“…In general, UD composites with fibres oriented in the span direction (0°) shows the domination of compressive failure as the compressive strength is typically lower than the tensile strength. 26 The same trend can be seen in Figure 13. The fibre buckling/kinking at the compression side of the specimen and mass accumulation of fibres without breakages at the tension side of the specimen are the dominating failure modes observed in the UD Kevlar®/PP composites.Figure 13.Microscopic view of (a) compression and (b) tensile failure sides of the UD Kevlar®/PP COM composites.…”
Section: Resultssupporting
confidence: 75%
“…Unlike the tensile strength test, which is fibre dominating property, the flexural strength is dominated mainly by the matrix system. 26 A total of five composite specimens with a thickness of 2.7 ± 0.1 mm and span length of 100 mm are flexed at a cross head velocity of 2 mm/min using a universal testing machine (T-72052, DAK Systems, Mumbai, India) equipped with 5kN load cell. The flexural strength (MPa) and modulus (GPa) are determined using equations (6) and (7), respectively.Where, FS and FM indicate flexural strength (MPa) and flexural modulus (GPa), while P represents peak load (N), L is the supporting span length (m), and B and D are the width and thickness of the composite (m).…”
Section: Materials Characterizationmentioning
confidence: 99%
“…The final void in the composite is determined by obtaining the theoretical and experimental densities of the sample. 26 The final void in the composite is determined using equation ( 4). The experimental density is obtained through the density column method using ethanol as per ASTM-D 317.…”
Section: Characterization Of Ud Compositesmentioning
The current study aims at optimizing nozzle diameter and processing conditions for producing quality Kevlar®/polypropylene commingled towpregs meant for thermoplastic composite applications. ANSYS 3D CFD simulation and various experimental techniques are used for the same purpose. The study also investigates the effect of optimized commingled towpregs on the consolidation quality, void % and flexural properties of the developed UD composites. It is concluded that the nozzle diameter of 7 mm has proven to be ideal for producing quality towpregs as it leads to the formation of high nip frequency at 4.5 bar air pressure. The other nozzle diameters, 3 mm, 5 mm, and 9 mm, performed poorly in forming nips. Among these diameters, the 7 mm nozzle has optimum free space between the internal wall of the nozzle and the feed fibre bundle. This optimum space keeps the filaments within the potential air interaction zone and thus leading to the individual filament displacement and entrapment to form stable nips. The Box-Behnken design expert is used for obtaining ideal commingling conditions. The optimized Kevlar®/PP towpregs are produced using a custom fabricated commingling machine with a 7 mm diameter nozzle at the processing conditions - 4.5 bar air pressure, 2 m/min delivery speed, 3% and 1% overfeed, respectively for Kevlar® and polypropylene (PP). These commingled towpregs are flexible, compact, and regular in structure. These towpregs have the highest nip frequency, nip stability, weavability and homogeneous fibre-matrix mixing quality in yarn cross-section along the length. Using such towpregs makes the textile pre-forming effortless and yields composites with better resin impregnation quality and low void content. The UD Kevlar®/PP composites made through these towpregs offered good consolidation quality with a low void (4.3%). These composites showed flexural strength and modulus of 130 MPa and 28 GPa, respectively.
“…In general, UD composites with fibres oriented in the span direction (0°) shows the domination of compressive failure as the compressive strength is typically lower than the tensile strength. 26 The same trend can be seen in Figure 13. The fibre buckling/kinking at the compression side of the specimen and mass accumulation of fibres without breakages at the tension side of the specimen are the dominating failure modes observed in the UD Kevlar®/PP composites.Figure 13.Microscopic view of (a) compression and (b) tensile failure sides of the UD Kevlar®/PP COM composites.…”
Section: Resultssupporting
confidence: 75%
“…Unlike the tensile strength test, which is fibre dominating property, the flexural strength is dominated mainly by the matrix system. 26 A total of five composite specimens with a thickness of 2.7 ± 0.1 mm and span length of 100 mm are flexed at a cross head velocity of 2 mm/min using a universal testing machine (T-72052, DAK Systems, Mumbai, India) equipped with 5kN load cell. The flexural strength (MPa) and modulus (GPa) are determined using equations (6) and (7), respectively.Where, FS and FM indicate flexural strength (MPa) and flexural modulus (GPa), while P represents peak load (N), L is the supporting span length (m), and B and D are the width and thickness of the composite (m).…”
Section: Materials Characterizationmentioning
confidence: 99%
“…The final void in the composite is determined by obtaining the theoretical and experimental densities of the sample. 26 The final void in the composite is determined using equation ( 4). The experimental density is obtained through the density column method using ethanol as per ASTM-D 317.…”
Section: Characterization Of Ud Compositesmentioning
