Shishir Kumar Sahu - Academia.edu (original) (raw)
Papers by Shishir Kumar Sahu
Trans Tech Publications Ltd. eBooks, Sep 11, 2014
Journal of Vibration Engineering & Technologies
Lecture Notes in Mechanical Engineering, 2021
Steel and Composite Structures, 2016
The effects of moisture and temperature on buckling of laminated composite cylindrical shell pane... more The effects of moisture and temperature on buckling of laminated composite cylindrical shell panels are investigated both numerically and experimentally. A quadratic isoparametric eight-noded shell element is used in the present analysis. First order shear deformation theory is used in the present finite element formulation for buckling analysis of shell panels subjected to hygrothermal loading. A program is developed using MATLAB for parametric study on the buckling of shell panels under hygrothermal field. Benchmark results on the critical loads of hygrothermally treated woven fiber glass/epoxy laminated composite cylindrical shell panels are obtained experimentally by using universal testing machine INSTRON 8862. The effects of curvature, lamination sequences, number of layers and aspect ratios on buckling of laminated composite cylindrical curved panels subjected to hygrothermal loading are considered. The results are presented showing the reduction in buckling load of laminated composite shells with the increase in temperature and moisture concentrations.
Journal of Vibration Engineering & Technologies
International Journal of Structural Stability and Dynamics, 2021
This paper reports for the first time the experimental investigation on the free vibration charac... more This paper reports for the first time the experimental investigation on the free vibration characteristics of angle-ply laminated composite stiffened plates along with the numerical investigation. The natural frequencies of these plates are computed experimentally using an FFT analyzer and numerically by employing the finite element method with combination of isoparametric nine nodded plate and three nodded beam elements. Angle-ply laminated stiffened plates are fabricated using woven glass fiber fabrics and epoxy by hand layup technique. The effects of various support conditions; number, orientation and types of stiffeners; aspect ratios of plates and different fiber orientations on the fundamental frequencies of the angle-ply laminated stiffened plates are investigated. These parameters significantly influence the natural frequencies. It is found that there is a very good agreement observed between the fundamental frequencies obtained from both experimental and numerical investiga...
International Journal of Structural Stability and Dynamics, 2018
The present study deals with numerical and experimental investigations on the vibration behavior ... more The present study deals with numerical and experimental investigations on the vibration behavior of fiber-metal-laminated (FML) plates, a new aircraft material. A finite element (FE)-based formulation is established for the plate using the first-order Reissner–Mindlin theory, including both fibers and metals of different material properties in alternate layers. A four-node isoparametric quadratic element with five degrees of freedom per node is adopted in the analysis. Convergence studies and comparison with previous studies are made to validate the present FE formulation. A set of experiments was conducted to get natural frequencies of vibration for glass FML (GFML) plates using Bruel and Kjaer (B&K) Fast Fourier Transform (FFT) analyzer with PULSE platform. The effects of different parameters such as aspect ratio, side-to-thickness ratio, ply orientation, and boundary conditions on the dynamic behavior of the FMLs are studied. Good agreement is achieved between the numerical and e...
Acta Mechanica, 2014
Hygrothermal influence on the buckling behavior of bidirectional glass/epoxy composite panels hav... more Hygrothermal influence on the buckling behavior of bidirectional glass/epoxy composite panels having delaminations was studied numerically and verified by conducting several experiments. First-order shear deformation theory was used to develope a finite element model for numerical predictions with an 8noded quadratic isoparametric element that takes care of the effects of delamination area and hygrothermal conditions of composite panels. Verification of results of the numerical analysis was done by conducting several experiments showing the effects of various parameters like temperature, moisture, area of delaminations, orientations of fibers, stacking sequence and boundary conditions on the buckling characteristics of bidirectional glass/epoxy composite panels. Experimental buckling loads were calculated using an INSTRON 8862 universal testing machine for hygrothermally treated composite panels having delaminations. It was observed that there is a good comparison of predicted and experimental buckling loads. The effects of various parameters on the buckling behavior of composite panels are presented. The buckling results can be utilized as a tool for detection of delamination damage in composite plates subjected to hygrothermal environment.
