SOLAR POWERED GRASS CUTTER - IJAEGT
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ISSN No: 2309-4893
International Journal of Advanced Engineering and Global Technology
I Vol-06, Issue-01, 2018
SOLAR POWERED GRASS CUTTER
1Avin Palocaren, 2Harris devassy, 3Immanuel Wilson, 4jerin Jose M, 5Sivakumar C Shaji,
6 Mathew Thomas
1-5
B-Tech students, Department of Mechanical Engineering, Nirmala College of Engineering,
Thrissur,( Calicut University) Kerala, India
6
Assistant professor, Department of Mechanical Engineering, Nirmala College of Engineering,
Thrissur, Kerala India
Abstract – A grass cutter machine is used 1. INTRODUCTION
for cutting and levelling the grass in a In the present scenario pollution had
particular area. This machine is used for become one of the major issue the earth is
undergoing. Here we are taking the
aesthetic and recreational purposes. In our
atmospheric or the air pollution into
project we are trying to fabricate a grass consideration With the increase in the
cutting machine by using solar panels, automobiles and the automotive
batteries and electric motor. We have equipments and the exhaust gases emitting
focussed on the design and fabrication of from these have played a huge role in the
the existing grass cutters and to study the increase rate of pollution. Now it is the time
characteristics of the rotary cutting blades we need to consider the problem and act
accordingly in such a way so as to reduce
for effective cutting action. The frame and
the pollution rate. Thus we came up with
the cutting blade has been analysed with the the idea using the solar panels and batteries
help of ANSYS Workbench 16.0. Suitable instead of fuel. we are using the solar panels
materials for the frame and blade was made of crystalline cells and batteries to run
selected and the properties of it was the motor. The shaft of the motor will be
researched. The frame was joined using the connected to a blade which rotates
Welding procedure. After joining, proper horizontally. The horizontal blades are easy
to remove, sharpen and replace.
inspection was done on all the components
for the dimensions. All the electrical According to the “Rotory Mower
components like the Solar panels, Motor, Basics” [1] The basic component of a grass
Battery, Switch etc and the mechanical cutter is the cutting blade, to understand the
components like the Bearing, Cutting blade, cutting blade, first, we must know about the
cutting clip. Clip can be defined as the
and the Wheel are assembled on the main forward distance travelled by the cutting
frame. .After the assembling of each unit during one revolution of the blade.
material on the main frame, the project was Although the blade cutting edge may be 3”-
taken into the open ground and was tested 4” long, the very tip is the primary contact
point with the grass plates on each pass. The
Keywords-Solar grass cutter, Cutting remaining portion of the cutting edge will
Blade Design,CFD, Static Structural tend to cut off the stragglers from the
Analysis. previous blade pass. The blade tips are
normally lower than the rest of the blade to
avoid any drag on the turf absorbing
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ISSN No: 2309-4893
International Journal of Advanced Engineering and Global Technology
I Vol-06, Issue-01, 2018
rotating horsepower and damaging the BLADE DESIGN 2
grass.
According to “Basil Okafor” For
smooth grass cutting, a motor power of not
less than 628.3W (0.84hp) having a
rotational speed of not less than 3,000
rev/min and producing a shear force of
about 10.5 N is recommended. If the speed
of the motor is not sufficiently enough a
speed multiplication pulley systems can be
used, considering the torque produced by th
motor.The shearing force of most annual
and perennial grasses found on most lawns Fig 1:Basic blade design D2
is usually between 9.2N ~ 11.51N.
According to O’ Dogherty that blades
used in forage chopping should have a
blade angle in the range 30-40. The
optimum radius of the cutting edge is
approximately 0.05 mm. The blades needs
to be between 25-30 for the minimum
power requirements. More research on this
have shown that high impact velocity is
required by the grass for the easy cutting of
the grass.
2. DESIGN OF THE CUTTING
BLADE
In order to design an effective cutting blade.
we decided to analyze an already existing
simple design of cutting blade using ANSYS
Workbench 16.0.The length of cutting blade
taken as 20 inch (508mm) and width 2
Fig 2 :Mesh View Of D2 Blade
inch(50mm).A 300 cutting angle was taken
as recommended as of O‘Dogherty. This
purposes. The streame of air touching the
speed of rotation was taken as 3000 rpm as
blade causes a rotating effect so called
recommended by Basil Okafor, which
vortex effect. This increases the
produces an angular velocity of 80 m/S for a
turbulence. In order to prevent the grass
blade of 20 inch length.There as to be
from scattering away the turbulence has to
minimum turbulence inside the cutter deck.
be reduced. Several designs were put
Also the parameters like down force and
forward by us to reduce this, of which one
drag must be considered to decrease the load
found to be most effective they are shown
on the motor and the increasing the
below. Here we made changes to the length
efficiency.
of the blade 2 keeping the others parameters
same. The mesh generated was the default
fine mapped meshing. The number of nodes
is 6146 and the number of elements is 819.
