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The same observation was reported for impact damage of hemp/carbon hybrid laminates, which was studied by Pinto. According to Sezgin and Berkalp , strong bonding at the interface and strong adhesion between the carbon ply and matrix improved the mechanical strength of the laminates. The same absorbed energy trend was reported by Giasin et al. while studying the impact properties of carbon/glass laminates . When the impact energy is delivered at a low level, the computations demonstrate that quasi-isotropic laminates absorb less energy than the cross- and angle-ply laminates. Figure 15c,d illustrate the energy profiling diagrams of the laminates at ply orientation quasi-isotropic. This could contribute to the bending stiffness of the laminates; additional elements affect the amount of energy absorbed when the ply orientation changes .

Trash Pineapple Leaf Fiber Reinforced Polymer Composite Materials for Light Applications

If a natural frequency of the structure is close to an excitation frequency, then severe vibration of the structure could occur. In designing structures, it is critical to know the natural frequencies of the structure. The composite beam members have been increasingly used over the past few decades in the fields of aerospace, civil and mechanical engineering due to their excellent engineering features. The composite materials are well known by their excellent combination of high structural stiffness and low weight. Figure 6 illustrates the optical micrograph of the specimen under flexural loading. This is due to the longitudinal arrangement of the fibre, which provides high resistance towards tensile loading 31,37,38.
Energy profiling diagram of the hybrid laminates at ply orientations of (a) 0°/90°8, (b) ±45°8, (c) ±45°2, 0°/90°2 s, and (d) 0°/90°2, ±45°2s. Figure 15 illustrates the energy profiling diagram of the PALF/carbon hybrid laminate composite. Contact force–time of the hybrid laminates at ply orientations of 0°/90°2, ±45°2s.
The primary mechanism of internal damage at the rebounding stage of failure is matrix cracking. Upon impact, local separation from one another causes frequent damage to such systems 59,67. Therefore, delamination occurred at the interfaces of the varyingly oriented PALF and carbon layers. When the critical load is reached, the hemp layers’ presence changes the material’s response, resulting in larger damage growth at both the carbon and hemp interfaces based on c-scan images. CPPC demonstrated less distortion because of the presence of carbon in the exterior layer. For the PCCP laminate, indentation (maximum) occurred at 15 J, followed by penetration at 20 J, before perforation at 22.5 J.

Figure 4.

Penetration and perforation are failures at the macroscopic level when the penetrators completely enter the material at which the failure of the fibres reaches a critical point . The catastrophic penetration mode in Table 4, Table 5 and Table 6 was preceded by fibre failure. High bending stresses and locally high strains under the penetrators cause fibre failure, whereas locally high stresses and the indentation effects of shear pressures cause fibre failure on the unaffected face . Matrix cracking and delamination typically occur earlier in the fracture process than fibre failure damage . The cracking is caused by tension, compression, or shear and happens parallel to the fibres.

3. Charpy Impact Response

In addition, the PPPP-treated sample exhibited approximately 30% less displacement indention than the PPPP-untreated sample. The PPPP-treated sample exhibited a significantly higher maximum contact force than the PPPP-untreated sample, 35% more than the contact force at 2.7 kN, as shown in Figure 5. The exterior top surface of the PALF layer experiences local bending and indentation in the surrounding impact region; however, the inner layer experiences a localised buckling contact force that reaches the peak load zone. A post-analysis was performed using MATLAB R2021a to compute energy absorption. In order to determine the specific perforated energy levels, a refinement test was performed between the unperforated and perforated energy levels.
The laminate of 0/90° fibers have the lowest torsional natural frequencies than the other lamination schemes and thus, because 50% of the fibers are oriented at 0° direction for 0/90° laminate, and thus appropriate for bending (Flexural Modes). To investigate the influence of laminate stacking sequence, dynamic modeling is performed to 3 set of symmetrical laminates with a total of 8 layers and dimension of 400 mm length, 40 mm width and total thickness 3.2 mm. For symmetric orthotropic laminated beam previously mentioned; the torsional stiffness of the beam can be obtained by this relation, A beam with two cross-sectional planes of symmetry may undergo flexural vibration in either of the two planes of symmetry and torsional vibration . The laminated beam is made of many plies of orthotropic materials, and the principal material axes of a ply may be oriented at an arbitrary angle with respect to the x-axis.
This characteristic exhibited by LM1 could be due to brittle fibre breakage and matrix cracking that are less obvious in other laminates (LM2, LM3, LM4 and LM5) with a multidirectional layup sequence. The fibre orientation in LM1 is unidirectional, while LM2 and LM3 are cross-ply laminates because the direction of the fibres is at 00 and 900. The failure modes exhibited by various stacking sequences under flexural loading were analysed by capturing the surface of damaged laminates using an optical micrograph. Therefore, the effect of stacking sequence on flexural, tensile and impact damage of composite laminate is yet to be adequately studied. The results showed that the hybrid stacking pattern improved the composite tensile, flexural and impact resistance.

