Advanced Deployable Shell-Based Composite Booms For Small ... · 1/31/2017 · Mini-CTM Boom Design from Parametric Analysis • Mini-CTM developed with requirements derived from

GAME CHANGING DEVELOPMENT PROGRAM

Advanced Deployable Shell-Based Composite Booms ForSmall Satellite Structural Applications Including Solar Sails

Juan (Johnny) FernandezNASA Langley Research Center, Structural Dynamics Branch

20 January 2017

Outline

MOTIVATION

Mini-CTM or OMEGA BOOMS

Ultra-Thin TRAC BOOMS

SHEARLESS BOOMS

BOOM STRUCTURAL CHARACTERIZATION TESTS

– Torsion Tests

– Axial Compression Loading Buckling Tests

CONCLUSIONS

2

Outline

MOTIVATION



SHEARLESS BOOMS


– Torsion Tests


CONCLUSIONS

3

Provides

250W

Motivation: Deployable/Rollable Composite Booms are a Cross-Cutting Space Structures Technology

60 x 300 cm = 1.8 m2 deployed

Deployable Solar

Arrays for Increased

Power and Solar

Electric Propulsion

Deployable Apertures

and Antennas for High

Data-Rate

Communications

Solar Sails and Drag

Augmenting Deployables

(propulsion, de-orbiting

and aerocapture)

Booms

Deployment

Mechanisms

Membranes

Structures

Telescoping solar arrays

Roll-out solar arrays

Rib Tensioned

Membrane Reflectors

Magnetometers,

instrument booms;

gravity gradient

stabilization

…for applications such as:

NEA ScoutEnd-of-life Deorbiting Sail

Log-Periodic Antenna

Used as

Components in…Credit: AFRL

Credit: AFRLCredit: ESA

Credit: Surrey

Length (m)

Volume (U*)

Cost($K)

< 100 > 150 > 500

< 40 > 30 > 100

< 20 > 3 > 20

< 5 > 0.5 > 10

< 2 > 0.1 > 1

Motivation: Current Boom/Mast Technology Limitations on Deployed Length, Stowed Volume & Affordable Cost

Technology gap in this range:

5-20 m long, 3-30 L (U) volume, $20-100K

* 1U = 10 cm x 10 cm x 10 cm = 1 liter

Tape-springs

TRACSTEM

Large CTM

Coilable/Articulated Trusses & Inflatables

Pantographs

Credit: ATK

Credit: L´Garde

Credit: DLRCredit: DLR

Credit: MMA Design

Outline

MOTIVATION



SHEARLESS BOOMS


– Torsion Tests


CONCLUSIONS

6

Mini-CTM Boom Design from Parametric Analysis

• Mini-CTM developed with requirements derived from high-level system req.

of NEA Scout: boom length, mass, volumen, structural, environmental, etc.

• In slender boom structures, the failure modes, global column or local wall

buckling, are both determined by stiffness (EI) rather than material strength.

• Initial parametric analysis run in Matlab to determine the optimal boom

cross-section geometry (maximize Ixx, Iyy) to comply with all system req.

• Conflict between stowed (low E, high ɛmax) and deployed (high E, low CTE)

requirements = Maximize E11 from a pool of 1-2 ply laminate designs that

could be realized with the thinnest available composite materials at hand.

• Vol. constraints: Boom flattened height = 45 mm; ID= 45 mm, OD= 97mm.

• Cross-section Geometric Parameters:

• Cross-Section geometry formed by 3 circular arcs that subtend an

angle α = 50º - 90º (ɛmax ≤ 0.8% const. for laminate fracture & creep).

• Wall thickness = 0.1 - 0.14 mm (material avail, coil OD ≤ 97 mm

constraints)

• Web width, w = 3 - 5 mm (shear stress, creep constraints).

• [±45/0] laminate for both boom halves chosen for bounded E11 maximiz.

• Central, axial 0º fibers provide bending stiffness and resistance to creep.

• Outer±45º biased fibers add shear stiffness and local bending stiffness.

Cross-section design for a 45 mm flattening height

boom with subtended angles α = 60° and α = 90°.

* Solid lines are for Ixx (out-of-plane)

and dashed lines are for Iyy (in-plane)* Solid lines are for e22 (flat. strain) and

dashed lines are for rsh (shell radius)

Boom design adopted: web width, w = 3mm, subtended angle, α = 80º, shell radius, Rsh= 7mm, shell thickness tsh= 0.115mm

LaRC 7m Mini-CTM High-Precision, Deployable

Composite Booms for NEA Scout compatible sail

Carbon foam mold reduces CTE mismatch with boom

laminate during cure producing much straighter booms (sub-

centimeter errors).

