Asif Israr - Profile on Academia.edu (original) (raw)

Papers by Asif Israr

Research paper thumbnail of Transverse Flow of Periodic Pressure Waves in Vessel

Journal of Space Technology

In this study derived differential equations are examined by using one of the famous Finite Eleme... more In this study derived differential equations are examined by using one of the famous Finite Element Method (FEM) i.e. Galerkin’s method under given boundary conditions. The flow in the pipe is considered to be periodic and moves transversely towards the walls of the pipe. It has been observed that this type of flow movement in the vessel may cause dynamic instability at the boundaries or cause sudden failure. The results obtained from Galerkin’s method is compared with the exact solution and found good in agreement between the two results.

Research paper thumbnail of Experimental Determination of Effect of Variable Resistance on Lead Zirconate Titanate (PZT-5A4E) under various Thermal and Frequency Conditions

A specially designed apparatus and circuit working on the principle of inverse piezoelectricity d... more A specially designed apparatus and circuit working on the principle of inverse piezoelectricity due to the effect of polarization was used to find the relationship between resistance and peak to peak voltage of Lead Zirconate Titanate (PZT-5A4E) by shocking it at variable frequencies and at variable resistances under various thermal conditions within Curie temperature limit using equivalent circuit method. It was found that by increasing temperature, peak to peak voltage increases and similarly by increasing frequency, peak to peak voltage decreases and with the increase in resistance peak to peak voltage decreases.

Research paper thumbnail of Vibration Analysis of Cracked Aluminium Plates

This research is concerned with analytical modelling of the effects of cracks in structural plate... more This research is concerned with analytical modelling of the effects of cracks in structural plates and panels within aerospace systems such as aeroplane fuselage, wing, and tail-plane structures, and, as such, is part of a larger body of research into damage detection methodologies in such systems. This study is based on generating a so-called reduced order analytical model of the behaviour of the plate panel, within which a crack with some arbitrary characteristics is present, and which is subjected to a force that causes it to vibrate. In practice such a scenario is potentially extremely dangerous as it can lead to failure, with obvious consequences. The equation that is obtained is in the form of the classical Duffing equation, in this case, the coefficients within the equation contain information about the geometrical and mass properties of the plate, the loading and boundary conditions, and the geometry, location, and potentially the orientation of the crack. This equation has ...

Research paper thumbnail of Wing Tip Kinematics of Ornithopters

Research paper thumbnail of Cracked Isotropic Plate Structures–A Review

Journal of Space Technology

Research paper thumbnail of Experimental Determination of Effect of Variable Resistance on Lead Zirconate Titanate (PZT-5A4E) under various Thermal and Frequency Conditions

A specially designed apparatus and circuit working on the principle of inverse piezoelectricity d... more A specially designed apparatus and circuit working on the principle of inverse piezoelectricity due to the effect of polarization was used to find the relationship between resistance and peak to peak voltage of Lead Zirconate Titanate (PZT-5A4E)by shocking it at variable frequencies and at variable resistances under various thermal conditions within Curie temperature limit using equivalent circuit method. It was found that by increasing temperature, peak to peak voltage increases and similarly by increasing frequency, peak to peak voltage decreases and with the increase in resistance peak to peak voltage decreases.

Research paper thumbnail of Transverse Flow of Periodic Pressure Waves in Vessel

Journal of Space Technology

In this study derived differential equations are examined by using one of the famous Finite Eleme... more In this study derived differential equations are examined by using one of the famous Finite Element Method (FEM) i.e. Galerkin’s method under given boundary conditions. The flow in the pipe is considered to be periodic and moves transversely towards the walls of the pipe. It has been observed that this type of flow movement in the vessel may cause dynamic instability at the boundaries or cause sudden failure. The results obtained from Galerkin’s method is compared with the exact solution and found good in agreement between the two results.

