The commercial finite element program ANSYS 10.0 is used to perform a dynamic modelling to the laminated beams by performing an eigenvalue analysis. Evangelos and Sapountzakis studied the Torsional vibrations of composite bars by (BEM) boundary element method which is developed for the nonuniform torsional vibration problem of doubly symmetric composite bars of arbitrary constant cross-section. Kameswara and Mirza studied the problem of free torsional vibration and buckling of doubly symmetric thin-walled beams of open section, subjected to an axial compressive static load and resting on continuous elastic foundation. Studied the torsional vibration of open and variable cross section bars by derive analytical method is to form the dynamic stiffness matrix of the bar, including the effect of warping. Exact torsional vibration frequencies were presented by for the case of circular cross-section shafts subjected to queenwin casino review classical boundary conditions avoiding in this way warping effects. Several researchers have dealt with torsional vibration of beams.
During this stage, indentations and damages were observed in the impact area of the top exterior carbon layer. The fracture of the laminate was initiated from the top exterior carbon layer, as shown by the contact force reaching the peak value. In comparison to Figure 5, the PPPP-untreated and PPPP-treated were stiffer at ±45°8 ply orientation compared to 0°, 90°8. The CPPC laminate exhibited a similar rebound curve trend up to the maximum contact force. The stiffness values of the PPPP-untreated and PPPP-treated samples were significantly different, at which PPPP-treated were able to almost withstand 20% more impact content force.
Table 3. Torsional natural frequencies (Hz) for different stacking sequences laminate
The CPPC laminate at ±45°2,0°/90°2s ply orientations demonstrated the maximum absorbed energy when it was subjected to the highest impact energy in which almost the entire impact energy was absorbed. Although they could sustain a higher impact, all laminates absorbed less impact energy than the laminates at 0°/90°8 ply orientation, particularly the pure PALF laminate. The energy profiling diagram of the hybrid laminates at a ply orientation of ±45°8 is illustrated in Figure 15b. Figure 15a shows the energy profiling diagram of the hybrid laminates at a ply orientation of 0°/90°8. Figure 6, Figure 7 and Figure 8 illustrate the impact behaviour of the hybrid laminates at a ply orientation of ±45°8. In order to comprehensively understand the behaviour of the composites after impact, the interplay between ply orientation and stacking sequences is required.
- It was revealed that the stacking pattern affects the damping and ageing time of the composites.
- Maximum contact force and displacement against impact energy of the hybrid laminates at ply orientations of 0°/90°2, ±45°2s.
- In the same investigation, natural fibre and hybrid composite laminates absorbed more energy than the GFRP composite laminates.
- The Charpy impact test was carried out on the samples to measure the amount of energy absorbed under an impact force normal to the laminates.
- The laminate of 0/90° fibers have the lowest torsional natural frequencies than the other lamination schemes and thus, because 50% of the fibers are oriented at 0° direction for 0/90° laminate, and thus appropriate for bending (Flexural Modes).
Ply orientation is important in designing composite laminates to withstand high-impact loads. The laminates with an exterior carbon layer can withstand high impact energy levels up to 27.5 J. The laminates were manufactured using a vacuum infusion approach with various stacking sequences and ply orientations classified as symmetric quasi-isotropic, angle-ply symmetric, and cross-ply symmetric. The finite element software package ANSYS is an efficient vibration prediction tool, because of its ability to model the laminated composite beam and reveal fundamental modal frequencies and modal shapes. This study is the first attempt to deal with the torsional natural frequencies of laminated composite beam with different lamination.
Modal Analysis by Finite-Element Method, ANSYS
A modal analysis will be carried out using ANSYS 10.0 finite element software to study the frequencies of free torsional vibrations of the mentioned composite laminated beam. In the present study, the torsional vibration behaviors of symmetrical laminated composite beams are studied. Yõldõrõm and Kõral studied the out-of-plane free vibration problem of symmetric cross-ply laminated beams using the transfer matrix method. With these requirements, this work considers the free torsional vibrations for laminated composite beams of doubly symmetrical cross sections. Finding free torsional vibrations characteristics of laminated composite beams is one of the bases for designing and modeling of industrial products. The bending mismatch coefficient between two adjacent laminates, different fibre orientations, and stacking sequences between the layers causes delamination; the delamination area increases as the mismatch coefficient increases .