Carbon foam mold.

7-m boom

post-cure.

Near zero

in-plane

curvature.

Outline

MOTIVATION



SHEARLESS BOOMS


– Torsion Tests


CONCLUSIONS

9

U-T Composite TRAC: Laminate Study

Ultra-Thin TRAC

_…

Inner Shell Material

[outer ply/inner ply]

Outer Shell Material[outer ply /inner ply]

Inner ShellThick (mm)

Outer ShellThick(mm)

Min Exp. Wrap Diam.

(mm)

Max Boom Length Allowedfor NEAS twin-coil config. (m)

Inner Shell E11

(Nm2)

Outer Shell E11

(Nm2)

Bi-stabil

ity

v1 [0-90PWC] [0-90PWC] 0.085 0.085 50 8.74 – 6.74 75.9 75.9

v2 [0C/0-90PWC] [0C/0-90PWC] 0.135 0.135 75 3.49 – 2.87 110.3 110.3

v3 [0C/0-90PWC] [0C/45PWC] 0.135 0.135 65 4.78 – 3.93 110.3 71.7

v4 [0C/45PWC] [0C/45PWC] 0.135 0.135 85 2.01 – 1.66 71.7 71.7

v5 [0-90PWC] [0C/45PWAQ/0C] 0.085 0.175 50 6.55 – 5.36 75.9 97.4

v6 [0-90PWC] [0C/45PWC/0C] 0.085 0.180 50 6.46 – 5.30 75.9 101.1

v7 [0C/45PWC/0C] [0-90PWC] 0.180 0.085 80 2.82 – 2.30 101.1 75.9

v8 [0C/45PWAQ/0C] [0C/0-90PWC] 0.175 0.135 65 4.31 – 3.61 97.4 110.3

v9 [0C/45PWAQ/0C] [0C/45PWAQ/0C] 0.175 0.175 140 N/A 97.4 97.4

v10 [0G/45PWAQ/0G] [0-90PWC] 0.190 0.085 65 4.72 – 3.89 41.7 75.9

v11 [0G/45PWAQ/0G] [0C/45PWC] 0.190 0.135 75 3.04 – 2.56 41.7 71.7

v12 [0G/45PWC/0G] [0C/0-90PWC] 0.190 0.135 85 1.75 – 1.48 43.7 110.3

v13 [0G/45PWC/0G] [45PWAQ/0C/45PWAQ] 0.190 0.200 55 4.48 – 3.82 43.7 51.2

v14 [45PWAQ/0-90PWC] [0C/0-90PWC] 0.155 0.135 60 5.09 – 4.22 47.7 110.3

v15 [45PWC/0C/45PWC] [0-90PWC] 0.215 0.085 72 (56)* 3.61 – 3.00 51.8 75.9 X

v16 [45PWC/0C/45PWC] [0C/45PWC] 0.215 0.135 79 (56)* 2.40 – 2.04 51.8 71.7 X

v17 [45PWC/0C/45PWC] [0G/45BRC] 0.215 0.16 70 (56)* 3.24 – 2.77 51.8 33.5 X

• Biggest design challenge of a composite TRAC Boom is to achieve small wrap diameters without

inner shell bifurcation (compression) & high packaging efficiencies.

• Objective: investigate laminate designs that could lead to packaged config. of the TRAC several times

smaller than previously produced, whether those could fit in an OD ≤ 97 mm or not for the 6.85 length.

• Many short (0.3 -1.8 m) TRAC boom samples with different stacking sequences were fabricated and tested to assess performance.

Standard (Monostable) TRAC vs Bi-TRAC

Standard TRAC: faster and less predictable

deployment.

• Requires additional constraint mechanisms

to avoid blossoming, incurring in more

complex, larger and heavier boom deployers.

Bistable TRAC: slower and more

controllable/coherent deployment.

• Minimal constraint mechanisms are required.

• Manageable strain energy for lower risk

actuation and enabling self-deploy. designs.

Newly discovered Bi-TRAC booms have a

secondary, stable, low strain energy configuration

in the coiled state.

The mechanics of the Bi-TRAC composite boom

are current focus of study to predict: stable coiling

diameter, strain energy release path, creep effects.