Research paper thumbnail of Dynamical System Analysis from Nonlinear Transiton to Chaos for a Cracked Plate)

Research paper thumbnail of Propagation of elastic waves in pre-stressed elements of structures

Propagation of elastic waves in pre-stressed elements of structures

Research paper thumbnail of An Empirical Relationship to Predict Damages in Carbon Fiber Reinforced Composites under Extreme Thermal Cycling Conditions

Key Engineering Materials, 2012

Research paper thumbnail of Methodologies for preliminary design of variable wing geometry aircraft

Methodologies for preliminary design of variable wing geometry aircraft

2013 International Conference on Aerospace Science & Engineering (ICASE), 2013

ABSTRACT This study presents one of the methodologies that can be adopted to design variable wing... more ABSTRACT This study presents one of the methodologies that can be adopted to design variable wing geometry and its functionality. With this concept the aircraft is able to perform optimally under a variety of flight conditions. The major aspects discussed include the basic geometry design of a double delta aircraft for initial sizing, the selection and importance of the correct airfoil for the selected geometry and lastly how to find the pivot point for the variable wing mechanism that produces least overlapping issues. In addition, 3D modeling tool in Pro Eng is used to verify the results of selected airfoil. The results indicate a better overall performance for both flight regimes of subsonic and supersonic.

Research paper thumbnail of Vibration and Modal Analysis of Low Earth Orbit Satellite

Shock and Vibration, 2014

This paper presents design, modeling, and analysis of satellite model used for remote sensing. A ... more This paper presents design, modeling, and analysis of satellite model used for remote sensing. A detailed study is carried out for the design and modeling of the satellite structure focusing on the factors such as the selection of material, optimization of shape and geometry, and accommodation of different subsystems and payload. The center of mass is required to be kept within the range of (1-2) cm from its geometric center. Once the model is finalized it is required to be analyzed by the use of Ansys, a tool for finite element analysis (FEA) under given loading and boundary conditions. Static, modal, and harmonic analyses in Ansys are performed at the time of ground testing and launching phase. The finite element analysis results are also validated and compared with the theoretical predictions. These analyses are quite helpful and suggest that the satellite structure does not fail and retains its structural integrity during launch environment.

Research paper thumbnail of Investigation of the nonlinear dynamics of a partially cracked plate

Journal of Physics: Conference Series, 2009

In this paper the nonlinear vibration of an aircraft panel structure modelled as an isotropic cra... more In this paper the nonlinear vibration of an aircraft panel structure modelled as an isotropic cracked plate and subjected to transverse harmonic excitation is considered for studying the dynamic response, both analytically and experimentally. A crack is arbitrarily located at the centre of the plate, consisting of a continuous line. This mathematical model is in the form of Duffing equation with a cubic nonlinear term. The perturbation method of multiple scales is used to solve the algebraic equation, and then investigated with the results of the direct integration within Mathematica™ and finite element analysis in ABAQUS for the first mode only. In addition, experimental measurements are also carried out to verify the dependence of the cracked plate's fundamental mode shape and resonance frequency on the vibration displacement amplitude. An extermely close agreement between these results is observed.

Research paper thumbnail of Analytical Modeling and Vibration Analysis of Partially Cracked Rectangular Plates With Different Boundary Conditions and Loading

Journal of Applied Mechanics, 2009

Arkadiusz (2009) Analytical modelling and vibration analysis of cracked rectangular plates with d... more Arkadiusz (2009) Analytical modelling and vibration analysis of cracked rectangular plates with different loading and boundary conditions.

Research paper thumbnail of An Analytical Modeling for Effective Thermal Conductivity of Multi-Phase Transversely Isotropic Fiberous Composites Using Generalized Self-Consistent Method

Applied Mechanics and Materials, 2012

In this paper a theoretical relationship for the effective thermal conductivity of a multiphase t... more In this paper a theoretical relationship for the effective thermal conductivity of a multiphase transversely isotropic composite system is obtained. The Generalized Self-Consistent Method and simple energy balance principle is employed to derive a more appropriate model. In the derivation, it is assumed that the orientation of fiber within the transversely isotropic composite system is unidirectional and surrounded by two different phases of porous and matrix phase. A combined effect of these three different phases on the effective thermal conductivity of the composite system in transverse direction is studied. The effect of the interfacial contact conductance between the fibers and porous medium is also considered. Results of effective thermal conductivity are plotted against volume fraction and conductance which shows extremely good agreement.

Research paper thumbnail of On Approximate Analytical Solutions for Vibrations in Cracked Plates

On Approximate Analytical Solutions for Vibrations in Cracked Plates

Applied Mechanics and Materials, 2006

Abstract Recent NATO funded research on methods for detection and interpretation methodologies fo... more Abstract Recent NATO funded research on methods for detection and interpretation methodologies for damage detection in aircraft panel structures has motivated work on low-order nonlinear analytical modelling of vibrations in cracked isotropic plates, typically in the form of aluminium aircraft panels. The work applies fundamental aspects of fracture mechanics to define an elliptical crack, and the local stress field and loading conditions, arbitrarily located at some point in the plate, and then derives an analytical expression for ...

