Characterization of low velocity impact damage of gamma-irradiated kevlar/oil palm empty fruit bunch hybrid composites
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 hybr...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/84375/1/FK%202019%20135%20-%20ir.pdf |
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| Summary: | 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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