Advances in Structural Engineering, 2014
The present study deals with the effect of transverse cracks on the dynamical characteristics of ... more The present study deals with the effect of transverse cracks on the dynamical characteristics of laminated composite beam based on first order shear deformation theory (FSDT) is investigated. The cracks formulation is derived from the fracture mechanics theory as the inverse of the compliance matrix calculated with the proper stress intensity factors and strain energy release rate expressions. The various parameters such as fiber orientation, volume fraction of fiber, crack depth and crack location in the presence of cracks on the natural frequency are studied in detail. The frequencies of vibration of a cracked beam is computed and compares with the results of other investigators. A program is developed in MATLAB environment to study the effects of various parameters on the natural frequencies of composite beam with transverse cracks.
The International Journal of Acoustics and Vibration, 2013
This study deals with the parametric instability of a beam with multiple cracks. The variation of... more This study deals with the parametric instability of a beam with multiple cracks. The variation of buckling load and dynamic stability regions, with respect to relative crack depth and position of cracks, are analysed using FEM. The loading on the beam is considered to be axial with a simple harmonic fluctuation with respect to time. The equation of motion represents a system of second order differential equations with periodic coefficients of the Mathieu-Hill type. The development of the regions of instability arises from Floquet's theory, and the periodic solution is obtained by Bolotin's approach using the finite element method. The stiffness matrix of the cracked beam element is obtained from the flexibility matrix of the intact beam, and the additional flexibility matrix due to the crack. The frequencies of vibration and buckling loads of the cracked cantilever beams reduce with the increase in crack depth and number of cracks. The onset of instability occurs earlier with the introduction of more cracks. The instability region for the crack location nearer to the fixed end occurs at a lower excitation frequency of the cracked beam. The vibration and instability results can be used as a technique for structural health monitoring or testing of structural integrity, performance, and safety.
Composites Part B: Engineering, 2019
An extensive experimental and numerical research was undertaken to study the vibration serviceabi... more An extensive experimental and numerical research was undertaken to study the vibration serviceability of a long-span fanshaped prestressed concrete floor system to be used in the lounge of a major airport. Specifically heel-drop and jumping impact tests were conducted to obtain the natural frequencies and modal damping ratios of the floor system, followed by the discussion on the distribution of peak accelerations. Running tests and simulation were also performed to capture the acceleration responses. Moreover, the finite element method was used to evaluate the dynamic characteristics. The floor system is found to have a low fundamental frequency (' 6.00 Hz) and the corresponding modal damping ratio (average ' 2.20%). The comparison of the experimental results with the published American institute of steel construction (AISC) design guide indicates that the prestressed concrete floor system exhibits satisfactory vibration perceptibility overall. The study results also show that the intensity and the location of impact excitation have a significant influence on the rate of acceleration decay. A crest factor b rp is proposed based on the test results to calculate the maximum root mean square acceleration for running for convenience.
European Journal of Mechanics - A/Solids, 2017
Journal of Sound and Vibration, 2002
The parametric instability behaviour of curved panels with cutouts subjected to in-plane static a... more The parametric instability behaviour of curved panels with cutouts subjected to in-plane static and periodic compressive edge loadings are studied using finite element analysis. The first order shear deformation theory is used to model the curved panels, considering the effects of transverse shear deformation and rotary inertia. The theory used is the extension of dynamic, shear deformable theory according to the Sander's first approximation for doubly curved shells, which can be reduced to Love's and Donnell's theories by means of tracers. The effects of static load factor, aspect ratio, radius to thickness ratio, shallowness ratio, boundary conditions and the load parameters on the principal instability regions of curved panels with cutouts are studied in detail using Bolotin's method. Quantitative results are presented to show the effects of shell geometry and load parameters on the stability boundaries. Results for plates are also presented as special cases and are compared with those available in the literature.
The static stability of the curved panels subjected to varieties of non-uniform loading including... more The static stability of the curved panels subjected to varieties of non-uniform loading including partial and concentrated in-plane compressive edge loading is studied using finite element method, considering the effects of transverse shear deformation and rotary inertia. An eight nodded quadratic isoparametric element is employed in the present analysis. The study reveals that the stability behaviour of the flat and curved panels is greatly influenced by the geometry, boundary conditions, the type and position of loads.
