The composite materials are replacing the traditional materials, because of its superior properties such as high tensile strength, low thermal expansion, high strength to weight ratio. The ...developments of new materials are on the anvil and are growing day by day. Natural fiber composites such as sisal and jute polymer composites became more attractive due to their high specific strength, lightweight and biodegradability. Mixing of natural fiber with Glass-Fiber Reinforced Polymers (GFRPs) are finding increased applications. In this study, sisal–jute–glass fiber reinforced polyester composites is developed and their mechanical properties such as tensile strength, flexural strength and impact strength are evaluated. The interfacial properties, internal cracks and internal structure of the fractured surfaces are evaluated by using Scanning Electron Microscope (SEM). The results indicated that the incorporation of sisal–jute fiber with GFRP can improve the properties and used as a alternate material for glass fiber reinforced polymer composites.
The present work aims to investigate the relationship between the mechanical behavior and composite structure of silicon carbide (SiC) particle reinforced aluminum matrix composites. On account of ...newly developed particle size analysis technique, a large number of SiC particles are experimentally measured to provide statistical particular structural information. According to the statistical analysis and physical observations of SiC particles, the composite structures of SiC/Al composites are numerically reproduced in line with their actual microscopic structures, in which a developed structural modeling program can build the randomly dispersions of the particle sizes, the particle shapes, the particle positions and the volume fractions of SiC particles. Elastoplastic material properties, strengthened matrix properties and particle–matrix interfacial behaviors are introduced to simulate the mechanical behavior of SiC/Al composites. Enough fine meshes and reasonable loads and boundaries conditions can efficiently guarantee the computing accuracy and reduce the computing cost. A lot of simulating results of SiC/Al composites are provided and verified with the related experimental results. This work makes an effective attempt to establish the relationship between the actual composite structures and the mechanical behaviors within the particle reinforced metal matrix composites.
Fiberglass reinforced composites (FRCs) are traditionally cured in an autoclave or hot press, which are equipment known for their high energy consumption and their imposed constraints on the cured ...component sizes. Furthermore, current composite repair techniques usually require removing the composite part from service and using traditional composite fabrication methods to apply patches in a workshop. As an alternative to such techniques, this work presents a new out-of-autoclave (OoA) FRC curing method that relies on the Joule heating potential of transfer-printed laser induced graphene (LIG) interlayers. LIG is initially generated on polyimide substrates before then being transfer-printed onto fiberglass prepregs to form uniform surface coatings. The excellent electrical properties of the transfer-printed LIG are then exploited to in-situ cure fiberglass laminates via Joule heating effect. The LIG-coated FRCs cured through Joule heating (LIG-cured FRCs) is found to have a high degree of cure of 96%, comparable to oven-cured ones, while requiring 89.39% less specific energy. The mechanical properties of LIG-cured FRCs are measured and determined to match those fabricated using traditional approaches. Furthermore, LIG-coated fiberglass prepregs are shown capable of acting as in-situ bonding agents for the joining of two composites structures, which indicates its potential of composite repair through healing at the site of structure damage. Finally, the Joule heating effect of the LIG interlayers in cured FRCs is investigated and found to enable the fast and energy-efficient deicing of such composite structures. Therefore, the proposed OoA-curing method provides a simple and cost-efficient approach to manufacture FRCs with multifunctionality.
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•New composite shear connectors are proposed for timber-concrete composite beams.•Structural behaviour of FRP bar/plate is compared with steel plate/screw system.•Composite behaviour in TCC beams is ...investigated using a DIC-based technique.•Steel plate and FRP bar illustrated highest bending stiffness and composite action.•CFRP rebar and steel screw TCC beams demonstrated highest ultimate load.
This research proposes new types of shear connectors made of carbon fibre reinforced polymer (CFRP) composites for effective stress transfer between the timber and concrete sections in cross laminated timber (CLT)-concrete composite beams. New shear connectors are designed and made of bidirectional carbon fibre reinforced polymer (CFRP) composite plates and crossed CFRP reinforcing bars. The mechanical performance, bending stiffness, ductility, and interfacial slippage and strain of timber-concrete composite (TCC) beams with CFRP connectors are compared with those with steel plate and screw systems through four-point flexure testing. Local slip, interfacial slip and strain behaviour are comparatively analysed for connections with equivalent axial stiffness using a Digital Image Correlation (DIC) based technique, so that relative composite behaviour could be determined. Furthermore, a cost evaluation is undertaken to compare the feasibility of proposed shear connectors for construction of TCC systems. Results from flexural tests demonstrate that CFRP rod specimens experience higher ultimate load and bending stiffness in elastic loading stage and ductility in failure while slippage at serviceability and ultimate load is minimal. These results demonstrate that CFRP reinforcing bars can be used as an alternative to existing steel plate/screw systems. Although CFRP plate connectors show lower ultimate strength, bending stiffness and ductility, the performance of the system can be further improved by using sufficient anchorage systems at the end of CFRP plate within the concrete.