Outline

MOTIVATION



SHEARLESS BOOMS


– Torsion Tests


CONCLUSIONS

12

SHEARLESS Composite Booms: Design

• Patent pending design derived my PhD at Surrey (CubeSail).

• Two composite tape-springs held front-to-front by a thin, tightly-fitted, seamless polymer tubing (FEP, Teflon) that acts as a low-friction coupling sheath allowing relative sliding between the two.

• Enables very small wrap diam. & has high packaging effic. (98%).

• To maximize MoA, large subtended angles preferred. However, this could lead to uncoupled edges or edge fracture during coiling.

• Subt. angles of α = 135º - 160º are a good design compromise.

• Extensive boom laminate study to maximize the boom length for a given volume constraint (coil OD).

• 7 m Bi-SHEARLESS have been tested for 6U CS-based solar sail.

Relative sliding

enabled during

coiling

Relative offset between tape-springs

when coiled.

Coupled edges of

the tape-springs in

deployed config.

Design space for a

SHEARLESS boom with a

flattened height of 45 mm

x

y

Outline

MOTIVATION



SHEARLESS BOOMS


– Torsion Tests


CONCLUSIONS

14

Booms Torsional Stiffness

Test Setup & Results

15

• 1.2 -1.8 m long boom samples tested.

• Torsional stiffness, GJ, calculated as the slope of the curved of the applied moment vs

twist angle for a given boom length.

Torsion test setup

• Closed-section Mini-CTM outperform the rest by 1-3 orders magnitude.

• The edge coupling sheath of the semi closed-section SHEARLESS helps improve the boom torsional

behavior by a factor of 2 and 10 w.r.t. open-section TRACs of 1 and 2 plies, respectively.

• SHEARLESS with completely decoupled edges still have 35-45% of the torsional stiff. of a fully coupled one.

Axial Compression Loading Buckling


BoomLoad lateral IP

eccentricity (cm)

Buckling Mode

Length, L(m)

Avg. Peak Load, Pcr(N)

Pcr scaled to 7 m as: 𝐿2 49 (N)

Mini-CTM [45PW/0]

2 Euler 3.27 19.46 4.26-3 Euler 3.27 16.38 3.58-8 Root 3.27 10.19 N/A

Mini-CTM [0-90PW]


SHEARLESS_v3

2 Euler 3.58 13.44 3.52-3 Euler 3.58 11.86 3.10-8 Euler 3.58 7.57 1.98

UT-TRAC_v12 Root 3.50 1.61 N/A-3 Root 3.50 1.34 N/A

16

Load direction 1: pairs tips of inner booms: offset = +3cm

NEA Scout booms arrangementWhiffle-tree off-

loading test setup Root BC showing the load

lateral (IP & OP) eccentricity

A

bo

ve

3N

re

qu

ire

me

nt

Outline

MOTIVATION



SHEARLESS BOOMS


– Torsion Tests


CONCLUSIONS

17

Conclusions

• It has been showcased that, for small satellites´ components, and in particular for CubeSats,many of the top-level system requirements for the deployable structure can all be flowed downto a material, thickness and cross-section design selection for the supporting booms, all of whichare interrelated.

• Several novel rollable composite boom concepts have been presented to comply with thestringent mass, volume and structural requirements of an 85 m2 solar sail 6U CubeSat, whileothers boom designs can enable similar solar sails on other small satellite platforms.

• The Mini-CTM boom with a [±45PW/0] laminate structurally outperforms the rest of the boomstested in terms of torsional stiffness and compressive buckling load. However, significant cross-section flattening after prolonged stowage was confirmed, reducing the buckling load by asmuch as 50%. Dedicated creep tests will soon commence to study and bound this detrimentalphenomenon.

• Designing an Ultra-Thin TRAC boom to comply with all the requirements proved verychallenging. Knowledge of the boom mechanics was gathered by extensive laminate study.

• The SHEARLESS boom was invented to solve some of the challenges of joined-shell boomconcepts. It showed great potential for finding a middle ground between the higher performanceand more scalable CTM boom, the larger MoA-per-unit-of-stowed-height TRAC boom, and themore accessible and lower cost production tape-springs or STEMs.

• Secondary stable coiled configurations with a strain energy minimum state were induced for thefirst time on TRACs, as well as on the new SHEARLESS boom. The natural coiled diameter ofthese two-shell bi-stable booms can be tailored by the bending stiffness (E11 I) ratio of the innerand outer shells.

