Royal Madan and Shubhankar Bhowmick
The purpose of this study is to investigate Thermo-mechanical limit elastic speed analysis of functionally graded (FG) rotating disks with the temperature-dependent material…
Abstract
Purpose
The purpose of this study is to investigate Thermo-mechanical limit elastic speed analysis of functionally graded (FG) rotating disks with the temperature-dependent material properties. Three different material models i.e. power law, sigmoid law and exponential law, along with varying disk profiles, namely, uniform thickness, tapered and exponential disk was considered.
Design/methodology/approach
The methodology adopted was variational principle wherein the solution was obtained by Galerkin’s error minimization principle. The Young’s modulus, coefficient of thermal expansion and yield stress variation were considered temperature-dependent.
Findings
The study shows a substantial increase in limit speed as disk profiles change from uniform thickness to exponentially varying thickness. At any radius in a disk, the difference in von Mises stress and yield strength shows the remaining stress-bearing capacity of material at that location.
Practical implications
Rotating disks are irreplaceable components in machinery and are used widely from power transmission assemblies (for example, gas turbine disks in an aircraft) to energy storage devices. During operations, these structures are mainly subjected to a combination of mechanical and thermal loadings.
Originality/value
The findings of the present study illustrate the best material models and their grading index, desired for the fabrication of uniform, as well as varying FG disks. Finite element analysis has been performed to validate the present study and good agreement between both the methods is seen.
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Royal Madan and Shubhankar Bhowmick
Functionally graded materials are a special class of composites in which material are graded either continuously or layered wise depending upon its applications. With such…
Abstract
Purpose
Functionally graded materials are a special class of composites in which material are graded either continuously or layered wise depending upon its applications. With such variations of materials, the properties of structure vary either lengthwise or thickness wise. This paper aims to investigate models for effective estimation of material properties, as it is necessary for industries to identify the properties of composites or functionally graded materials (FGM’s) before manufacturing and also to develop novel material combinations.
Design/methodology/approach
Available models were compared for different material combinations and tested with experimental data for properties such as Young’s modulus, density, coefficient of thermal expansion (CTE) and thermal conductivity. Combinations of metal–ceramic and metal–metal were selected such that their ratios cover a wide range of materials.
Findings
This study reveals different models will be required depending on the material used and properties to be identified.
Practical implications
The results of the present work will help researchers in the effective modeling of composites or FGM’s for any analysis.
Originality/value
This paper presents a comparison and review of various analytical methods with experimental data graphically to find out the best suitable method. For the first time, the Halpin-Tsai model was extended in the analysis of the CTE which shows good approximations.
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Royal Madan, Pallavi Khobragade and Shubhankar Bhowmick
This study aimed to analyze the free vibration of a radially graded Ni-Al2O3-based functionally graded (FG) disk with uniform thickness.
Abstract
Purpose
This study aimed to analyze the free vibration of a radially graded Ni-Al2O3-based functionally graded (FG) disk with uniform thickness.
Design/methodology/approach
Using the energy method, natural frequencies of rotating and non-rotating disks were determined at the limit elastic angular speed. Material properties were estimated using a modified rule of mixture. Both even and uneven porosity variation effects were considered in the material modeling. Finite element analysis validated the analytical approach.
Findings
The study explored limit angular speeds and natural frequencies across various grading indices, investigating the impact of porosity types and grading indices on these parameters.
Practical implications
Insights from this research are valuable for researchers and design engineers involved in modeling and fabricating porous FG disks, aiding in more effective design and manufacturing processes.
Originality/value
This study contributes to the field by providing a comprehensive analysis of free vibration behavior in radially graded Ni-Al2O3-based FG disks. The incorporation of material modeling considering both even and uneven porosity variation adds originality to the research. Additionally, the validation through finite element analysis enhances the credibility of the findings.
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Lakshman Sondhi, Rakesh Kumar Sahu, Shubhankar Bhowmick and Royal Madan
The purpose of this study was to perform thermo-mechanical deformation and stress analysis in a functionally graded (FG) hollow cylinder considering steady-state temperature…
Abstract
Purpose
The purpose of this study was to perform thermo-mechanical deformation and stress analysis in a functionally graded (FG) hollow cylinder considering steady-state temperature distribution under the effect of rotation, gravity and constant heat generation.
Design/methodology/approach
Navier's equation was used to solve the problem, and the obtained results were validated with benchmarks found to be in excellent agreement. The variation of temperature and other material properties such as Young's modulus, density, thermal expansion coefficient and thermal conductivity varied radially as per power-law variation.
Findings
The effect of rotation was found to be vital compared to gravity and heat generation when compared individually and in combination. The results of displacement and stresses were presented for varying grading indices.
Practical implications
FG cylinders have huge industrial applications as it opens the possibility of developing structures with a high strength/weight ratio. The present study will benefit industries in identifying the effective grading index that can be used by industries for fabricating FG structures.