Regulations to reduce emissions and make automobiles more energy-efficient require supplemental sustainable development. Fiber-reinforced polymers (FRPs), especially those based on carbon and glass ...fibers, have been of interest to the automotive sector over the past few decades owing to their low weight and high performance. However, the lack of high-speed and energy-efficient production, high material cost, insufficient design tools, and concern for repairability and recyclability have, in the past, constrained their use in the automotive industry on a large scale. Therefore, various composite manufacturing technologies have recently been developed to overcome these limitations. In this paper, composite manufacturing technologies for automotive applications are discussed. Many advancements in these technologies have been made over the years by automobile companies and researchers. A detailed comparison was performed based on the manufacturing cycle time, mechanical properties, cost of equipment, tooling, assembly, and energy. Furthermore, the composite properties achieved through each technology, composite manufacturing flaws, assembly methods, and shortcomings of the technology and materials are discussed.
•Particle size effect of EG on the thermal property of EG/paraffin composite was investigated.•Thermal conductivity enhancement of up to 1695% was observed with large particle sizeEG particles.•After ...50 cycles less than 5 wt% PCM leakage was found with large particle size EG particles.•A higher degradation temperature with up to 37 °C increase was observed with small particle size EG particles.
Expanded graphite (EG) is highly thermally conductive and has a porous structure, making it an ideal candidate for shape stabilisation of phase change materials (PCMs). We investigated the effect of EG size on the structure and properties of EG based paraffin composite PCMs for which no reports have been found in the literature. Large EG particles have a loose vermicular shape with a significant number of pores and voids of irregular shapes and varied sizes, which link together to form a strong networking structure. A higher degradation temperature with up to 31 °C increase was observed for the composite phase change material (CPCM) containing large EG particles, which also showed a significant level of thermal conductivity enhancement of up to 1695% compared with the paraffin. Phase change temperature hysteresis between the melting and solidification was observed on the CPCM made with large EG particles. A higher loading of the EG reduced the temperature hysteresis mainly attributed to a higher heat transfer rate. Fine EG particles are primarily in the form of loose graphite sheets. Such a structure gives a poor thermal cycling stability to composite PCMs containing fine EG particles than that using large EG particles. Composite PCMs made with fine EG particles also has a significantly higher thermal degradation temperature with up to 37 °C increase partially due to interfacial thermal resistance. The fine EG particles give also a good level of thermal conductivity enhancement of up to 340% to the composite PCMs, which is lower than those with large EG particles.
The effects of state of charge (SOC) on the elastic properties of 3D structural battery composites are studied. An analytical model based on micromechanical models is developed to estimate the ...effective elastic properties of 3D structural battery composite laminae at different SOC. A parametric study is performed to evaluate how different design parameters such as volume fraction of active materials, stiffness of constituents, type of positive electrode material, etc. affect the moduli of the composite lamina for extremes in SOC. Critical parameters and configurations resulting in large variations in elastic properties due to change in SOC are identified. As the extreme cases are of primary interest in structural design, the effective elastic properties are only estimated for the electrochemical states corresponding to discharged (SOC = 0) and fully charged (SOC = 1) battery. The change in SOC is simulated by varying the volume and elastic properties of the constituents based on data from literature. Parametric finite element (FE) models for square and hexagonal fibre packing arrangements are also analysed in the commercial FE software COMSOL and used to validate the analytical model. The present study shows that the transverse elastic properties E2 and G23 and the in-plane shear modulus G12 are strongly affected by the SOC while the longitudinal stiffness E1 is not. Fibre volume fraction and the properties of the coating (such as stiffness and Poisson's ratio) are identified as critical parameters that have significant impact on the effect of SOC on the effective elastic properties of the composite lamina. For configurations with fibre volume fraction Vf ≥ 0.4 and Young's modulus of the coating of 1 GPa or higher, the transverse properties E2 and G23 change more than 30% between extremes in SOC. Furthermore, for configurations with high volume fractions of electrode materials and coating properties approaching those of rubber the predicted change in transverse stiffness E2 is as high as +43%. This shows that it is crucial to take effects of SOC on the elastic properties into account when designing 3D structural battery composite components.
