Low Velocity Impact Response of Laminated Textile Coiraramids Epoxy Hybrid Composites Subjected to Transverse Penetration Loading

• Main Author: Abdul Rashid, Azrin Hani
• Format: Thesis
• Language: English
• Published: 2015
• Subjects: T Technology; TK7800-8360 Electronics
• Online Access: http://eprints.usm.my/40815/1/Low_Velocity_Impact_Response_of_Laminated_Textile_Coiraramids_Epoxy_Hybrid_Composites_Subjected_to_Transverse_Penetration_Loading.pdf; http://eprints.usm.my/40815/

Hibrid bagi gentian sintetik dan gentian semula jadi dalam sistem komposit telah mendapat perhatian dalam bidang penyelidikan disebabkan oleh kesedaran terhadap alam sekitar. Gentian sabut kelapa diketahui mempunyai potensi yang tinggi sebagai rintangan hentaman, iaitu gentian yang rapuh membantu menyebarkan tenaga hentaman ke kawasan yang lebih luas. Fokus kajian ini ialah untuk menentukan jika terdapat sebarang penambahbaikan dalam tindak balas terhadap hentaman disebabkan oleh penggabungan serat Kevlar yang berprestasi tinggi dan gentian sabut kelapa dalam urutan susunan berlamina tertentu. Dalam kajian ini, eksperimen kuasi-statik dijalankan pada kelajuan 1.25 mm/s, dan ujian hentaman halaju rendah dijalankan dengan menggunakan penghentam berbentuk hemisfera 12.7 mm pada kelajuan yang berbeza-beza, iaitu daripada 5 m/s ke 17 m/s. Perisian Matlab digunakan untuk penyesuaian lengkung bagi data mentah, manakala ANOVA dan DOE melalui perisian Minitab digunakan bagi pemeriksaan statistik untuk menyokong hasil kajian. Kawasan komposit yang rosak dinilai menggunakan teknik analisis imej oleh peralatan pemprosesan imej daripada perisian Matlab. Analisis morfologi bagi permukaan yang retak disebabkan oleh hentaman juga diperhatikan menggunakan SEM. Pada peringkat permulaan, tindak balas hentaman optimum terhadap komposit epoksi serat kelapa bagi pelbagai reka bentuk yang diperkukuhkan, kaedah pembuatan komposit, pengubahsuaian fabrik dan ketumpatan fabrik telah ditentukan. Dapatan menunjukkan tindak balas hentaman boleh dikawal secara berkesan dengan parameter-parameter bahan yang berubah. Gentian sabut kelapa dalam bentuk struktur yang ditenun dengan ketumpatan tinggi, dirawat menggunakan larutan NaOH 6% dan dibuat menggunakan kaedah pengacuan mampatan didapati berkesan dalam menyerap dan menyebarluaskan tenaga hentaman. Spesifikasi serat kelapa tersebut kemudiannya digunakan dalam lamina hibrid. Komposit hibrid epoksi sabut kelapa/Kevlar yang mengandungi tiga lapisan luaran lamina bagi enam konfigurasi susunan yang berbeza telah dihasilkan. Komposit hibrid (dua lapisan sabut dan satu lapisan Kevlar) dikenal pasti mempunyai penyerapan jumlah tenaga khusus yang sama seperti Kevlar berlamina 100% (pada tiga lapisan). Secara kesimpulannya, komposit hibrid epoksi sabut kelapa/Kevlar menunjukkan peningkatan dalam tindak balas hentaman. Ia juga memberikan penjimatan kos bahan serta menyumbang ke arah teknologi hijau yang memberikan manfaat besar kepada industri dan komuniti. _____________________________________________________________________________________________________________________________ The hybrid of natural and synthetic fibres in a composite system has gained interest in research field due to the environmental consciousness. Coir natural fibre has been found to have a high potential as impact resistance, in which brittle fibre helps to spread the impact energy over a wider area. The focus of the study is to determine if any improvement in impact response exists as a result of combining high performance Kevlar synthetic fibre and coir natural fibre in a specified laminated stacking sequence. In this research, quasi-static experiments were conducted at the speed of 1.25 mm/s, and low velocity impact tests were conducted using a 12.7 mm hemispherical impactor at the speed varying from 5 m/s to 17 m/s. Matlab software was used for curve fitting of the raw data, whereas ANOVA and DOE via Minitab software were employed for statistical examination to support the results. The area of the damaged composite was evaluated using the image analysis technique by Matlab image processing tool. The morphology analysis of the impact fractured surfaces was also observed by SEM. At the beginning stage, the optimum impact responses of coir epoxy composites subjected to different reinforcement architecture, composite manufacturing method, fabric modification and fabric density were determined. The findings showed that the impact responses could be effectively controlled by varying material parameters. Coir fibre in the form of woven structure with dense structure, treated using 6% of NaOH solution and manufactured by compression moulding method was found to be effective in absorbing and propagating impact energy. The respective coir was then used in hybrid laminates. Coir/Kevlar epoxy hybrid composites consisted of three interply laminates layers at six different stacking configurations were developed. It was observed that the hybrid composite (two coir layers and one Kevlar layer) had equivalent specific total energy absorption as 100% Kevlar laminate (at three layers). It can be concluded that the hybrid of coir/Kevlar-epoxy laminated composites had shown an improved in impact response. It also provides cost-effective materials and contributes towards green technology which will be of great benefit to the industry and community.