1. Forming Simulation of Front Hood of a Missile
Abhishek Kumar Ch. Venkateswarlu B. Shiv Dayal Rao Dr. K Ramesh Kumar
Scientist ‘C’ Scientist ‘D’ Scientist ‘F’ Scientist ‘G’
DRDO DRDO DRDO DRDO
Kanchanbagh Kanchanbagh, Hyderabad Kanchanbagh Kanchanbagh,
Hyderabad Hyderabad Hyderabad
Keywords: Forming, Maraging Steel, HyperForm, Simulation
The paper deals with forming simulation of front hood. The front hood is one of the critical
components of the missile and houses the bunch of wires which communicates the electric signals from one
section of the missile to another. It is made up of maraging steel and having the thickness of 0.8mm.
Simulation was carried out using HYPERFORM to predict the tonnage requirement and zones of thinning
and wrinkling. The good correlation is found between simulated results and actual formed component.
Introduction
Front hood plays a very important role in proper functioning in the missile. It covers the cables which
run along the different sections on the missile. These cables connect the different electronic components
housed inside the missile during the flight. Thus, the protection of cables is very essential and should not be
neglected at any cost. Front hood safeguards the cables from external aerodynamic loads and protect them
against kinetic heating. At the same time, the shape of conduits should be aerodynamically friendly so that
they should not cause additional drag to the missile.
Figure 1: Front Hood
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2. Fig.1 shows the CAD Model of front hood. It is fastened with the missile section using screws. Front hood is
made up of maraging steel material and having the sheet thickness of 0.8mm. Maraging steel is an ultra
high strength material and commonly used in defence industry. The limiting factor in design process of sheet
metal components is the necessity of producing the desired shape without any cracks or wrinkles. The
aerospace industries are growing rapidly and the demand for precise and accurate information concerning
parts design and formability of metal sheet becomes essential. Sheet metal forming simulation plays an
indispensable role in integrating manufacturing necessities into the product design process at an early
stage. The objects of this works will focus on simulating the forming process using HyperForm module of
HyperWorks Software in order to come up with a clear and better understanding of metal flow of sheet metal
forming process.
Process Methodology
CAD model of Die, Punch are modeled using Solidworks software. Figure 2 illustrates the assembly forming
set up. . It consists of base plate punch (for holding the punch), punch, die and base plate of die (for holding
the die). The Solid models of press tools (die and punch) are imported to the HyperForm and outermost skin
profiles are extracted. These extracted surfaces act as die and punch for sheet metal forming simulation.
The front hood is modeled as a sheet metal component. The Blank size is calculated analytically by using
constant volume criterion. The material properties of maraging steel are obtained using tensile test
specimens. The planar anisotropy also known as plastic strain ratio is calculated by conducting the separate
tensile tests as per prescribed ASTM standards.
Figure 2: Tool Assembly
The process is modeled as close as possible to the actual process. Fig. 3 shows the model set up in
HYPERFORM.
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3. PUNCH
DIE
BLANK
Figure 3: Model Set Up in HYPERFORM
Results & Discussions
The simulated results and actual formed component are shown in the figure 4. The thickness plot indicates
the probable zones thinning and wrinkling. The formed component is also having the similar wrinkling and
thinning zones. The maximum thinning is 10 percent and wrinkling of 8 percent.
Wrinkling Zones
Figure 4: Percentage thinning plot
The forming limit diagram (FLD) as shown in figure 5, clearly indicates that the process is completely safe
and does not result into any tearing. The maximum load acting on the punch is approximately 20 Tons.
Figure 6 shows the tonnage requirement with respect to time.
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4. Figure 5: FLD Plot
Force vs Time Plot Formed Front Hood
Figure 6: Force vs Time Plot and Formed Front Hood
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5. Benefits Summary:
The software helped in gaining confidence on the forming process and its various parameters.
Challenges :
HYPERFORM should have database of aerospace materials such as maraging steel etc. and must
incorporate tonnage requirement in the incremental analysis.
Future Plans:
The similar procedure can be extended for similar type of the component made up of ultra high str
strength
material.
Conclusions:
The use of HyperForm simulation gave the better understanding of forming operations and it has provided
orm
efficient way to determine important process parameters and helped in minimizing the tool tryouts. This
paper presented a simulation study concerning the sheet metal forming process and its evaluation using
FLD.
ACKNOWLEDGEMENTS
The authors would like to thank Karthik Guda, DesignTech, Hyderabad, and Yogesh Altair Engineering for
Yogesh,
his active technical support. The authors would also like to thank Dr. D R Yadav Sc'G for their continuous
support and encouragement to carry out this activity.
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