Originality/value
The effect of rotation, body force and heat generation on a cylindrical body has not been studied before. Furthermore, the combined effect of rotation, body force and heat generation has been studied to understand the behaviour of cylinders operating under similar conditions.
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Royal Madan, Shubhankar Bhowmick, Lazreg Hadji and Ali Alnujaie
In this work, the effect of porosity volume fraction, porosity types, material grading index, variable disk profiles and aspect ratio on disk performance was studied by performing…
Abstract
Purpose
In this work, the effect of porosity volume fraction, porosity types, material grading index, variable disk profiles and aspect ratio on disk performance was studied by performing limit elastic speed analysis of functionally graded porous rotating disks (PFGM) under thermo-mechanical loading.
Design/methodology/approach
The composition change was varied by employing the power law function. The thermo-mechanical properties of PFGM such as Young's modulus and yield strength were estimated using modified rule of mixture, for density and coefficient of thermal expansion rule of mixture was used. The even and uneven distribution of porosity in a disk was taken as uniform, symmetrical, inner maximum and outer maximum. The problem was then solved with the help of the variational principle and Galerkin's error minimization theory.
Findings
The research reveals that the grading parameter, disk geometry and porosity distribution have a significant impact on the limit elastic speed in comparison to the aspect ratio.
Practical implications
The study determines a range of operable speeds for porous and non-porous disk profiles that the industry can utilize to estimate structural performance.
Originality/value
A finite element investigation was conducted to validate the findings of the present study. Limit elastic analysis of porous FG disks under thermo-mechanical loading has not been studied before.
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Royal Madan and Shubhankar Bhowmick
The purpose of this study is to investigate the performance of disks that can be increased by functionally grading the disk in the radial direction; there are several but distinct…
Abstract
Purpose
The purpose of this study is to investigate the performance of disks that can be increased by functionally grading the disk in the radial direction; there are several but distinct categories of literature that pertain to the fabrication of disk in the thickness direction, but to the best of the authors’ knowledge, no study has been conducted yet, in which gradient composition changes radially.
Design/methodology/approach
A powder metallurgy technique was used for the fabrication of Al-SiC-based, three-and five-layered functionally graded (FG) disk. The variation of volume fraction of reinforcement particles (SiC) in a disk changes radially. Finite element analysis has been performed to investigate stress distribution in a layered disk.
Findings
The microstructural investigation was carried out under an optical microscope and scanning electron microscopy integrated with EDS, confirming a uniform distribution of SiC in the matrix (Al). Interface microstructure indicates a successful fabrication of FG material because the transition is uniform in the graded layer without any development of crack or void at the interface. The grain size in the layers decreases with the addition of SiC particles. Additionally, the disk hardness increases as the SiC composition in the layer increases.
Practical implications
An FG disk can be used in a wide range of machinery, from power transmission assemblies to energy storage devices (e.g. flywheel, gears, rotors and disk brake).
Originality/value
The proposed powder metallurgy technique could be used in industries for the fabrication of simple to complicated geometries with FG properties.
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Sanjay Kumar Singh, Lakshman Sondhi, Rakesh Kumar Sahu and Royal Madan
The purpose of the study is to perform elastic stress and deformation analysis of a functionally graded hollow disk under different conditions (rotation, gravity, internal…
Abstract
Purpose
The purpose of the study is to perform elastic stress and deformation analysis of a functionally graded hollow disk under different conditions (rotation, gravity, internal pressure, temperature with variable heat generation) and their combinations.
Design/methodology/approach
The classical method of solution, Navier's equation, is used to solve the governing equation. The analysis considers thermal and mechanical boundary conditions and takes into account the variation of material properties according to a power law function of the radius of the disk and grading parameter.
Findings
The findings of the study reveal distinct trends and behaviors based on different grading parameters. The influence of gravity is found to be negligible, resulting in similar patterns to the pure rotation case. Variable heat generation introduces non-linear temperature profiles and higher displacements, with stress values influenced by grading parameters.
Practical implications
The study provides valuable insights into the behavior of displacement and stresses in hollow disks, offering a deeper understanding of their mechanical response under varying conditions. These insights can be useful in the design and analysis of functionally graded hollow disks in various engineering applications.
Originality/value
The originality and value of this study lies in the consideration of various loading combinations of rotation, gravity, internal pressure and temperature with variable heat generation. Furthermore, the study of effect of various angular rotations, temperatures and pressures expands the understanding of the mechanical behavior of such structures, contributing to the existing body of knowledge in the field.
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Royal Madan, Kashinath Saha and Shubhankar Bhowmick
The limit elastic speed of rotating disk is an important design criterion, as it defines the limit before onset of yielding initiates. The purpose of this paper is to establish…
Abstract
Purpose
The limit elastic speed of rotating disk is an important design criterion, as it defines the limit before onset of yielding initiates. The purpose of this paper is to establish the limit elastic speeds for S-FG disks and report the stresses induced at such speeds.
