Vinay Gupta

Steady-state creep analysis of a functionally graded thick cylinder subjected to internal pressure and thermal gradient

Abstract The steady-state creep behavior in an isotropic functionally graded composite cylinder subjected to internal pressure has been analyzed in the presence of a thermal gradient. The cylinder is assumed to be made of a functionally graded composite containing silicon carbide particles in a matrix of pure aluminum. The effect of imposing a linear particle as well as a thermal gradient on the distribution of creep stresses and creep rates in the functionally graded cylinder has been investigated. The study shows that in the presence of both thermal and particle gradients, the radial stress decreases throughout the cylinder, whereas the tangential, axial, and effective stresses increase significantly near the inner radius but show a significant decrease towards the outer radius. The strain rates as well as strain-rate inhomogeneity in the composite cylinder could be reduced to a significant extent by imposing thermal and particle gradients alone or together, while keeping the same average amount of reinforcement.

Steady state creep in a rotating composite disc of variable thickness

Abstract The steady state creep in a rotating disc having variable thickness and made of isotropic aluminium–silicon carbide particulate composite has been investigated. Using threshold stress based creep law, the general expressions for stresses and strain rates in the discs have been obtained. The expressions are used to calculate the distributions of stresses and strain rates in different discs viz (i) disc having constant thickness (ii) disc having linearly varying thickness and (iii) disc having hyperbolically varying thickness. The volume of different discs is kept the same. The study revealed that the stresses and strain rates in the disc could be reduced to a significant extent by varying the disc profile. The linearly varying disc exhibits the lowest values of stresses and strain rates compared to those observed in hyperbolic or uniform thickness disc.

Modeling creep in a thick composite cylinder subjected to internal and external pressures

Abstract A mathematical model to describe secondary creep in a thick composite cylinder made of Al–SiCp and subjected to both internal and external pressures has been developed. The creep behavior of the composite has been described by a threshold stress based creep law with a stress exponent of 5. The model developed has been used to investigate the effect of varying size and content of the SiCp dispersoid on the stresses and strain rates in a composite cylinder. It is observed that the stress distributions in the cylinder do not have significant variation with varying size and content of the SiCp. Unlike stresses, the strain rates in the cylinder are reduced to a significant extent by decreasing the size of SiCp and increasing the content of SiCp.

Investigating the effect of thickness profile of a rotating functionally graded disc on its creep behavior

Creep behavior of rotating discs made of functionally graded materials with linearly varying thickness has been investigated. The discs contain silicon carbide particles in a matrix of pure aluminum. The effect of varying disc thickness gradient (TG) has been investigated on the stresses and strain rates in the composite disc. The study shows that with the increase in disc TG, the radial, tangential and effective stresses decrease throughout the disc. The strain rates in the disc also reduce significantly with the increase in TG of the disc.

Effect of Anisotropy on Steady Creep in a Whisker Reinforced Functionally Graded Composite Disc

T present study focused on carrying out the creep analysis in an isotropic thick-walled composite cylindrical pressure vessel composed of aluminium matrix reinforced with silicon-carbide in particulate form. The creep behaviour of the composite material has been described by the threshold stress based creep law. The value of stress exponent appearing in the creep law was selected as 3, 5 and 8. The constitutive equations were developed using well known von-Mises yield criteria. Models were developed to find out the distributions of creep stresses and strain rate in thick-walled composite cylindrical pressure vessels under internal pressure. In order to obtain the stress distributions in the cylinder, the equilibrium equation of the continuum mechanics and the constitutive equations are solved together. It was observed that the radial stress, tangential stress and axial stress increases along with the radial distance. The cross-over was also obtained almost at the middle region of cylindrical vessel for tangential and axial stress for different values of stress exponent. The strain rates were also decreasing in nature along the entire radius.T comfort is crucial to ascertain the energy consumption in buildings and is a key factor for decision making in the design of sustainable building envelopes. This study presents a methodology to assess the combined performance of thermal mass and insulation thickness quantitatively on the basis of their impact on thermal comfort. A framework is proposed to deal with the risk of climate change temperature increases in the UK. Initially, a simple building model with five of the most commonly used, high performance construction systems for dwellings was examined for a range of low, medium and high thermal masses and afterwards systems were applied to a typical UK flat. Furthermore, the study used novel integration of phase change materials (PCM) with air gap to provide high level of thermal mass on a light system and quantified the effect. Manchester and London were the sites chosen for the modeling and current and future climate scenarios were examined. The dynamic thermal simulation used the software Design Builder, which employs EnergyPlus as its calculation engine. In essence, the study establishes a new approach for the assessing the performance of thermal mass and insulation thickness on the basis of overall annual thermal comfort hours.I this study, the effects of post-plasma treatment on synthesized carbon nanowalls (CNWs) grown with a microwave were investigated. CNWs were synthesized by microwave plasma enhanced chemical vapor deposition (PECVD), employing a mixture of CH4 and H2 gases. The plasma treatment was done in different plasma environments (O2 and H2) but under the same condition of synthesized CNWs. Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and fourier transform infrared spectroscopy (FT-IR) were used to analyze the effects of the post-plasma treatment on the synthesized CNWs. After the H2 post-plasma treatment, no significant changes in the appearance and characteristics of the CNWs were observed. After the O2 post-plasma treatment, on the other hand, the CNWs were etched at a rate of 18.05 nm/sec. The Raman analysis confirmed, however, that the structural changes in the CNWs caused by the O2 post-plasma treatment were insignificant.I photo detector can be used for a variety of applications in the industrial, security, military, scientific, and medical areas. Various device materials been used for the growth of infrared device structures, such as quantum dots, quantum well and Type-II superlattices (T2SL). InAs/GaSb T2SLs are a considerable interest the last decade as a promising candidate in middle and long infrared photodetector and imaging application. InAs/GaSb T2SL was proposed by Sai-Halase et al. in 1977 [1]. The T2SL is formed by alternating InAs and GaSb layer over several periods. These structure have broken-gap energy alignment, where the separation of electrons and holes into the InAs and GaSb, respectively. The T2SL can be easily tuning optical and electronic properties by varying the layer thickness. One of major challenge is the control of overall strain, caused by the small lattice mismatch between InAs and GaSb.

