Formulation of Cohesive Finite Element for Analysing Strength of Wrinkles in Glass-Epoxy Laminates
Authors
Christensen, Esben Toke ; Sjølund, Jonas Heidemann ; Glud, Jens Ammitzbøll
Term
4. term
Education
Publication year
2013
Submitted on
2013-06-04
Pages
156
Abstract
Denne kandidatafhandling udvikler og anvender en sammenhængszone-model (cohesive zone modelling) inden for den numeriske beregningsmetode finite element metoden. Formålet er at beskrive, hvordan lagdelte materialer begynder at revne og skille ad. Et sammenhængselement programmeres og valideres ved at sammenligne med publicerede resultater. Afhandlingen gennemgår desuden praktiske udfordringer ved metoden og drøfter, hvad de betyder for pålidelige beregninger. Modellen bruges derefter til at analysere, hvordan rynkefejl i glas-epoxy laminater påvirker materialets styrke. Dette undersøges gennem en parametrisk undersøgelse, hvor rynkens geometri varieres for at se, hvordan størrelse og form påvirker styrken. På baggrund af en normaliseret analyse foreslås et enkelt udtryk, der kan bruges til at estimere styrkereduktionen som følge af en rynke.
This thesis develops and applies a cohesive zone model within the finite element method, a computer-based approach used to predict how layered materials start to crack and separate. A cohesive element is implemented and validated by comparing its results with published studies. The thesis also discusses practical challenges of the approach and what they mean for reliable predictions. The model is then used to assess how wrinkle defects in glass–epoxy laminates affect strength. This is explored through a parametric study that varies the wrinkle’s geometry to examine how size and shape influence strength. Based on a normalized analysis, the work proposes a simple expression that can estimate the strength reduction caused by a wrinkle.
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