The current study aims at optimizing nozzle diameter and processing conditions for producing quality Kevlar®/polypropylene commingled towpregs meant for thermoplastic composite applications. ANSYS 3D CFD simulation and various experimental techniques are used for the same purpose. The study also investigates the effect of optimized commingled towpregs on the consolidation quality, void % and flexural properties of the developed UD composites. It is concluded that the nozzle diameter of 7 mm has proven to be ideal for producing quality towpregs as it leads to the formation of high nip frequency at 4.5 bar air pressure. The other nozzle diameters, 3 mm, 5 mm, and 9 mm, performed poorly in forming nips. Among these diameters, the 7 mm nozzle has optimum free space between the internal wall of the nozzle and the feed fibre bundle. This optimum space keeps the filaments within the potential air interaction zone and thus leading to the individual filament displacement and entrapment to form stable nips. The Box-Behnken design expert is used for obtaining ideal commingling conditions. The optimized Kevlar®/PP towpregs are produced using a custom fabricated commingling machine with a 7 mm diameter nozzle at the processing conditions - 4.5 bar air pressure, 2 m/min delivery speed, 3% and 1% overfeed, respectively for Kevlar® and polypropylene (PP). These commingled towpregs are flexible, compact, and regular in structure. These towpregs have the highest nip frequency, nip stability, weavability and homogeneous fibre-matrix mixing quality in yarn cross-section along the length. Using such towpregs makes the textile pre-forming effortless and yields composites with better resin impregnation quality and low void content. The UD Kevlar®/PP composites made through these towpregs offered good consolidation quality with a low void (4.3%). These composites showed flexural strength and modulus of 130 MPa and 28 GPa, respectively.
“…Several works have given an overview on the different properties of glass-plant hybrid composites [9][10][11]. In recent years, there has been substantial interest in the application of basalt fibres as reinforcement of polymer matrices mainly as replacement for glass fibres in view of their advantages in terms of environmental cost relative to their chemical and mechanical properties [12][13][14]. This has triggered the development of hybrids including plant fibre and basalt fibre laminates [15][16][17][18][19][20].…”
Investigation on the fatigue life of hybrid composites is critical to extend their structural applications.However, there is a lack of research on fatigue performance of hybrid composites. In this study, the fatigue life of a flax-basalt woven-ply hybrid composite is investigated and compared with the behaviour of 100% flax and 100% basalt composites. After the optimisation of the epoxy resin curing cycle, tension-tension fatigue tests were performed on samples with two orientations, 0°/90° and ± 45°. S-N curves with absolute values and with normalised values are discussed. Results showed that the hybridisation was able to produce a positive effect on the fatigue resistance of basalt laminates: a better normalised fatigue resistance was obtained for the hybrid composite in comparison with the 100% basalt one in both orientations. A two-parameter fatigue life model was then applied and showed its ability to predict the fatigue behaviour of the hybrid composite for the two orientations. An analysis of damage mechanisms by means of infrared thermography and scanning electron microscopy allowed observing the different types of damage occurring during fatigue loading in hybrid composites.
“…This interchangeably incorporates the desired mechanical properties from each reinforcement while minimizing undesired behavior [18,23]. Basalt fibre is known to offer high strength and modulus but being brittle in nature it is often hybridized with ductile aramid fibres [59,60]. Ductile materials like aramid absorb most of the applied load in the form of plastic deformation, hence they attain lower tensile strength.…”
The open hole tensile and flexural test of composites holds immense importance in aerospace and structural engineering. These tests provide critical insights into how composites perform under real-world conditions, allowing for the development of materials that meet rigorous standards, thereby ensuring the safety and durability of aircraft and other applications. This study investigates the influence of hole size on the open hole tensile (OHT) and flexural properties (OHF) of plane woven aramid/epoxy (AFRP), basalt/epoxy (BFRP), and aramid-basalt/epoxy (ABFRP) sandwiched laminates. Specimens with three different hole sizes viz., 4 mm, 6 mm, 8 mm were prepared and tested according to ASTM D5766 and ASTM D7264 for OHT and OHF performance respectively. Results indicated that the hybridization of aramid-basalt layers in a sandwich lay up significantly improved the mechanical performance when compared to only aramid laminate. However, with the increase in hole size the mechanical properties declined irrespective of the material. Basalt fibres showed higher hole sensitivity under tensile loading due to its brittle fracture mechanism while aramid fibres exhibited higher hole sensitivity under flexural loading which can be attributed to its the poor compressive strength. The effect of hole size on the damage mechanism has also been highlighted through scanning electron microscope (SEM). Major failure modes observed are delamination around the hole edges, ductile and brittle fibre fractures, and delamination.
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