Materials Science Forum Vol. 1112

Abstract: Beam-column joint is the most vulnerable location of a moment-resisting reinforced concrete frame structure. The joint region experiences the maximum shear stress both in vertically and horizontally which is generated due to the shear transfer mechanism from the adjoining beams and columns. The shear capacity and bond stress capacity are the two major factors affecting the strength of a joint core in RC structure. An important discovery recently is the ductile behaviour of the whole structure under repeated loading. The behaviour of the concrete beyond elastic limit which is in the concrete hardening zone can drastically influence the ductility of the concrete. The non-linear stress-strain behaviour after the onset of the initial crack and up to ultimate compressive strength plays an important role in improving ductility. Beyond the ultimate compressive strength, concrete will undergo softening which is neglected in this study as once concrete reaches ultimate stress it is unsafe for service. This material ductility can be fulfilled with the application of high-strength fibres with ductile behaviour. However, the hybridization of two or more fibres can incorporate two different characteristics of the fibre used. The use of ordinary-grade of concrete moreover reduces the shear-resisting capacity of the joint. A hybrid mix of hooked-end steel fibre with basalt fibre and crimpled steel fibre with polypropylene fibre are used with a volume fraction of 1% to 1.4% of the concrete. In this study, ordinary M25 grade concrete and fibre mixed M25 grade concrete is employed under static and cyclic loading. The laboratory tests are also conducted to evaluate the compressive strength, split-tensile strength, and flexural strength of the hybrid mix fibre-reinforced concrete at the age of 28^th days. Five full-scale models of the beam-column joint are designed as per the Bureau of Indian Standards. Numerical models of concrete and steel reinforcement are developed. Numerical analysis is carried out using finite element software ANSYS-v21. The behaviours of the beam-column joint are observed under static as well as cyclic loading. Crack patterns, first crack load, initial displacement, ultimate load, and ultimate displacement are observed under static conditions. And under cyclic loading, hysteresis load vs displacement, energy dissipation, and stiffness degradation are observed. The hybridization of hooked steel with basalt fibre gives better results in mechanical strengths and the hybrid effect of crimpled steel with polypropylene fibre gives better results in mechanical strengths. And also under numerical study, the above specimens show an improvement in energy dissipation capacity. Keywords beam-column joint, hybrid fibre reinforced concrete, numerical concrete model, ANSYS, static, reverse cyclic, energy dissipation, stiffness, crack

Abstract: Fibre reinforced polymer composites are employed instead of metal and wood because they are stronger, more lightweight, have a favourable strength to weight ratio, and are noncorrosive. In the current research, sisal, carbon fibre, and industrial waste tea leaf fibre (WTLF) reinforced hybrid epoxy composites are being examined for their chemical, mechanical and acoustical properties with experimental study. The sisal and WTLF were chemically treated with 5% sodium hydroxide (NaOH) solution. By modifying the weight percentage of sisal and WTLF with a structure of 40 weight percent fibre and 60 weight percent matrix, five different compositions of natural fibre reinforced hybrid composites were fabricated using an automatic compression moulding technique. As per the ASTM standard the manufactured hybrid composites are tested for mechanical, chemical and acoustic characteristics. According to the experimental findings, sisal fibre with a 25 wt% and WTLF with a 5 wt% demonstrated superior mechanical properties, while these materials also demonstrated an excellent acoustic absorption coefficient (AAC) of 0.62 between the frequency range of 2000 to 6300 Hz. The morphology of failure samples revealed the matrix micro crack, void formation, fiber pullout and layers of fractured fibers which are being examined using Scanning Electron Microscopy (SEM). The superior bonding between fibre and matrix was seen in the FTIR study of 5% alkali treated composites.