18

QUESTIONS?

19

[email protected]

BACK UP

20

NASA Game Changing Development Project: Advanced Deployable

Shell-Based Composites Booms for Small Satellite Applications

Small Sat Solar Power

ArraysSmall Sat Science

Instrument Booms

Small Sat Antennas for Deep Space

Communications

Small Sat Solar

Sail/Aerocapture Propulsion

Big Idea: Develop High Power, High Data Rate, High Delta V Propulsion Capabilities for

Low-Cost, Small Satellite Deep Space Science and Exploration Missions.

Approach: Mature deployable shell-based composite boom technology for use in

low-cost, small volume, rideshare-class satellite (e.g., CubeSat, ESPA)

deployable systems.

Concept: Develop one or more shell-based deployable composite boom concepts

specifically for very small satellite system requirements, and demonstrate

their capabilities through analysis and test. Concepts shall:

• Meet unique requirements of Small Satellites

• Maximize ground testability

• Permit the use of low-cost manufacturing processes;

• Be scalable for use as elements of hierarchical structures (e.g., trusses)

• Have high deployment reliability

• Have controlled deployment behavior and predictable deployed dynamics.

Goal: Mature, at least, one boom concept to a TRL of 6. Establish the basis for a

follow-on Technology Demonstrator Mission (TDM) that will benefit from them.



Instrument Booms


Communications

Small Sat Solar




Instrument Booms


Communications

Small Sat Solar


6U CubeSat-based solar sail boom requirements

In line with NASA’s NEA Scout Solar Sail System high-level requirements:

• Deployed highly reflective surface area ≥ 85 m2.

• Stowed solar sail system volume ≤ 100 cm x 20 cm x 15 cm (3 U).

• Stowed solar sail system mass ≤ 3.5 kg (2.5 kg preferred).

• Nominal sail membrane stress ≥ 70 kPa (10 psi).

• Minimum deployed natural frequency ≥ 0.1 Hz.

• Pre-operational life ≥ 1 year in a stored condition.

• Mission operational life ≥ 3 years in deep space (≤ 2 AU from the Sun) including lunar vicinity.

• Deployed sail surface as flat as possible considering all thermal and mechanical loads and residual stresses.

22

These can be translated into the following high-level Boom Requirements:

• Deployed boom length ≥ 6.85 m.

• Stowed volume for four booms and deployment mechanisms ≤ 10 cm x 20 cm x 6 cm (1.2 U)

• Mass of each boom ≤ 0.25 kg (≤ 0.15 kg preferred), assuming a 1.25 kg (1 kg) boom deployer.

• Boom buckling load under flight-like boundary conditions ≥ 3 N. Includes a safety factor of 2.5.

• Stowage creep effect should produce ≤ 30% boom cross-section flattening, and ≤ 10 cm boom

axial curvature (out-of-true lateral tip deflection) over pre-operational life of ≥ 1 year.

• Withstand deep space (≤ 2 AU from the Sun) environ. (thermal, UH vacuum, radiation) ≥ 3 years.

• Coefficient of thermal expansion in the boom axial direction ≤ 1 E-6 m/m-ºC.

• Reduce the strain energy level of the coiled configuration compared to similar metallic booms

by a factor of ≥ 2.

Ultra-Thin Composite TRAC Boom

• Biggest design challenge of a composite TRAC Boom is

to achieve small wrap diameters without inner shell

bifurcation (compression) & high packaging efficiencies.

• The boom cross-section geometry adopted aimed at

maximizing the MoA about the x and y axis for a flattened

height of the boom of h = 45 mm, web width of w = 6 mm,

and the use of a standard mandrel size for fabrication, i.e.

1” (25 mm), 1.5” (38 mm), 2” (50 mm),... in diameter.

• Cross-section geometry chosen: flange shell radius of

rsh = 25mm (2” diam. mandrel size) and flange subtended

angle of α = 88°.

v7 laminate: [0C/45PWC/0C] inner shell, [0-90PWC] outer shell:

Inner shell bifurcation at ID = 75mm causing global deformation.

Complete loss of packaging efficiency.

v6 laminate: [0-90PWC] inner shell, [0C/45PWC/0C] outer shell:

Inner shell local buckling contained within the coil at ID = 50mm.

