Advances in Materials, Mechanical and Industrial Engineering

Friction and wear characteristics of heat-treated (350 °C for 1 h) electroless Ni–B coating at different operating temperatures are investigated systematically in the present work. Load and sliding speed are also considered as the design variables. Mass loss and coefficient of friction are considered as the responses. The design variables are varied at three equally spaced levels. Taguchi’s L27 orthogonal array is used to carry out tribological tests on a pin-on-disk tribotester. Grey relational analysis is used to predict the optimal parametric setting to minimize mass loss and coefficient of friction. The optimal condition predicted by grey relational analysis is 500 °C operating temperature, 10 N load, and 60 rpm speed. Prior to tribological tests, coating characteristics are determined using energy-dispersive X-ray analysis, scanning electron microscope, and X-ray diffraction techniques. A globular surface morphology is exhibited by the as-deposited coatings. On heat treatment, the surface of the coating resembles a cauliflower. Coating microhardness is determined by Vicker’s microindentation technique. Heat treatment leads to a significant improvement in microhardness in comparison with as-deposited coatings due to precipitation of crystalline and hard boride phases of nickel.

Graphene nanoplatelets (GnPs) belong to a category of recently innovated inexpensive materials that comprises of a small pile of graphite layers that has often been employed to augment the tensile strength of composites. In this work, acid modified Polyacroyl chloride (PACl)-functionalized GnP has been incorporated in epoxy (Epon 828) matrix and the effect of solution processing on the thermal, viscoelastic and mechanical properties of the nanocomposites was investigated. As a result of the acid treatment, hydroxl groups were incorporated on to the GnP backbone which in turn served as a site for covalent bonding with the acyl chloride groups of PACl. The unreacted acyl chloride groups bonded to the epoxy in the nanocomposite. The nanocomposites were prepared in the presence of acetone as a solvent (solvent processed) and also in the absence of solvent. The fractured surfaces of the prepared nanocomposites upon tensile testing were examined using scanning electron microscopy (SEM) which revealed the strong interfacial bonding between the functionalized GnPs and epoxy matrix. The thermal and viscoelastic properties of the nanocomposites were characterized by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA), respectively. It could be concluded that the mechanical and thermal properties of epoxy nanocomposites were improved to an appreciable extent upon the incorporation of functionalized GnPs and the processing conditions played a pivotal role in controlling the aforementioned properties.

This study presents the deposition and tribological characterization of nickel–boron (Ni–B) coatings deposited by electroless technique on AISI 1040 steel specimens. Coated specimens are annealed (heat-treated) at 350 °C for 1 h. It is seen from scanning electron micrographs that the surface resembles a typical cauliflower-like appearance. A remarkable improvement in microhardness of the coatings takes place on annealing. Structural analysis of the coatings using X-ray diffraction technique reveals that Ni–B coatings exhibit amorphous nature in as-deposited condition. Upon annealing at 350 °C for 1 h, the coating turns crystalline due to phase transformation. Due to this, hardness of the coatings increases. The annealed coatings are subjected to tribological experiments on a pin-on-disc type tribotester under dry and lubricated conditions at various loads, rotational speed and duration of sliding. COF and wear depth are recorded. It is seen that COF decreases with an increase in load under dry and lubricated conditions. The wear depth is seen to increase as the load and speed increase under both the sliding conditions. The tribological characteristics of the coatings under dry and lubricated condition are compared by generating 3D surface plots of the coefficient of friction and wear characteristics. The worn surface morphologies mainly indicate abrasive wear under both the sliding conditions.