Research paper thumbnail of An Integrated Approach for Optimization of Honeycomb Sandwich Structure under Impact Load

An Integrated Approach for Optimization of Honeycomb Sandwich Structure under Impact Load

Applied Mechanics and Materials, 2012

Abstract In this paper weight optimization of sandwich structure consisting of a honeycomb core s... more Abstract In this paper weight optimization of sandwich structure consisting of a honeycomb core sandwiched between two layers is presented through the use of Sequential Quadratic Programming & Genetic Algorithm by constraining of certain parameters such as buckling ...

Research paper thumbnail of To Analyze the Effects of Geometric Misalignment in a Cylindrical Pressure Vessel

To Analyze the Effects of Geometric Misalignment in a Cylindrical Pressure Vessel

Applied Mechanics and Materials, 2012

Abstract This particular work consider a pressurized vessel typically made of high strength low a... more Abstract This particular work consider a pressurized vessel typically made of high strength low alloy steel and containing the geometric misalignment at the cylinder-to-cylinder junction. This misalignment produce in the vessel's structure is because of girth weld that ...

Research paper thumbnail of Analytical modelling and vibration analysis of cracked rectangular plates with different loading and boundary conditions

This study proposes an analytical model for vibrations in a cracked rectangular plate as one of t... more This study proposes an analytical model for vibrations in a cracked rectangular plate as one of the results from a programme of research on vibration based damage detection in aircraft panel structures. This particular work considers an isotropic plate, typically made of aluminium, and containing a crack in the form of a continuous line with its centre located at the centre of the plate, and parallel to one edge of the plate. The plate is subjected to a point load on its surface for three different possible boundary conditions, and one examined in detail. Galerkin's method is applied to reformulate the governing equation of the cracked plate into time dependent modal coordinates. Nonlinearity is introduced by appropriate formulations introduced by applying Berger's method. An approximate solution technique, the method of multiple scales, is applied to solve the nonlinear equation of the cracked plate. Results are presented in terms of natural frequency versus crack length and plate thickness, and the nonlinear amplitude response of the plate is calculated for one set of boundary conditions and three different load locations, over a practical range of external excitation frequencies.

Research paper thumbnail of Transverse Flow of Periodic Pressure Waves in Vessel

Journal of Space Technology

In this study derived differential equations are examined by using one of the famous Finite Eleme... more In this study derived differential equations are examined by using one of the famous Finite Element Method (FEM) i.e. Galerkin’s method under given boundary conditions. The flow in the pipe is considered to be periodic and moves transversely towards the walls of the pipe. It has been observed that this type of flow movement in the vessel may cause dynamic instability at the boundaries or cause sudden failure. The results obtained from Galerkin’s method is compared with the exact solution and found good in agreement between the two results.

Research paper thumbnail of Experimental Determination of Effect of Variable Resistance on Lead Zirconate Titanate (PZT-5A4E) under various Thermal and Frequency Conditions

A specially designed apparatus and circuit working on the principle of inverse piezoelectricity d... more A specially designed apparatus and circuit working on the principle of inverse piezoelectricity due to the effect of polarization was used to find the relationship between resistance and peak to peak voltage of Lead Zirconate Titanate (PZT-5A4E) by shocking it at variable frequencies and at variable resistances under various thermal conditions within Curie temperature limit using equivalent circuit method. It was found that by increasing temperature, peak to peak voltage increases and similarly by increasing frequency, peak to peak voltage decreases and with the increase in resistance peak to peak voltage decreases.

Research paper thumbnail of Vibration Analysis of Cracked Aluminium Plates

This research is concerned with analytical modelling of the effects of cracks in structural plate... more This research is concerned with analytical modelling of the effects of cracks in structural plates and panels within aerospace systems such as aeroplane fuselage, wing, and tail-plane structures, and, as such, is part of a larger body of research into damage detection methodologies in such systems. This study is based on generating a so-called reduced order analytical model of the behaviour of the plate panel, within which a crack with some arbitrary characteristics is present, and which is subjected to a force that causes it to vibrate. In practice such a scenario is potentially extremely dangerous as it can lead to failure, with obvious consequences. The equation that is obtained is in the form of the classical Duffing equation, in this case, the coefficients within the equation contain information about the geometrical and mass properties of the plate, the loading and boundary conditions, and the geometry, location, and potentially the orientation of the crack. This equation has ...

