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In the present research, measurement of residual stress induced during turning and threading operations for the fabrication of two types of pin profiled friction stir processing/welding (FSP/FSW) tools, i.e. cylindrical profiled pin tool and cylindrical threaded profiled pin tool, is being dealt with. Workpiece was chosen to be H13 tool steel with a diameter of 22 mm and 110 mm length. Turning and threading was done on CNC machine tools using CNMG 12404-THM uncoated tungsten carbide cutting tool. For residual stress measurement of the workpieces, an XRD-based Pulsetec μ -X360n portable residual stress analyzer setup was used. The experimental results show that the cylindrical pin profile tool had a compressive residual stress of σ (x) = 3 0 1 MPa and compressive residual shear stress of τ (x y) = 6 0 MPa, while the cylindrical threaded pin profile tool had a compressive residual stress of σ (x) = 4 5 7 MPa (51.8% more) and compressive residual shear stress of τ (x y) = 3 6 MPa (40% less). It has been concluded that due to threading operation on the cylindrical threaded pin profile, the value of residual stress is more in it, and since the stress is compressive in nature, it would have a better positive impact while doing FSP/FSW than that of the cylindrical profiled pin tool. [ABSTRACT FROM AUTHOR]

Fracture toughness behaviour of [Al/Si3N4/Al2O3]P Nanocomposites was examined in the current research work. The nanocomposites were fabricated using powder metallurgical route for various compositions under the compacting pressure of 12.06 MPa and at a sintering temperature of 650 °C. The fracture toughness for all sample compositions estimated for longitudinal direction was accessed through apparent fracture toughness (KQ), Equivalent energy fracture toughness (Kee) and J integral (J) measurement. The result revealed the exceptionally good fracture toughness parameters (KQ-17.6 MPa√m, Kee-20.5 MPa√m and J integral-3.9 kJ/m2) of 2 wt% mixed Al2O3 and Si3N4 as compared to the pure sintered sample (KQ-10.7 MPa√m, Kee-13.4 MPa√m and J integral-1.0 kJ/m2). The fracture toughness parameters for 2 wt% mix Al2O3 and Si3N4 were observed to be maximum out of all sample compositions ranging from P to M3, substantiating the role of transgranular ductile fracture mechanism as compared to the rest of the samples where the transgranular brittle fracture was dominant. [ABSTRACT FROM AUTHOR]

The cellulosic bast fibers are recognized as a justifiable and biodegradable substitute for producing moderate strength polymer composite materials because of their characteristics of renewability, ecofriendliness, and higher specific strength. Hence the aim of this research work is to fabricate Himalayan bast fibers (Nettle fiber (NF)/bauhinia vahlii fiber (BF)) based mono/hybrid epoxy composites at varying weight percentage of 2e6 wt% and evaluate the physical (void fraction and water absorption), mechanical (tensile strength, flexural strength, hardness) and sliding wear properties of as-fabricated composites. The 6 wt% NBF reinforced composites exhibited higher mechanical properties as compared to NF and BF composites with tensile strength of 34.04MPa, flexural strength of 42.45 MPa, and hardness of 37.01 Hv respectively. The influence of various control factors (sliding velocity, NF/BF/NBF contents, normal load and sliding distance) on specific sliding wear rate of composites was evaluated by Taguchi (three factors at three levels) experimental design and the percentage contribution of these selected parameters on sliding wear performance was examined by Analysis of variance (ANOVA). The sliding wear property of as-developed composites was found to be greatly influenced by sliding velocity and the wear resistance was observed to be improved with the NF/BF/NBF contents. The wear mechanism of the as-fabricated composites has been elucidated by scanning electron microscopy analysis. The research outcomes demonstrated that the hybridization of Bauhinia vahlii fiber with Nettle fiber led to improve the mechanical and wear properties of epoxy composites. [ABSTRACT FROM AUTHOR]