The impact resistance of the GFRP laminates was higher than that of hybrid laminates. The low-velocity impact testing by Sarasini et al. investigated the damage tolerance of carbon/flax composites to determine their failure. Two types of hybrid composite plates (glass–carbon/epoxy) were subjected to impact tests until they were completely perforated.
Modal Analysis by Finite-Element Method, ANSYS
- A post-analysis was performed using MATLAB R2021a to compute energy absorption.
- The laminates were analysed using an IMATEK IM10 drop weight impact tester with an increment of 5 J until the samples were perforated.
- The 90° layers in the cross-ply structure prevented the matrix crack from spreading across the layer thickness since the mechanism of loading during impact is an out-of-plane transverse loading.
- Fibre-reinforced polymer composites (FRPs) are considered in an application where a high strength-to-weight ratio is desirable.
- Free vibration analysis of laminated beams has been conducted by significant amount of research.
- Teh and Huang presented two finite element models based on a first-order theory for the free vibration analysis of fixed-free beams of general orthotropy.
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 .
- The PPPP-untreated exhibited no visible indentation compared to PPPP-treated with a mild circular indentation at the top side and a hairline crack propagated along the ply direction.
- Therefore, a hybrid synthetic with natural fibres was introduced to ensure environmental sustainability and reduce the carbon footprint.
- However, the effects of ply orientation and stacking sequences on the low-energy impact of PALF/carbon hybrid laminate composites are yet to be investigated.
- Grigoriou and Mouritz showed the influence of stacking patterns on the fire resistance of CFRP laminates.
- Both laminates exhibited the same impact level of indentation (maximum), penetration, and perforation, at 15, 17.5, and 20 J, respectively.
- Thus, in this study, a pre-impregnated carbon/epoxy tape was utilised to produce the laminate composite.
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.
Table 3.
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.
The PPPP-untreated laminate exhibited a rebound effect at 5 and 10 J impact energy levels, followed by penetration at 12.5 J with a maximum curve peak of 2.0 kN, as shown in Figure 11. This is due to the hybridisation effect of the ply orientation that results in varying stiffness along with the thickness of the laminate . The contact force–displacement curves for the laminates with ply orientations of ±45°2, 0°/90°2s are shown in Figure 9. The laminates withstand high impact energy before penetration occurs at 25 J, followed by perforation at 27.5 J. The theoretical prediction explained the phenomenon that the laminate with ±45° ply orientation had better transverse shear strain than that with 0°, 90° ply orientation, which is useful to withstand the impact load . For the PCCP laminate, the curves exhibited a rebound pattern at low impact energy.
Figure 8.
Researchers studied the reactions of four different hybrid laminates under low-velocity impact loading 26,27. Quaresimin et al. observed that the impact energy absorption capabilities may be affected by the thickness and fibre orientation, with a 0°/45° interface demonstrating the least impact damage. Natural-synthetic fibre hybrid composites have been the subject of previous research, which mostly focused on reducing the use of synthetic fibres 8,9.
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.
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.
This phenomenon was explained by removing hemicellulose, lignin, waxes, and other 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.
Figure 4.
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.
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 queenwin casino review 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.
Even though there are multiple orientation configurations, one could reasonably deem that transverse and off-axial detachment of the fibre significantly affects the overall resistance of the laminates. Similar behaviour has been reported by Bezazi et al. during flexural testing of a hybrid kevlar/glass cross-ply laminate. However, influencing material behaviour by manufacturing composite laminates with different stacking patterns may be an essential technique for improving the capability to withstand bending force before failure. The Charpy impact test was carried out on the samples to measure the amount of energy absorbed under an impact force normal to the laminates.
Table 3. Torsional natural frequencies (Hz) for different stacking sequences laminate
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.
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.