The present study involves extensive experimental works to investigate the free vibration of wove... more The present study involves extensive experimental works to investigate the free vibration of woven fiber Glass/Epoxy composite plates in free-free boundary conditions. The specimens of woven glass fiber and epoxy matrix composite plates are manufactured by the hand-layup technique. Elastic parameters of the plate are also determined experimentally by tensile testing of specimens using Instron 1195. An experimental investigation is carried out using modal analysis technique with Fast Fourier Transform Analyzer, PULSE lab shop, impact hammer and contact accelerometer to obtain the Frequency Response Functions. Also, this experiment is used to validate the results obtained from the FEM numerical analysis based on a first order shear deformation theory. The effects of different geometrical parameters including number of layers, aspect ratio, and fiber orientation of woven fiber composite plates are studied in free-free boundary conditions in details. This study may provide valuable info...
The world community is experiencing plenty of construction activities for infrastructure includin... more The world community is experiencing plenty of construction activities for infrastructure including High rise buildings, airports, stadiums, rails, bridges, low cost housing for the poor and so on. Besides this, the engineers are working on interdisplinary areas of automotive, naval and especially aerospace engineering. The global research community is working towards new materials including smart and nanocomposites, its characterization and utilization of new materials and product development for specific applications. The advances in digital computers with their enormous computing speed, core memory capacity has changed the outlook of the structural analysis. This also caused the evolution and advancement of various numerical methods such as Finite element method (FEM), meshless methods for solution of static, dynamic and stability analysis of one dimensional beams and frames to multi-dimensional plates and shells. The advances in experimental mechanics give an insight to the actual behavior of structure. The various advances in mechanics engineering are discussed in this study.
The parametric resonance characteristics of laminated composite curved panels subjected to variou... more The parametric resonance characteristics of laminated composite curved panels subjected to various in-plane periodic concentrated edge loadings are studied using finite element analysis. The first order shear deformation theory is used to model the curved panels, considering the effects of transverse shear deformation and rotary inertia. The effects of number of layers, static load factor, boundary conditions and ply orientations for different positions of loading on the principal instability regions of curved panels are studied in detail using Bolotin's method. Quantitative results are presented to show the effects of shell geometry, lamination details and load parameters on the stability boundaries. Key words-Parametric resonance, composite, concentrated loading, instability region
For many engineering applications, beams are essential models for the structural elements and hav... more For many engineering applications, beams are essential models for the structural elements and have been studied extensively. The structures planned to support high speed engines and turbines are subjected to vibration. Mild steel specimens of square area of cross section are considered for the experiment and the experimental results are contrasted with numerical analysis using Finite Element Method (FEM) in MATLAB environment. The crack considered is transverse crack which open in nature. Due to the presence of crack, the total flexibility matrix is established by adding local additional flexibility matrix to the flexibility matrix of the corresponding intact beam element .The local additional flexibility matrix is obtained from Linear Elastic Fracture Mechanics theory. Numerical study to validate the accuracy of the present (FEM) analysis is done. Experimental work is carried out to study the affect of presence of crack in uniform beams of square area of cross section for cantileve...
Cutouts are inevitable in structures due to practical consideration. The present study involves v... more Cutouts are inevitable in structures due to practical consideration. The present study involves vibration and stability of laminated composite curved panels with cutouts using finite element method. The first order shear deformation (FSDT) is used to model the curved panels, considering the effects of transverse shear deformation and rotary inertia. Since the stress field is non -uniform due to cutout, plane stress analysis is carried out using the finite element method to determine the stresses and these are used to formulate the geometric stiffness matrix. The global matrices are obtained using skyline technique. The eigenvalues are obtained us ing subspace iteration scheme. The study reveals that the fundamental frequencies of vibration of an angle ply flat panel decrease with introduction of small cutouts but again rise with increase in size of cutout. However the higher frequencies of vibratio n continue to decrease up to a moderate size of cutout and then rise with further inc...
