stress(MPa)

0 1.4 7.8

15 5 61

30 10 959

Main landing gear dynamic analysis results

Normal landing and landing with an angle of 15 degrees are safe. The max. Tsai-Wu failure index is 0.372

Tsai-Wu failure index for the main landing gear (Dynamic Analysis)Back

2. Design and Structural Analysis for an Autonomous UAV System Consisting of Slave MAVs with Obstacle Detection Capability Guided by a Master UAV Using Swarm Control by Lakshmi Narashiman Aswin et al. (2013) [11]

Master and Slave control theory where one UAV acts as a master while the others act as slaves.

For master quadrotor, maximum deformation takes place at the end of the arms, where the motors are located.

The displacements in master and slave MAVs are negligible.

  Master Quadrotor Slave Birotor

Max. Deformation (mm) 0.0000296 0.00000215

Max. Stress (N/mm2) 0.0163 0.00039

Max. Reaction Forces (N) 0.409 0.0244

Displacement in master UAV Displacement in slave UAVBack

3. Low Velocity Impact Analysis Of A Composite Mini Unmanned Air Vehicle During Belly Landing by Serhan Yüksel (2009) [1]

The objective of this study was to design a mini UAV that is tolerable to low velocity impact loads.

Fiber reinforced composite materials are used for strength and integrity. Velocity = 9 m/s, Safety factor = 4/3, approach angle= 3.5 degrees. Outer body modeling:

Maximum stress = 350 MPa (at the bottom of the fuselage). Internal structure modeling:

Maximum stress = 378.02 MPa (at internal layer of element at RHS)

Max. stress at the bottom of fuselage Max. stress at internal layer of right hand side element

Internal structure modeling with wings:Maximum stress = 700MPa (at Wing-fuselage junction )

It can be concluded from the results that, cracks or fractures at that point if necessary precautions are not taken.

Max. stress at the wing fuselage junction

Belly Landing of “Güventürk”

Back

4. Design and aerodynamic analysis of a flapping-wing micro aerial vehicle by Bor-Jang Tsai et al. (2009) [12]

Objective is to analyse the flapping wing under different frequencies and angles of attack.

Flapping angle = 73 degrees, 8 g gross weight, the 15 cm wingspan, and 5 cm chord length.

Conceptual Design Meshing of wing

AOA ( ) ͦ CL CD Lift (g) Thrust (g)

0 0 − 0.018 0 0.4214

5 0.1875 − 0.0325 4.39 0.7609

10 0.3625 − 0.0775 8.4874 1.8146

The velocity vector diagram of a flap cycle for K = 0.3, AOA = 10 , t/T = 3/6◦

It ranges from 0.00366 to 16.7 m/s

The lift and thrust force increases with increase in angle of attack.Moderate increase in angle of attack is advantageous for producing

average lifting force and average thrust force.

Back

5. Design And Analysis of Engine Mounting Frame Of An UAV by Santhosh N et al. (2014) [13]

Normal mode analysis is carried out in NISA II Software for 10 different mode shapes.

Mode No. 1 2 3 4 5Frequency (cycles/sec) 1.727722E+01 1.806157E+01 3.263030E+01 3.671007E+01 3.841202E+01

Mode No. 6 7 8 9 10

Frequency (cycles/sec) 1.041444E+02 1.280067E+02 1.557057E+02 1.645914E+02 1.983670E+02

Frequency analysis of an UAV frame – Mode shape plot for mode no. 10.

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