To investigate the surface micro-hardness (VHN) and fracture toughness (KIC) of resin-composites, with and without incorporated short fibers, after solvent storage.
Three resin-composites ...incorporating fibers, additional to particle reinforcement, were examined: everX™, NovoPro Fill™ and NovoPro Flow™. Four composites were used as controls, with only particle reinforcement: Filtek bulk Fill™, Filtek bulk one™, Filtek XTE™, and Filtek Flow XTE™. For hardness measurement, materials were cured in 2mm thick molds for 20s by a LED source of average irradiance 1.2W/cm2. Specimens (n=6/group) were stored dry for 1h and then in either water or 75% ethanol/water for 1h, 1 day and 30 days at 37±1°C. Vickers hardness was measured under a load of 300g for 15s. For fracture toughness (KIC) measurements, single-edge-notched specimens (n=6/group) were prepared: (32×6×3mm) for 3-point bending and stored for 1 and 7 days in water at 37°C. Fractured surfaces of fiber-reinforced composite were examined by scanning electron microscopy (SEM). VHN data were analyzed using three-way ANOVA, one-way ANOVA and the Tukey post hoc test (p≤0.05). KIC data were analyzed by two-way ANOVA and one-way ANOVA and the Tukey post hoc test (p≤0.05). An independent t-test was used to detect differences (α=0.05) in KIC between stored groups for each material.
VHN decreased for all composites with storage time in both solvents, but more appreciably in 75% ethanol/water (an average of 20%). KIC ranged from 2.14 (everX Posterior) to 0.96 NovoPro Flow) MPa.m0.5. The longer storage period (7 days) had no significant effect on this property relative to 1 day storage.
Reinforcement with short fibers, and possibly matrix compositional differences, significantly enhanced the fracture toughness of EVX. However, for nano-fiber containing composites, there were no evident beneficial effects upon either their fracture toughness or hardness compared to a range of control composites. Water storage for 7 days of all these resin-composites produced no significant change in their KIC values, relative to 1 day storage.
Research activities related to functionally graded materials (FGMs) have increased rapidly in recent years. The superlative properties of carbon nanotubes, i.e. high strength, high stiffness, high ...aspect ratio and low density have made them an excellent reinforcement for composite materials. Inspired by the concept of FGMs, the functionally graded (FG) pattern of reinforcement has been applied for functionally graded carbon nanotube reinforced composite (FG-CNTRC) materials. This paper attempts to identify and highlight topics relevant to FG-CNTRC and reviews the recent research works that have been reported in these topics. The present review includes: (i) a brief introduction of carbon nanotube reinforced composite (CNTRC) material; (ii) a review of mechanical analysis of FG-CNTRC; and (iii) a detailed discussion on the recent advances of FG-CNTRC and its prospect.
•The pultruded profile significantly enhanced the behavior of traditional RC beam.•GFRP wrapping considerably improved the behavior of the pultruded profile infilled with RC.•Hybrid reinforcements ...are recommended for the pultruded profile infilled with RC.•116–394% increase in energy dissipation capacity can be achieved with the pultruded profile.•180–237% increase in load carrying capacity can be achieved with the pultruded profile.
This paper presents the experimental, analytical and numerical analyses on the behavior of the pultruded GFRP composite beams infilled with hybrid fiber reinforced concrete under four-point loading. The examined experimental variables included: (1) effect of pultruded GFRP box profile, (2) effect of conventional steel bars, GFRP bars and hybrid bars, (3) effect of externally GFRP wrapping. Pursuant to this goal, a total of 9 medium-sized beam specimens were constructed. The experimental tests were simulated using finite element models with ABAQUS program. A novel analytical method for analyzing the flexure behavior of beams has been presented. Applying the first order shear deformation beam theory and introducing auxiliary functions, the equation of motion is derived using the Hamiltonian approach. Initial stiffness, ductility, energy dissipation capacity were compared based on the load–displacement relationship. The pultruded profile significantly enhanced the behavior of traditional reinforced concrete beam and GFRP composite wrapping also considerably improved the behavior of the pultruded profile infilled with reinforced concrete beam. More importantly is that hybrid reinforcements are recommended for all cases. Moreover, detailed damage analyses are provided.
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