Modelling of Creep in a Thick-Walled Cylindrical Vessel Subjected to Internal Pressure

T present study focused on carrying out the creep analysis in an isotropic thick-walled composite cylindrical pressure vessel composed of aluminium matrix reinforced with silicon-carbide in particulate form. The creep behaviour of the composite material has been described by the threshold stress based creep law. The value of stress exponent appearing in the creep law was selected as 3, 5 and 8. The constitutive equations were developed using well known von-Mises yield criteria. Models were developed to find out the distributions of creep stresses and strain rate in thick-walled composite cylindrical pressure vessels under internal pressure. In order to obtain the stress distributions in the cylinder, the equilibrium equation of the continuum mechanics and the constitutive equations are solved together. It was observed that the radial stress, tangential stress and axial stress increases along with the radial distance. The cross-over was also obtained almost at the middle region of cylindrical vessel for tangential and axial stress for different values of stress exponent. The strain rates were also decreasing in nature along the entire radius.T comfort is crucial to ascertain the energy consumption in buildings and is a key factor for decision making in the design of sustainable building envelopes. This study presents a methodology to assess the combined performance of thermal mass and insulation thickness quantitatively on the basis of their impact on thermal comfort. A framework is proposed to deal with the risk of climate change temperature increases in the UK. Initially, a simple building model with five of the most commonly used, high performance construction systems for dwellings was examined for a range of low, medium and high thermal masses and afterwards systems were applied to a typical UK flat. Furthermore, the study used novel integration of phase change materials (PCM) with air gap to provide high level of thermal mass on a light system and quantified the effect. Manchester and London were the sites chosen for the modeling and current and future climate scenarios were examined. The dynamic thermal simulation used the software Design Builder, which employs EnergyPlus as its calculation engine. In essence, the study establishes a new approach for the assessing the performance of thermal mass and insulation thickness on the basis of overall annual thermal comfort hours.I this study, the effects of post-plasma treatment on synthesized carbon nanowalls (CNWs) grown with a microwave were investigated. CNWs were synthesized by microwave plasma enhanced chemical vapor deposition (PECVD), employing a mixture of CH4 and H2 gases. The plasma treatment was done in different plasma environments (O2 and H2) but under the same condition of synthesized CNWs. Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and fourier transform infrared spectroscopy (FT-IR) were used to analyze the effects of the post-plasma treatment on the synthesized CNWs. After the H2 post-plasma treatment, no significant changes in the appearance and characteristics of the CNWs were observed. After the O2 post-plasma treatment, on the other hand, the CNWs were etched at a rate of 18.05 nm/sec. The Raman analysis confirmed, however, that the structural changes in the CNWs caused by the O2 post-plasma treatment were insignificant.I photo detector can be used for a variety of applications in the industrial, security, military, scientific, and medical areas. Various device materials been used for the growth of infrared device structures, such as quantum dots, quantum well and Type-II superlattices (T2SL). InAs/GaSb T2SLs are a considerable interest the last decade as a promising candidate in middle and long infrared photodetector and imaging application. InAs/GaSb T2SL was proposed by Sai-Halase et al. in 1977 [1]. The T2SL is formed by alternating InAs and GaSb layer over several periods. These structure have broken-gap energy alignment, where the separation of electrons and holes into the InAs and GaSb, respectively. The T2SL can be easily tuning optical and electronic properties by varying the layer thickness. One of major challenge is the control of overall strain, caused by the small lattice mismatch between InAs and GaSb.