Trans Tech Publications Ltd. eBooks, Sep 11, 2014
Journal of Vibration Engineering & Technologies
Lecture Notes in Mechanical Engineering, 2021
Steel and Composite Structures, 2016
The effects of moisture and temperature on buckling of laminated composite cylindrical shell pane... more The effects of moisture and temperature on buckling of laminated composite cylindrical shell panels are investigated both numerically and experimentally. A quadratic isoparametric eight-noded shell element is used in the present analysis. First order shear deformation theory is used in the present finite element formulation for buckling analysis of shell panels subjected to hygrothermal loading. A program is developed using MATLAB for parametric study on the buckling of shell panels under hygrothermal field. Benchmark results on the critical loads of hygrothermally treated woven fiber glass/epoxy laminated composite cylindrical shell panels are obtained experimentally by using universal testing machine INSTRON 8862. The effects of curvature, lamination sequences, number of layers and aspect ratios on buckling of laminated composite cylindrical curved panels subjected to hygrothermal loading are considered. The results are presented showing the reduction in buckling load of laminated composite shells with the increase in temperature and moisture concentrations.
Journal of Vibration Engineering & Technologies
International Journal of Structural Stability and Dynamics, 2021
This paper reports for the first time the experimental investigation on the free vibration charac... more This paper reports for the first time the experimental investigation on the free vibration characteristics of angle-ply laminated composite stiffened plates along with the numerical investigation. The natural frequencies of these plates are computed experimentally using an FFT analyzer and numerically by employing the finite element method with combination of isoparametric nine nodded plate and three nodded beam elements. Angle-ply laminated stiffened plates are fabricated using woven glass fiber fabrics and epoxy by hand layup technique. The effects of various support conditions; number, orientation and types of stiffeners; aspect ratios of plates and different fiber orientations on the fundamental frequencies of the angle-ply laminated stiffened plates are investigated. These parameters significantly influence the natural frequencies. It is found that there is a very good agreement observed between the fundamental frequencies obtained from both experimental and numerical investiga...
International Journal of Structural Stability and Dynamics, 2018
The present study deals with numerical and experimental investigations on the vibration behavior ... more The present study deals with numerical and experimental investigations on the vibration behavior of fiber-metal-laminated (FML) plates, a new aircraft material. A finite element (FE)-based formulation is established for the plate using the first-order Reissner–Mindlin theory, including both fibers and metals of different material properties in alternate layers. A four-node isoparametric quadratic element with five degrees of freedom per node is adopted in the analysis. Convergence studies and comparison with previous studies are made to validate the present FE formulation. A set of experiments was conducted to get natural frequencies of vibration for glass FML (GFML) plates using Bruel and Kjaer (B&K) Fast Fourier Transform (FFT) analyzer with PULSE platform. The effects of different parameters such as aspect ratio, side-to-thickness ratio, ply orientation, and boundary conditions on the dynamic behavior of the FMLs are studied. Good agreement is achieved between the numerical and e...
Acta Mechanica, 2014
Hygrothermal influence on the buckling behavior of bidirectional glass/epoxy composite panels hav... more Hygrothermal influence on the buckling behavior of bidirectional glass/epoxy composite panels having delaminations was studied numerically and verified by conducting several experiments. First-order shear deformation theory was used to develope a finite element model for numerical predictions with an 8noded quadratic isoparametric element that takes care of the effects of delamination area and hygrothermal conditions of composite panels. Verification of results of the numerical analysis was done by conducting several experiments showing the effects of various parameters like temperature, moisture, area of delaminations, orientations of fibers, stacking sequence and boundary conditions on the buckling characteristics of bidirectional glass/epoxy composite panels. Experimental buckling loads were calculated using an INSTRON 8862 universal testing machine for hygrothermally treated composite panels having delaminations. It was observed that there is a good comparison of predicted and experimental buckling loads. The effects of various parameters on the buckling behavior of composite panels are presented. The buckling results can be utilized as a tool for detection of delamination damage in composite plates subjected to hygrothermal environment.
