Abstract:The aim of the present study is to investigate the mechanical behavior of carbon/flax hybrid composites under static and fatigue tensile loading. The failure characteristics and parameters used in the fatigue tests were deduced from the static ones. The effect of the applied stress level, hybridization and stacking sequences on the stiffness, hysteresis loops, dissipated energy and damping, were studied for a various number of cycles during fatigue tests. The Wohler S-N curves were constructed to investigate t… Show more
“…Bagheri et al 18 investigated the tensile fatigue performance of carbon/flax/epoxy under stress-controlled amplitude, showing significant improvement in fatigue strength compared with previous work on neat flax. Ben Ameur et al 19 studied the mechanical performance of carbon/flax composites under static and tensile fatigue loading, the study demonstrated that the increase of the carbon fiber volume fraction resulted in an increase in the fatigue performance and resistance of the hybrid composite. Manteghi et al 20 examined the compressive fatigue performance of hybrid glass/flax/epoxy thermographic and conventional testing, which both showed similar high cycle fatigue strength.…”
This is the first study on the fatigue tensile performance of a novel hybrid composite made as Type A (i.e. woven carbon fibers plus unidirectional flax fibers [WC2/0F12/WC2]) or Type B (i.e. woven carbon fibers plus oblique flax fibers [WC2/(±45)F6S/WC2]) in epoxy resin. Composite plates were examined under constant strain amplitude using conventional fatigue tests and constant stress amplitude using thermographic stress analysis at 5 Hz cycling with a constant amplitude ratio of 0.1. For conventional fatigue, the max strain εmax versus cycles to failure Nf curve for Type A was log (Nf) = 9.7–588.2εmax, while for Type B it was log (Nf) = 14.9–1000εmax; neither material had a true endurance limit since curves never became horizontal. For thermographic stress analysis, high-cycle fatigue strength for Type A was 231.7 MPa (i.e. 56% of ultimate tensile stress σut), while for Type B it was 203.2 MPa (i.e. 60% of σut).
“…Bagheri et al 18 investigated the tensile fatigue performance of carbon/flax/epoxy under stress-controlled amplitude, showing significant improvement in fatigue strength compared with previous work on neat flax. Ben Ameur et al 19 studied the mechanical performance of carbon/flax composites under static and tensile fatigue loading, the study demonstrated that the increase of the carbon fiber volume fraction resulted in an increase in the fatigue performance and resistance of the hybrid composite. Manteghi et al 20 examined the compressive fatigue performance of hybrid glass/flax/epoxy thermographic and conventional testing, which both showed similar high cycle fatigue strength.…”
This is the first study on the fatigue tensile performance of a novel hybrid composite made as Type A (i.e. woven carbon fibers plus unidirectional flax fibers [WC2/0F12/WC2]) or Type B (i.e. woven carbon fibers plus oblique flax fibers [WC2/(±45)F6S/WC2]) in epoxy resin. Composite plates were examined under constant strain amplitude using conventional fatigue tests and constant stress amplitude using thermographic stress analysis at 5 Hz cycling with a constant amplitude ratio of 0.1. For conventional fatigue, the max strain εmax versus cycles to failure Nf curve for Type A was log (Nf) = 9.7–588.2εmax, while for Type B it was log (Nf) = 14.9–1000εmax; neither material had a true endurance limit since curves never became horizontal. For thermographic stress analysis, high-cycle fatigue strength for Type A was 231.7 MPa (i.e. 56% of ultimate tensile stress σut), while for Type B it was 203.2 MPa (i.e. 60% of σut).
