International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 6- June 2015
Design Optimization and Analysis of Rocket Structure for Aerospace
Applications
Anoop Thankachen1, Santosh kumar2
1
M.Tech student, 2Assitant professor, Department of mechanical engineering AMC Engineering College,
VTU University, Bangalore, India
Abstract— Stress analysis plays important role in the
structural design and safety. Due to the advances with
numerical software’s, the simulation helps in estimating the
safety of the structures without actual prototype built up and
testing. Rockets are important elements in
many
engineering lines like transport, surveillance and military.
Since they fly at very high speeds and altitudes, proper
design is essential for the safety of the equipment and life if
any. In the present work, a test rocket structure will be
designed for aerodynamic loads. The test rocket comprises
main parts of Nose, body, tail and Fins. Firstly we design
these parts and assembled it later. After completion of the
design part by using computational fluid analysis we
analyze .Theoretical calculations will be carried out for the
sectional requirement of the various members and later the
overall rocket structure will be design optimized using
Ansys design optimizer.
The important aspects the structural design must satisfy are
presented and the detail procedure for designing the rocket
structure using SOLID EDGE tools is also presented. The
model is then imported into hyper mesh software in order to
mesh the model properly and then exported into the ANSYS
software to conduct the analysis,
Keywords — Rocket, Design, Ansys, Hypermesh, Solidedge.
I. INTRODUCTION
. A Rocket is a vehicle which acquires push by the response
of the rocket to the discharge of plane of quick moving
liquid fumes from rocket engine. Solid fuel rockets make
their fumes by the ignition of strong charge grain. The
subsequent gasses are extended through the spout whose
capacity is to change over this inward weight into a
supersonic fumes speed. Rocket engine fumes are shaped
altogether from force conveyed inside of the rocket before
use. Rocket motors work by activity and response. Rocket
motors push rockets forward by ousting their fumes the
other way at fast. Rockets depend on energy, airfoils, helper
response motors, gimbaled push, force wheels, diversion
of the fumes stream, charge stream, turn, and/or gravity to
help control flight.
Rockets are moderately lightweight and intense, fit for
creating expansive increasing velocities and of achieving
amazingly high speeds with sensible productivity. Rockets
are not dependent on the climate and work extremely well in
space. Rockets for military and recreational uses go back to at
any rate 13th century China. Significant logical, interplanetary
and modern utilization did not happen until the 20th century,
ISSN: 2231-5381
when rocketry was the empowering innovation for the Space
Age, including setting foot on the moon. Rockets are presently
utilized for firecrackers, weaponry, launch seats, dispatch
vehicles for simulated satellites, human spaceflight, and space
investigation.
Substance rockets are the most widely recognized sort of high
power rocket, commonly making a rapid fumes by the burning
of fuel with an oxidizer. The put away force can be a basic
pressurized gas or a solitary fluid fuel that disassociates in the
vicinity of an impetus (monopropellants), two fluids that
suddenly respond on contact (hypergolic fuels), two fluids that
must be touched off to respond, a strong mix of one or more
fills with one or more oxidizers (strong fuel), or strong fuel
with fluid oxidant (half and half charge framework).
Concoction rockets store a lot of vitality in an effortlessly
discharged frame, and can be exceptionally perilous.
Notwithstanding, watchful configuration, testing, development
and utilization minimizes dangers.
II.DESIGN OF ROCKET COMPONENTS
In this designing and modelling the rocket structure is done by
Solid Edge tool. Here in this proposed rocket structure have
five main parts that is nose, nose cone, body, tail and fin.
These parts are individually design first with the respective
dimensions. After the modelling of each part they assembled
and we got the final design of the rocket structure.
A.DESIGN OF NOSE PART
Nose part is the foremost part in a rocket structure where the
nozzle is attached. First we design the nose part of the rocket.
Fig 1 Design of Nose part of rocket
B.DESIGN OF NOSE CONE
After nose part next is nose cone design. Nozzles are carried
in this nose cone part. The nose cone is on of the most
pivotal piece of a rocket. The nose cone of a rocket goes
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 6- June 2015
about as an approach to punch an opening in the
environment.
Fig 4 Design of Tail part of rocket
Fig 2 Design of Nose Cone part of rocket
C.DESIGN OF MAIN BODY
The body of a rocket is one of the more persuasive parts.
The reason for the body is to house the fuel. It is frequently
as an empty chamber in light of the fact that it diminishes
the sum surface territory that is in contact with the air. This
thusly lessens drag.
E.DESIGN OF FIN PART
The final design is Fin or blade part of the rocket. The
reason for putting blades on a rocket is to give strength amid
flight, that is, to permit the rocket to keep up its introduction
and planned flight way.
.
Fig. 3 Design Of Main Body Of Rocket
D.DESIGN OF TAIL PART
Fig 5 Design of Fin Or Blade Part Of Rocket
Next part is tail part. The design of tail is part is crucial
reason that the climate vane bolt focuses into the wind is
that the tail of the bolt has a much bigger surface region
than the sharpened stone. The streaming air confers a more
noteworthy power to the tail than the head, and in this
manner the tail is pushed away. There is a point on the bolt
where the surface territory is the same on one side as the
other. This spot is known as the focal point of weight
Fig 6 Final Three Dimensional View of Rocket after Assembling
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 6- June 2015
III.MESHING EACH PARTS USING HEPERMESH
The analysis of the rocket structure for stress distribution is
done by using ANSYS software. Before analysing the
structure meshing should be done. Meshing of the parts is
done by hepermesh tool. The model is meshed with solid45
elements using hypermesh with varying mesh size, the
minimum size of elements is found to be 1mm and
maximum elements size is found to be 10mm.
first stage of the rocket model comparing the displacement
and contour results for the aluminium and the carbon epoxy
materials respectively.
