mse300 ppt
TRANSCRIPT
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Material for the Egress Phase:
Critical Analysis of Aluminium for Possible Applications
in Lander of Mars Rover-II
Aditya Shankar (12052) (Methology)
Archit Agrawal (12153) (Suggestions)
Semanti Mukhopadhyay (12645) (Introduction)
Shivam Tripathi (12676) (Discussion and Conclusions)
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For Science is Nothing but Perception..--Plato
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Introduction and Objective
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Mission Timeline
• Pre-Launch: Preparation for the mission, landing site
selection, assembly and testing, and delivery to Sri
Harikota
• Launch: Lift-off from Earth
• Cruise: Voyage through space
• Approach: Nearing the red planet Mars
• Entry, Descent, and Landing: Journey through the
martian atmosphere to the surface
• Rover Egress: Leaving the lander to begin exploration
• Surface Operations: Learning about Mars through the
day-to-day activities of the rovers4 Image source: http://mars.isro.gov/mer/mission/images/merl4.jpg
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Landing/Egress Sequence
• An aeroshell and a parachute decelerate the lander through the Martian atmosphere.
• Prior to surface impact, retro-rockets are fired to slow the lander´s speed of descent, and airbags are
inflated to cushion the lander at surface impact.
• After its initial impact, the lander bounces along the Martian surface until it rolls to a stop.
• The airbags are then deflated and retracted, and the lander petals and rover egress aids are deployed.
• Once the petals have opened, the rover deploys its solar arrays, and places the system in a safe state.
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Lander Design
• The component of main importance in the Lander
Petal.
• Lander Petal: Retraction system that slowly drag the
airbags
• toward the lander to get them out of the path of the
rover.
• Small ramps or “ramplets”, connected to the petals
fan out and create "driving surfaces" that fill in large
spaces between the lander petals.
• Ramplets nicknamed “Batwings”
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Motivation for Present Work
• Ramplet Design: Requisite Properties
• Strong enough to bear shock and stress during landing at low
temperatures.
• Must be able to cover dangerous, uneven terrain, rock obstacles,
and leftover airbag material that could get entangled in the rover
wheels.
• The rover must not succumb to stresses even when it bangs its
belly on a rock or smashes into the ground as it was moving off
the lander.
• Resistance to collision by high speed particles in atmosphere
• Withstand extreme temperatures.
Material Under Scrutiny:
Metals!!
Metal Required??
High Stiffness, High
Ductility, Low Specific
Volume, High Strength,
High Impact Toughness
Processing Required??
Grain Size Engineering
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Effect of grain size on the Yield strength and Young’s
modulus of elasticity of metallic material
• Producing a relationship between grain size and yield strength of metallic
material by Hall-Petch equation.
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Methodology:
• 1)Sample Preparation:
• Firstly we need to prepare samples with a range of different grain
size, d.
• We will do this by deforming (rolling) a plate by different amount,
cutting samples at each stage.
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Methodology:
• We will then anneal the sample to fully recrystallize them.
• Heavily deform samples should recrystallize to a final grain size
• After measuring a grain size , We will do Vicker’s Hardness measurements on each ,
and convert hardness to yield stress and will end up with a relationship between
grain size and yield strength and Young’s modulus of elasticity
2)Vickers Hardness Test:
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Observation:
Grain Size d(micrometre) Yield Stress (Mpa)
3.4 365.0
5.6 343.2
11.2 269.6
21.0 240.4
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Discussion And Conclusion:
• We need materials having High Stiffness, High Ductility, Low Specific
Volume, High Strength, High Impact Toughness
• As per experiment lower the grain size higher will be the yield strength
• Also firstly Young’s modulus of elasticity will increase linearly with grain
size and will constant after a critical value.
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Suggestions :
• So to have a good Young’s modulus and yield strength we should fabricate a material
having both type of grains (small and large both).
• Smaller grains provide restriction to movement of dislocation and yield strength
increases and large grains will provide a good Young’s modulus
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Thank You!