Design and Static Structural Analysis of Hover Bike Frame with AL-7075

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 10, October 2017)

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Design and Static Structural Analysis of Hover Bike Frame

with AL-7075

Vennishmuthu.V

1

, Wondie Chanie

2

1_Lecturer,2_{Student, Faculty of Mechanical and Industrial Engineering, Bahirdar Institute of Technology, Ethiopia}

Abstract - Hover bike is a combination of motor bike and helicopter. It does not require any runway to take off and landing. This type of bikes will be very beneficial for surveillance and military uses. To design a hover bike requires lot of calculations and analysis because it has to fly on air with maximum efficiency. To develop a hover bike material selection is important to reduce total weight of the bike. Basically hover bike needs static calculations and dynamic calculations. Manufacturing of effective hover bike is very difficult because of those calculations. This paper explains static calculations and displacement analysis of hover bike structure. CATIA software was used to show the displacement analysis. AL-7075 material was used to do the calculations and analysis.

Keywords - Hover bike, Structural analysis, Displacement analysis, AL-7075, Vertical landing and take off

I. INTRODUCTION

Main working principle behind a hover bike is newton’s third law of motion, i.e. for every force there is an equivalent reaction force. According to this law when propeller generates a thrust force towards ground, an equivalent lift force will act on the body of hover bike. With this lift force hover bike can hover on air. An England scientist call Charles Rhodes, build a hover bike and patented it first. Name of the bike is “Hover Scoter”. The engine capacity of the bike is 250cc and it was made by plastic and aluminum. But due to lot of constrain it hovered up to 6 inches from the ground. A New Zealand inventor Chris Malloy had been developed a modern hover bike called “Malloy Hover bike”. It was single seated turbo fan powered hover bike, developed in the year of 2006. It has been contracted by an American engineering firm to produce such bikes for the United States Department of Defense. Turbofans gives good control and ability to the user to hover on the air like a helicopter in the manner of riding a motorbike. Aero – X is the first commercial vehicle in the market created by Mr.Aerofox who is an aerospace engineering at Los Angeles. That hover bike can carry up to two persons. The vehicle rises 10 feet from the ground and can travel at a maximum of 72 Km per hour. It is expected to weigh 356Kg and be 15 feet in length. The bike runs for around 75 minutes on a full tank of fuel.

Different models of hover bikes are being prepared by the researchers. In single propeller type only one propeller is used to generate thrust force at the center part of hover bike. In dual propeller type two propellers are used to generate thrust force one in front and another one in rear. In co-axial type two propellers are in same engine shaft and same axis but rotates in opposite direction. This paper disuses structural analysis for dual propeller type hover bike.

II. DESIGN OF HOVER BIKE STRUCTURE

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As discussed in chapter-1 hover bike has many types in that, dual propeller type was chosen to design. This model had two propellers one in front and another one in rear. Both propellers are attached with separate engine. Rider seat was placed in between of two engines. Figure 1. Shows the model sketch of hover bike design. Main Parts of the hover bike is followed by propeller, Engine and Chasses or body. In general an aircraft should have minimum weight to save fuel and get better efficiency. So to make body of hover bike aluminum 7075 alloy was chosen. Aluminum 7075 is an alloy made by zinc as primary element. Al-7075 is very strong when compare to steel and has good fatigue strength

and average

machinability. Corrosion of Al-7075 is very less when compare to other Al alloys.

TABLE I

Mechanical property of AL-7075

Mechanical Property Metric

Ultimate Tensile Strength 572 MPa Tensile Yield Strength 503 MPa

Modulus of Elasticity 71.7GPa Poission’s Ratio 0.33 Fatigue strength 159MPa

Shear Modulus 26. 9GPa

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Along with aluminum, Al-7075 contains 5.6 – 6.1 % of zinc, 2.1 to 2.5 % of magnesium, 1.2 – 1.6 % of copper and less than a half percent of silicon, iron, manganese, titanium, chromium. These characteristics of Al-7075 made suitable for the hover bike. Density of Al-7075 is 2.81g/cc. Table.1 indicates the important mechanical properties of Al-7075.

