A previous study discussed the potential benefits of natural-synthetic fibre hybridisation and its implementation . This possibility makes once more these materials very attractive since it makes possible to obtain the desired torsional natural frequencies without increasing mass or changing geometry. This gives the designer one additional degree of freedom to design the laminate – the possibility to change fiber orientations in order to get more (or less) structure stiffness in torsion. Also, effects of boundary conditions on torsional natural frequencies are demonstrated.
At a glance: Figures
It was observed that the fibre direction has damping effects on applied force. Lately, the research on the performance of composite structures subjected to different loading conditions has generated much interest. However, due to the organic nature of the matrix, FRPs are impermeable to vapour, they are flammable and their application on a wet surface at low temperatures is not readily achievable. In recent years, the use of advanced composite materials in many industries has been growing considerably higher due to their numerous advantages compared to other conventional materials 1,2,3.
- In designing structures, it is critical to know the natural frequencies of the structure.
- As shown in Figure 12, the PPPP-untreated and PPPP-treated laminates exhibited almost the same force–displacement curve.
- The prepreg consists of unidirectional (UD), continuous, high-elongation carbon fibres and an epoxy resin system.
- The analysis can be applied to the laminated beam previously mentioned with the same dimensions and geometry.
- The stiffness values of the PPPP-untreated and PPPP-treated samples were significantly different, at which PPPP-treated were able to almost withstand 20% more impact content force.
- Five laminates with different stacking configurations were produced using the hand-laying-up technique.
The crack density depends on the degree of mismatch in the properties between the matrix and the fibre, either due to fibre material or orientation . The fracture pattern was also identical at each impact level; however, the direction of crack propagation varied due to different ply orientations. In the study, the c-scan images showed that the hemp layers at the midplane do not affect the laminate’s elasticity at low impact energy levels. As summarised in Table 5, crack propagation was substantially slower in laminates with exterior carbon layers than in laminates with PALF exterior layers. The internal matrix cracking and delamination was the main damage mechanism at the impact energy levels of rebounding . Table 4 lists the damaged areas exhibited by PPPP-untreated and PPPP-treated at ply orientations of 0°/90°8.
Therefore, a hybrid synthetic with natural fibres was introduced to ensure environmental sustainability and reduce the carbon footprint. Carbon-fibre-reinforced polymer (CFRPs) composites are widely used in modern industries because of their superior mechanical strength . Through visual inspection, delamination was observed to occur at the interfaces of different stacking sequences and ply orientations. This investigation reveals that the overall impact properties of PALF and carbon as reinforcements were improved by a beneficial hybridised effect.
The Effect of Fiber Orientation and Laminate Stacking Sequences on the Torsional Natural Frequencies…
At 5, 10, and 15 J impact energy, the laminates exhibited a rebound effect after the impactor contact force reached the peak force zone. Contact force–time of the hybrid laminates at ply orientations of ±45°2, 0°/90°2s. Contact force–displacement of the hybrid laminates at ply orientations of ±45°2, 0°/90°2s.
- Yildirim, V. used the stiffness method for the solution of the purely in-plane free vibration problem of symmetric cross-ply laminated beams with the rotary inertia, axial and transverse shear deformation effects included by the first-order shear deformation theory.
- Et al. gave analytical solutions for the free vibration problem of laminated composite beams.
- For the PCCP laminate, indentation (maximum) occurred at 15 J, followed by penetration at 20 J, before perforation at 22.5 J.
- In cross-ply laminate, this phenomenon initiates short delamination, which further coalesces within reinforcing plies, thereby causing instability propagation above and below the midplane of the laminates.
- The PPPP-treated laminate exhibited approximately the same energy absorption trend as that of the PPPP-untreated laminate, with a 10–20% improvement.
- These stacking patterns help in the evaluation of mechanical properties and modes of failure under different loading conditions.
- Ply orientation in composites has a complex relationship with their impact damage resistance because of the multidirectional behaviour of the composite and the mechanism through which the damage propagates through the laminate.
Figure 2.
Et al. used the dynamic stiffness analysis and the first-order shear deformation theory to study the free vibration of laminated beams. Abramovich and Livshits studied the free vibration of non symmetric Cross-ply laminated Composite Beams based on Timoshenko type equations. Investigated the free vibrations of axially loaded composite Timoshenko beams using the dynamic stiffness matrix method by developing an exact dynamic stiffness matrix of composite beams taking into account the effects of an axial force, shear deformation, and rotatory inertia. Free vibration analysis of laminated beams has been conducted by significant amount of research.
Figure 10.
The machine was outfitted with a 9.68 kg impactor and a hemispherical impact head with a diameter of 10 mm and a mass of 0.71 kg. The PALF and carbon plies were layered on the glass surface and protected by a plastic layer. The load–deflection curves and photographs of the damaged samples acquired from the impacted and non-impacted sides were compared to determine the failure processes of the damaged specimens for various impact energies. The leaf produces a lot of cellulose fibre, with cellulose making up the majority (70–82%) and lignin (5–12%) and ash making up the remainder (1.1%) . PALF is the most often used fibre in the textile industry for various reasons, including its abundance, low cost, superior thermal and acoustic insulation, exceptional tensile strength, and high toughness. One of the best options for natural reinforcement fibre is pineapple leaf fibre (PALF), a massive amount of biomass waste abundantly available in tropical countries .
Mechanical and Morphological Properties of Pineapple Leaf Fibre/Kenaf Fibre Reinforced Vinyl Ester Hybrid Composites
The flexural strength and modulus of the materials were determined using Equations (1) and (2). Five samples from each laminate were tested to ensure the reliability of the result. These stacking patterns help in the evaluation of mechanical properties and modes of failure under different loading conditions. This process was conducted by applying a small portion of the adhesive to the surface using a paper towel and then allowing the liquid to react for 15 min before applying the next coating layer.
Materials and Methods
This phenomenon was explained by removing hemicellulose, lignin, waxes, and other queenwin casino review contaminants from pure PALF, which improved the fibre–matrix interaction and resulted in better impact strength . Thereafter, the cracks spread along and perpendicular to the entire surface of carbon ply as the impactor moved downwards; as a consequence, force indentation indicates a prolonged stable plateau right after the peak force. The CPPC laminate exhibited the greatest impact strength by referring to the prolonged curve on the rebound zone until penetration occurred at 25 J. The laminate was penetrated only when the impact energy reached 17.5 J and was perforated at 20 J.
The PPPP-treated laminate exhibited a slight increase in impact strength as the laminate withstood the rebound effect zone up to 15 J before penetration at 17.5 J with a maximum force peak at 3.1 kN. By comparing the PCCP and CPPC laminates, the CPPC laminate exhibited higher stiffness compared to the PCCP laminate. For the PCCP laminate, the curves exhibited a rebound pattern at low impact energies of 5, 10, and 15 J.
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