Modelling of Anisotropic Viscoelastic Behaviour in Super-Pressure Balloons

Pellegrino, Sergio; Gerngroß, Tobias

doi:10.2514/6.2007-1808

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…Additionally the Schapery 15 nonlinear viscoelastic constitutive material model has been implemented as a user defined material (UMAT) for use in Abaqus/Standard and verified by means of cylindrical balloon structures. 3,4 This alternative approach is quite accurate and will be used in the following sections.…”

Section: Iib1 Creep Lawmentioning

confidence: 99%

Anisotropic Viscoelasticity and Wrinkling of Superpressure Balloons: Simulation and Experimental Verification

Gerngroß

Pellegrino

2009

AIAA Balloon Systems Conference

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Super-pressure balloons are currently under development by the NASA Balloon Program Office for use in stratospheric balloon missions. They are made of thin polyethylene film forming a sealed envelope that is contained by stiff meridional tendons. The film is subject to a state of stress whose details depend on the cutting pattern, stiffness of the film vs. stiffness of the tendons, etc. and the viscoelastic behavior in the film plays an important role. This paper extends the modeling approach presented by the same authors at the AIAA Balloon Systems Conference 2007. The current model captures nonlinear viscoelasticity in a wrinkled, anisotropic membrane, and the analysis has been successfully applied to several balloon designs. Because the effects of wrinkling on the stress history are modeled correctly, the behavior of the balloon can be simulated with high fidelity, starting from pressures as low as 5-20 Pa. The creep strains at selected points of a 4 m diameter balloon were measured using photogrammetry and the results were compared to results from the numerical model. At a pressure of 700 Pa the balloon had a maximum stress of 6.0 MPa in the meridional direction (2.5 MPa hoop stress) and meridional strains of up to 6.4% (-2.7% hoop strain). A detailed model of gore seams and tendon attachments provides insight into the asymmetry of the strain distribution that results from the actual asymmetry of the gore seams. This also allows the numerical replication of an experimentally observed pressure-dependent rotation of the end-fittings.

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Section: Iib1 Creep Lawmentioning

confidence: 99%

Anisotropic Viscoelasticity and Wrinkling of Superpressure Balloons: Simulation and Experimental Verification

Gerngroß

Pellegrino

2009

AIAA Balloon Systems Conference

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“…Kang and Im 10 proposed an iterative scheme for the finite element analysis of wrinkling in orthotropic membrane structures, which was later adopted by Gerngross and Pellegrino. [11][12][13] Alternative approaches have been proposed by Epstein and Forcinito 14 and Raible et al…”

Section: B Wrinkling Of Orthotropic Filmsmentioning

confidence: 99%

Wrinkling of Orthotropic Viscoelastic Membranes

Deng¹,

Pellegrino²

2010

51st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials ConferenceSelf Cite

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This paper presents a simplified simulation technique for orthotropic viscoelastic films. Wrinkling is detected by a combined stress-strain criterion and an iterative scheme searches for the wrinkle angle using a pseudo-elastic material stiffness matrix based on a nonlinear viscoelastic constitutive model. This simplified model has been implemented in ABAQUS/Explicit and is able to compute the behavior of a membrane structure by superposition of a small number of response increments. The model has been tested against a published solution for a time-independent isotropic membrane under simple shear and also against experimental results on StratoFilm 420 under simple shear.

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“…Additionally the Schapery 16 nonlinear viscoelastic constitutive material model has been implemented as a user defined material (UMAT) for the use in ABAQUS and verified by means of cylindrical balloon structures. 3,4 This alternative approach is quite accurate and will be being used in the following sections.…”

Section: Iib Viscoelastic Modelmentioning
confidence: 99%

“…As the complexity of these balloons is better grasped, 11,20 detailed experimental validation of the analysis models is being initiated, and this in turn requires that details of the time-dependent material behavior be also included in the models. A finite element model of Schapery's nonlinear viscoelastic material model has been developed 3,4 and verified by means of cylindrical balloon structures that provide uniform states of stress. Further investigation of more complex states of stress is needed in order to enable realistic models of ULDBs.…”

Section: Introductionmentioning
confidence: 99%

Implementation and Validation of Schapery-Rand Anisotropic Viscoelasticity Model for Super-Pressure Balloons
Gerngroß
¹
,
Pellegrino
²

2007
AIAA Balloon Systems Conference
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The thin film used for the NASA Ultra Long Duration Balloons (ULDB) shows considerable time-dependent behaviour. Furthermore, experiments on scaled ULDB balloons have revealed that wrinkles are present over a wide range of pressures. A numerical model has been developed describing the nonlinear anisotropic viscoelastic material behaviour by means of a Schapery-type model and this model has been extended to model wrinkling by means of a user-defined subroutine in the finite-element package ABAQUS. After a description of the viscoelastic modelling approach, a lobe of a 48 gore ULDB flat facet balloon is modelled and compared to experimental results. Additionally two test cases of anisotropic wrinkling are presented, one involving a flat membrane and one a cylindrical balloon structure.

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Modelling of Anisotropic Viscoelastic Behaviour in Super-Pressure Balloons

Cited by 5 publications

References 10 publications

Anisotropic Viscoelasticity and Wrinkling of Superpressure Balloons: Simulation and Experimental Verification

Anisotropic Viscoelasticity and Wrinkling of Superpressure Balloons: Simulation and Experimental Verification

Wrinkling of Orthotropic Viscoelastic Membranes

Implementation and Validation of Schapery-Rand Anisotropic Viscoelasticity Model for Super-Pressure Balloons

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