Modelling of creep in a thick-walled cylindrical vessel subjected to internal pressure

T present study focused on carrying out the creep analysis in an isotropic thick-walled composite cylindrical pressure vessel composed of aluminium matrix reinforced with silicon-carbide in particulate form. The creep behaviour of the composite material has been described by the threshold stress based creep law. The value of stress exponent appearing in the creep law was selected as 3, 5 and 8. The constitutive equations were developed using well known von-Mises yield criteria. Models were developed to find out the distributions of creep stresses and strain rate in thick-walled composite cylindrical pressure vessels under internal pressure. In order to obtain the stress distributions in the cylinder, the equilibrium equation of the continuum mechanics and the constitutive equations are solved together. It was observed that the radial stress, tangential stress and axial stress increases along with the radial distance. The cross-over was also obtained almost at the middle region of cylindrical vessel for tangential and axial stress for different values of stress exponent. The strain rates were also decreasing in nature along the entire radius.T comfort is crucial to ascertain the energy consumption in buildings and is a key factor for decision making in the design of sustainable building envelopes. This study presents a methodology to assess the combined performance of thermal mass and insulation thickness quantitatively on the basis of their impact on thermal comfort. A framework is proposed to deal with the risk of climate change temperature increases in the UK. Initially, a simple building model with five of the most commonly used, high performance construction systems for dwellings was examined for a range of low, medium and high thermal masses and afterwards systems were applied to a typical UK flat. Furthermore, the study used novel integration of phase change materials (PCM) with air gap to provide high level of thermal mass on a light system and quantified the effect. Manchester and London were the sites chosen for the modeling and current and future climate scenarios were examined. The dynamic thermal simulation used the software Design Builder, which employs EnergyPlus as its calculation engine. In essence, the study establishes a new approach for the assessing the performance of thermal mass and insulation thickness on the basis of overall annual thermal comfort hours.I this study, the effects of post-plasma treatment on synthesized carbon nanowalls (CNWs) grown with a microwave were investigated. CNWs were synthesized by microwave plasma enhanced chemical vapor deposition (PECVD), employing a mixture of CH4 and H2 gases. The plasma treatment was done in different plasma environments (O2 and H2) but under the same condition of synthesized CNWs. Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and fourier transform infrared spectroscopy (FT-IR) were used to analyze the effects of the post-plasma treatment on the synthesized CNWs. After the H2 post-plasma treatment, no significant changes in the appearance and characteristics of the CNWs were observed. After the O2 post-plasma treatment, on the other hand, the CNWs were etched at a rate of 18.05 nm/sec. The Raman analysis confirmed, however, that the structural changes in the CNWs caused by the O2 post-plasma treatment were insignificant.I photo detector can be used for a variety of applications in the industrial, security, military, scientific, and medical areas. Various device materials been used for the growth of infrared device structures, such as quantum dots, quantum well and Type-II superlattices (T2SL). InAs/GaSb T2SLs are a considerable interest the last decade as a promising candidate in middle and long infrared photodetector and imaging application. InAs/GaSb T2SL was proposed by Sai-Halase et al. in 1977 [1]. The T2SL is formed by alternating InAs and GaSb layer over several periods. These structure have broken-gap energy alignment, where the separation of electrons and holes into the InAs and GaSb, respectively. The T2SL can be easily tuning optical and electronic properties by varying the layer thickness. One of major challenge is the control of overall strain, caused by the small lattice mismatch between InAs and GaSb.

FE modeling of creep in linear and non-linear FGM cylinder under internal pressure

Purpose – The purpose of this paper is to investigate creep in an internally pressurized thick-walled, closed ends cylinder made of functionally graded composite, having linear and non-linear distribution of reinforcement, using finite element (FE) analysis. Design/methodology/approach – FE-based Abaqus software is used to investigate creep behavior of a functionally graded cylinder. The cylinder is made of composite containing linear and non-linearly varying distributions of reinforcement along the radius. The creep behavior has been described by Nortons power law. The creep stresses and strains have been estimated in linear and non-linear functionally graded materials (FGM) cylinders and compared with those estimated for a similar composite cylinder but having uniform distribution of reinforcement. Findings – The radial stress in the composite cylinder is observed to decreases over the entire radius upon imposing linear or non-linear reinforcement gradients. However, the tangential stress in the cylind...

Mathematical modelling of steady state creep in a functionally graded rotating disc of variable thickness

A mathematical model has been developed to investigate steady state creep in a rotating disc having linearly varying thickness. The disc is assumed to be composed of functionally graded (FG) composite containing linearly varying content of silicon carbide particles (SiCp) reinforced in a matrix of pure aluminium (Al). The disc material undergoes steady state creep as described by a creep law based on threshold stress with a stress exponent of 5. The mathematical model developed has been employed to investigate the effect of imposing various linear gradients of SiCp on the creep performance of the FG disc. The study indicates that with the increase in SiCp gradient, the radial stress increases throughout the disc. However, the increase in SiCp gradient results in increase of tangential and effective stresses near the inner radius of the disc but a decrease near the outer radius. The tangential as well as radial strain rates in the FG disc reduce to a significant extent with the increase in SiCp gradient.