tractor unit module – breakable connection design
Post on 19-Dec-2015
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![Page 1: TRACTOR UNIT MODULE – BREAKABLE CONNECTION DESIGN](https://reader035.vdocuments.site/reader035/viewer/2022062714/56649d2b5503460f94a011fb/html5/thumbnails/1.jpg)
TRACTOR UNIT MODULE –
BREAKABLE CONNECTION
DESIGN
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Aim
Drive over landmines safely, without damaging the power tiller body
(allow only minor adjustments in the field)
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Explosion 1/2The energy released during a detonation of an explosive charge, driven by the blast/shock wave within the ambient is transmitted to all what is found on the way.
Wave: disturbance which progresses from one point in a medium to other points without giving the medium as a whole any permanent displacement.
Like a mexican wave in a stadium
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Explosion 2/2Characteristics of blast waves:
- pressure riches very high values
(i.e. 13.6 bar at 1.71m from 3kg of TNT charge)
- speed of propagation is supersonic
- the wave compresses and heats the material that it flows through an irreversible process
- wave looses energy while traveling
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Idea
Absorb energy transported by shock wave before it enters the drive train through the axle
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Some ideas from the state of the artWheel of Mars Rover Possible wheel for
power tillerCable isolators
Wheel structure filled in with water
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IDEA: interrupt physical connection between axle and wheel, by letting the wheel to drop-off in case of explosion
Characteristics: - brittle material – cast iron- able to withstand normal load conditions and break under explosion - adaptable to the existing flange- low cost
Idea investigated: breakable connection
design of a breakable joint solving the double function of protecting body and wheels
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Design Features:
- fitting to existing flange- 8 holes:
4 cone shaped, hosting screws to fasten the connection to the flange
4 simple, hosting bolts to fasten the connection to the wheel -ring shape with reduced material between holes to weaken the structure and favour failure in case of explosion-material: cast iron ASTM 30 class
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Design – virtual testing (FEM analysis)
EXPLOSION load
Model
2dmII
l
a
IM
GA
AA
l
AG d
a > 50g
][1026375 3 mmNM A
Fw
Fw
Fw
Fw
Fem
Fem
l
MF Ae Fe
Fe
Fe
Feh
bFF eem
2
h
h
TF ww
4
Cast iron 30ASTM grade:Sut = 213.59 MPa tensile strengthSuc = 751.01 MPa compressive strength
b
Stress Max Princ 1000 MPa
Finite Element Method
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WORKING load
Model
2dmII
l
a
IM
GA
AA
l
AG d
a > 50g
][1026375 3 mmNM A
Fw
Fw
Fw
Fw
Fpm
Fpm
Fp/4
h
bFF ppm
2
h
h
TF ww
4
Cast iron 30ASTM grade:Sut = 213.59 MPa tensile strengthSuc = 751.01 MPa compressive strength
b
mgFp 2
1
Fp/4Fp/4
Fp/4
Stress Max Princ 200 MPa
Design – virtual testing (FEM analysis)
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Design Dimensions: