Fatigue properties of carbon fibre nano-composites

• Main Author: Lee, Jin Sheng.
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Aeronautical engineering::Materials of construction
• Online Access: http://hdl.handle.net/10356/53548
• Institution: Nanyang Technological University

Composites are getting more popular in the aerospace industry over the past decades. In recent years, researches on nano-composites are getting increasing attentions. Addition of nanoparticles was found to be able to improve the properties of composites. This report focuses on the research of carbon fibre silver composites. Silver nanoparticles were introduced to the carbon fibre epoxy composites in the form of silver paste. Carbon fibre silver composites with three different fibre orientations (0°/90°, 45°/-45° and 0°/45°), each with two different silver paste content (5%wt. and 15%wt.) were fabricated. Addition of silver nanoparticles is believed to be able to increase the electrical conductivity of the material. An electrically conductive material helps to improve lightning strike protection and electromagnetic interference shielding of an aircraft. From Dynamic Mechanical Analysis, it was found that addition of silver nanoparticles has no effect on the glass transition temperature of the material. Effect of curing on the glass transition temperature of the carbon fibre silver composites is also minimal. Besides that, it was also discovered that silver paste content of the carbon fibre composites has little or no effect on the ultimate tensile strength (UTS) and Young’s Modulus of samples with fibre orientation of 0°/90°. However, for samples with fibre orientation of 45°/-45°, increasing silver paste content from 5%wt. to 15%wt. caused the Young’s Modulus and UTS strength of the composites to drop from 6.96GPa and 77.5MPa to 3.25GPa and 59.5MPa respectively. From fatigue analysis of samples with fibre orientation of 0°/90°, it was obvious that introduction of silver paste is unfavourable to the fatigue life of the samples. Fatigue life reduced by as much as 30% and 90% respectively for fatigue tests of Smax=90%Peak Load and fatigue tests of Smax=70%Peak Load when silver paste content increased from 5% to 15%wt. On the other side, it was found that addition of silver nanoparticles improve the electrical conductivity of the carbon fibre composites tremendously. Conductivity of carbon fibre silver composites was found to be about 60 times higher than that of carbon fibre composites with no nano fillers. For future works, it is recommended that pure silver nanoparticles or nanoparticles of other cheaper metals instead of silver paste be used for the fabrication of the carbon fibre nano-composites for better analysis.