Tribological characteristics of Ni–P–W coatings at elevated temperature developed via autocatalytic deposition over mild steel have been researched. The film is portrayed for its crystallographic arrangement, morphology, solidity and the tribological attributes. A pin-on-disc set-up in which EN 31 plate is used as static counterpart is employed. All the wear experiments are done under room condition and also to 500 °C. The deposited Ni–P–W covered surface has a blend of amorphous and crystalline phase, and it ends up fully crystalline with the formation of Ni–W and Ni3P after heating operation at 400 °C for 1 h. EDX investigation reveals the content of tungsten in the Ni–P–W combination to be around 4.5 wt%. Wear resistance of coating is observed to be negatively affected by the test temperature. Wear rate is inversely related with sliding velocity for a fixed value of load in high-temperature tests. Coefficient of friction, however, remained almost passive to elevated temperature tests. Wear rate is also found to vary with the applied load for a fixed sliding velocity. Increase in temperature causes increase in wear rate because of material softening at elevated temperature. Abrasive wear mechanism is observed for the Ni–P–W film examined at room condition, while for the same tested at a temperature of 500 °C, a mix adhesive and abrasive wear system are noted.

The motive of this work is to analyze the effect of heating temperature on hardness along with wear characteristics of electroless Ni-W-P coating. In binary (Ni-P) coating, tungsten (around 5.22 wt%) is incorporated and heat-treated at 200, 400 and 800 °C for constant time period (1 h). Hardness and tribological tests are conducted on both as-deposited and heat-treated specimens. Hardness is found to be in a co-relative state with wear resistance for the present coatings. However, hardness as well as wear resistance decreases upon heat treatment at 800 °C. Ni-W-P coating is also found to display a quite low and stable COF value with testing duration. Microstructural analysis shows the morphology of the coating to be nodular. With heat treatment, the coating turns fully crystalline with the precipitation of harder Ni3P phases. At higher temperature, oxide formation over the coating is also observed. Both abrasive and adhesive wear mechanisms are found to govern the wear behavior of the present electroless Ni-W-P coatings. It is found that inclusion of tungsten promotes the tribological properties of Ni-P coatings even when subjected to high-temperature heat treatment.

Fracture toughness is the main designing criterion of nuclear power plant. Due to neutron embrittlement, fracture toughness of reactor pressure vessel steel becomes low. This type of phenomenon can also be observed in cryogenic temperature. But in between a certain subzero temperature range, values of fracture toughness of ferritic steel are scatter in nature. This scatter is modelled by a methodology named master curve. Master curve can be governed by a single parameter which is called reference temperature (T0). T0 is defined as a measurement of embrittlement. Crack length, thickness and loading rate have influence on fracture toughness of RPV steel. The influence of loading rate over T0 has been studied on different materials in several researches. Kim Wallin established an empirical relation between loading rate and reference temperature with the help of huge data set of different RPV steels. Sreenivasan has also proposed an empirical relation to compute quasi-static T0 from dynamic T0. In the present study, 1T-CT fracture experiments are conducted at subzero temperature (−100 °C) with varying loading rates ranging from 0.625 MPa√m/s to 417.3 MPa√m/s for 20MnMoNi55 reactor pressure vessel (RPV) steel. Master curve methodology (ASTM E1921-09a) is then used for determination of T0 for each loading rates. T0 is also estimated from Wallin’s empirical relationship and compared with experimental results for this particular material. Quasi-static T0 has also been estimated from T0 at different higher loading rates using empirical relationship proposed by Sreenivasan.

Cyclic hardening and softening of materials can be modelled by a single exponential decay function. Marquis proposed that similar function can be used to modify the dynamic recovery contribution of kinematic hardening rule to simulate cyclic hardening or softening by changing only the sign of a function parameter. According to Marquis, only kinematic hardening rule, then, can be able to simulate cyclic hardening and softening with reasonable physical justification. Though it is observed that, adoption of the function in multi-segmented kinematic hardening rule is not very capable, and a separate softening approach is proposed using the same Marquis function. The cyclic plastic response of SA333 steel subjected to uniaxial tension–compression cyclic loading is experimented, and predominant cyclic softening is observed with initially non-Masing plastic curvature. Three different softening models approached with multi-segmented Ohno–Wang kinematic hardening rule in commercial FE platform. The simulations are discussed in a comparative manner, and the modification proposed is found to be showing promising agreement with experimental results.

