Obtaining non-linear orthotropic material models for PVC-coated polyester via inverse bubble inflation

Jekel, Charles F. (2016-03)

Thesis (MEng)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Uniaxial tests in the warp, fill, and 45° bias direction were performed on PVCcoated polyester to determine a non-linear orthotropic material model. Optimization was used to minimize the load displacement error of the uniaxial test results and uniaxial finite element models. A method for determining non-linear orthotropic material models from an inverse bubble inflation test is described. The inverse bubble inflation method is demonstrated with a known non-linear orthotropic material model. Inverse bubble inflation analyses were performed on four PVC-coated polyester samples, and a unique non-linear orthotropic material model was determined from each sample. Three point bending tests of inflatable PVC-coated polyester cylinders were used to compare and validate the material models. Finite element models were created replicating the three point bending tests. It was shown that the bubble material models overestimate the stiffness of the inflatable beams, while the uniaxial material model underestimates the stiffness.

AFRIKAANSE OPSOMMING: Eenassige (of uniaksiale) toetse in die skering-, inslag- en 45° skuins-rigtings is uitgevoer op PVC -bedekte poliëster om 'n nie-liniêre ortotropiese materiaal model vas te stel. Optimering is gebruik om die ladingsverplasingsfout van die uniaksiaaltoets se resultate en uniaksiaal eindige element-modelle te minimeer. 'n Metode vir die vasstelling van nie-liniêre ortotropiese materiaalmodelle vanaf 'n omgekeerde borrel-opblaastoets word beskryf. Die omgekeerde borrel-opblaasmetode word gedemonstreer met 'n bekende nie-liniêre ortotropiese materiaalmodel. Omgekeerde borrel-opblaas-analise is uitgevoer op vier PVC-bedekte poliëster voorbeelde, en 'n unieke nie-liniêre ortotropiese materiaalmodel is vasgestel uit elke voorbeeld. Drie-punt buigtoetse op die opblaasbare PVC-bedekte poliëster-silinders is gebruik om die materiaalmodelle te vergelyk en te verifieer. Eindige element-modelle is geskep deur die drie-punt toetse te dupliseer. Die resultate het gewys dat die borrel-materiaalmodelle die styfheid van die opblaasbare balke oorskat, en die uniaksiale materiaalmodel die styfheid onderskat.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98627
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