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 .
- For the PCCP laminate, the curves exhibited a rebound pattern at low impact energies of 5, 10, and 15 J.
- 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.
- Similar behaviour has been reported by Bezazi et al. during flexural testing of a hybrid kevlar/glass cross-ply laminate.
- Although this theory is useful for slender beams, it does not give accurate solutions for thick beams.
- 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.
- Jesthi et al. observed the influence of carbon glass fibre symmetric inter-ply sequence on the mechanical performance of polymer matrix composite.
- Where the torsional shear stiffness is given by,
Figure 2.
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.
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
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.
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 the elastic potential energy of the laminates is transformed into impactor kinetic energy, decreasing the absorbed energy .
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.
ICSIMMA 2024 – Materials interaction on physical, chemical and mechanical science
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.
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.
Trash Pineapple Leaf Fiber Reinforced Polymer Composite Materials for Light Applications
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.
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.
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.
- With these requirements, this work considers the free torsional vibrations for laminated composite beams of doubly symmetrical cross sections.
- 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.
- Abramovich and Livshits studied the free vibration of non symmetric Cross-ply laminated Composite Beams based on Timoshenko type equations.
- Contact force–displacement of the hybrid laminates at ply orientations of ±45°2, 0°/90°2s.
- Upon impact, local separation from one another causes frequent damage to such systems 59,67.
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.
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.
Materials and Methods
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 queenwin casino review carbon ply in the PCCP laminate.
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.