Advances in Structural Engineering, 2014
The present study deals with the effect of transverse cracks on the dynamical characteristics of ... more The present study deals with the effect of transverse cracks on the dynamical characteristics of laminated composite beam based on first order shear deformation theory (FSDT) is investigated. The cracks formulation is derived from the fracture mechanics theory as the inverse of the compliance matrix calculated with the proper stress intensity factors and strain energy release rate expressions. The various parameters such as fiber orientation, volume fraction of fiber, crack depth and crack location in the presence of cracks on the natural frequency are studied in detail. The frequencies of vibration of a cracked beam is computed and compares with the results of other investigators. A program is developed in MATLAB environment to study the effects of various parameters on the natural frequencies of composite beam with transverse cracks.
The International Journal of Acoustics and Vibration, 2013
This study deals with the parametric instability of a beam with multiple cracks. The variation of... more This study deals with the parametric instability of a beam with multiple cracks. The variation of buckling load and dynamic stability regions, with respect to relative crack depth and position of cracks, are analysed using FEM. The loading on the beam is considered to be axial with a simple harmonic fluctuation with respect to time. The equation of motion represents a system of second order differential equations with periodic coefficients of the Mathieu-Hill type. The development of the regions of instability arises from Floquet's theory, and the periodic solution is obtained by Bolotin's approach using the finite element method. The stiffness matrix of the cracked beam element is obtained from the flexibility matrix of the intact beam, and the additional flexibility matrix due to the crack. The frequencies of vibration and buckling loads of the cracked cantilever beams reduce with the increase in crack depth and number of cracks. The onset of instability occurs earlier with the introduction of more cracks. The instability region for the crack location nearer to the fixed end occurs at a lower excitation frequency of the cracked beam. The vibration and instability results can be used as a technique for structural health monitoring or testing of structural integrity, performance, and safety.
Composites Part B: Engineering, 2019
An extensive experimental and numerical research was undertaken to study the vibration serviceabi... more An extensive experimental and numerical research was undertaken to study the vibration serviceability of a long-span fanshaped prestressed concrete floor system to be used in the lounge of a major airport. Specifically heel-drop and jumping impact tests were conducted to obtain the natural frequencies and modal damping ratios of the floor system, followed by the discussion on the distribution of peak accelerations. Running tests and simulation were also performed to capture the acceleration responses. Moreover, the finite element method was used to evaluate the dynamic characteristics. The floor system is found to have a low fundamental frequency (' 6.00 Hz) and the corresponding modal damping ratio (average ' 2.20%). The comparison of the experimental results with the published American institute of steel construction (AISC) design guide indicates that the prestressed concrete floor system exhibits satisfactory vibration perceptibility overall. The study results also show that the intensity and the location of impact excitation have a significant influence on the rate of acceleration decay. A crest factor b rp is proposed based on the test results to calculate the maximum root mean square acceleration for running for convenience.
European Journal of Mechanics - A/Solids, 2017
Journal of Sound and Vibration, 2002
The parametric instability behaviour of curved panels with cutouts subjected to in-plane static a... more The parametric instability behaviour of curved panels with cutouts subjected to in-plane static and periodic compressive edge loadings are studied using finite element analysis. The first order shear deformation theory is used to model the curved panels, considering the effects of transverse shear deformation and rotary inertia. The theory used is the extension of dynamic, shear deformable theory according to the Sander's first approximation for doubly curved shells, which can be reduced to Love's and Donnell's theories by means of tracers. The effects of static load factor, aspect ratio, radius to thickness ratio, shallowness ratio, boundary conditions and the load parameters on the principal instability regions of curved panels with cutouts are studied in detail using Bolotin's method. Quantitative results are presented to show the effects of shell geometry and load parameters on the stability boundaries. Results for plates are also presented as special cases and are compared with those available in the literature.
The static stability of the curved panels subjected to varieties of non-uniform loading including... more The static stability of the curved panels subjected to varieties of non-uniform loading including partial and concentrated in-plane compressive edge loading is studied using finite element method, considering the effects of transverse shear deformation and rotary inertia. An eight nodded quadratic isoparametric element is employed in the present analysis. The study reveals that the stability behaviour of the flat and curved panels is greatly influenced by the geometry, boundary conditions, the type and position of loads.