Nitinol shows superelasticity and clearly defined hysteresis that possesses close resemblance to biological components. This is attributed to stress-induced phase transformation of Nitinol. The present article proposes a new constitutive model based on a simple schematic arrangement of friction block, spring, and rigid walls to replicate this unique behavior of Nitinol. In addition to superelasticity, the strain hardening and viscoplasticity are thoroughly explored and also incorporated in the model. Results of simulation closely match with the experimental data obtained from uniaxial testing of Nitinol wire. This model can be readily used for any case of superelasticity either due to phase transformation or any other microstructural behavior.

The micro-abrasive particles bomberding is becoming one of the most effective material removal techniques in many engineering applications like brittle material machining, surface preparation of metals for welding, cladding, and thermally sprayed coatings, performance testing of turbine and propeller blades against erosion, surface hardening of machine elements by shot-peening, micro-machining, micro-channels polishing, etching, etc. Various types of operations using abrasive jet are gaining interest day-by-day in research and manufacturing fields. In the present investigation, an indigenous abrasive jet system has been designed and developed. The abrasive jet drilling operations are performed on the soda lime glass workpieces and porcelain tiles by using the developed abrasive jet system to investigate the performance. The variation in the drilled hole diameters with changing of pressure and stand off distance is investigated. The effects of input parameters on taper angle and out of roundness of the holes are also explored.

The present study focused on the Friction stir welding (FSW) of 4-mm-thick plate of low-carbon steel at different welding conditions. FSW tool made up of tungsten carbide alloy (WC-10wt.% Co) was used to perform the welds at the rotational speeds of 300 rpm and 600 rpm at a constant welding speed of 132 mm/min. The welding was carried out along the rolling direction in the butt joint configuration. Joint was characterized in respect of microstructure, tensile strength, and microhardness. Transient thermal history was recorded using K-type thermocouples during the welding. Microhardness values were higher in the weld zones than the base material. Peak hardness values were observed in the stir zone, which were decreasing on moving toward the base material. Welded sample failed in the base material and demonstrated comparably higher yield and ultimate tensile strength than the base material. However, the ductility of the weld joints was reduced as compared to the base material. Surface roughness measurement was carried out which confirmed more twear at the tool pin than the tool shoulder. From the results, it is concluded that FSW can produce successful welds in low-carbon steel with higher tensile strength and hardness values than the base material.

Microsurface textures, especially micro-circular patterns, have played a significant role in many micromanufacturing applications, i.e., biomedical, aerospace, tribological, etc., for improving their functionality and service life. Micro-circular pattern enhances the product duration and functionalization of mechanical systems for enhancing machining efficiency. In this article, an alternative approach, i.e., maskless micro-electrochemical texturing process, namely maskless electrochemical micromachining (EMM) method, is introduced for generation of microsurface textures. The developed micro-electrochemical texturing setup consisting of EMM cell, electrode fixtures, electrical connections, electrolyte flow guiding scheme, etc., has been utilized for experiments. One masked patterned tool can produce more than twenty-five samples. Effects of EMM process variables, i.e., voltage, inter-electrode gap, duty ratio, and pulse frequency on machined responses such as overcut and surface roughness(Ra), have been investigated for three different types of electrolytes, i.e., NaNO3(0.17 M/L), NaCl(0.25 M/L), and NaCl(0.25 M/L) + NaNO3(0.17 M/L). An attempt has been done to analyze the influence of process variables using various micrographs, which are generated using three different electrolytes. The friction test has also been carried out to demonstrate the tribological effects of micro-circular patterned surfaces.

The present study shows the benefit of using casting simulation software in investment casting to analyze different defects like shrinkage porosity, cold shut, blowholes, and hard zones. In this context, three industrial case studies are discussed. For the first case, 100NB flange is taken as component and simulation is done by considering different types of in-gates to study the effect of shape of in-gate on different casting defects. In the second case, effect of pouring temperature on shrinkage size is examined by considering flange as component and proper methoding is done with the help of simulation software. In third case study, pistol body is taken as component and effect of pouring temperature and need of proper methoding on different casting defects are examined. All the simulation results are validated with shop-floor trial results.

