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 impact behaviour of hybrid composite plates was examined by Sayer et al. . Hybrid composites are more advanced than conventional fibre-reinforced composites and have more potential for application than other composite materials. There are several different definitions of hybrid composites provided by different researchers.
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.
Therefore, detailed analyses of the low-velocity impact behaviour of PALF/carbon hybrid laminate composites were performed in this study. In the same investigation, natural fibre and hybrid composite laminates absorbed more energy than the queenwin casino review GFRP composite laminates. The results demonstrated that the load-carrying capabilities of hybrid composites are significantly improved than carbon/epoxy laminates, with only a minor compromise in stiffness. According to their findings, 0/90° laminates exhibited the highest impact resistance across all the examined lay-ups, mainly due to the failure strain, which is highly influenced by the fibre orientation in the laminate.
- The maximum force peak for the average stage increased by approximately 40% more than the PPPP-treated laminate.
- In addition, the PPPP-treated sample exhibited approximately 30% less displacement indention than the PPPP-untreated sample.
- Hybrid composites are more advanced than conventional fibre-reinforced composites and have more potential for application than other composite materials.
- Glass fiber (E-Glass) is used as reinforcement in the form of unidirectional fibers with epoxy resin as matrix for the laminated composite beams.
- Both exhibited a circular penetration pattern at the top side and a crack opening on the bottom side.
- In addition, the penetration and perforation occurred at the same impact energy level because of using the carbon ply as the interior layer.
- Maximum contact force and displacement against impact energy of the hybrid laminates at ply orientations of ±45°2, 0°/90°2s.
The Effect of Fiber Orientation and Laminate Stacking Sequences on the Torsional Natural Frequencies…
The test specimens were prepared by cutting the laminates along the 0° fibre orientation using a waterjet cutter. 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. Singh and Mahesh studied the effect of ply position switching on the impact performance of quasi-isotropic glass fibre-reinforced polymer composite. Kaboglu et al. studied the impact performances and failure modes of glass fibre-reinforced polymer composite with different curvature and stacking sequences. However, only a few studies emphasise the influence of stacking sequence on the behaviour of composite laminates. Therefore, this failure mode explains the importance of studying composite laminates to achieve a stacking configuration that offers high resistance to deformation and improves tolerance and reliability.
Subsequently, UD prepreg tape was cut into sections of approximately 400 mm by 450 mm before laying up each ply with varying stacking patterns into the mould by hand. The prepreg consists of unidirectional (UD), continuous, high-elongation carbon fibres and an epoxy resin system. Likewise, FRP composites’ brittleness and disastrous failure without sufficient onset warning are generally unacceptable in most engineering applications 12,13,14,15. Fibre-reinforced polymer composites (FRPs) are considered in an application where a high strength-to-weight ratio is desirable. However, because of their superior characteristics, synthetic fibres cannot be completely replaced.
At a glance: Figures
The flexural test reveals the capability of the composite to resist bending deflection under loading conditions. The laminates were evacuated from the autoclave and then demoulded before cutting them into the required dimensions. As shown in Table 2, five laminates were produced, with each sample containing eight layup plies with a total thickness of 3.50 mm.
It was discovered that the stacking pattern influenced the impact performance and stiffness of the laminate. In civil engineering, fibre-reinforced polymer composites (FRPs) are used in reinforcing bars, sandwich panels and structural retrofitting 8,9. Moreover, as a result of material symmetry, the flexural and tensile modulus of symmetric cross-ply laminate improved by 59.5% and 3.97% compared to the unsymmetric counterpart. This includes a unidirectional laminate, cross-ply laminates, and quasi-isotropic laminates.
Figure 6
- 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 contact force–displacement curves for the laminates with ply orientations of ±45°2, 0°/90°2s are shown in Figure 9.
- 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.
- The beams to be studied are orthotropic and its cross section has two axes of symmetry y and z.
- The laminates withstand high impact energy before penetration occurs at 25 J, followed by perforation at 27.5 J.