Fig 12 Model Showing Loads and Boundary Conditions
Fig 7 Meshed Nose part
Fig 8 Meshed Nose cone part
Fig 9 Meshed Body part
Fig 13 Stress Analysis On Nose
From the fig 13 the Aerodynamic loads the maximum stress
in the nose part is found to be 0.418E8 N/m2
Fig 10 Meshed Tail part
Fig 11 Meshed Fin part
IV.ANALYSIS OF ROCKET STRUCTURE USING
ANSYS
The analysis is conducted by applying the loads on each of
the parts of the rocket model by using aluminium and steel
materials as already mentioned. Here we used ANSYS
software. The comparison is made by applying same value
of loads, boundary conditions and constraints on the model
for both the materials considered separately. The results
exhibited below are obtained when load is applied on the
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Fig14 Stress Analysis on Nose Cone
From the fig 14 Aerodynamic analysis, the maximum stress
in the nose part is found to be 0.406E8 N/m2near the whole
region.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 6- June 2015
and numerical results are compared. Later analysis is
extended with all the loads. The results are summarised.
Table I
Factor of Safety under Aerodynamic loads (Only pressure)
Sl Section Theoretical
No
calculation
Results
N/mm2
Fig15 Stress Analysis on Main Body Part
From the fig 15 Maximum stress from the results for tail
part is found to be 0.282 E+08 N/m2(28.2N/mm2), ie at the
hole region.
1
2
3
4
5
Nose
Cone
Body
Tail
Fin
35
43.2
23.4
13.29
80.27
Finite
element
analysis
results
N/mm2
41.8
40.6
28.2
14.6
92.6
Yield
Factor
Stress of
N/mm2 Safety
215
279
279
279
279
5
6.87
9.89
19.1
3
V.DESIGN OPTIMISATION
Since theoretical calculations are not possible with all
complicated loads, finite element analysis is carried out to
optimise the region of stress concentration. Here the drag
loads along with lateral loads are considered for analysis
along the fin and the members. Since nose is a solid part
which is completely required the member is not considered
for the analysis. Its load is replaced by RBE 3 element for
load transfer.
Fig16 Stress Analysis on Tail Part
From the fig 16 Maximum stress from the results for tail
part is found to be 0.146 E+08 N/m2 at the fin joints
Fig 17 Stress Analysis on Fin
Fig 18 Hyper Mesh Files for Design Optimisation
.
Fig19 Real Constants Used In the Problem
From the fig 17 Maximum stresses from the results is found
to be 0.92.6E8 N/m2
The mesh shown with different colours representing cross
sections. Hyper mesh is the best tool for shell meshing
along with attaching properties to the different regions.
The rocket structure has been analysed for aerodynamic, drag
and lateral loads. Initially for theoretical analysis, only
aerodynamic pressure loads are considered. Both theoretical
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 6- June 2015
Table II
After Design Optimisation
Sl
No
Section
FEM
Yield
Stress
Factor
of
Safety
1
Tail
71.864
279
3.882
2
Fin
187
279
1.49
Since all the factor of safeties are more than allowable limit
of 1.4 the design safe for the given loads. Various material
grades can be selected to suit the developed stresses to
reduce the cross sections of the problem
Fig 20 Overall Stresses in the Problem
:
Fig 21 Boundary Conditions in the Problem
The boundary conditions are shown for the problem. Along
with aerodynamic pressure loads, thrust and lateral loads are
applied on the problem. The size of arrows represents the
magnitude of the problem.
Fig 23 Design after Modification
VI.CONCLUSION
Fig 21 Design modification area
Leaving the stress concentration region, remaining regions
are well within the allowable limits. No optimisation is
required in these regions. So the region thickness has been
iteratively increased from 4mm to 8mm. Similarly the blade
base is increased from 8mm to 12mm to maintain the safety.
The final results are as follows.
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Analysis has been carried out along with theoretical
calculations to find the structural safety of the rocket
structure. The overall summary is as follows initially the
geometry is created as per the specified dimensions. The
three dimensional modelling Software Solid Edge V19 is
used to built the geometry in the three dimensional space.
The drafting is carried out to represent dimensions of the
problem Initially analysis is carried out for aerodynamic
constant pressure loads to check theoretically the validity of
the finite element software. The loads are applied and results
are obtained for deformation and stress. The individual
component results are represented. The results for all five
parts (Nose, Nose Cone, Body, Tail and Fins) results are
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 6- June 2015
represented in SI system. Further theoretical calculations are
carried out to find the validity of the results. Simple beam
concept based on mechanics of material concept is used to
represent the comparison. The stress concentration effects are
considered in the theoretical calculations. The results are
represented and compared in a tabular form. The results show
closeness of theoretical and finite element results. Further
analysis is carried out with drag, lateral and aerodynamic
pressure loads. The results shows, the stress is maximum in
the fin and blade regions. So improvement is required in
these two parts. So design optimised by varying the thickness
in these regions. Again analysis is carried out results are
presented. The results shows safety of the complete rocket
structure as all the stresses are within the limit or less then
the yield stress of the members. Also factor of safety
calculations shows, safety in the process as the factor of
safety value is more than the design specification of 1.4 for
the rocket structure. All the results are represented in the
appropriate graphical plots.
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