In advanced manufacturing, the laser applications are dominated by laser micro-machining, a most effective technique for marking in many production industries. Laser marking on aluminum 6061 alloy using fiber laser has been investigated in the present project. Experimental analysis on the basis of response surface methodology (RSM) has been carried out for determination mathematical model, and an optimization analysis on marking quality, e.g., mark width and mark depth has been carried out. The most influencing laser marking process parameters under consideration on are power setting, duty cycle, pulse frequency, scanning speed, and defocus height (deviation of the focal plane from material top surface). Defocus height, a relatively uncommon process variable, plays a very important role in determining the mark characteristics. Experimental validation of the proposed models shows that desired mark width and mark depth can be optimized by adjustment of proper process parameters.

Direct metal laser sintering (DMLS) is an advanced manufacturing process in the class of modern additive manufacturing, which produces three-dimensional complex shapes from the powder material in a layered approach. It plays a significant role to manufacture metallic components directly from the metallic powders. Technological parameters of direct metal laser sintering determine the quality of the parts produced, i.e., porosity, residual stresses, and strength. The qualities of build parts are dependent on thermal and sintering behavior, which directly affected by the process parameters. In this process, a high-energy laser beam was utilized as the heat source to melt and fuse the powder particles and hence builds the three-dimensional solid object. To control the quality of the build parts, it necessitates to fundamentally understand the heat transfer mechanism. In this process, rapid heating and cooling take place which results in an unexpected change in temperature in the scanned layers. This change in temperature persuade thermal stresses in the build part after the accomplishment of the process, and it can be destructive to the quality and performance of the build parts which hinders its end-user applications. In response to this fact, it is important to analyze the heat transfer mechanism during the direct metal laser sintering process. The present research work focused on to simulate the three-dimensional transient temperature field in the build part in direct metal laser sintering of AlSi10Mg alloy powder by using ANSYS platform. The model consists of a stainless steel substrate with the dimension of 3 mm × 3 mm × 2 mm and AlSi10Mg powder layer having the dimension of 3 mm × 3 mm × 1 mm. The simulations were carried out by considering radiation, convection, and temperature-dependent thermo-physical properties of alloy powder. The heat source was presumed as the Gaussian heat source. The temperature variation, thermal history, molten pool dimension, and sintering depth with respect to process parameters in the direct metal laser sintering process were investigated. From the simulation result, the temperature profile along the scanned layers was predicted as a function of process parameters. It has been observed that with the increase in scan speed from 100 to 400 mm/s, the temperature in the build part decreases from 1483 to 1196 °C and reverse phenomena was observed with increase in laser power. Similarly, the sintering depth of the powder bed increases from 0.061 to 0.872 mm with the increase in laser power from 50 to 130 W. This model will act as an important tool for the design and optimization of process parameters in DMLS process.

The mechanical properties of welded joint mainly depend on the correct selection of welding process parameters. The present work has been planned to investigate the effects of process parameters such as welding current, welding speed and shielding gas flow rate on the weld joint quality for tungsten inert gas (TIG) welding of 316L austenitic stainless steel material. Experimental runs have been planned on TIG welding machine as per Box–Behnken design of response surface methodology (RSM). Based on the experimental data, the mathematical models have been developed by RSM to identify the effect of input process parameters on tensile properties. Optimization has been done to find out the most favourable welding parametric condition to achieve maximum ultimate tensile strength as well as percentage elongation of welded specimens simultaneously. Confirmatory tests have also been made at optimum parametric conditions to check/validate the accuracy of predicted welding condition. Good agreement has been identified between the predicted and measured values. The result indicates that the gas flow rate has the greatest influence on ultimate tensile strength and it is followed by welding current and travel speed. For percentage elongation, welding current is found to be the most influencing factor.

Plate on elastic foundation is an important realization of actual boundary condition of structures. The present paper studies the effect of the stiffness value of the elastic foundation on large deflection and free vibration of AFG non-uniform plate. Governing set of equation of the system is obtained by energy principle through variational method. Derived nonlinear equations are handled through utilizing an iterative method, which is direct substitution method. The effects of the elastic foundations are represented through load versus maximum deflection plot, deflected shape plot and backbone curves. The effects of the edged boundary conditions and non-uniformity of the plate shape are also highlighted.