- The mechanical properties for fiber and matrix are presented in Table 1 .
They developed the exact dynamic stiffness matrix by directly solving the governing differential equations of an axially loaded laminated beam. Thus, in the dynamic analyses, it is quite essential to consider an overview of the free vibration characteristics, including the natural frequencies of these composite structures. The main feature of these anisotropic materials is their ability to be tailored for specific applications by optimizing design parameters such as stacking sequence, ply orientation and performance targets. It is observed that tensile strength and flexural strength of the laminate at orientation angle 30° attained highest strength compared with other orientation angle with an average percentage increment in the strength about 24%. Polymer composites using reinforced natural fibres, such as those obtained from pineapple, hemp or bamboo, are in advance popularity. Additionally, LM4 and LM5 exhibited lower interlayer delamination than other specimens, while fibre kinking and matrix debonding were also observed.
ICSIMMA 2024 – Materials interaction on physical, chemical and mechanical science
Numerical results, obtained by the ANSYS 10.0, classical lamination theory, and shear deformation theory are presented to highlight the effects of fibers orientation and layers stacking sequence on torsional frequencies of the beams. The influence of fiber directions and stacking sequences of laminates on torsional natural frequencies were investigated. The finite element software package ANSYS 10.0 is used to perform the numerical analyses using an eight-node layered shell element to describe the torsional vibration of the laminated beams. Also, the torsional vibrations of the laminated beams analyzed by shear deformation theory in which the shear deformation effects are considered. This study examined the effect of stacking configuration of CFRP laminates subjected to flexural, tensile and impact loading.
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. Song and Waas have been studied both buckling and free vibration analyses of laminated composite beams. Et al. gave analytical solutions for the free vibration problem of laminated composite beams. Khdeir and Reddy have been studied free vibrations of cross-ply laminated beams with arbitrary boundary conditions. The increased use of laminated composite beams requires a better understanding of vibration characteristics of these beams; it is quite essential in the design of composite beams subjected to dynamic loads.
Pure torsional vibrations are focused in this study. The mass is also symmetrical with respect to these axes, and, accordingly, the center of mass coincides with the origin of the y-z coordinate system, so that the flexural-torsional coupling not occurs. The laminated beam is modeled and analyzed by the FEM. Also, composite structural elements consisting of a relatively weak matrix reinforced by stronger inclusions or of different materials in contact are of increasing technological importance in engineering. Qiao Pizhong and Zou Guiping presented an analytical study for dynamic behavior of pultruded fiber-reinforced plastic (FRP) composite cantilever I-beams based on a Vlasov-type linear hypothesis.
Table 2.
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. As can be seen, the unidirectional laminate, LM1, absorbed lower energy (92.10 kJ/m2) compared to the multidirectional, LM2 (102.21 kJ/m2), LM3 (109.40 kJ/m2), LM4 (116.2 kJ/m2) and LM5 (115.12 kJ/m2) laminates. Therefore, the degree of damage due to an impact force depends on the amount of energy absorbed by the laminate. 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. When 0° plies are substituted with 90° plies, as in the case of LM2 and LM3 layup, the number of carbon fibres parallel to the longitudinal loading of the composite decreases, resulting in lower modulus and tensile strength than LM1. As can be seen, the specimens exhibited a similar trend as in the case of the flexural properties by undergoing a linear relationship in their elastic zone before experiencing a brittle rupture due to the breakage of the fibres.
The FE analysis by using ANSYS is performed to investigate the influences of boundary conditions on torsional frequencies of the laminated beams. In the present paper, the free torsional vibrations of symmetric laminated beams are studied by the classical lamination theory and shear deformation theory. Glass fiber (E-Glass) is used as reinforcement in the form of unidirectional fibers with epoxy resin as matrix for the laminated composite beams. Also, the effects of boundary conditions on the torsional frequencies of the laminated beams are demonstrated. The effects of fiber direction and laminate stacking sequence on the frequencies of torsional vibrations were investigated.
