redesign of the stol ch 701 landing gear strut group members: peter chiu cameron clark dave maharaj...
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Redesign of the STOL CH 701 Redesign of the STOL CH 701 Landing Gear StrutLanding Gear Strut
Group Members: Peter ChiuCameron Clark
Dave MaharajOkason Morrison
Problem DefinitionProblem Definition
Design a single-piece double cantilever leaf Design a single-piece double cantilever leaf spring capable of surviving the landing spring capable of surviving the landing conditions set forth by the FAR.conditions set forth by the FAR.
SpecificationsSpecificationsDescent velocity range 7 - 10 ft/s (2.134 m/s - 3.048 m/s)
Descent load factor range 1.67g – 2.67g
Wing Area 122 ft2 (11.2 m2)
Empty Weight 580lbs (263 kg)
Gross Weight 1,100 lbs (500 kg)
Payload 520 lbs (236 kg)
Max Reaction Load on tire 1350 lbs (6005 N)
Tire Diameter 16 in (0.406 m)
Theoretical Analysis 1: Theoretical Analysis 1: Newton’s Equation of MotionNewton’s Equation of Motion
AssumptionsAssumptions
Plane can be treated as point massPlane can be treated as point mass
Constant deceleration (vertical component Constant deceleration (vertical component only)only)
Neglecting material propertiesNeglecting material properties
Plane has zero final velocityPlane has zero final velocity
CalculationsCalculations
mma
us
a
us
mmrs
sss
strut
total
tiretire
struttiretotal
2.712
2
2.71*%35
2
2
The displacement, s is a The displacement, s is a function of 2 variables: u & a function of 2 variables: u & a
sstrut = f (u, a) surface plot
sstrut
stire
Maximum Displacement: 3-dMaximum Displacement: 3-d
S is max at
a =1.67g
u= 10 ft/s
Sstrut(max) = 212 mm (8.36 in)
s total
Theoretical Analysis 2: Theoretical Analysis 2: Beam DeflectionBeam Deflection
Geometry SimplificationGeometry SimplificationStrut can be modeled as a cantilever beamStrut can be modeled as a cantilever beam
Only a portion of strut needs to be analyze due Only a portion of strut needs to be analyze due to symmetry to symmetry
Beam subjected to 1 load and 1 momentBeam subjected to 1 load and 1 moment
R = 1350 lbs
Ry
YX
M
Deflection EquationsDeflection Equations
Deflection Equations 2Deflection Equations 2
I b( )b h
312
Y1 b( )R y
6 E I b( )L
33 L
3 Y2 b( )M
2 E I b( )
L2
y b( ) Y1 b( ) Y2 b( )
b
h
Beam AnalysisBeam AnalysisStrut Width vs Deflection: Beam Analysis
0
100
200
300
400
500
600
700
800
10 60 110
Width (mm)
De
fle
cti
on
(m
m)
Beam Analysis
Newton's Law
Suitable strut width 65 mm (2.6 in)
Width
Finite Element AnalysisFinite Element Analysis
ModelingModeling
Material: Al 2014
σyield: 414 MPa
Optimization StudyOptimization Study
Engineering Drawings of Final DesignEngineering Drawings of Final Design
Deflection VideoDeflection Video
DeflectionDeflection
Sstrut(max) = 45 mm (1.77 in)
Von Mises StressVon Mises Stress
σvm: 307 MPa S.F. = 1.3
Summary TableSummary TableMaterialMaterial Al 2014Al 2014
Strut WidthStrut Width 120 mm120 mm
Strut HeightStrut Height 354 mm354 mm
Strut thicknessStrut thickness 17 – 20 mm17 – 20 mm
Max Strut Deflection (Newton’s Law)Max Strut Deflection (Newton’s Law) 212 mm212 mm
Max Deflection (Beam Analysis)Max Deflection (Beam Analysis) 111 mm111 mm
Max Deflection (FEA)Max Deflection (FEA) 45 mm
Max Von MisesMax Von Mises 307 MPa307 MPa
Yield StrengthYield Strength 414 MPa414 MPa
Safety FactorSafety Factor 1.31.3
% of max allowable Displacement % of max allowable Displacement 14.2 %14.2 %
QuestionsQuestions
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