Abstract: The economic, performance, and environmental advantages of accepting Aluminium (Al) metal matrix composites (MMCs) over steel, cast iron and light alloys are driving forces behind their utilisation. The transportation industry benefits from reduced noise, reduced emissions from airplanes, and reduced fuel use. Continuous research in this field has resulted in improved manufacturing procedures, allowing these Aluminium based composite materials to be used in aerospace industry, marine and vehicle applications rather than most monolithic materials. The industrial sector is rapidly developing, which increases demand for innovative materials. In cases where 'wear' is a critical issue, conservative materials and alloys have limits in reaching the appropriate hard characteristic. Al-MMCs are composite materials that contain Al or an alloy of Al. It acts as the matrix and the reinforcement distributed across the matrix. Common reinforcing materials include fibres, whiskers, and particles. Because of its enhanced density, great hardness, and thermal stability, ceramic reinforcement is the most used. However, they have limits such as less ability to wet and compatibility with the Al matrix. The major production processes for Al-MMCs are powder and liquid metallurgy. All the manufacturing procedures outlined are appropriate, however casting with stir to mix is cost-effective, particularly for big production runs. The distribution of reinforcement evenly to generate a flaw-free structure at micro level and hence raise the resistance to hard behaviour is a critical difficulty in the synthesis of MMCs of Al. Al-MMCs with particle reinforcement have increased mechanical characteristics and wear resistance. Furthermore, the production of MMCs reinforced with particulates is an exciting task, with questions arising due to ductility decline as the weight percent of ceramic particulate reinforcement is increased, gravity segregation due to denser particulates, and oxidation due to the use of Al alloy, which is very susceptible to oxidation. In the present study Al6061-3% B₄C MMCs have been developed by stir casting technique. Al6061 is an extruded raw material as purchased from the supplier (and not an ingot) used before remelting and manufacturing the MMCs. The microstructure of the manufactured Al-alloy and Al-MMCs are evaluated. It is observed that stir casting is a suitable method to manufacture Al-MMCs.

Abstract: A study of hyacinth plant fibres derived from aquatic wastewater aimed at developing lightweight, durable synthetic materials reinforced with banana fibres. The availability and sustainability of banana fibre make it one of the best choices for natural fibres. Traditional materials are extremely heavy, heavy, and expensive when compared to banana fiber materials. Their strength, lightness, and affordability make them ideal for this purpose. Recently, natural fibres have gained attention from scientists as reinforcement materials for polymeric composites and technical applications. There are many advantages to using natural fibres, including continuous supply, easier handling, and biodegradability. Particle boards on the market have a lower hardness strength than banana fibre composite boards. ASTM standards determine parameters such as hardness strength and absorption. According to their hardness strength, banana composites have hardness values of 95 shore D. The absorption levels of banana composites can be increased by 15 to 30%, depending on reinforcement. Compared to the other samples, 30% of the composite samples were able to achieve the high performance. The use of metal as a wood alternative for automobile bodies has been found to be promising in a number of applications.

Abstract: Quality and productivity have been used as terms to control process parameters and lower process defects. Several defects emerge when products are manufactured using the compression moulding process.Since the second-largest industrial process used to produce plastic goods and also the most popular method of producing thermoset and thermoplastic polymer composites is compression moulding.By this method control of temperature and pressure gives the desired shape of product. This method can be applied to both thermoset and thermoplastic materials. Due to the low flow index of thermoset plastics, considerable pressure is needed, which can only be achieved by the compression moulding method.The components, functionality, equipment, and tooling behaviour of the compression moulding process are covered in this study of paper. The advantages, drawbacks, and equipment used, as well as the material processing parameters, part design, tooling, and cost of compression moulding process parts are also discussed.In this work, many process variables—including moulding temperature, pressure, preheat time, and material weight are taken into account for the response research of the mechanical properties and internal defects created by the compression moulding process.