Figure.1: Design and Parts of hover bike

III.

PROPELLER DESIGN

The National Advisory Committee for Aeronautics (NACA) is a U.S. federal agency founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. Propeller or airfoil for the hover bike has done with the standards of NACA. The propeller blade was designed by Al-7075 alloy. By using NACA 4 digit air foil generator (NACA 4412 AIRFOIL), can estimate the shape. The data necessary for the designing of propeller are the break horsepower of the engine and it was considered as 5hp. The approximate speed consideration of the rotor is 4000rpm. For the above data the performance co efficient of the propeller is 1.01. Taken from the NACA data base. Outer diameter of propeller hub is 0.73m. Blade angle is the angle that chord line of the air foil makes with the propellers rotational plane. The blade angle will vary throughout its length because of the twist. So normally the standard blade angle is measured at the blade station 75% of the distance from the hub center to the blade tip. The designed blade angle is ⍺ = 13˚. Figure.2 shows the remaining dimensions of the propeller.

Figure.2. Propeller with dimension

IV. SELECTION OF ENGINE

Selection of engine is depending upon horsepower and required RPM. To do stress analysis approximate engine weight is required so we considered a small single cylinder, four stroke internal combustion diesel engine with kick starter. The dimension of the engine is 380mmx325mmx340mm. Total weight of the engine without fuel is 14.5Kg.

V. DESIGN OF BEVEL GEAR

The engine of hover bike is planned to place in horizontal direction so the rotor shaft of the engine will rotate in the axis of horizontal. But propeller should rotate in the axis of vertical. To convert horizontal rotation of engine shaft to vertical rotation of propeller a bevel gear is required. Bevel gears are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped. Velocity ratio of the bevel gear has been considered by one. Pitch angle between the gears is 45˚. Number of teeth is 34. Figure.3 shows the axis of rotation of crank shaft of the engine and propeller rotation.

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VI. DESIGN OF BODY

To design frame of the hover bike standard Al-7075 tubes was used. External diameter of the tube is 40mm and internal diameter is 34mm (standard metric aluminum round tube to find material weight). Total approximate length required to design one leg of hover bike is 500mm. Density of Al7075 is 2.800Kg/m3. To find total weight of one leg equation (a) was used.

W = AL --- (a) where

=density of Al7075 =2.800×10-6 kg/m3

A=Area of tube = L= Length of tube=500mm,

W = 

W = = 0.487956 kg

There are four legs Wleg= 4 × 0.487956

=1.9518kg

Total length of one frame is 1200mm, so weight of one frame is

WFrame =



--- (b)

= 

= 1.171 kg

Thereare two frame tube so 2 × 1.171

=2.3421kg

Two aluminum metal sheets were used to cover propellers. Dimension of the sheet is (L × W) 2000mm × 1000mm and thickness is 2mm.

wsheet =  × L × W × t

= 11.2kg

There are two metal sheets so 2 × 11.2

= 22.4kg

VII. STATIC STRESS ANALYSIS OF FRAME

To find out total weight of the body above mentioned weights should be added together.

Wbody = Wleg + Wframe + Wsheet + Wpropeller

Weight of the propeller was taken from NACA four digit airfoil generation data

Wbody = 1.9518+ 2.3421 + 22.4 + 3.666

= 30.35kg+1.64kg (accessory parts) = 32 kg

Total weight of hover bike Wtotal = Wbody + Wengine +

Wfuel

= 32 + (15 + 15) + 5 = 67 kg

As per above calculation the total weight of hover bike is 67kg without rider. With this data following stress analysis was done by using analytical method. Body weight of the hover bike is uniformly distributed load, Engine and fuel weight is point load and rider weight also point load. Figure.4 shows various loads acting on the body of hover bike.

Figure.4: Load distribution on frame

The UDL load of 32kg converted into point load and added with rider weight so the center point load weight becomes 82kg. The line diagram of the hover bike load distribution has been mention in figure N.