“…The use of hysteresis curves is an effective approach for investigating the fatigue damage mechanisms as reported by Ameur et al 27 Therefore, the stress-local strain values were recorded for each fatigue cycle during the following: 1 to 10, 20 to100, 100 to 1000, 1000 to 10,000, 10,000 to 100,000 and from 100,000 up to failure. The increment within each interval equal to the initial range value.…”
Section: Discussionmentioning
confidence: 99%
“…21,29,30 The stored elastic potential energy ( U p ) in the adhesive joint equal to the area under the loading (upper) curve of the hysteresis loop, Figure 5. 16,21,31 The U p and the U d can be calculated for any given cycle ( N ) by equations (3) and (4), respectively 21,27,30 Figure 4.Schematic of stress-strain hysteresis loop.Figure 5.Terms and nomenclatures of the potential and dissipated energies calculations.…”
Section: Discussionmentioning
confidence: 99%
“…21,29,30 The stored elastic potential energy (U p ) in the adhesive joint equal to the area under the loading (upper) curve of the hysteresis loop, Figure 5. 16,21,31 The U p and the U d can be calculated for any given cycle (N) by equations ( 3) and (4), respectively 21,27,30 U p ¼ 1 2…”
In this study, fatigue results of the scarf adhesive joints (SAJs) were extensively analyzed regarding the effect of the adhesive materials (neat epoxy (NE), and SiC and Al2O3-nanocomposite), bond thickness (0.17 mm and 0.25 mm) on their dynamic properties, which include loss factor (tan δ), loss modulus ( E''), dissipated energy ( U d), potential energy ( U p), and storage modulus ( E'). Safe fatigue lives of the NE, SiC, and Al2O3-SAJs were estimated at different reliability levels. The experimental measurements revelated that reducing the adhesive layer thickness from 0.25 mm to 0.17 mm result in enhancing the tensile strength and stiffness of the SiC-SAJs by 9.6% and 4.4%, respectively, in return of 9.5% and 5.4% for the Al2O3-SAJ relative to the NE-SAJ. The strength and stiffness of the SiC-SAJs with 0.17 mm bond thickness are higher than those of the Al2O3-SAJ by 15.4% and 3.3%, respectively. The highest improvement of 22.0% in the fatigue strength was occurred for the SiC-SAJ with bond thickness of 0.17 mm in return of 4.8% for the Al2O3-SAJ. The U p was used for the first time (except author works) for monitoring and predicting the damage in the adhesive joints practically the change in the enclosed area of the hysteresis loop is too small to cause a large variation in the tan δ, E'', and U d. Damping factor of the NE-SAJs is marginally increased with the stress levels compared to the aggravated increase of both SiC and Al2O3-SAJs. Zhang model predicts well the potential energy and storage modulus specially at higher stress levels.
“…On the other hand, for hybrid composite with carbon ply exterior (CPPC), cracks propagated rapidly in the carbon plies and buckled at pineapple leaf fibre layers leading to delamination in the region between the two fibres at the tension sides, as shown in Figure 8. Sezgin and Berkalp [182] reported higher impact resistance and high tensile strength whenever highstrength glass or carbon layers were placed as the outer and inner layers of the hybrid composite, respectively.…”
The global drive towards a circular economy that emphasizes sustainability in production processes has increased the use of agro-based raw materials like natural fibres in applications that have long been dependent on inorganic raw materials. Natural fibres provide an eco-friendly, more sustainable, and low cost alternative to synthetic fibres that have been used for a long time in the development of composite materials. However, natural fibres are associated with high water absorption capacity due to their hydrophilic nature leading to poor compatibility with hydrophobic polymeric matrices, thus lower mechanical properties for various applications. Hybridization of natural fibres with synthetic fibres enhances the mechanical performance of natural fibres for structural and nonstructural applications such as automobile, aerospace, marine, sporting, and defense. There have been increased research interests towards natural/synthetic fibre hybrid composites in the past two decades (2001–2021) to overcome the identified limitations of natural fibres. Therefore, understanding the parameters affecting the properties and potential of using natural and synthetic fibre reinforcements to develop hybrid composites is of great interest. The review showed that using appropriate fibre orientation, fibre weight fraction and stacking sequence yields good mechanical, physical, and thermal properties that are competitive with what only synthetic fibre reinforced composites can achieve. In addition, these properties can be improved through pretreatment of natural fibres using different chemicals. This paper provides in review form the parameters affecting the mechanical, physical, and thermal properties of natural/synthetic fibre hybrid reinforced polymer composites from the year 2001 to 2021.
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