Research paper thumbnail of Wing Tip Kinematics of Ornithopters

Research paper thumbnail of Cracked Isotropic Plate Structures–A Review

Journal of Space Technology

Research paper thumbnail of Experimental Determination of Effect of Variable Resistance on Lead Zirconate Titanate (PZT-5A4E) under various Thermal and Frequency Conditions

A specially designed apparatus and circuit working on the principle of inverse piezoelectricity d... more A specially designed apparatus and circuit working on the principle of inverse piezoelectricity due to the effect of polarization was used to find the relationship between resistance and peak to peak voltage of Lead Zirconate Titanate (PZT-5A4E)by shocking it at variable frequencies and at variable resistances under various thermal conditions within Curie temperature limit using equivalent circuit method. It was found that by increasing temperature, peak to peak voltage increases and similarly by increasing frequency, peak to peak voltage decreases and with the increase in resistance peak to peak voltage decreases.

Research paper thumbnail of Transverse Flow of Periodic Pressure Waves in Vessel

Journal of Space Technology

In this study derived differential equations are examined by using one of the famous Finite Eleme... more In this study derived differential equations are examined by using one of the famous Finite Element Method (FEM) i.e. Galerkin’s method under given boundary conditions. The flow in the pipe is considered to be periodic and moves transversely towards the walls of the pipe. It has been observed that this type of flow movement in the vessel may cause dynamic instability at the boundaries or cause sudden failure. The results obtained from Galerkin’s method is compared with the exact solution and found good in agreement between the two results.

Research paper thumbnail of Dynamical System Analysis from Nonlinear Transiton to Chaos for a Cracked Plate)

Research paper thumbnail of Propagation of elastic waves in pre-stressed elements of structures

Propagation of elastic waves in pre-stressed elements of structures

Research paper thumbnail of An Empirical Relationship to Predict Damages in Carbon Fiber Reinforced Composites under Extreme Thermal Cycling Conditions

Key Engineering Materials, 2012

Research paper thumbnail of Methodologies for preliminary design of variable wing geometry aircraft

Methodologies for preliminary design of variable wing geometry aircraft

2013 International Conference on Aerospace Science & Engineering (ICASE), 2013

ABSTRACT This study presents one of the methodologies that can be adopted to design variable wing... more ABSTRACT This study presents one of the methodologies that can be adopted to design variable wing geometry and its functionality. With this concept the aircraft is able to perform optimally under a variety of flight conditions. The major aspects discussed include the basic geometry design of a double delta aircraft for initial sizing, the selection and importance of the correct airfoil for the selected geometry and lastly how to find the pivot point for the variable wing mechanism that produces least overlapping issues. In addition, 3D modeling tool in Pro Eng is used to verify the results of selected airfoil. The results indicate a better overall performance for both flight regimes of subsonic and supersonic.

Research paper thumbnail of Vibration and Modal Analysis of Low Earth Orbit Satellite

Shock and Vibration, 2014

This paper presents design, modeling, and analysis of satellite model used for remote sensing. A ... more This paper presents design, modeling, and analysis of satellite model used for remote sensing. A detailed study is carried out for the design and modeling of the satellite structure focusing on the factors such as the selection of material, optimization of shape and geometry, and accommodation of different subsystems and payload. The center of mass is required to be kept within the range of (1-2) cm from its geometric center. Once the model is finalized it is required to be analyzed by the use of Ansys, a tool for finite element analysis (FEA) under given loading and boundary conditions. Static, modal, and harmonic analyses in Ansys are performed at the time of ground testing and launching phase. The finite element analysis results are also validated and compared with the theoretical predictions. These analyses are quite helpful and suggest that the satellite structure does not fail and retains its structural integrity during launch environment.

Research paper thumbnail of Investigation of the nonlinear dynamics of a partially cracked plate

Journal of Physics: Conference Series, 2009

In this paper the nonlinear vibration of an aircraft panel structure modelled as an isotropic cra... more In this paper the nonlinear vibration of an aircraft panel structure modelled as an isotropic cracked plate and subjected to transverse harmonic excitation is considered for studying the dynamic response, both analytically and experimentally. A crack is arbitrarily located at the centre of the plate, consisting of a continuous line. This mathematical model is in the form of Duffing equation with a cubic nonlinear term. The perturbation method of multiple scales is used to solve the algebraic equation, and then investigated with the results of the direct integration within Mathematica™ and finite element analysis in ABAQUS for the first mode only. In addition, experimental measurements are also carried out to verify the dependence of the cracked plate's fundamental mode shape and resonance frequency on the vibration displacement amplitude. An extermely close agreement between these results is observed.