The negative effect towards packaging efficiency is acceptable.

w = 6 mm

Rsh =

25 mm

α = 88°

h =

45

mm

outer inner

Bi-TRAC Boom

24

Monostable TRAC

(requires constrains)Bi-stable

TRACBi-stable

tape-spring

Bi-TRAC in the secondary stable coiled state

• A Bi-TRAC as a secondary, stable strain energy configuration in the coiled state requiring no constraints while in that state.

• The mechanics of the Bi-TRAC composite boom are current focus of study in order to:

– Generate & tailor laminate designs for bistable or semi-bistable TRAC booms.

– Predict stable coiling diameter for a given laminate design.

– Calculate the release path of stored strain energy to predict deployment behaviour.

– Assess possible negative creep effect on boom self-deployment approach.

? predictable

Highly bi-stable inner shell

Compliant outer shell

e.g. [45PWC/0C/45PWC]

e.g. [0C/45PWC]

UT-TRAC_v16

Bi-SHEARLESS Composite Booms

• Bistable versions of this lenticular boom have been produced for the

first time too. The mechanics are also current focus of study.

• Opposite to the Bi-TRAC, a bi-stable outer shell, that will coil in an

equal-sense around a spool, is needed. The inner shell needs to be compliant enough.

• Tailoring of the secondary, stable coiled diameter of the Bi-SHEARLESS boom can be done by:

– Bending stiffness (E11 I) ratio of the bi-stable outer shell to the non-bistable, compliant inner shell.

– The smaller the ratio (stiffer inner shell) the less bi-stable the SHEARLESS boom is. In fact, it can

lose bi-stability all together for relatively stiff inner shells.

– The subtended angle or shell radius can also be used to tailor the stable coiled. diameter.

Stable coiled diameter difference for bistable tape-

spring (left) and Bi-SHEARLESS that uses the

same bi-stable tape-spring as the outer shell (right) Bi-SHEARLESS with a shallower cross-section

design (α=100 deg) for a larger stable wrap diam.

Outer shell:

[45PWC/0C/45PWC]

Inner shell:[0-90PWC]

innerouter

Motivation: Composite Booms can Dramatically Improve System Structural Performance, e.g. NEA Scout Solar Sail

Current baselineMetallic TRAC boom

Alternative Composite boomDown-selected: Mini-CTM

Material Elgiloy (Co-Cr-Ni alloy) Carbon Fiber/ Epoxy

Packaged height 35 mm 45 mm

Wall thickness 0.1 mm 0.115 mm

Can four (4) 7 m booms fit in 2U footprint area?

Yes Yes

Boom linear density 59.8 g/m 16.5 g/m

Mass saving for four (4) 7 m booms

-- 1.22 kg

Linear CTE 15.21 ppm/°C -0.11 ppm/°C

Buckling Load at 7m 3.9 N 3.9 N

Torsional Stiffness 3.6E-3 N-m2 1.1 N-m2

Cost per boom $ 25K $ 10K

Composite shell-based boom technology can provide significant mass savings and

improved thermal and structural performance.

Scalability of system is improved for future larger solar sails.

Significant

performance

benefits

realized

It is all down to the boom thickness!

27

• VOLUME REQ.: Boom coil OD ≤ 97 mm is used to derive the max. boom thickness permitted from left graph,

e.g. max boom thickness for two-wall booms = 0.37mm and 0.32 mm for ID of 45 mm and 55 mm, respectively.

• VOLUME REQ.: ε𝑦11, 𝑦 ≤ 0.8% is used to derive the max shell thickness permitted from right graph.

e.g. max shell thickness for a 45 mm ID = 0.18mm and 0.37 mm for joined and separate-shell booms respectively.

• MASS REQ.: Boom linear density LD ≤ 36.5 g/m (≤ 21.8 g/m preferred) = max boom thickness tb ≤ 0.52mm (≤ 0.31 mm

pref.), considering carbon fiber/epoxy boom material at 60% FVF (density ≈ 1.570 kg/m3).

• Thickness needs to be optimized for volume, mass, and structural requirements.

