Pressurized Metal Bellows Shock Absorber for Space

159 Pages·2017·5.61 MB·English

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Electronic Theses and Dissertations, 2004-2019
2015
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John Trautwein
University of Central Florida
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Trautwein, John, "Pressurized Metal Bellows Shock Absorber for Space Applications." (2015). Electronic
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PRESSURIZEDMETALBELLOWSSHOCKABSORBERFORSPACEAPPLICATIONS
by
JOHNTRAUTWEIN
B.S.RutgersUniversity,1996
B.S.FloridaStateUniversity,2004
Athesissubmittedinpartialfulfilmentoftherequirements
forthedegreeofMasterofScience
intheDepartmentofMechanicalandAerospaceEngineering
intheCollegeofEngineering&ComputerScience
attheUniversityofCentralFlorida
Orlando,Florida
FallTerm
2015
MajorProfessor:JeffreyL.Kauffman
©2015JohnTrautwein
ii
ABSTRACT
Numerous spacecraft designs exist for exploring the surfaces of planetary bodies and each have
their own advantages and disadvantages. All successful landings have been made by stationary
landers or wheeled rovers that rely on one-time use mechanisms, such as crushable aluminum
honeycombshockabsorbersorinflatableairbags,toreduceshockloadingtothespacecraftduring
landing. The stationary lander is the simplest type of lander, but can only take data from one
location. Wheeled rovers add complexity in exchange for mobility to explore different locations.
Roversarelimitedbytheterraintheycantraverse;roversbecomingstuckhaveendedmissions. In
contrast to rovers and stationary landers, hoppers explore by making multiple launch and landing
hops. They have the advantage of being able to avoid terrain that would cause a rover to become
stuck. A hopper may require a landing shock absorber that can reliably operate multiple times in
harshenvironments.
Mostterrestrialshockabsorbersusehydraulicfluid,allowingforcompactandinexpensivedevices.
Hydraulics have been used in space applications, but require thermal controls to maintain the
proper fluid viscosity. They also require dynamic seals which, in the case of a leak, can degrade
performance,shortenmissionlife,andcontaminatesensitivescienceequipment. Leakageisalsoa
concerninpressurizedsystemsinspacebecausemissionscantakedecadesfromwhenasystemis
installedtowhenitactuallyisused.
To address these issues, a pressurized metal bellows shock absorber is proposed. This shock ab-
sorber could operate at nearly any expected spacecraft environment. Metal bellows are designed
to operate from cryogenic temperatures to several hundred degrees Celsius. Ahermetically sealed
system eliminates the risks of a system with seals. Metal bellows are in common use for terres-
trial harsh environments and vacuum applications. Small metal bellows are used as dampers for
iii
pressurecontrolsystemswithsmalldisplacements.
Models for the dynamics of this device are developed and presented here. Starting from the ideal
gas law, polytropic compression, and compressible flow through an orifice, differential equations
of motion and pressure are derived. These equations are nonlinear for the displacements under
considerationandarenondimensionalizedtohelpprovideinsight. Equationsforstaticequilibrium,
maximuminitialdisplacementbounds,andestimatednaturalfrequencyarepresented.
Metal bellows can operate as a passive damper with a simple orifice between the control volumes.
Optimization is performed for the nondimensional model of a passive damper. Because the re-
sponseishighlynonlinear,amethodisdevelopedtoestimateadampingcoefficientthatisusedas
the objective function for this optimization. Feasibility of this concept is investigated through an
exampledesignproblemusingdatafromametalbellowsmanufacturerasconstraints. Anoptimal
massconfigurationisfoundthatmeetsthedesignconstraints.
Performancecanbeimprovedoverthepassivesystembyaddingcontrol. Thefirstcontrolstrategy
involves a check valve, such that the effective orifice size varies between compression and exten-
sion. Thenextcontrolstrategyreplacestheorificewithacontrolvalve. Varyingthevalveopening
and closing timing can achieve optimal performance. Finally, using the metal bellows as an ac-
tuator to help launch the hopper is investigated. While the valve is closed, the gas in the second
volumeiscompressed. Thenthevalveisopenedthehopperislaunched.
