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 .
Table 1.
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 queenwin casino review 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 .
The Influence of Ply Stacking Sequence on Mechanical Properties of Carbon/Epoxy Composite Laminates
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.
Table 2. The constants μBi and μGi for for different types of end supports
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 4.
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.
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.
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.
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.
- In the present paper, the free torsional vibrations of symmetric laminated beams are studied by the classical lamination theory and shear deformation theory.
- Figure 5 shows the result of the Charpy impact test of the specimens in terms of the energy absorbed.
- 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 .
- The laminate was penetrated only when the impact energy reached 17.5 J and was perforated at 20 J.
- Figure 6 illustrates the optical micrograph of the specimen under flexural loading.
- Average flexural and tensile properties of the CFRP with different stacking sequences.
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.
1. Flexural Properties
- 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.
- Therefore, the degree of damage due to an impact force depends on the amount of energy absorbed by the laminate.
- Fibre-reinforced polymer composites (FRPs) are considered in an application where a high strength-to-weight ratio is desirable.
- However, this phenomenon exhibited by the PPPP-untreated and PPPP-treated laminates, which oriented at 0°, 90°8, produced higher tensile strength compared to laminates with ±45°8 ply orientation .
- The laminates were analysed using an IMATEK IM10 drop weight impact tester with an increment of 5 J until the samples were perforated.
- For the PCCP laminate, the curves exhibited a rebound pattern at low impact energy.
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.