Fabrication and testing of GLARE specimens

• Main Author: Lai, Wei Hong
• Other Authors: Chai Gin Boay
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Aeronautical engineering::Materials of construction
• Online Access: http://hdl.handle.net/10356/65014
• Institution: Nanyang Technological University

This report first presents the steps involved in fabrication of composites such as CFRP and GLARE. Fabrication involved hand lay-up method, vacuum bagging, and autoclave curing. The next chapter of the report investigates the effects of adding elasto-plastic aluminium interleaves in between plies of carbon fibre reinforced polymer. Aluminium foil interleaves can reduce the stress concentration between the plies of carbon fibre during bending and indentation. The plastic deformation of aluminium foil interleaves redistribute the stress built up in between the plies and delays failure of the composite. Consumer grade aluminium foil for food wrapping was used instead of 99% aluminium in order to determine its effectiveness, which can result in cost savings in production if it can replace 99% aluminium. It was found that for thin and long specimens, the foils did not form good adhesion with carbon fibre layers during curing. The inclusion of foils became more of administering inter-laminar cracks. Three-point bending test of these specimens yielded poorer performance of peak load and flexural rigidity as compared to those without aluminium foil interleaves. However, square plate specimens showed better adhesion of carbon fibre layers to the aluminium foils. After normalizing with area density, the energy absorbed by the specimens with interleaves only showed slight improvement, but ductility index was higher with the inclusion of interleaves. The interleaves encouraged delamination, which created a more global damage, resulting in a more damage tolerant structure. The final chapter aims to determine the difference in physical properties and failure characteristics of GLARE with different stacking sequence, but with the same metal volume fraction and thickness. GLARE 2/1, 3/2, and 4/3 were used in the experiments. Three-point bending test indicated that GLARE 4/3 can withstand the highest load followed by 3/2, and lastly 2/1. However static indentation test returned reverse results, with GLARE 2/1 withstanding highest indentation load and absorbing the most energy, followed by 3/2, and lastly 4/3. From ductility index standpoint, GLARE 3/2 was the best, while 2/1 and 4/3 were less desirable.