The unidirectional laminates have higher flexural and tensile strength compared to the cross-ply and quasi-isotropic laminates. Following the autoclave curing process, the responses of the composites to bending, tension and impact force were determined according to ASTM standards, and their corresponding strength, stiffness as well as impact energy were evaluated. Delamination is a fracture that occurs between plies with various fibre orientations in the matrix-rich region . When the applied impact energy is beyond a certain level, the matrix cracking reaches the maximum level, exceeding energy causing the second mode of internal damage mechanism, delamination . The density matrix cracking was predicted to be higher at interface bonding between carbon fibre and matrix than PALF and matrix.
Figure 10.
- The catastrophic penetration mode in Table 4, Table 5 and Table 6 was preceded by fibre failure.
- This could contribute to the bending stiffness of the laminates; additional elements affect the amount of energy absorbed when the ply orientation changes .
- The commercial finite element program ANSYS 10.0 is used to perform a dynamic modelling to the laminated beams by performing an eigenvalue analysis.
- The impact resistance of the GFRP laminates was higher than that of hybrid laminates.
- The composite materials are well known by their excellent combination of high structural stiffness and low weight.
- The perforation threshold of the hybrid composite with a carbon face sheet was 30% more than that of the hybrid composite with a glass face sheet.
- PALF/carbon hybrid laminate composites have the potential to replace synthetic fibres due to their good mechanical qualities.
Caminero, Rodriguez and Munoz studied the effect of stacking sequence on the Charpy and flexural damage of carbon fibre-reinforced polymer composite (CFRP) laminates. In this work, the effect of ply stacking sequence of carbon/epoxy laminates subjected to flexural, tensile and impact loading was investigated. PALF/carbon hybrid laminate composites have the potential to replace synthetic fibres due to their good mechanical qualities.
Furthermore, they can be incorporated into two or more reinforcing and filling materials in a single matrix of queenwin casino review reinforcement and filling materials . From the results, It is seen that the clamped-clamped condition has a larger torsional frequency than other boundary fixations, and thus for all fiber angles. Each layer in the laminate has the same thickness.
These fibres can be utilised as another possibility to synthetic-fibres, resulting in more environmentally friendly composite products. 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. An optical micrograph of the damaged laminate surface was used to explain the failure mode of the composite. Likewise, LM3 displayed a similar mode of failure as LM2 but minimal interlayer delamination due to the symmetry and balanced nature of the cross-ply laminate. On the other hand, LM2 exhibited high interlayer delamination between 0°/90° stacking configuration, as revealed in Figure 6. This behaviour has been reported in previous works on Charpy impact loading of composite 43,44,45,46,47.
Figure 2.
The influences of fiber orientation are investigated by modeling laminated beams of different lay-up construction of clamped – free boundary condition as shown in Figure 1. The bending–torsion coupling due to stiffness coupling presented in composite beams due to fiber orientation and stacking sequence is neglected. Et al. studied the flexural–torsional behavior of thin-walled composite beams with closed cross-section and a number of nonclassical effects, such as material anisotropy, transverse shear, are considered in the study. This model is based on the classical lamination theory, and accounts for the coupling of flexural and torsional modes for arbitrary laminate stacking sequence. Lee and Kim studied free vibration of a thin-walled laminated composite beam, where a general analytical model applicable to the dynamic behavior of a thin-walled channel section composite is developed. Chandrashekhara and Bangera investigated the free vibration of angle-ply composite beams by a higher-order shear deformation theory using the shear flexible FEM.
Materials and Methodology
- Likewise, FRP composites’ brittleness and disastrous failure without sufficient onset warning are generally unacceptable in most engineering applications 12,13,14,15.
- Maximum contact force and displacement against impact energy of the hybrid laminates at a ply orientation of ±45°n.
- However, the CPPC laminate demonstrated better impact resistance; the laminate was penetrated at 25 J and perforated at 27.5 J.
- In order to comprehensively understand the behaviour of the composites after impact, the interplay between ply orientation and stacking sequences is required.
