The results obtained after modeling the beams are presented in Figure 3. Where the torsional shear stiffness is given by, The beams to be studied are orthotropic and its cross section has two axes of symmetry y and z. Although this theory is useful for slender beams, it does not give accurate solutions for thick beams. The beams were discretized using (type shell 99) finite element as shown in Figure 2, available in the commercial package ANSYS 10.0. The mechanical properties for fiber and matrix are presented in Table 1 .
Figure 6.
Jesthi et al. observed the influence of carbon glass fibre symmetric inter-ply sequence on the mechanical performance of polymer matrix composite. The randomly oriented crack patterns align with the laminates’ ply orientation, as shown in Table 4, Table 5 and Table 6. The interlinear interface between laminates with different ply orientations is weak . Consequently, a laminate with varied ply orientations limits energy transfer over its thickness and fails when subjected to higher loads . Both laminates exhibited the same impact level of indentation (maximum), penetration, and perforation, at 15, 17.5, and 20 J, respectively.
The Influence of Ply Stacking Sequence on Mechanical Properties of Carbon/Epoxy Composite Laminates
- The failure modes exhibited by various stacking sequences under flexural loading were analysed by capturing the surface of damaged laminates using an optical micrograph.
- The same absorbed energy trend was reported by Giasin et al. while studying the impact properties of carbon/glass laminates .
- Stacking sequences inter-ply along with orientations (0°,30°,45°,60°,90°) are used.
- 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).
- In order to determine the specific perforated energy levels, a refinement test was performed between the unperforated and perforated energy levels.
PCCP and CPPC laminates absorbed energy well at low impact; however, they degraded significantly at high impact energies. The situation is visible at the maximum impact energy for both laminates, with the PCCP absorbing nearly all of the energy and the CPPC absorbing just approximately 80%. This explains why queenwin casino review the elastic potential energy of the laminates is transformed into impactor kinetic energy, decreasing the absorbed energy .
- Thwe et al. described hybrid composites as reinforcing materials that combine multiple reinforcement fibres or matrices (blends) to provide strength and durability.
- The laminate with different stacking sequences had a lower energy transfer rate and ruptured at higher impact energy.
- 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.
- When an impact force acts upon a composite, energy is released, with part of it utilised in elastic deformation, while excess energy is dissipated through various mechanism that leads to the failure of the material 39,40,41,42.
- The density matrix cracking was predicted to be higher at interface bonding between carbon fibre and matrix than PALF and matrix.
1. Impact Behavior
As shown in Figure 12, the PPPP-untreated and PPPP-treated laminates exhibited almost the same force–displacement curve. Figure 12, Figure 13 and Figure 14 illustrate the force–displacement and maximum force–displacement curves, respectively, for the laminates with ply orientations of 0°/90°2, ±45°2s. The overall impact strength increased by approximately double that of the PPPP-treated laminate by incorporating the interior carbon ply in the PCCP laminate.
Trash Pineapple Leaf Fiber Reinforced Polymer Composite Materials for Light Applications
The absorbed energy of the laminates increased to predetermined impact energy and gradually decreased after reaching the maximum energy value. In general, the low-velocity impact of the laminates demonstrated that the stacking sequence had a significant effect on the impact damage response of the laminate, which is in agreement with previous studies 28,53,54. In addition, the penetration and perforation occurred at the same impact energy level because of using the carbon ply as the interior layer. All the PPPP-treated laminates exhibited better impact strength compared to PPPP-untreated laminates.
The stacking layering sequence in the composite structure is another factor that influences the impact strength in addition to ply orientation. Another investigation was performed by Sikarwar et al. on the impact response of woven glass fibre composites as a function of thickness and fibre orientation. The quality and strength of adhesion (bonding) within the fibre/matrix system are important components of the resistance of the composites to impact damage . 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.
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.
Materials and Methods
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.
The same trend was reported in previous studies, which concluded only a slight effect on energy absorption after fibre treatment . The maximum energy absorbed was recorded at 12.5 J with 75% absorption, and the adsorbed energy decreased when the laminate perforated at 15 J. However, the CPPC laminate demonstrated better impact resistance; the laminate was penetrated at 25 J and perforated at 27.5 J. The maximum force peak for each impact stage of the PPPP-treated laminate was 25%, which is slightly higher than that of the PPPP-untreated laminate. Furthermore, the external carbon layer was oriented at 45°, which improved the fracture propagation resistance of the laminate . The interior PALF layer provides sufficient force resistance to hold the laminate and to stop the impactor from penetrating or perforating the laminate at 20 and 25 J, respectively.
Figure 12.
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.
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