Effects of temperature, strain-rate & hygrothermal aging on the mechanical properties of composites

• Main Author: Muhammad Johan Jamil.
• Other Authors: Seah Leong Keey
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/54238
• Institution: Nanyang Technological University

Fiber Reinforced Polymer (FRP) composites are fast becoming the material of choice for underwater marine applications due to their high strength to weight ratio and good corrosion resistance. However, FRP composites utilized in marine applications are constantly subjected to the effects of the marine environment and an assessment of their performance and servicibility when subjected to these effects is important. This project investigates the moisture diffusion characteristics of Carbon Fiber Reinforced Polymer (CFRP) composite specimens through moisture diffusion tests and it also investigates temperature, strain-rate and hygrothermal aging effects on the mechanical properties of the specimens through 3-point bending (in-flexure) tests. Diffusion rates and maximum moisture contents of the specimens were found to exhibit time-dependence as characterized by the Fickian diffusion model. An increase in temperatures from 30℃ to 100℃ resulted in a 31.9% flexure strength reduction at a strain-rate of 2 mm/min. An increase in strain rate from 2mm/min to 20 mm/min resulted in a 4.32% to 15.0% increase in flexure strength across constant temperatures of 30℃, 50℃, 80℃ and 100℃ and an estimated 90.0% reduction in time to failure. Hygrothermal aging of the specimens resulted in an estimated 20.0% flexure strength reduction at temperatures of 100℃ due to matrix plasticization and glass transitioning. Hygrothermal aging also enhanced the viscoelasticity of the polymer matrix, enhancing its temperature sensitivity but its effects on the time to failure of the specimens are inconclusive. The subsequent analysis and discussion of the acquired data will aid in predicting the performance and suitability of CFRP composites in marine applications.