- An essential factor determining the type of failure exhibited by a composite laminate is the ply stacking sequence that also determines the orientation of the fibre 20,48,49.
- This study examined the effect of stacking configuration of CFRP laminates subjected to flexural, tensile and impact loading.
Sudarisman and Davies reported a maximum Ef of 61.10 GPa for a unidirectional carbon fibre-reinforced, epoxy laminate fabricated using an autoclave processing technology. 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. Among all the configurations studied, LM1 with unidirectional fibre orientation (Table 3) is the most efficient in providing flexural resistance and stiffness, with an average flexural stress σf of 1100 MPa and modulus Ef of 98.40 GPa. The laminates were covered with the release film and breather before enclosing them in a vacuum bag, as shown in Figure 1. In a similar manner, the tensile properties of the composites were determined on a universal tensile machine, while their impact performances were measured using a pendulum impact tester. A three-point bending test was conducted to investigate the flexural properties of the laminates.
2. Impact Energy Profile
Both exhibited a circular penetration pattern at the top side and a crack opening on the bottom side. The penetration energy levels were 12.5 and 17.5 J for the PPPP-untreated and PPPP-treated, respectively. The penetration level was determined at the point of the greatest contact force and energy absorption. Table 4, Table 5 and Table 6 summarise the results of the investigations on the damage caused by the fracture of the impact. This could be because carbon has a higher failure strain than PALF due to its greater elongation.
Mechanical and Morphological Properties of Pineapple Leaf Fibre/Kenaf Fibre Reinforced Vinyl Ester Hybrid Composites
This experiment utilised a 650 mm wide and 900 mm long glass mould to fabricate the composite. The resin content of the material is 35 ± 3% by weight, while the aerial weight of the fibre is 450 g/m2. The carbon/epoxy prepreg tape used in the experiment was sourced from Gurit Composite Company. The results revealed that the position of the lamina influences the impact response.
The maximum force peak for the average stage increased by approximately 40% more than the PPPP-treated laminate. Chunhong et al. demonstrated that alkali treatment decreases surface polarity and exposes cellulose, increasing the number of potential reaction sites and contact regions between the PALF and matrix. Because of the hydrophilic character of PALF and the hydrophobic nature of the polymer matrix, they have weak contact bonding . 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. The PPPP-treated laminate revealed approximately 50% contact force higher than the PPPP-untreated, as shown in Figure 8. Even with a similar trend, the curve displacement is identically different due to the varying stacking sequences.
Figure 4.
Thwe et al. described hybrid composites as reinforcing materials that combine multiple reinforcement fibres or matrices (blends) to provide strength and durability. Hybrid fibre-reinforced composites comprise at least one pair of two different fibres combined in a solitary polymer matrix, resulting in improved properties compared to a normal polymer composite. The laminate with different stacking sequences had a lower energy transfer rate and ruptured at higher impact energy. Finally this study is useful for the designer in order to select the fiber orientation angle to shift the torsional natural frequencies as desired or to control the vibration level. From the results, it is clear that changes in fiber angle as well as laminate stacking sequences yield to different dynamic behavior of the component, that is, different torsional natural frequencies for the same geometry, mass and boundary conditions.
Maximum contact force and displacement against impact energy of the hybrid laminates at a ply orientation of ±45°n. Maximum contact force and displacement against impact energy of the hybrid laminates at ply orientations of 0°/90°8. The impact behaviours of the hybrid laminates at varying ply orientations and stacking sequences are shown in Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9 and Figure 10. For this, the influences of ply angle as well as laminate stacking sequences on the torsional natural frequencies of the laminated beams with doubly symmetrical cross- sections are investigated. The torsional vibrations of the laminated beams are analyzed analytically based on the classical lamination theory, and accounts for the coupling of flexural and torsional modes due to fiber orientation of the laminated beams are neglected. An essential factor determining the type of failure exhibited by a composite laminate is the ply stacking sequence that also determines the orientation of the fibre 20,48,49.