On Final Year Project at Bharat Electronics Limited
On Final Year Project at Bharat Electronics Limited
On Final Year Project at Bharat Electronics Limited
There is a weight restriction provided for the movement of Defense trucks over
Bridges in high altitude locations especially in North-eastern states.
NUMERICAL DATA
1)Overall Truck Weight – 13000 Kg
2)Weight of Radar equipment and its Auxiliaries – 6000 Kg
3)Overall Weight of Sub-Frame – 1170 Kg (By Analysis)(Initial Designed Value)
TOTAL = 21170 KG
So, the total weight of the entire vehicle should be reduced from 21170 to 18000 Kg
In that the weight of the sub-frame must be reduced nearly to 850-900kg.
EXPERIMENTATION METHODOLOGY
• The first step taken by us is the part modelling of various mechanical
member of the sub-frame using Solid works Software.
• Further, we assembled the parts with the guidance of BEL executives
and obtained the complete sub-frame structure.
• Later, we analyzed the sub-frame in static condition with certain
inputs such as loads, Constraining parts etc.
• Test was carried out for fixtures, Connections, external load &
Mesh(FEM).
• The sub-frame was tested with SAILMA 350 – High structural Steel
• Fig shows a Reference Sub-frame.
DEMAND SPECIFICATIONS OF SUB-FRAME
• The frame has to take the thrust from the engine and the
transmission and other components.
• It has to with stand the torsional force trying to twist the whole
structure of vehicle.
• It acts as a base or support for the body, automobile component.
• It has to bear the longitude tensile forces during starting and
acceleration and compressive force during braking.
FUNCTIONS OF SUBFRAME
1.Distribute the load evenly over the chassis frame.
2. Provide clearance for wheels and other parts which project above the
frame.
3. Connect the bodywork to the chassis frame.
4. Provide rigidity and reduce the stress in the rear overhang.
5. Contributes to dampening chassis oscillations.
LOADS ACTING ON THE SUBFRAME
• Self weight with engine, transmission system, suspension system,
steering system, fuel tank, body and passengers.
• Torque produced by the engine and drive axle.
• Resistances due to air, tyre rolling, friction gradient of road.
• Impacts and vibrations while riding.
• Inertia loads due to brake application.
• Torsional load when vehicle passes over a road bump.
• Collision impact when the vehicle collide with some other object.
DESIGN CONSIDERATIONS
• Functionality Cost
• Strength Weight
• Distortion Life
• Wear
• Safety
• Reliability
• Manufacturability
• Utility
• Thermal property
STEPS TAKEN DURING DESIGN PROCESS
• IDENTIFICATION OF NEED
• DEFENATION OF PROBLEM
• SYNTHESIS
• ANALYSIS AND OPTIMIZATION
• EVALUATION
• ITERATION
• PRESENTATION
SELECTION OF MATERIALS
Weight of sub-frame using different materials :(Iteration Process)
• CAST IRON= 1031.03kg
• WROUGHT IRON=1110.34kg
• STAINLESS STEEL=1131.97kg
• SAILMA350=1124kg
• Fe 540=1117.55kg
Due to high weight Stainless steel is rejected. Wrought iron cannot with
stand high strength, durability of cast iron is less and it undergoes Rust,
hence SAILMA350 and Fe540 is selected for the sake of design.
FACTOR OF SAFETY FOR DIFFERENT
MATERIALS:
• CI=1.84
•WI=2.3
•SS=2.48
•SAILMA350=1.45
•Fe540=1.6
The FOS for SS is more but machining and welding for SS and WS is difficult.
Therefore Fe540 is preferred than SAILMA350 due to less weight and high
factor of safety.
DESIGN ITERATIONS
• Iteration 1:
The initial thickness was 8mm. By analysing the drawing,
the forces acting on the frame was known. Leaving that point
the other thickness was reduced to 6mm.
• Iteration 2:
The unwanted parts which were supporting the frame
was removed and then the analysis was carried out.
•Iteration 3:
In the place of nut and bolt, welding operations can be carried
out. So removing this small part made reduction in weight of the
frame.
•Iteration 4:
The holes were drilled to reduce the volume in the horizontal
member. Keeping stress concentration in mind holes are drilled. Then
improvising this idea, volume is still reduced.
HOLES DRILLED IN SUB-FRAME
Fea analysis
The analysis can be done using the inbuilt software in SOLID WORKS
Here the automatic meshing process is done. Once the complete
boundary of the structure is defined, the analysis is done by the
software itself. The mesh density increase as more element are placed
within a given region. Results generally improve when the mesh density
are meshed smoothly. Mesh refinement is also done to yeild improved
results. When stress concentration are present, it is necessary to have a
very fine mesh in order to get realistic results.
ANALYSIS CARRIED OUT
• Static Nodal Stress:
• STATIC DISPLACEMENT
• FACTOR OF SAFETY
FINAL SUBFRAME DESIGNED
SUBFRAME BEFORE AND AFTER ANALYSIS
Conclusion
The following conclusions were made after analysis of the sub-
frame:
• Von-mises stress : 510.01MPa
• Factor of safety : 1.6
• Displacement : 2.6mm
• Final Reduced Weight:922Kg
ABOUT THE TEAM
PROJECT MENTOR( INTERNAL)
Sri. Dr. T. Anil Kumar
Associate Professor
Department of Mechanical Engineering,RIT
PROJECT MENTOR(EXTERNAL)
Sri. Sandeep G.S
Manager, D&E,Military Radars, BEL,Bengaluru.
1)Shivashankar K 1MS15ME170
2)Sanath N 1MS16ME431
3)Santosh B 1MS15ME421
THE END