Figure.5.Free body diagram of the frame

Momentum at point A

MA = 0

MA = (102 ×600) + (17.36× 1200) – (PB ×1200)

PB=68.36 kg FY =0

PA+PB= 17.36 + 102 + 17.36

PA =68.36 kg

Bending momentum

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were,

P- Total load on center in N L- Length in mm Mb = (102 × 9.81) × 600

=600372Nmm

Bending stress

b =

--- (d)

Were,

Mb – Bending moment in Nmm

Y –Perpendicular distance to the neutral axis in mm (20mm)

I – Moment of inertia

I =

= 60066.466 mm4--- (e)

b= 200 N/mm 2

Ultimate strength of Al-7075 is 572MPa so design is safe.

Deflection of frame tube

 =

--- (f)

where, P= load in N

L= length of frame in mm I = moment of inertia in mm4

E = Modulus of Elasticity in N/mm2 (from table-1)

 = 8.43mm

After theoretical analysis as mentioned above software analysis has been done with CATIA.

VIII. LOAD TEST ANALYSIS OF AL-7075BODY

As per above mentioned dimensions frame, leg, sheet and propeller has been designed by using CATIA V5. The CATIA design was meshed into several nodes to do stress distribution simulation. After meshing corresponding load was given as mentioned in figure.5. The simulation results are mentioned in the figure.6.

Figure.6: Stress distribution on Al-7075 frame

From figure.6 it come to know that the minimum stress taking place on the structure of hover bike is 4360KN/m2 and maximum stress taking place on frame is 8730KN/m2. This analysis has been done for the static position of the structure. For the same structure deflection analysis also done by using CATIA. Figure.7 shows the result of displacement analysis. From the result it come to know that minimum displacement of the structure is zero it happens on the center of the body, in figure.7 it was clearly mentioned with dark blue color. The maximum displacement occur on the right side tip of the hove bike the value of maximum displacement is 0.696mm. This displacement values are very small so this will not affect the structure of the hover bike.

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IX. RESULTS

From the calculation of static stress analysis the obtained maximum bending stress is 200MPa and the ultimate strength of the selected material is 572MPa. The obtained stress is lesser than the ultimate strength of the material so the design of hover bike is safe in the static position. From the displacement calculation the maximum displacement on the structure is 8.43mm. The maximum displacement value given by the software is 0.69mm. There is a large difference between this two values hover ever both displacement values are very small so it will not affect the structure of hover bike.

X. CONCLUSION

The static stress and displacement analysis has been done as mentioned above. To design a good hover bike static stress analysis is not enough along with this dynamic analysis is very important. To do dynamic analysis thrust force must be consider along with static forces. This thrust force may vary for takeoff and landing and this force is depending upon the rpm of propeller. When propeller rotates with high rpm body of hover bike may get more deflection that the expected one so as per the result of dynamic analysis few change may require for the above mentioned specification of the hover bike.

Among a lot of research on hover bike we hope this research work may contribute a small amount of progress in development of hover bike. The day when human can use hover bikes like normal motorbike is not so far.

REFERENCES

[1] Umesh Carpenter, Nitin Rathi “ Design and Development of Hover bike” IJIERE, Volum-4, Issue-1, 2017, ISSN: 2394-3343 [2] Aditya M. Intwala “Design & Analysis of Vertical Takeoff and

Landing Vehicle” IJAER, Volum-10, Issue-11, 2015, ISSN 0973-4562.

[3] John K. Sanders, Jr,J. Kenneth Sanders, Arturo Aviles, Jr., Arturo F. Aviles "Quiet vertical takeoff and landing aircraft using ducted, magnetic induction air-impeller rotors" US 7,032,861 B2 (2006). [4] Zhao, Huiwhen, and Cees Bil. "Aerodynamic design and analysis of

a VTOL ducted-fan UAV." 26th_{AIAA Applied Aerodynamics} Conference. American Institute of Aeronautics and Astronautics, 2008.

[5] Demarco, Dolores, and Eduardo N. Dvorkin. "An Eulerian finite element formulation for modelling stationary finite strain elastic deformation processes."International journal for numerical methods in engineering Volum-62, Issue-8(2005): ISSN1038-1063.