Thin-Ply Materials

Material (fiber / resin) Form Lamina AW (g/m2)

Measured Cured Ply Thickness (mm)

E11

(GPa)ε11u, C

(%)Vendor (fiber / resin)

MR60H / PMT-F7 (CF) UD SpT 56 0.040 ± 0.05 174.3 1.10 Oxeon / Patz M&T

IM7 / RS-36 (CF) UD SpT 44 0.032 ± 0.05 166.0 1.06 Tencate / Tencate

HTA40 / PMT-F7 (CF) PW SpT 90 0.075 ± 0.01 75.9 1.03 TCS / Patz M&T

T300-1K /PMT-F7 (CF) BR 125 0.100 ± 0.01 73.8 1.06 A&P / Patz M&T

AstroQuartz II/PMT-F7 PW (525) 93 0.080 ± 0.01 25.6 2.24 JPS Comp /Patz M&T

S2-Glass / PMT-F7 UD SpT 100 0.055 ± 0.05 57.2 2.56 Patz M&T/Patz M&T

28

• Thin-Ply Materials available at LaRC

The properties presented are for laminae where the fibers are aligned with the boom

axial direction (0º) and for a 60% FVF.

*CF – carbon fiber; UD – unidirectional; PW – plain weave; BR – braid; SpT – Spread Tow.

LaRC Composite Boom Concepts and Downselect

• LaRC Solar Sail Structures Team has three thin-shell, deployable composite boom concepts under development:

– SHEARLESS: SHEAth-based RollableLEnticular-Shaped and low-Stiction boom.

• U.S. Patent filed.

– Composite ultra-thin Triangular Rollable And Collapsible (TRAC) Boom

• Composite version of AFRL/Nexolve metallic TRAC boom.

– Mini Collapsible Tubular Mast (CTM)/Omega Boom

• Miniature thin-shell version of DLR closed-section, lenticular composite booms.

• Mini-CTM/Omega boom selected as best option for accelerated development:

– Closed-section geometry yields best structural performance (compression, bending & torsion) for NEA Scout volume constraints.

– Highest uniformity and deployed precision.

– Most developed of three current concepts. Minimum development time to NEA Scout readiness.

– No significant difference in development costs relative to other concepts.

29

Mini-

CTM/Omega

concept Stif

fnes

s

Pack

agea

bili

ty

Ease

of

man

ufa

ctu

re

Pre

dic

tab

ility

;re

liab

ility

SHEARLESS 2 2 1 2

C-TRAC 3 3 2 3

Mini-CTM/W 1 1 3 1

Their flattened height: 45 mm. Thickness: 0.3 - 0.5 mm. Mass: 16 - 32 g/m

Demonstrated that 14 m booms fit in a 10 cm x 10 cm x 5 cm (0.5 U) vol.

Full-scale, high-precision, 7 m Mini-CTM booms

30

7 m booms fabricated in-house using composite

materials and adhesives with space heritage.

New fabrication process that cures the two boom

halves and bonds them in a single step using a

single bottom mold and an inner silicone plug.

Achieved negligible boom straightness errors (sub-

centimeter), and boom-to-boom variability with new

low-CTE carbon foam mold.

Booms may be safely wrapped around 45 mm OD

spool without delamination or fracture = vol. req.

No appreciable creep induced boom axial

curvature (bow) after several months of storage.

Boom cross-section flattening of up to 30% due to

high strains in stowed configuration (not expected

to increase more over time - plateaued).

7.2 m

Small axial curvature of

EDU Booms

< 5”

Boom self-supported under 1g for ease of testing

Boom keeps desired cross-section

after curing, but flattens after

prolonged stowage = 50% drop in Pcr

Boom coils around 45

mm spool without

delamination or fracture

Near zero

in-plane

curvature

7-m boom

post-cured

Carbon foam mold

23 mm

16 mm

(-30%)

TRAC Boom Laminates Studied

Ultra-Thin TRAC

_…

Inner Shell Material

[outer ply/inner ply]

Outer Shell Material[outer ply /inner ply]

Inner ShellThick (mm)

Outer ShellThick(mm)

Min Exp. Wrap Diam.

(mm)

Max Boom Length

Allowed† (m)

Inner Shell E11

(Nm2)

Outer Shell E11

(Nm2)

