| Abstract: | Poly (methyl methacrylate) organic glass is used in aircraft windshield application; these structures should have better fatigue and fracture resistance to yield good service life. The tendency towards achieving these properties is lost during manufacturing process. This study aims to determine the effect of grooving on PMMA Organic glass. The grooves are manufactured using two different processes namely Micro-Milling (MM) and Laser Ablation (LA). The tribological properties of laser ablated PMMA (LA-PMMA) and micro-milled PMMA (MM-PMMA) were studied using Pin-on-disc tribometer. The grooved surface roughness of both MM-PMMA and LA-PMMA samples has decreased with increase in wear time, whereas after reaching minimum roughness the coefficient of friction has increased; due to higher adhesion between polymer and sliding metal. The tensile properties of differently machined samples have not shown significant difference; whereas the fracture toughness values were higher with LA-PMMA samples. This effect indicated LA-PMMA had greater capacity to resist crack propagation compare to MM-PMMA samples. Similarly the fatigue endurance limit was found higher with LA-PMMA compared to MM-PMMA, due to better finish of LA-PMMA. Further, the microscopic analysis of laser grooved sample before and after fracture have also shown smoother surface and less conic shapes (fracture point) compare to MM-PMMA. |
