General practices to enhance bast fiber composite properties for state of art applications – a review

Composite materials are revolutionizing to realize the demanding needs of aeronautical, automobile, construction, chemical, and biomedical applications. The natural fiber composite is chosen as one of the best choices among composites due to its sustainable goods like eco-friendly nature, better properties and Greenhouse gas (GHG) balance. Furthermore, the bast fiber composites are identified as promising industrial composites based on the availability, strength-to-weight ratio, manufacturing ease, and economics for commercialization. However, product quality and production volume significantly influence commercial adoption of the bast fiber composites. Especially the product quality primarily suffer due to climatic conditions, damage while harvesting, extraction method, retting issues, and extraction location. Consequently, this review aims to provide an overview of the bast fibers & their composites, properties enhancement techniques, overall mechanical behaviours and thermal stability with suitable applications.

Effect of Coating Bath Parameters on Properties of Electroless Nickel-Boron Alloy Coatings

Electroless nickel-boron binary coatings were obtained with various bath compositions to investigate the effect of bath parameters on tribological and mechanical behaviours of the coating. Characterisation of the coating for surface morphology and phase structure is done using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), respectively, whereas tribological behaviour of coatings is evaluated on a pin-on-disc tribo-tester. Elastic modulus and surface hardness of coatings have been obtained using nano-indentation technique, while the scratch behaviour of the coatings has been determined using micro-scratch test. Corrosion resistance of coatings is also determined. It is observed that surface roughness of the coatings increased with increase in sodium borohydride concentration but decreased slightly with increase in nickel chloride concentration. Friction and wear characteristics are found to increase with surface roughness which occurs due to increased boron content. Surface hardness and scratch hardness are also seen to vary with coating bath parameters.

Exploration on Mechanical Behaviours of Hyacinth Fibre Particles Reinforced Polymer Matrix-Based Hybrid Composites for Electronic Applications

Biocomposites with polylactic acid (PLA), nanosilica parts, and water hyacinth fibres have been developed in this experimental study. By changing the weight percentage of nanosilica particulate matter (0, 2, 4, 6, and 8 percent) with PLA and water hyacinth fibres, five composite mates were produced through a double screw extruder and compression moulding machine. According to the ASTM standards, the process to machine, the composite specimens have been adopted from the water jet machining process. The tensile, compression, flexural, impact, hardness, and water absorption tests were performed on the composite specimens to assess various mechanical properties and absorbance behaviour. The test findings reveal the significant improvement in the tensile and flexural properties of the composites. Composites contain 6 percent of the fine nanosilica particles by weight. Concerning adding the growing weight percentage (4 percent) of nanosilica particles to the composites, the water absorption properties of the composites have significantly improved. The tensile strength of 6% nanosilica mixed specimens showed the highest tensile stress rate as 36.93 MPa; the value was nearly 3.5% higher than the 4% nanosilica mixed composite specimens.

Twinning-assisted dynamic adjustment of grain boundary mobility

Grain boundary (GB) plasticity dominates the mechanical behaviours of nanocrystalline materials. Under mechanical loading, GB configuration and its local deformation geometry change dynamically with the deformation; the dynamic variation of GB deformability, however, remains largely elusive, especially regarding its relation with the frequently-observed GB-associated deformation twins in nanocrystalline materials. Attention here is focused on the GB dynamics in metallic nanocrystals, by means of well-designed in situ nanomechanical testing integrated with molecular dynamics simulations. GBs with low mobility are found to dynamically adjust their configurations and local deformation geometries via crystallographic twinning, which instantly changes the GB dynamics and enhances the GB mobility. This self-adjust twin-assisted GB dynamics is found common in a wide range of face-centred cubic nanocrystalline metals under different deformation conditions. These findings enrich our understanding of GB-mediated plasticity, especially the dynamic behaviour of GBs, and bear practical implication for developing high performance nanocrystalline materials through interface engineering.

Linear equation systems for structural analysis: imagining resolutions

This work is based on a study into new ways of resolving the equilibrium equation systems for manual analyses of certain structures commonly found in building. It suggests finding solutions based on images that reproduce the operations of current methods, which may inspire the design of others that qualitatively reflect those of other more effective procedures. To date three methods (Gauss, Cholesky & Crout) have been imagined: (i) by “visualising” their operations through the mechanical behaviour of models during the equilibrium phase. These visualisations may help suggest other physical responses that can balance models more quickly and identify with new, more direct numerical methods; (ii) by “geometrising” operations by means of lines sketched freehand. This geometrisation may reveal hidden links between the parts of the calculation of current methods that enable more direct but equally precise new methods to be created. The paper shows four images to reinforce these viewpoints. Two visualise the methods of Gauss-Jordan and Cramer, confirming that the abstract procedures that resolve the systems may be linked to specific mechanical behaviours. The other two geometrise the resolutions by Gauss and Gauss-Jordan when the stiffness matrices are asymmetric. Their systems could emerge from the analysis of cracked models or from obtaining the equivalent actions in the P-Δ method, in line with a procedure drawn up previously. The paper ends by geometrising the resolution of a system at different scales and comparing the outcomes with those of numerical methods. The results (i) confirm that geometrising scalar and vectorial magnitudes for numerical analysis procedures reduces application times if they are calculated freehand; and (ii) point to possible lines of research for developing further graphic methods that can analyse other types of structure directly and accurately.