The present study involves extensive experimental works to investigate the free vibration of wove... more The present study involves extensive experimental works to investigate the free vibration of woven fiber Glass/Epoxy composite plates in free-free boundary conditions. The specimens of woven glass fiber and epoxy matrix composite plates are manufactured by the hand-layup technique. Elastic parameters of the plate are also determined experimentally by tensile testing of specimens using Instron 1195. An experimental investigation is carried out using modal analysis technique with Fast Fourier Transform Analyzer, PULSE lab shop, impact hammer and contact accelerometer to obtain the Frequency Response Functions. Also, this experiment is used to validate the results obtained from the FEM numerical analysis based on a first order shear deformation theory. The effects of different geometrical parameters including number of layers, aspect ratio, and fiber orientation of woven fiber composite plates are studied in free-free boundary conditions in details. This study may provide valuable info...
The world community is experiencing plenty of construction activities for infrastructure includin... more The world community is experiencing plenty of construction activities for infrastructure including High rise buildings, airports, stadiums, rails, bridges, low cost housing for the poor and so on. Besides this, the engineers are working on interdisplinary areas of automotive, naval and especially aerospace engineering. The global research community is working towards new materials including smart and nanocomposites, its characterization and utilization of new materials and product development for specific applications. The advances in digital computers with their enormous computing speed, core memory capacity has changed the outlook of the structural analysis. This also caused the evolution and advancement of various numerical methods such as Finite element method (FEM), meshless methods for solution of static, dynamic and stability analysis of one dimensional beams and frames to multi-dimensional plates and shells. The advances in experimental mechanics give an insight to the actual behavior of structure. The various advances in mechanics engineering are discussed in this study.
The parametric resonance characteristics of laminated composite curved panels subjected to variou... more The parametric resonance characteristics of laminated composite curved panels subjected to various in-plane periodic concentrated edge loadings are studied using finite element analysis. The first order shear deformation theory is used to model the curved panels, considering the effects of transverse shear deformation and rotary inertia. The effects of number of layers, static load factor, boundary conditions and ply orientations for different positions of loading on the principal instability regions of curved panels are studied in detail using Bolotin's method. Quantitative results are presented to show the effects of shell geometry, lamination details and load parameters on the stability boundaries. Key words-Parametric resonance, composite, concentrated loading, instability region
For many engineering applications, beams are essential models for the structural elements and hav... more For many engineering applications, beams are essential models for the structural elements and have been studied extensively. The structures planned to support high speed engines and turbines are subjected to vibration. Mild steel specimens of square area of cross section are considered for the experiment and the experimental results are contrasted with numerical analysis using Finite Element Method (FEM) in MATLAB environment. The crack considered is transverse crack which open in nature. Due to the presence of crack, the total flexibility matrix is established by adding local additional flexibility matrix to the flexibility matrix of the corresponding intact beam element .The local additional flexibility matrix is obtained from Linear Elastic Fracture Mechanics theory. Numerical study to validate the accuracy of the present (FEM) analysis is done. Experimental work is carried out to study the affect of presence of crack in uniform beams of square area of cross section for cantileve...
Cutouts are inevitable in structures due to practical consideration. The present study involves v... more Cutouts are inevitable in structures due to practical consideration. The present study involves vibration and stability of laminated composite curved panels with cutouts using finite element method. The first order shear deformation (FSDT) is used to model the curved panels, considering the effects of transverse shear deformation and rotary inertia. Since the stress field is non -uniform due to cutout, plane stress analysis is carried out using the finite element method to determine the stresses and these are used to formulate the geometric stiffness matrix. The global matrices are obtained using skyline technique. The eigenvalues are obtained us ing subspace iteration scheme. The study reveals that the fundamental frequencies of vibration of an angle ply flat panel decrease with introduction of small cutouts but again rise with increase in size of cutout. However the higher frequencies of vibratio n continue to decrease up to a moderate size of cutout and then rise with further inc...