The paper presents a first-order shear deformation-based finite element model to investigate the free vibration response of the rotating twisted composite stiffened plate. An eight-noded isoparametric plate element having five degrees of freedom per node is combined with an isoparametric three-noded beam element of four degrees of freedom per node for modelling the plate and the stiffener element, respectively. The present formulation employs a constraint method to calculate the stiffness and mass matrices of the stiffener element attached to the plate element, wherein the degrees of freedom of the nodes of the stiffener element are transferred to the respective nodes of the plate element considering eccentricity to maintain the compatibility between plate and stiffener. The advantage of such method is that total number of degrees of freedom due to addition of the stiffener does not increase, thereby reducing the computational time. The governing equilibrium equation is derived from Lagrangian equation of motion. The Coriolis effect is not considered as the stiffened plate is allowed to rotate at moderate rotational speed only. Parametric studies have been conducted to investigate the effect of angle of fibre orientation, pretwist angle, stiffener depth-to-plate thickness ratio and rotational speeds on the fundamental frequency and mode shapes of the stiffened plate.

This study concentrates on the yield front propagation of functionally graded material (FGM) non-uniform bars subjected to thermal loads. Under the action of thermal load, the bar is considered to be axisymmetric and the axisymmetry persists with plane cross sections of the bar. The modelling of FGM is done for continuous distributions of constituents of ceramic and metal along length of the bar by utilizing variation of power law for volume fraction. Moreover, the FGM bar is modelled by assuming the metal’s material behaviour to be linear elastic and linear strain hardening whereas the ceramic to be linear elastic. The problem is solved through a variational method, taking modulus of elasticity and yield stress of the metallic part, being a function of temperature, whereas the ambient temperature value for elasticity modulus is considered for the ceramic part. The post-elastic investigation is carried out on the basis of deformation theory of plasticity and von Mises yield criterion by a series approximation assumption for the unknown displacement field. The governing differential equation is solved through Galerkin’s principle. The propagation of yield front is located by applying an iterative process for the approximate solution and for the prescribed temperature field. MATLAB® computational simulation software is used to implement the solution algorithm. Clamped–clamped FGM bars of various geometries subjected to different temperature distributions are considered, and their effect on the thermo-elasto-plastic performance is emphasized through some results in graphical form. The parametric study reveals the nature of temperature field distribution, the effect of geometry parameters and material parameters on the elasto-plastic deformation of FG bars under thermal loading.

In the present work, static analysis and subsequently superharmonic influence on the nonlinear dynamic behavior of externally excited thick beams are investigated. Energy equations are derived considering Timoshenko beam theory. For the static analysis, classical Ritz method is followed. Nonlinear load–deflection response is obtained considering various geometric parameters such as length-to-depth ratio and load application points. For the vibration analysis, differential equations are obtained considering the Lagrange’s equation. Subsequently, harmonic balance method is employed for multi-DOF systems, which reduce the differential equations into nonlinear set of algebraic equation. These equations are tackled by enforcing an iterative scheme based on modified direct substitution method. Simple harmonic assumption although provides a very good prediction for small amplitude vibration problem. However, it is inadequate for the system having large amplitude vibration. It is shown that for accurate solution higher-order harmonics must be considered.

In this paper, dynamic behavior of free transverse vibration of an isotropic beam having single crack has been captured for cantilever boundary condition. Condition of the crack is granted stay open throughout the operation. The free vibration experimentation is carried out by exciting the system at its deflected configuration with the blow of a hammer of soft rubber, and the feedback is collected by applying an accelerometer mounted on the test specimen. Then, finite element model of beam with different boundary conditions with single and multiple open and breathing transverse cracks is developed in ANSYS environment. Followed by cracked beam is modeled and three-dimensional FEM analysis is implemented using ANSYS. Comparison studies of experimental result with finite element analysis are executed. Results collected by the experimentation are applied in cascade neural network, genetic algorithm, and cascade neuro-GA crack identification optimization techniques. The ‘Inverse problem’ consists of calculating the damage parameters from the frequency shifts of crack beams. The merit and demerit of these optimization techniques are focused.