The results of this research show that a metal bellows device holds promise as a landing shock
absorberandlaunchactuatortoextendtherangeofhopperspacecraft.
iv
ACKNOWLEDGMENTS
I would like to thank my graduate adviser Jefferey L. Kauffman for his guidance and patience
during my journey through graduate school and this research. He always seems to provide just
enough direction to keep me from getting hopelessly lost but the freedom to explore this topic.
I would also like to thank Joette Feeney from Kennedy Space Center for selecting me for the
KennedySpaceCenterGraduateFellowshipProgramwhichprovidedthefundingformyMaster’s
Degree and my supervisors Todd Steinrock and Ned Voska for allowing the flexibility to juggle
work and school responsibilities. I appreciate all of the help from my coworkers at the NASA
PrototypeLaboratoryforputtingupwithwhatmustseemtobearandomscheduleforthepasttwo
and a half years. Finally I could not have done this without the support of my loving wife Ileana
and my children Robert, Victoria, and Thomas. We have spent many nights together around the
kitchentableonourschoolworkandthisthesisistheculminationoftheseefforts.
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TABLE OF CONTENTS
LISTOFFIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
LISTOFTABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
CHAPTER1: INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 HopperSpacecraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 ShockAbsorbersandDampingMechanisms . . . . . . . . . . . . . . . . . . . . . 2
1.3 MetalBellowsShockAbsorber . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5 GoalsforCurrentResearch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
CHAPTER2: LITERATUREREVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 PlanetaryLandersandHoppers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.1 Apollo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1.2 PHOBOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1.3 Hayabusa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.4 Rosetta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
vi
2.1.5 TalarisPlanetaryHopper . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 ShockAbsorbersandDampers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.1 HydraulicShockAbsorbers . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.2 PneumaticCylinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.3 LinearModelsforGasSpring . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.4 NonlinearModelsforGasSpring . . . . . . . . . . . . . . . . . . . . . . 15
2.2.5 NondimensionalizationofDampedPneumaticShockIsolators . . . . . . . 19
2.2.6 MetalBellows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2.7 AdaptivePneumaticImpactAbsorber . . . . . . . . . . . . . . . . . . . . 20
CHAPTER3: METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1 MetalBellowEffectiveArea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 MetalBellowsShockAbsorber . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.2.1 EquationofMotion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.2.2 Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2.3 IdealGasLaw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2.4 AdiabaticCompression . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2.5 Conservationofmass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
vii
3.2.6 Massflowthroughanorifice . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2.7 NondimensionalParameters . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.2.8 NondimensionalEquationofMotion . . . . . . . . . . . . . . . . . . . . 33
3.2.9 NondimensionalMassFlow . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2.10 BoundaryConditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.3 InitialDesignEquations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.3.1 StaticEquilibriumSolution . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.3.2 MaximumInitialDisplacementBounds . . . . . . . . . . . . . . . . . . . 39
3.3.3 EstimatedNaturalFrequency . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.4 ControlConcepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.4.1 CheckValveandOrificeConcept . . . . . . . . . . . . . . . . . . . . . . 43
3.4.2 On/OffValveControlConcept . . . . . . . . . . . . . . . . . . . . . . . . 45
3.4.3 AdaptiveControlConcept . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.4.4 On/OffValveHopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.5 Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.5.1 NondimensionalOptimization . . . . . . . . . . . . . . . . . . . . . . . . 48
3.5.2 DimensionalOptimizationUsingVendorsData . . . . . . . . . . . . . . . 50
viii
CHAPTER4: FINDINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.1 InitialVerification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.2 InitialDesignEquationsVerification . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.3 On/OffControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.4 AdaptiveControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.5 NondimensionalOptimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.6 OptimizationusingVendorData . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
CHAPTER5: CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.1 EffectiveArea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.2 EquationsofMotion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.3 AnalyticalEstimations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.4 ResponsetoParameterVariation . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.5 ControlConcepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
5.6 LinearEquivalentDampingCoefficientforNonlinearResponse . . . . . . . . . . 85
5.7 Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.8 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
APPENDIXA: ANDERSONNONLINEARSPRING . . . . . . . . . . . . . . . . . . . . 87
ix