Influence of water ageing on the fatigue behaviour of rubberwood reinforced recycled polypropylene

• 第一著者: Tuan Nawi, Tuan Muhammad Idzuddin
• フォーマット: 学位論文
• 言語: 英語; 英語
• 出版事項: 2021
• 主題: T Technology (General); TA Engineering (General). Civil engineering (General)
• オンライン･アクセス: http://eprints.utem.edu.my/id/eprint/26716/1/Influence%20of%20water%20ageing%20on%20the%20fatigue%20behaviour%20of%20rubberwood%20reinforced%20recycled%20polypropylene.pdf; http://eprints.utem.edu.my/id/eprint/26716/2/Influence%20of%20water%20ageing%20on%20the%20fatigue%20behaviour%20of%20rubberwood%20reinforced%20recycled%20polypropylene.pdf

Wood polymer composite (WPC) is considered as one of the emerging materials that have been frequently used because of its outstanding properties. WPC provides an alternative to preserve the timber. In general, composite materials will degrade in performance over time, particularly for structural under cyclic conditions, however not much attention was given to the analysis of the fatigue characteristic in determining WPCs performances for long-term usage. Wood flour, being a natural fibre is also sensitive to moisture. Therefore, the aim of this study to evaluate the fatigue properties of wood flour reinforced recycle polypropylene as well as the influence of water aging on their fatigue strength. The composite granule was compressed moulded at 190°C, 1000 psi for 20 minutes. The quasi-static tensile was carried out for dry specimens and aging specimens subjected to 30 days of water immersion. Tension–tension fatigue test was carried out at various stress levels (40 - 80% UTS), stress ratio of 0.1, and frequency of 4Hz. The initial tensile strength and modulus of the dry specimens is 26.33 MPa and 1.69 GPa, and subsequently reduced to 12.19 MPa and to 0.74 GPa respectively after water immersion. The fatigue life for dry WPC is in the range of 100 cycles to 600,000 cycles when tested at 60 to 80% UTS. At a lower stress level (40% UTS), the number of cycles to failure is more than 1.5 million cycles. A similar observation is seen in water aging WPC. The secant modulus was reduced while energy dissipation was increased with the increasing fatigue life cycle. The morphology study shows water aging induces composite degradation due to fibre swelling and plasticising. The statistical analysis was used to estimate the safety designed life of the material under different reliability levels. The reliability shows that 50% of the specimen are predicted to survive in the range of 200 to 700 cycles at 80% UTS while 50% of the specimen are predicted to survive in the range of 2.0 x105 to 6.0 x105 cycles at 60% UTS for both specimens.