Experimental investigation and simulation study of different types of concentrically stiffened plates under static and dynamic conditions are accomplished in the present paper with an objective to establish the static deflection and natural frequency characteristics under loading. One unstiffened plate and five types of concentrically stiffened plate specimens are experimented upon in the laboratory with the help a specialized setup that simulates clamped end condition at the plate edges. There is provision for pneumatic application of transverse uniformly distributed load. The above-mentioned plate specimens are categorized on the basis of number and arrangement of the concentric stiffeners on the plate face. Finite element simulation is also performed through commercial software ANSYS Mechanical APDL 15.0 for independent validation and comparison of experimental data. Load–deflection plots and backbone curves in non-dimensional planes are presented as results.

The objective of the present work is to formulate a finite element model for viscoelastic tapered rotor using tapered rotor elements. Maxwell–Wiechert model with one elastic spring and three Maxwell branches has been taken to model the linear viscoelastic property. A comparative numerical study for assessing rotor stability and frequency response has been performed using both tapered, hollow tapered rotor element and stepped cylindrical rotor element. It has been found that the former produces equally accurate results but with fewer elements.

We analyze the characteristics of thermal transport along with entropy generation in a quadrantal cavity, which is non-uniformly heated along the bottom boundary wall, the upright wall maintained at a constant temperature, while the arched wall being maintained adiabatic. The numerical experimentation is carried out for Rayleigh number (Ra) in the range of 103–106. The results are depicted through the distribution of streamline contour and isotherm contour within the enclosure, local heat transfer rate (Nu) along the bottom boundary wall and cold upright wall, and also average heat transfer rate. Further, the irreversibility characteristics are also presented in the form of distribution of local entropy generation due to heat transfer attributes and fluid friction attributes within the enclosure and the average Bejan number. The results reveal that Nu at the bottom wall follows a sinusoidal variation and primarily at lesser values of Ra chosen for the study, the means of heat transfer is conduction, while at higher Ra the mechanism is essentially convection. The study also enlightens the fact that at low Ra (=103), the irreversibility is essentially owing to heat transfer irreversibility (IHT) while at larger values of Ra (=105 as well 106) fluid friction irreversibility (IFF) is predominant over IHT. For an intermediate range of Ra, both IHT and IFF are comparable.

Combined effect of magnetic field and buoyancy on the thermo-fluid flow in a porous cavity is examined in this work considering top cold, bottom insulated and sidewalls linearly heated. The study is conducted extensively using an indigenous code. Fundamentals of thermo-fluid flow in the cavity are explored to appreciate heat transfer characteristics under the parametric variations of Rayleigh number (Ra), Hartmann number (Ha) and Darcy number (Da). The ranges of these parameters are Ra = 103 − 105, Ha = 10–100, Da = 10−7–10−3. Moreover, the variations in magnetic field inclination angle ( $$\gamma$$  = 0 − 180°, with respect to the cavity base) and porosity ( $$\varepsilon$$  = 0 − 1) are included. The temperature and flow fields are analyzed using isotherms and streamlines, whereas the visualization of convective heat flow is presented using heatlines. The exceptions in the general trends of the obtained average Nusselt number for clear domain as well as porous domain with the magnetic fields are noted along with the heat transfer characterization.

The object of the present article is to theoretically study the effect of turbulence on the stability of finite hydrodynamic journal bearing lubricated with micropolar fluid. Both linear and non-linear stability analyses have been carried out. In linear stability analysis, first-order perturbation method has been applied to obtain the steady-state and dynamic pressure equations. These equations have been solved to obtain the steady-state and dynamic pressures. These pressures were used to compute the dynamic film forces along with the stiffness and damping coefficients. These force components and dynamic response coefficients have been used to obtain the critical mass parameter and whirl ratio. In non-linear analysis, the transient Reynolds equation was solved using successive over relaxation scheme to obtain dynamic pressure field which in turn used to obtain the film forces and steady-state load capacity. The equations of motion have been solved using fourth-order Runge–Kutta method to obtain the threshold of stability. It is observed that the stability of the journal bearing system decreases with increase in turbulence.