The length of the new blade is 300 mm and
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ISSN No: 2309-4893
International Journal of Advanced Engineering and Global Technology
I Vol-06, Issue-01, 2018
the analysis procedures are done as BLADE DESIGN 3
previous
Fig 4 : Basic blade design D3
Fig3:Blade D2 vortex
In order to study the capabilty of the blade
a test domain was created for test
.
Fig 5: Blade D3 Mesh
pressure forces, in which drag will be acting
on theY-Z planes and downforce on X-Z
planes. The pressureforce was calculated by
2072 www.ijaegt.com
ISSN No: 2309-4893
International Journal of Advanced Engineering and Global Technology
I Vol-06, Issue-01, 2018
dividing the forces obtained from Fluent mapped meshing. The number of nodes is
analysis with the combined area of surfaces 6146 and the number of elements is 819.
on the blade in which these forces are acting The length of
Here we made changes to the length of the the new blade is 300 mm and the analysis
blade 2 keeping the others parameters same. procedures are done as previous.Forces are
The mesh generated was the default fine acting.
Test design 3 was preceded by several other
designs which went through analysis in
ANSYS. The test design 3 was the one
which gave us the satisfactory results.
Inorder to reduce the downforce of the
blade a tapered profile was given to the
blade, since area of the wing is directly
proportional to the downforce produced.
3. BLADE D3 IN STATIC
STRUCTURAL ANALYSIS
Due to the forces acting on the blade while
rotating.The blade has to be analyzed
statically for various stresses created on it
as a result of drag and downforce. Static
structural analysis was carried out on this
Fig6:Blade D3 vortex blade design in ANSYS Workbench 16.
The drag and downforces weretaken as
Table 1: Cutting Blade Static Analysis
Parameters Value
Maximum 0.80943mm
Deflection
Maximum 80.583mpa
Principal Stress
Maximum 3.4563× 10−4
Principal Strain
Maximum Shear 22.743Mpa
Stress
Maximum Strain 37.201 J
Energy Fig 7:Total Deformation of Blade 3
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ISSN No: 2309-4893
International Journal of Advanced Engineering and Global Technology
I Vol-06, Issue-01, 2018
Fig 9:Maximum Principle Strain
Fig8:Maximum Principal Stress of Blade 3
Fig10:Shear Stress of Blade 3 Fig 11:Strain Energy f Blade 3
Fig 7 shows the deflection of the blade as a
result of the combined effect of forces
acting on it. The deflection of the blade is
increasing when it goes to the tip of the
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ISSN No: 2309-4893
International Journal of Advanced Engineering and Global Technology
I Vol-06, Issue-01, 2018
blade with a reading of 0.80943mm. Fig 8
shows the Maximum Principal Stress
distribution with a maximum reading of
80.583mpa which is less than the yield
strength of the structural steel which is 250
Mpa, so we can say the design is safe. Fig 9
represents maximum strain energy
distribution with a maximum value of
3.4563× 10−4 . Fig 10 gives the shear stress
of the blade with a maximum value of Fig 12 : Basic Sketch D3 Blade
22.743Mpa. Fig 11 represents the strain
energy of the blade with a maximum value 3. FINAL ASSEMBLY
of 37.201 J
Fig 14 : Fabricated image of the solar grass
cutter
through fluent analysis which showed us
satisfactory results. The blade was also
found to be safe under various forces acting
on it while rotating. The frame was joined
using the Welding procedure. After joining,
Fig 13 :Blade D3 3D Rendered proper inspection was done on all the
components for the dimensions. All the
electrical components like the Solar panels,
Motor, Battery, Switch etc and the
mechanical components like the Bearing,
Cutting blade, and the Wheel are assembled
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ISSN No: 2309-4893
International Journal of Advanced Engineering and Global Technology
I Vol-06, Issue-01, 2018
on the main frame.After the assembling of
each material on the main frame, the project
was taken into the open ground and was
tested.
5. CONCLUSION An effective design of
the cutting blade for rotary lawn mower has
been achieved. FLUENT analysis of the
existing basic blade design produced a lot
of undesirable turbulence resulting in
scattering of grass. These designs were
eliminated to a great extend in our final
design . Design of the blade was perfected .
6. REFERENCES
[1]The “Rotory Mower Basics, TORO University,
NO. 09167SL”
[2] Basil Okafor, “Simple Design of Self Powered
Lawn Mower”,International Journal of Engineering
and Technology, OCT2013,(Volume 3 No.10).
[3] O'Dogherty, M.J., “A Review of Research on
Forage Chopping”,Journal of Agricultural
Engineering Research, 1982, 27(4), 267-289
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