Design/methodology/approach
For S-FGM disk, effective Young’s modulus is calculated using modified rule of mixture and subsequently effective yield stress is also calculated by taking into consideration of stress-strain transfer ratio. The S-FGM disk is subject to centrifugal loading and the stress and deformation characteristics are investigated using variational principle wherein the solution is obtained by Galerkin’s error minimization principle. Based on von-Mises yield criteria, equivalent stress is calculated at different angular speeds till the equivalent stress at any given location in the disk attains the value of effective yield stress at the given location (location of yield initiation). This defines the limit elastic speed for the S-FGM disk (for given n).
Findings
The limit elastic speed of S-FGM disks for a range of grading index (n) and corresponding stresses within the disk are reported. Results are reported for uniform disks of different aspect ratio and the results reported could be used as practical design data.
Practical implications
Functional grading of material in structures opens a new horizon to explore the possibility of manufacturing high strength component at low weight. Material grading plays a significant role in achieving desired material properties, and literature review reveals reporting of numerous grading functions to approximate material distribution in structure.
Originality/value
The work has not been addressed earlier and findings provide a pioneering insight into the performance of S-FG disks.
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This chapter shifts contemporary debates on Eurocentrism from its focus on European social theory to an analysis of its moorings in non-Atlantic sociological traditions and…
Abstract
This chapter shifts contemporary debates on Eurocentrism from its focus on European social theory to an analysis of its moorings in non-Atlantic sociological traditions and especially those within ex-colonial countries. It discusses the sociological/anthropological visions of two first generation sociologists/anthropologists from India, G. S. Ghurye (1893–1983) and D. P. Mukerji (1894–1961), within Orientalist-Eurocentric positions and explores how these are reinvented in the work of contemporary sociologist T. N. Madan (1933–). It suggests that colonial processes and its institutions together with “derivative” nationalist ideas have played and continue to play important mediatory role in organizing these Orientalist-Eurocentric visions.
The chapter presents three sets of arguments. First it suggests that in order to understand postcolonialism it is imperative to lay out the organic links between Orientalism and Eurocentrism. Eurocentrism and its mirror Orientalism mediated to frame social science language in terms of the binaries of universal (the West) and particular (the East). The particular was represented in India through the discipline of anthropology. The latter studied “traditions” through the themes of religion, caste, and family and kinship. When sociology emerged as a discipline in India in the early twentieth century, it continued to use the language organized by anthropology to analyze the particular cultural traditions of the country. Second, I suggest that these binaries also framed nationalist thought and the latter mediated in framing the sociological ideas of G. S. Ghurye and D. P. Mukerji which were embedded in Eurocentric-Orientalist principles. Third, I analyze the ideas of the contemporary social theorist T. N. Madan to indicate how his perspective continues to derive its positions from Orientalist-Eurocentric positions and ignores an engagement with critics who have questioned Orientalist Eurocentrism. Disregarding these arguments implies the legitimation of the latter perspective derived from the disciplines of sociology/anthropology.
The chapter contends that a decolonized critique of colonial social science has existed in other regions of the world including India, and that this perspective needs to be retrieved by social theorists to reformulate the sociological discourse as a study of modern India. It also suggests that contemporary analysis of Eurocentrism needs to move out from within the circuits of knowledge defined by received colonial geopolitical enclaves in order to assess the way production, distribution, and consumption of Orientalist-Eurocentric perspectives have organized sociological traditions across the world including the Global South.
Miljenka Perovic, Vaughan Coffey, Stephen Kajewski and Ashok Madan
The purpose of this paper is to provide an overview of the diverse issues that affect heritage projects during their lifecycle and in particular, why heritage-listed projects…
Abstract
Purpose
The purpose of this paper is to provide an overview of the diverse issues that affect heritage projects during their lifecycle and in particular, why heritage-listed projects often fail to meet the delivery goals of time, budget, quality and scope.
Design/methodology/approach
This research was undertaken on a qualitative basis by conducting series of semi-structured interviews drawn from three case studies in SE Queensland. Qualitative research involves the evaluation of people’s experiences, feelings, social interactions, and the data gathered from this type of methodology is often varied and rich. A case study allows a researcher to test and generate theories based on real-world practice.
Findings
This paper presents the findings from a data collection exercise accomplished by conducting a series of qualitative case studies. Using a cross-case analysis approach, this paper highlights critical heritage project delivery issues and their causes.
Practical implications
The lessons learned from the study cases could be used in helping to prevent potential heritage project failures in the future.
Originality/value
The paper aims to bring greater awareness to practitioners and academics of the repeating issues that every heritage project is likely to face and offers some insight in how these may be mitigated.