Abstract: Fiber-reinforced plastic (FRP) composites are subjected to micro-level defects such as fiber-matrix debond and/or matrix cracks after a period of their service due to the increasing brittleness of matrix material. Prediction of the degraded elastic properties of a lamina through micromechanical studies by incorporating micro-level defects gives an idea of the health condition of such structures. Due to the limitations of classical mathematical approaches in solving complex structures, numerical mathematical methods like the finite element method (FEM) can be employed. The present investigation deals with the micromechanical analysis of Glass fiber-reinforced plastic (GFRP) composite with micro-level defects to predict some of the elastic properties. The composite is idealized as an array of square unit cells, and the micromechanical behavior of one such unit cell is simulated in ANSYS software using the three-dimensional finite element method to predict Young’s moduli and Poisson’s ratios in principal material directions. The converged finite element solution for longitudinal modulus is validated by the rule of mixtures and the other properties using the Maxwell–Betti reciprocal theorem. Variations of Young’s moduli and Poisson’s ratios due to an incremental internal failure of composite such as low-level, medium-level, and high-level defects at an expected range of fiber volume fractions (50% - 60%) are evaluated and estimated the percentage degradation with respect to a corresponding defect-free composite.

Abstract: Fused deposition modelling (FDM) is a spectrum of techniques that enables the fabrication of objects from diverse materials, layer-by-layer, and directly from a CAD file. With the advancement of technology, the procedure has grown more adaptable and swifter. In this study, the mechanical performance and topology optimization of the polylactic acid (PLA) 3D printed hollow and thin-walled structures produced by FDM was investigated via integration of Taguchi method and Principal Component Analysis (PCA). Eleven factors namely topology design (square), wall thickness (1 mm), layer height (0.3 mm), infill density (20%), infill layer thickness (0.6 mm), infill flow (80%), infill pattern (Octet), print speed (80 mm/s), printing temperature (210°C), bed temperature (65°C), and orientation direction (flat along the y-axis) were identified as the optimal factors for the 3D printed part. The integration approach concurrently solves the problem in particular for numerous quality criteria, especially in 3D printing. Integrating the Taguchi method with PCA can help to improve the quality of the final product or process, and enhance the understanding of the underlying relationships between variables.

Abstract: Multi-material Additive manufacturing (AM) has opened new opportunities for the creation of multifunctional structures that enables value-added structural product designs. Among the multi-material AM techniques, multi-nozzle fused filament fabrication which is a type of material extrusion technique is found to be the more popular choice for multi-material polymer fabrication. One major challenge of multi-material additive manufacturing of polymers is the poor mechanical strength at the interface of the dissimilar materials such as polylactic acid (PLA) and thermoplastic polyurethane (TPU) due to the lack of chemical affinity. Therefore, understanding the mechanical strength at the interface of these dissimilar materials becomes an important topic as it allows product designers to do necessary tweak to the design to compensate for the weaker link in the structural design. In this work, we investigated the tensile strength and the shear strength of different combinations of PLA and TPU and their respective nanocomposites, as well as the fatigue analysis of the bi-layer structures made of these dissimilar materials in a 3-point bending test configuration. Generally, when functional fillers or particles are added to the polymer in composites, they tend to adversely affect the interlaminar adhesion property and fatigue life of the soft-rigid bilayer structure. It was found, that the interlaminar tensile strength and the interlaminar shear strength can reduce as high as 44% and 78%, respectively, compared to the baseline samples with no fillers.

Abstract: Metal-Organic Frameworks (MOFs) have gained traction as an adsorbent due to their high surface area and porosity. MIL-101(Fe), a MOF that has been used for removing dyes in water by adsorption, faces the problem of being inseparable from water after use. To get around this difficulty, MIL-101(Fe) was incorporated into composite beads consisting of polymers Chitosan (CS), and Polyvinyl Alcohol (PVA) crosslinked with Glutaraldehyde (GLA) to remove Methyl Orange (MO) from water. The resulting CS/MIL-101(Fe)/PVA beads were optimized based on the right combination of synthesis parameters that gave the highest percent MO removal. It was found that the maximum MO removal can be achieved by beads made of 1500 ppm MIL-101(Fe), 2.0 % PVA, crosslinked in 2.5% GLA. Using FTIR analysis and SEM imaging, the beads exhibited favorable properties for adsorption, as shown by their coarse and porous structure. The beads proved viable for adsorption, exhibiting a percent MO removal of 69.62% upon validation.