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Characterization of low velocity impact damage of gamma-irradiated kevlar/oil palm empty fruit bunch hybrid composites


Muhammad Amir, Siti Madiha (2019) Characterization of low velocity impact damage of gamma-irradiated kevlar/oil palm empty fruit bunch hybrid composites. Doctoral thesis, Universiti Putra Malaysia.


Malaysia, the second world largest exporter of palm oil has generated abundance of oil palm empty fruit bunch (EFB) waste. The oil palm EFB has the potential as the reinforcement in composites for energy absorption applications. In this work, the oil palm EFB were hybridized with Kevlar fabric using hand lay-up technique with different layering patterns. The composites were exposed to gamma radiation dose, i.e. 25 kGy, 50 kGy and 150 kGy. Material characterization were carried out to evaluate the effects of radiation on its mechanical and physical properties of the materials. Low velocity impact and compression after impact tests were performed in this study. Damage propagation were observed using Ultrasonic C-Scan, Computed Thermography and Acoustic Emission methods. The tensile and flexural showed that hybrid composites were 48% and 45% respectively higher in hybrid composites with Kevlar as the skin. The compressive strength was 69% for hybrid composites with oil palm EFB as the skin. The optimum dose for tensile was at 25 kGy and 50 kGy for flexural and compression. At 150 kGy, the degradation of mechanical properties were observed. The density of hybrid composites for Kevlar as the skin was 0.89 g/cm³. Irradiated composites were observed to have lower water absorption capacity. The impact resistance of the irradiated Kevlar/oil palm EFB hybrid composites was up to 35 J. In damage detection, the images from ultrasonic-C-Scan method did not reflect the actual images observed. Computed tomography and acoustic emission complemented each other in detecting the matrix cracking, delamination and fibre breakage damages in the hybrid composites. From the compression after impact test, it was observed that the compressive residual strength was decreased when the impact energy increased. The optimum radiation dose to withstand the compressive residual strength for 35 J was at 50 kGy. The newly developed hybrid Kevlar/oil palm EFB composites have the potential to be used in energy absorption applications and exposure to gamma radiation is one of the methods to improve its mechanical strength of the hybrid materials for monotonic loading applications.

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Additional Metadata

Item Type: Thesis (Doctoral)
Subject: Composite materials
Call Number: FK 2019 135
Chairman Supervisor: Mohamed Thariq bin Hameed Sultan, PhD, PEng, CEng, PTech
Divisions: Faculty of Engineering
Depositing User: Ms. Nur Faseha Mohd Kadim
Date Deposited: 27 Jan 2021 03:21
Last Modified: 04 Jan 2022 00:54
URI: http://psasir.upm.edu.my/id/eprint/84375
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