Development of test tool for evaluation of cohesive zone parameters in DCB composite specimens
Translated title
Udvikling af test værktøj til evaluering af kohæsiv zone parametre i DCB kompositemner
Author
Svenninggaard, Jon
Term
4. term
Education
Publication year
2014
Submitted on
2014-12-19
Pages
204
Abstract
Dette speciale udvikler og bygger et prøveredskab, der påfører rene bøjningsmomenter på dobbelt udkragningsbjælke (DCB) prøver af fiberarmerede kompositter. Målet er at bestemme brudmekaniske parametre ved last i mode I (åbning), mode II (glidning) og kombineret mode, samtidig med at uønskede forskydningskræfter undgås. Redskabet er designet og fremstillet på Aalborg Universitet. For at verificere, at opstillingen leverer de ønskede momenter uden spuriøse forskydningskræfter, blev en særlig verifikationsopsætning med pålimede tøjningsmålere brugt sammen med Digital Image Correlation (DIC), en optisk metode der sporer overfladedeformationer. Prøverne var glasfiber/epoxy-laminater med en 20 μm slipfilm indlagt mellem midterlagene som kontrolleret revnestarter i en standard DCB-geometri. Der blev gennemført vellykkede mode I-forsøg. De målte brudparametre herfra blev anvendt i et finit element (FE) script, der kan simulere revneudbredelsen i en prøve med samme egenskaber som de testede.
This thesis develops and builds a test rig that applies pure bending moments to double-cantilever beam (DCB) specimens made from fiber-reinforced composites. The goal is to measure fracture mechanics parameters under mode I (opening), mode II (sliding), and mixed-mode loading while avoiding unintended shear forces. The rig was designed and manufactured at Aalborg University. To verify that the fixture delivers the intended moments without spurious shear, a dedicated setup with bonded strain gauges was used together with Digital Image Correlation (DIC), an optical method that tracks surface deformation. Test specimens were fiberglass/epoxy laminates with a 20 μm slip film inserted between the middle plies to act as a controlled crack starter in a standard DCB configuration. Successful mode I tests were conducted. The fracture parameters measured in these tests were then used in a finite element (FE) script capable of simulating the crack growth process in a specimen with the same properties as those tested.
[This abstract was generated with the help of AI]
Keywords
DCB ; Cohesive zone ; Fracture mechanics ; Composite ; glass fiber ; Test ; digital image correlation ; mode I ; Mode II
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