The present study deals with the magnetic-field-affected heat generation–absorption undergoing natural convection in a differentially heated cavity packed with porous media. A two-dimensional porous cavity with adiabatic top and bottom is investigated numerically considering its left wall heated isothermally and right wall maintained at ambient temperature. The solution of the governing equations and subsequent post-processing is conducted using finite volume-based in-house CFD code. The flow through the porous medium has been modeled using Brinkman–Forchheimer–Darcy model (BFDM). The results obtained from the wide range of parameters are examined graphically using streamlines, isotherms, and average Nusselt number (Nu) plots and discussed to know the effects of different flow parameters like modified Rayleigh number (Ram = 1–1000), Darcy number (Da = 10−3 − 10−6), porosity (ε = 0.1 − 1.0), Hartmann number (Ha = 10 − 100) along with its inclination angle (γ = 0 − 180°), in the presence of heat generation and absorption. It is found that as the magnetic field strength increases, heat transfer rate decreases substantially, and it is further affected by heat generation–absorption parameter.

The present work considers fluid flow analysis within a straight microchannel of elliptical cross section. Variational method with slip boundary conditions is adopted to determine velocity distribution. One can use no-slip boundary conditions with incorporating an average slip velocity with little modifications. The proposed result is validated with existing literature and agrees well. The velocity distribution thus obtained is also used to determine Poiseuille number and slip coefficient. Finally, the velocity profile, Poiseuille number, and slip coefficient are presented graphically as the function of aspect ratio and Knudsen number. It is predicted that the velocity profile and Poiseuille number greatly depend on the Knudsen number and aspect ratio, whereas slip coefficient has negligible dependency on the Knudsen number. The present work is further extended to determine velocity profile, Poiseuille number, and slip coefficient for a rectangular microchannel and thus the results obtained have been compared with the elliptical microchannel. The present analytical solutions offer a suitable and power technique for studying fluid flow analysis in a variety of fundamental and engineering applications such as in microfluidics.

Disks of rotating machineries like gas turbine engines of aircraft are subjected to very high centrifugal stresses during extreme maneuvering conditions. These disks operate in nonlinear plastic region and may grow plastically during over-speed/over-load resulting in permanent deformation. As per certification criterion, disks should have acceptable permanent growth after over-speed. A closed-form solution is developed to predict permanent residual growth in rotating disk with variable thickness for linearly strain hardening material behavior using Tresca’s yield criteria and its associated flow rule. Results obtained using analytical solutions have been compared with finite element method (FEM) and experimental tests results for uniform thickness disks

Heat transfer and flow field characteristics past surface-mounted finite height circular cylinder in the presence of vortex generators (VGs) have been investigated numerically. Aspect ratio of circular cylinder such that the ratio of height to diameter of cylinder is kept fixed as 2.0 and Reynolds number based on diameter of cylinder and free stream velocity has been varied in the range from 1000 to 4000. Vortex generators in the form of rectangular winglet pair (RWP) in common flow down configuration with an angle of attack equal to 35° are considered for the present study. Present study aims to investigate the effect of combination of finite height cylinder and RWP on heat transfer enhancement by varying location of RWP relative to center of the cylinder. To illustrate the behavior of flow field, streamlines plots have been used and are compared with heat transfer field by using temperature contours. Pressure loss and heat transfer enhancement are quantified in terms of friction factor and overall surface-averaged Nusselt number, respectively. The concept of secondary flow intensity has been used to estimate the relationship between heat transfer and secondary flow. Effect of RWP location on thermal performance factor has also been reported.