• 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.
• Consequently, the effects of the glass/natural fibre-reinforcement stacking sequence were also examined in various hybrid formulations with GFRP 30,31,32.
• When the impact energy is delivered at a low level, the computations demonstrate that quasi-isotropic laminates absorb less energy than the cross- and angle-ply laminates.
• At 5, 10, and 15 J impact energy, the laminates exhibited a rebound effect after the impactor contact force reached the peak force zone.
• Consequently, a laminate with varied ply orientations limits energy transfer over its thickness and fails when subjected to higher loads .
• 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%) .

All the samples with different stacking orders were tested for their flexural strength. Reinforcement fibres are the primary load-bearing components, accounting for the majority of the strength and stiffness of the composite. Furthermore, among the several natural fibres extracted from plant leaves, PALF has the largest portion of fibre content and the minimum microfibrillar angle, which is the primary reason for its excellent impact performance .

Table 1. Material elastic properties

The PPPP-treated laminate exhibited approximately the same energy absorption trend as that of the PPPP-untreated laminate, with a 10–20% improvement. The PPPP-untreated sample exhibited approximately 50% energy absorption at low impact energies of 5 and 10 J. This demonstrates that some energy is dissipated and that not all the energy supplied to the laminate is redirected back to the impactor . The laminate exhibits a fluctuated force–displacement curve at a high impact energy level. This observation was in agreement with previous studies on the response to the impact of sisal/epoxy composites .
This can be explained by the fact that the fibers oriented at 0° are more appropriate to flexural loads and the fibers oriented at 45° are more appropriate to torsional loads. The torsional frequencies are obtained by the analytical methods and by FE package, Table 3. It presents the variation of the lowest three torsional natural frequencies of the beam with respect to fiber angle. Where a66 is element 6–6 of the laminate extensional compliance matrix (m/N) In shear deformation theory the effect of the shear deformation is considered in torsional frequencies calculation as given by (La's zlo' and George, 2003).
Qiao et al. presented a combined analytical and experimental approach to characterize the vibration behavior of pultruded Fiber-Reinforced Plastic (FRP) composite cantilever I-beams. Investigated the analysis of Flexural-torsional vibration of open section composite beam with including shear deformation. Several researchers have carried out studies on experimental and theoretical evaluations of flexural- torsional vibration analysis for FRP structural members. queenwin casino review Make study intended to analyze free and forced vibrations of non-uniform composite beams in the Laplace domain.

Table 2.

The typical rebounding effect was defined by typical load increase and discharge decrease phases with a single-peak load that is often observed in lower impact energy scenarios . The curves generally show the energy levels at which rebounding, penetration, and perforation occur during the impact test. The collected raw data demonstrate an oscillating and noisy behaviour response to the natural modes of vibration of the impacting system; shaft, hammer, and impact sensor . As illustrated in Figure 1, the laminate was clamped between two metal features with a central circular aperture where the impact occurred. The layering sequences of the laminates are summarised and illustrated in Table 2a,b.

Thus, in this study, a pre-impregnated carbon/epoxy tape was utilised to produce the laminate composite. Grigoriou and Mouritz showed the influence of stacking patterns on the fire resistance of CFRP laminates. It was revealed that the stacking pattern affects the damping and ageing time of the composites. Mlyniec, Korta, Kudelski and Uhl studied the influence of thickness, stacking sequence and thermal ageing on the behaviour of CFRP laminates.

• The laminates were manufactured using a vacuum infusion approach with various stacking sequences and ply orientations classified as symmetric quasi-isotropic, angle-ply symmetric, and cross-ply symmetric.
• The difference between them was that the PPPP-untreated laminate was penetrated at 12.5 J, whereas the PPPP-treated laminate was penetrated at 17.5 J.
• On the other hand, LM2 exhibited high interlayer delamination between 0°/90° stacking configuration, as revealed in Figure 6.
• Further research is required to study the compression and shear properties, which can play a vital role in further analysing the internal and interface failure of the laminates.
• The practical significance of this study is to provide structural engineers with a better understanding of how the ply stacking pattern of the laminates can be tailored to strengthen structural reinforcement.
• This observation was in agreement with previous studies on the response to the impact of sisal/epoxy composites .
• 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.

The PPPP-untreated exhibited a unique fracture pattern with multidirectional cranking propagation. In his study, based on c-scan images for front and back sides, the delamination starts around the laminate’s central plane and spreads beneath it, giving the impression that the virtually rectangular zone is a little thinner. The finding was agreed upon by Romasko in his study on composite oriented at 0°/90° .