- Also, the torsional vibrations of the laminated beams analyzed by shear deformation theory in which the shear deformation effects are considered.
- Contact force–displacement of the hybrid laminates at a ply orientation of ±45°8.
- It was discovered that the stacking pattern influenced the impact performance and stiffness of the laminate.
- The beams were discretized using (type shell 99) finite element as shown in Figure 2, available in the commercial package ANSYS 10.0.
- The PPPP-treated laminate revealed approximately 50% contact force higher than the PPPP-untreated, as shown in Figure 8.
- The load–deflection curves and photographs of the damaged samples acquired from the impacted and non-impacted sides were compared to determine the failure processes of the damaged specimens for various impact energies.
The torsional frequency for clamped-simply supported condition comes to be lower than clamped-clamped condition, then simply supported-simply supported comes to be lower than clamped-simply supported, and finally clamped-free condition comes to be lower than other supports. The influence of boundary conditions on torsional natural frequencies is investigated for the 1st torsional frequency as shown in Figure 6. The analysis can be applied to the laminated beam previously mentioned with the same dimensions and geometry. They are deduced by FEM ANSYS for the first six torsional frequencies.
Materials and Methods
This behaviour could result from a random distribution of carbon fibres across the plies since the lamina geometry above and below the midplane are identical 35,36. Average flexural and tensile properties of the CFRP with different stacking sequences. However, one notable observation in this case (Figure 3a) is that the laminate spontaneous catastrophic failure occurred immediately after the maximum load was attained due to fibre breakage. Subsequently, the laminates experience a sudden drop in load due to failure within the internal plies, followed by continuous stress fluctuations at an increasing deformation rate. Five specimens per laminate with dimensions of 75 mm ×10 mm×3.5 (±0.1) mm, as shown in Figure 2c, were also tested on a Zwick Roell HIT25P pendulum impact tester with a working capacity of 7.50 J following the ASTM D6110 recommendation.
Mechanical and Morphological Properties of Pineapple Leaf Fibre/Kenaf Fibre Reinforced Vinyl Ester Hybrid Composites
Contact force–displacement of the hybrid laminates at ply orientations of 0°/90°2, ±45°2s. The laminates with ply orientations of ±45°n, 0°/90°ns exhibited force–displacement curves that revealed mixed tendencies. 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 .
A generally laminated composite beam with a solid rectangular cross-section of doubly symmetrical cross sections, as shown in Figure 1, is considered to be studied. In the analytical models, the flexural-torsional coupling effects are ignored and pure torsional vibrations are taken. Also, analytical models are developed by classical lamination theory and shear deformation theory to study the torsional vibrations of the beams. Mindlin eight-node isoparametric layered shell elements (SHELL 99) are employed in the modeling for describing the torsional vibrations of these beams.
1. Flexural Properties
Thus, in this study, a pre-impregnated carbon/epoxy tape was utilised to produce the laminate composite. Grigoriou and Mouritz showed the influence of stacking patterns on the fire resistance of CFRP laminates. It was revealed that the stacking pattern affects the damping and ageing time of the composites. Mlyniec, Korta, Kudelski and Uhl studied the influence of thickness, stacking sequence and thermal ageing on the behaviour of CFRP laminates.
However, the effects of ply orientation and stacking sequences on the low-energy impact of PALF/carbon hybrid laminate composites are yet to be investigated. This study investigated the impact response behaviours of pineapple leaf fibre (PALF)/carbon hybrid laminate composites for different ply orientations and stacking sequences. In this study, an in-depth analysis of the low-velocity impact behavior of PALF/carbon hybrid laminate composites at various ply orientations and stacking sequences was performed. The purpose of impact testing was to determine the influence of ply orientation and stacking sequence on the behaviour of the PALF/carbon hybrid laminate composite. Maximum contact force and displacement against impact energy of the hybrid laminates at ply orientations of 0°/90°2, ±45°2s. Maximum contact force and displacement against impact energy of the hybrid laminates at ply orientations of ±45°2, 0°/90°2s.
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