http://localhost:80/xmlui/handle/123456789/1067 2026-04-05T17:20:40Z http://localhost:80/xmlui/handle/123456789/8681 Title: Computational study of shock diffraction over convex edges Authors: Debiprasad Banerjee and Pabitra Halder Abstract: Abstract Numerical analysis of normal shock diffraction over various step corners is presented using an implicit second-order upwind least squares cell-based method. Slipstream angle calculation for various corner angles and Mach numbers, variation of pressure load and specific heat flux with incident shock Mach numbers and different step corners along the step wall, separation point movement, and reattachment of the streamlines are some of the key features of the present study. Detailed studies have been conducted about the perturbed region enclosed within the diffracted shock wave and the last running expansion wave with the increase in the incident shock Mach numbers. The finite Volume Method is used to solve the governing equations numerically for the simulation of the moving shock. Various flow characteristics such as secondary shock, contact surface, expansion wave, slipstream, vortex, etc are well captured. Apart from isopycnics; Mach contours, isobars, and isotherms are plotted as well. The reattachment region formed after the flow separation near the step edge is mentioned and corresponding lengths over various steps are presented. Separation point movement along the step wall is highlighted and a relevant increase in reattachment length is reported. The slipstream angles get increased with incident shock Mach numbers and with corner angles. However, the rate of increment of slipstream angle decreases gradually. The core of the vortices generated and the reattachment of the separated streamlines are indicated by the two downfalls in the heat flux values. Nomenclature a acoustic velocity cp specific heat at constant pressure h specific enthalpy M Mach number Ms incident shock Mach number p pressure of the gas s specific entropy t time T temperature u x-directional velocity of the gas up induced gas velocity v y-directional velocity of the gas W shock wave velocity Subscripts&Symbols 0 total quantities 1 quantities ahead of the incident shock Description: https://doi.org/10.1088/2631-8695/ad0f02 2024-02-13T00:00:00Z http://localhost:80/xmlui/handle/123456789/8657 Title: Higher Order Approximations for Bending of FG Beams Using B-Spline Collocation Technique Authors: Biswas, Amalendu Abstract: In the present study, a functionally graded cantilever beam has been analyzed to observe its deformation behavior and stress variations. While the material properties (modulus of elasticity, modulus of rigidity, and density) have been varied along the height of the beam, Poisson’s ratio has been considered a constant. The governing equations have been derived using Hamilton’s Principle in the framework of higher-order beam theory. The derived equations are then simplified to a single equation, which is similar to that of isotropic beams. However, the work is extended to include a few higher-order terms and to study the effect of the incorporation of these terms on the resulting FG beam behavior. The development of a single governing equation for studying the statics and dynamics of an FG beam with the incorporation of higher-order terms is a unique part of the report. The solution of the governing equation is approached using approximate methods; in this work, the B-spline collocation technique is used to arrive at the results. A sixth-order Bspline basis function is used as an approximating polynomial, and the Greville abscissa has been used to generate collocation points. The obtained results have been verified against standard literature to find a satisfactory match. The results include comparative plots for normalized bending and transverse shear stresses, with and without the inclusion of higher-order terms. The results are then extended to study the effect of material index on the deformation and stress behavior of FG beams. The effect of aspect ratio on results is also studied for comparison of various beam theories. 2024-01-01T00:00:00Z http://localhost:80/xmlui/handle/123456789/8656 Title: Probing the photo induced micro actuation properties of optimized Cu doped Co-34at%-Ni-35at%-Al-31at% ferromagnetic shape memory alloys Authors: Biswas, Amalendu Abstract: The strange Photo induced micro actuation (PIMA) properties associated with Cu doped Co-Ni-Al Ferromagnetic Shape Memory Alloys (FSMA) has showed enhancement of mechanical properties in our early studies. This enhancement and optimized PIMA properties have opened a scope of various laser-controlled real engineering applications. In this study, we have explored the microstructural scaling and determined the evolved force due to the laser action in optimized Cu doped Co-Ni-Al alloy system with a detailed insight. This unique PIMA property is rare in literature and actual reason are still not explored. EBSD, TEM, AFM/MFM based techniques were further adopted to understand the role of microstructure in more detail. The evolved magnetic domain patterns for actuating and non-actuating alloys have been analyzed in details. Atomic Force Microscopy was adopted to estimate the constitutive mechanical properties of the thin alloy samples by mechanical spectrometry. This estimation was directly used to predict a general trend in force distribution pattern of the Cu-Co-Ni-Al alloys strips through FEM analysis. The crux of FEM based model and its simulated results can be applied for real time PIMA oriented engineering application and device manufacturing. The detail microstructural exploration and its effect in the PIMA response along with generalized deflection-force model have been presented in the current study. 2023-01-01T00:00:00Z http://localhost:80/xmlui/handle/123456789/8655 Title: Corrosion Behaviour of Borohydride Reduced Ni–B, Ni–B–W, Ni–B–Mo, Ni–B–W–Mo Coatings with Varying Composition: A Comparison Authors: Barman, Manik; Barman, Tapan Kumar; Sahoo, Prasanta Abstract: The borohydride reduced binary (Ni–B), ternary (Ni–B–W, Ni–B–Mo) and quaternary (Ni–B–Mo) alloy coatings are deposited by chemical deposition method. The same coatings are used to study the variation in corrosion behavior of the coatings with the inclusion of W, Mo individually or together. The coatings are deposited over steel substrate with changing bath composition to study the role of coating bath parameters on corrosion resistance behavior. The coating characterization based on roughness, morphology and phase structure are performed using stylus type roughness tester, scanning electron microscopy (SEM) and x-ray difraction (XRD), respectively. A potentiostat is employed to measure corrosion response of the coatings by potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopy (EIS) test method. The tests are carried out using a corrosive medium of 3.5% NaCl solution. All the coatings are observed to exhibit caulifower like surface morphology. The roughness of the coatings increases with bath parameter concentration. The corrosion resistance of the Ni–B–Mo coatings are found to be better than other three variants till mid-level of concentrations. The Ni–B coated specimens show higher corrosion resistance at higher level of concentrations compared to the ternary and quaternary coatings. 2023-10-01T00:00:00Z