Research paper thumbnail of Analytical Modeling and Vibration Analysis of Partially Cracked Rectangular Plates With Different Boundary Conditions and Loading

Journal of Applied Mechanics, 2009

Arkadiusz (2009) Analytical modelling and vibration analysis of cracked rectangular plates with d... more Arkadiusz (2009) Analytical modelling and vibration analysis of cracked rectangular plates with different loading and boundary conditions.

Research paper thumbnail of An Analytical Modeling for Effective Thermal Conductivity of Multi-Phase Transversely Isotropic Fiberous Composites Using Generalized Self-Consistent Method

Applied Mechanics and Materials, 2012

In this paper a theoretical relationship for the effective thermal conductivity of a multiphase t... more In this paper a theoretical relationship for the effective thermal conductivity of a multiphase transversely isotropic composite system is obtained. The Generalized Self-Consistent Method and simple energy balance principle is employed to derive a more appropriate model. In the derivation, it is assumed that the orientation of fiber within the transversely isotropic composite system is unidirectional and surrounded by two different phases of porous and matrix phase. A combined effect of these three different phases on the effective thermal conductivity of the composite system in transverse direction is studied. The effect of the interfacial contact conductance between the fibers and porous medium is also considered. Results of effective thermal conductivity are plotted against volume fraction and conductance which shows extremely good agreement.

Research paper thumbnail of On Approximate Analytical Solutions for Vibrations in Cracked Plates

On Approximate Analytical Solutions for Vibrations in Cracked Plates

Applied Mechanics and Materials, 2006

Abstract Recent NATO funded research on methods for detection and interpretation methodologies fo... more Abstract Recent NATO funded research on methods for detection and interpretation methodologies for damage detection in aircraft panel structures has motivated work on low-order nonlinear analytical modelling of vibrations in cracked isotropic plates, typically in the form of aluminium aircraft panels. The work applies fundamental aspects of fracture mechanics to define an elliptical crack, and the local stress field and loading conditions, arbitrarily located at some point in the plate, and then derives an analytical expression for ...

Research paper thumbnail of An Integrated Approach for Optimization of Honeycomb Sandwich Structure under Impact Load

An Integrated Approach for Optimization of Honeycomb Sandwich Structure under Impact Load

Applied Mechanics and Materials, 2012

Abstract In this paper weight optimization of sandwich structure consisting of a honeycomb core s... more Abstract In this paper weight optimization of sandwich structure consisting of a honeycomb core sandwiched between two layers is presented through the use of Sequential Quadratic Programming & Genetic Algorithm by constraining of certain parameters such as buckling ...

Research paper thumbnail of To Analyze the Effects of Geometric Misalignment in a Cylindrical Pressure Vessel

To Analyze the Effects of Geometric Misalignment in a Cylindrical Pressure Vessel

Applied Mechanics and Materials, 2012

Abstract This particular work consider a pressurized vessel typically made of high strength low a... more Abstract This particular work consider a pressurized vessel typically made of high strength low alloy steel and containing the geometric misalignment at the cylinder-to-cylinder junction. This misalignment produce in the vessel's structure is because of girth weld that ...

Research paper thumbnail of Analytical modelling and vibration analysis of cracked rectangular plates with different loading and boundary conditions

This study proposes an analytical model for vibrations in a cracked rectangular plate as one of t... more This study proposes an analytical model for vibrations in a cracked rectangular plate as one of the results from a programme of research on vibration based damage detection in aircraft panel structures. This particular work considers an isotropic plate, typically made of aluminium, and containing a crack in the form of a continuous line with its centre located at the centre of the plate, and parallel to one edge of the plate. The plate is subjected to a point load on its surface for three different possible boundary conditions, and one examined in detail. Galerkin's method is applied to reformulate the governing equation of the cracked plate into time dependent modal coordinates. Nonlinearity is introduced by appropriate formulations introduced by applying Berger's method. An approximate solution technique, the method of multiple scales, is applied to solve the nonlinear equation of the cracked plate. Results are presented in terms of natural frequency versus crack length and plate thickness, and the nonlinear amplitude response of the plate is calculated for one set of boundary conditions and three different load locations, over a practical range of external excitation frequencies.