Effect of selective particle dispersion on impact performance of composite laminates

• Main Author: Quek, Gary Wei Quan.
• Other Authors: Sunil Chandrakant Joshi
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Aeronautical engineering::Materials of construction
• Online Access: http://hdl.handle.net/10356/53445
• Institution: Nanyang Technological University

Composite materials are gaining extensive popularity in aerospace industry due to their better mechanical performance over traditional materials. High specific strength, stiffness, fatigue strength and resistance to corrosion make it a material of choice. However, the major challenge in the use of composite materials in the aerospace industry is in protecting it from impact events. Impact events are common and damage to the aerospace structures with composite materials has to be minimized. This project studies the improvement in impact performance of glass fibre-reinforced polymer (GFRP) composites through the dispersion of core shell polymer (CSP) particles in the interfaces of the laminates. The effect of varying particle density was first investigated and it was observed that a particle density of 40g/m2 provided the best improvement in terms of impact performance. Parameters which improved included peak force by 17.6%, contact time by 10.0% and damping index by 58.2%. Visual examination presented significant reduction of damage on the composite laminate and scanning electron microscope (SEM) observations, allowed the identification of the deforming CSP particles as the mechanism allowing greater absorption of impact energy and restricting damage propagation. 4-point bending tests conducted indicated a reduction in stiffness with increasing particle density, confirming that the CSP particles have toughened the matrix, allowing more energy to be absorbed elastically. The effect of selective dispersion of particles in the interface was studied in the second part of the project. Specimens with particles dispersed in 3, 5 and 7 interfaces were tested. It was observed that particle dispersion on the non-impact side typically experienced better impact performance due to the CSP particles being able to absorb more energy on the bottom plies, reducing the flexural tensile stresses which propagate fibre breakage through the plies. The performance of specimens with particles in 3 interfaces was also significantly better than for 5 interfaces. The performance of specimens with particles in the bottom 3 interfaces was found to be comparable with that of specimens with 7 interfaces. The study is concluded with the observation that dispersing CSP particles of particle density 40g/m2 in the bottom 3 interfaces of a composite laminate, provides the best improvement in impact performance and most effective use of particle dispersion.