Bi-stabil

ity

v1 [0-90PWC] [0-90PWC] 0.085 0.085 50 8.74 – 6.74 75.9 75.9

v2 [0C/0-90PWC] [0C/0-90PWC] 0.135 0.135 75 3.49 – 2.87 110.3 110.3

v3 [0C/0-90PWC] [0C/45PWC] 0.135 0.135 65 4.78 – 3.93 110.3 71.7

v4 [0C/45PWC] [0C/45PWC] 0.135 0.135 85 2.01 – 1.66 71.7 71.7

v5 [0-90PWC] [0C/45PWAQ/0C] 0.085 0.175 50 6.55 – 5.36 75.9 97.4

v6 [0-90PWC] [0C/45PWC/0C] 0.085 0.180 50 6.46 – 5.30 75.9 101.1

v7 [0C/45PWC/0C] [0-90PWC] 0.180 0.085 80 2.82 – 2.30 101.1 75.9

v8 [0C/45PWAQ/0C] [0C/0-90PWC] 0.175 0.135 65 4.31 – 3.61 97.4 110.3

v9 [0C/45PWAQ/0C] [0C/45PWAQ/0C] 0.175 0.175 140 N/A 97.4 97.4

v10 [0G/45PWAQ/0G] [0-90PWC] 0.190 0.085 65 4.72 – 3.89 41.7 75.9

v11 [0G/45PWAQ/0G] [0C/45PWC] 0.190 0.135 75 3.04 – 2.56 41.7 71.7

v12 [0G/45PWC/0G] [0C/0-90PWC] 0.190 0.135 85 1.75 – 1.48 43.7 110.3

v13 [0G/45PWC/0G] [45PWAQ/0C/45PWAQ] 0.190 0.200 55 4.48 – 3.82 43.7 51.2

v14 [45PWAQ/0-90PWC] [0C/0-90PWC] 0.155 0.135 60 5.09 – 4.22 47.7 110.3

v15 [45PWC/0C/45PWC] [0-90PWC] 0.215 0.085 72 (56)* 3.61 – 3.00 51.8 75.9 X

v16 [45PWC/0C/45PWC] [0C/45PWC] 0.215 0.135 79 (56)* 2.40 – 2.04 51.8 71.7 X

v17 [45PWC/0C/45PWC] [0G/45BRC] 0.215 0.16 70 (56)* 3.24 – 2.77 51.8 33.5 X

• Objective: investigate laminate designs that could lead to packaged configurations of the TRAC boom several times smaller than

previously produced, whether those could fit in an OD ≤ 97 mm or not for the 6.85 length requirement.

• Many short (0.3 -1.8 m) TRAC boom samples with different stacking sequences were fabricated and tested to assess performance.

Low-Cost Scalable Manufacturing Process of

Composite TRAC Booms

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SHEARLESS Cross-Section Design

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• For a given flattened height (45 mm is the case shown), the way to maximize both Area MoI is to achieve the

highest subtended angle of the cross-section (lowest radius) possible, i.e. circular shape.

• However, there is a maximum angle allowed to be able to flatten the cross-section in a comfortable way

without braking the edges of the inner tape-spring or incurring in decoupled edges during deployment.

• Subtended angles of 135-160º are a good design compromise.

Rsh

α

x

y

Axial Compression Loading Buckling


BoomLoad lateral IP

eccentricity (cm)

Buckling Mode

Length, L(m)

Avg. Peak Load, Pcr(N)

Pcr scaled to 7 m as: 𝐿2 49 (N)

Mini-CTM [45PW/0]


Mini-CTM [0-90PW]


SHEARLESS_v3

2 Euler 3.58 13.44 3.52-3 Euler 3.58 11.86 3.10-8 Euler 3.58 7.57 1.98

UT-TRAC_v12 Root 3.50 1.61 N/A-3 Root 3.50 1.34 N/A

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NEA Scout booms arrangementWhiffle-tree off-

loading test setup Root BC showing the load

lateral (IP & OP) eccentricity

Mini-CTM Buckling Test Results

• Test Results:

Buckling load and mode suggests that full-scale booms would buckle well above the 1.5 N required.

Three tests for each IP offset were carried out showing very similar results. Tests were repeated with

booms flipped 180° too, again yielding similar values.

Limit load = 3.75 N – 4.10 depending on boom pair, i.e. lateral offset distance (- 2cm or +3 cm).

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Load direction 2: pairs tips of outer booms: offset = -2cm

IP Loading Offset

Buckling Mode Avg Bucklingload at 3.27 m

Scaled Bucklingload at 6.85 m

-2 cm Euler 17.97 N 4.10 N

+3 cm Euler 16.38 N 3.75 N

+8 cm Root 9.72 N 2.22 N

Documents

Advanced Deployable Shell-Based Composite Booms For Small ... · 1/31/2017 · Mini-CTM Boom Design from Parametric Analysis • Mini-CTM developed with requirements derived from