Low-velocity impact performance of glass fiber, kenaf fiber, and hybrid glass/kenaf fiber reinforced epoxy composite laminates

The goal to decrease global dependency on petroleum-based materials has created a demand for bio-based composites. Composites that are reinforced with natural fibers often display reduced strength compared with those using synthetic reinforcement, and hybridizing both types of reinforcement within a common matrix system offers a possibly useful compromise. This research investigated the low-velocity impact performance of glass, kenaf, and hybrid glass/kenaf reinforced epoxy composite plates. The aim of the study was to determine the low-velocity impact behavior of biocomposite material in assessing its potential for application in the radome structures of aircraft. Natural fibers possess low dielectric constants, which is a primary requirement for radome. However, the structural integrity of the material to impact damage is also a concern. Composite samples were prepared via a vacuum infusion method. A drop weight impact test was performed at energy levels of 3 J, 6 J, and 9 J. The Impact tests showed that the impact peak force and displacement increased with the energy level. Hybrid glass/kenaf composites displayed damage modes of circular and biaxial cracking. The former is analogous to the damage observed in glass-reinforced composite, while the latter is unique to woven kenaf reinforced composites. The severity of the damage increased with impact energy and was found to be significant at 3 J

Quasi static analysis of a biocomposite aircraft radome

This paper investigates the quasi static compression analysis behavior of a biocomposite radome using nonlinear static modeling. Bio-based fiber is proposed to be used in aircraft radome due to its low dielectric constant. In this instance, kenaf was being utilized as the natural fiber to form a hybrid combination of fiberglass/kenaf epoxy laminates. The quasi static behavior was modeled using MDNastran SOL106 Nonlinear Static. The radome was modeled as a hemispherical shell based on Beechcraft’s radome geometric configuration. The radome is designed as a four-layered laminates with randomly oriented fiberglass and kenaf. The nonlinear compression was performed in the range of 0.01 mm to 0.49 mm with a maximum reaction force of 189 N. The radome was not displaced equally or symmetrically as the translational load applied since the shape of radome is asymmetry and the surface at the top is uneven. The increment of the forces leads to elastic local flattening deformation at the apex of the radome. Its shape influences in determining the displacement and the stress to the radome

Perceptions of Disability among University Students

Perceptions of disability are important constructs that influence not only the well-being of people with disabilities but also the moral compass of society. Negative attitudes toward disability can lead to social exclusion and isolation of people with disabilities, whereas positive attitudes promote social inclusion. The present study was conducted to examine the main predictors of disability perceptions among university students, provided that understanding these factors can help develop effective interventions to improve students’ attitudes toward peers with disabilities and reduce intergroup prejudice. Using 110 responses from university students at a public university, the study found that knowledge and exposure contribute significantly to perceptions among university students. Management of the university plays a critical role in shaping positive perceptions by facilitating meaningful interactions with people with disabilities, promoting disability awareness and education, and creating an environment that values diversity

Validation of low velocity impact on a biocomposite flat plate laminates

Impact analysis under low velocity was carried out on flat plate structure at normal and oblique impact with energy level of 3J to 9J with interval of 3J. Utilization of natural fiber reinforced with polymer and hybridizing it with synthetic fiber were introduced. The aim of the study was to assess the effects of low velocity impact on biocomposite structure composed of chopped strand mat (CSM) glass fiber, kenaf fiber and hybrid of both materials and epoxy as resin material. Drop weight impact test of flat plate structure and determination of mechanical characterization were carried out with samples prepared under vacuum infusion method for glass/epoxy, kenaf/epoxy and hybrid composites composed of those two material. Glass/epoxy composites exhibit better mechanical properties as compared to kenaf/epoxy composites. From the experimental work, it was found that the impact energy level influenced the impact peak force proportionately. Hybrid composites generates damage propagation with combination of damage propagation from individual fiber of glass and kenaf reinforced polymer. The severity of damage was high at higher impact energy although significant damage at impact energy of 3J was detected under drop weight impact test where internal damage on all three configurations had occurred which further suggested reduction in residual strength. Finite element analysis was then carried out for flat plate model of all three configurations and validated against the experimental work. It was found that validation on all configurations meet the agreement with experimental results. Further finite element analysis considered all configuration based on the validation results for flat plate on oblique impact. The influence of impact angle was found to affect the maximum impact force of the impacted material where at higher impact energy the respond of maximum impact force was significant. However, there is slightly impact damage detected at lower impact energies under oblique impact