Steel industries employ run-out tables [ROTs] in order to cool hot steel billets at desired rates, to achieve different steel grades. They usually consist of air, water or mixed cooling jets coming out of nozzle banks on both sides of the billet. The cooling behaviour of the billet is dependent upon multiple factors, including but not limited to the initial temperature, the nozzle bank distance, the cooling jet flow rate and the velocity of the billet. When two or more of these parameters vary, it is difficult to maximize the cooling rate. Optimization techniques are very handy in such cases, where single or multiple objective functions are to be minimized or maximized depending on multiple factors. In this study, genetic algorithm [GA], a bio-inspired optimization algorithm, is used to optimize the cooling rate of a hot mild steel [MS] plate subject to variation in the air flow rate and the upper and lower nozzle bank distances. The initial temperature of the plate is kept constant, and the plate remains stationary. A laboratory-scale ROT is used to experimentally determine the initial set of data for the GA and then optimize the same for maximization of cooling rate.

Aerofoils have been used comprehensively in the research and development of aerodynamic equipment and machineries. Implementation of computational fluid dynamics (CFD) for study of aerofoils for numerous conditions has been on the rise. Despite the reduction in cost and efforts, the simulation data still differ considerably from the real-life data as a result of several assumptions taken in numerical simulations. Henceforth, validation against experimental data is of utmost importance. Furthermore, determination of numerical and experimental data for new aerofoil sections has been a necessity as the use of such sections may enhance the aerodynamic properties of various vehicles and instruments. In this paper, a numerical simulation has been performed to obtain the velocity profile for a non-standard aerofoil over five angles-of-attack (AoAs) including negative ones which have been validated against the data obtained from wind tunnel experimentation for conditions compatible with the simulation. The contemporary results obtained show commendable convergence.

A two-dimensional, laminar transient flow past a cylindrical bluff body, with methane injection perpendicular to the direction of the free stream flow, i.e. the cross-flow arrangement, is numerically studied. An unstructured grid finite volume method is used and simulations were carried out. The methane mass fraction and the injection velocity of methane injected from the slotted cylinder are altered simultaneously, and their effects on the combustion, flame characteristics, and fluid mechanics are investigated. The flame is anchored right in front of the cylinder and is stabilized by the wake of the bluff body. The current investigation illustrates the qualitative aspects of the vortex shedding phenomena. A particular case of injection velocity and mass fraction is studied in detail and its vortex shedding phenomena are analysed minutely. The non-reacting flow exhibits 2P mode of vortex shedding while the reacting flow exhibits the more common 2S mode. Fast Fourier transform analysis of the temporally fluctuating lift coefficient is performed for the different cases carried out in the present study.

Globalization widens the platform of small-, medium- and large-scale industries for achieving success by exploring their competitive advantages for continual development. New product development (NPD) is one of those constituents which enrich the competence of companies for industrial sustainability. In today’s era, entrepreneurship has become one of the essential cultures of the company to support and develop innovative products by encouraging the NPD activities. This empirical study accumulates primary data from 76 Indian manufacturing companies and identifies the role of entrepreneurial culture to promote the technical improvements which again accelerate the NPD success by developing quality products as per customer demand. Interrelationship model of these constructs is developed by structural equation modelling (SEM) approach using IBM SPSS Amos 21.0 software packages. This model developed from the experts’ opinion depicts that entrepreneurial culture positively encourages the technological advancement of companies which helps to develop innovative products of better quality to attain customer satisfaction and in turn the NPD success.

New product development (NPD) has become inevitable constituent of the various scales of industries for industrial sustainability. Global market introduces an enormous scope for exploring new products and expanding product families for developing competitive advantage. This approach not only brings innovativeness to the companies but also accompanied by challenging environment for success and survival. Support from top managers motivates research and development (R&D) operations and practices in the company which helps to develop new and innovative products by proper utilization of available resources. This empirical study identifies the influential role of top management to control the R&D activities in optimal way to develop new products with technological advancement. The primary data have been collected from 76 Indian manufacturing companies to depict the role of top management support to expand R&D operations and practices for technological developments which in turn accelerate NPD success. Structural equation modeling (SEM) approach has been used to develop the structural model using IBM SPSS AMOS 21.0 software package.