Browsing by Author "Jeyaraj, P."

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A novel approach to determine the thermal transition of gum powder/hydro-gels using dynamic mechanical analysis
(American Institute of Physics Inc. subs@aip.org, 2018) Nagamadhu, M.; Jeyaraj, P.; Mohan Kumar, G.C.
The dynamic characterization of materials plays a major role in the present area. The many researchers are worked on solid materials and its characterization, it can be tested using dynamic mechanical analyzer (DMA), however, no such work on powder a semiliquid samples. The powder and liquid samples can also easily characterization as like solid samples using DMA. These powder samples are analyzed with a material pocket method which can be used to accurately determine very low levels of variation in powder properties, due to the high sensitivity of DMA to glass transitions. No such DMA studies on hydrogel and Gum powders. The gum powders are used in various applications start from food industries, pharmacy, natural gums paste, biomedical applications etc. among all this applications gum Ghatti is one of the powders using for varies applications. Around 50 milligrams of Ghatti powders are placed inside material pocket and analyzed storage modulus (Gâ€²), loss modulus (Gâ€³) and tan delta (Î´). Also, understand the curing and glass transition effect using water, glycerin and superplastic from room temperature to 200Â°C. The result shows that storage modulus decreases with increase in temperature in pure Ghatti powder. The surprising improvement in storage modulus was found with an increase in temperature with addition of water, glycerin, and superplastic. However, loss modulus and tan delta are also having very significant influence and also shows a clear peak of the tan delta. The loss modulus results were found to be improved by adding solidifying agents, along with this water and superplastic better influence. But glycerine found to be hydrogel in nature and thermodynamic properties are much influenced by frequency. Â© 2018 Author(s).
Aeroelastic flutter of triply periodic minimal surface (TPMS) beams
(Elsevier B.V., 2023) Kurup, M.; Jeyaraj, P.
This work unveils the linear aeroelastic flutter attributes of functionally graded triply periodic minimal surface (FG-TPMS) beams. The Euler-Bernoulli theory including neutral axis shift effect is used to model the FG-TPMS beams. The functional grading is achieved by varying the wall thickness of unit cells according to power-law form. Analysis is carried out for four TPMS patterns, mainly gyroid, primitive, diamond and IWP, under various boundary conditions. Using Hamilton's principle, governing differential equations are derived whose solutions are obtained numerically using the Ritz method. The mode shapes at various values of aerodynamic pressure have also been evaluated. It can be concluded that the type of pattern, boundary conditions, relative cell density, neutral axis shift effect and gradient index plays a crucial role in the prediction of flutter instability. © 2023
Bending and free vibration analysis of foam-filled truss core sandwich panel
(SAGE Publications Ltd info@sagepub.co.uk, 2018) Arunkumar, M.P.; Jeyaraj, P.; Gangadharan, K.V.
This paper presents the studies carried out on bending and free vibration behavior of truss core sandwich panel filled with foam typically used in aerospace applications. Equivalent stiffness properties for foam-filled truss core sandwich panel are derived by idealizing 3D foam-filled sandwich panel to an equivalent 2D orthotropic thick plate continuum. The accuracy of the derived elastic property is ensured by the numerical comparison of free vibration response of 3D and its equivalent 2D finite element model. The derived stiffness constants were used in closed form solution to evaluate the maximum deflection of the continuum. The results show that the free vibration and static behavior of the sandwich panel can be enhanced in due consideration to the space constraint by filling foam in the empty space of core. The results also reveal that triangular core foam-filled sandwich panel deflects less compared to other cores. From the free vibration analysis, effect of filling foam is effective in cellular and trapezoidal core. © 2016, © The Author(s) 2016.
Bending, buckling and free vibration characteristics of FG-CNT-reinforced polymer composite beam under non-uniform thermal load
(2015) Mayandi, K.; Jeyaraj, P.
Bending, buckling and free vibration behaviors of functionally graded (FG) carbon nanotube (CNT)-reinforced polymer composite beam under different non-uniform thermal loads have been analyzed using finite element method. Extended rule of mixture is used to obtain effective material property of the composite. Four different types of FG beam exposed to four different assumed one-dimensional temperature distributions along the length of the beam are analyzed. Parameters studies are carried out to investigate influences of the volume fraction of the carbon nanotube, functional grading and the nature of temperature variation on bending, buckling and free vibration characteristics. It is found that bending deflection reduces with increase in volume fraction of the CNT except for unsymmetrical functional graded beam. The static bending deflection and deformed shape of the beams are significantly influenced by the nature of temperature field. The critical buckling temperature of the beam with symmetric CNT distribution (where CNTs concentration is far from the neutral axis) is greater than other beams under different temperature fields and its value is less when the beams are exposed to uniform temperature rise above ambient temperature compared to other non-uniform temperature variations. However, the critical buckling temperature is not increasing significantly with increase in volume fraction of the CNT. The fundamental buckling mode shape is not sensitive to the nature of temperature variation but bending amplitude of the buckling mode shape is significantly influenced by functional grading of CNT and volume fraction of the CNT. The natural frequency of the beams reduces significantly with increase in temperature and the free vibration mode shapes are not influenced by temperature rise, nature of temperature variation and volume fraction of the CNT. � 2013 IMechE.
Bending, buckling and free vibration characteristics of FG-CNT-reinforced polymer composite beam under non-uniform thermal load
(2015) Mayandi, K.; Jeyaraj, P.
Bending, buckling and free vibration behaviors of functionally graded (FG) carbon nanotube (CNT)-reinforced polymer composite beam under different non-uniform thermal loads have been analyzed using finite element method. Extended rule of mixture is used to obtain effective material property of the composite. Four different types of FG beam exposed to four different assumed one-dimensional temperature distributions along the length of the beam are analyzed. Parameters studies are carried out to investigate influences of the volume fraction of the carbon nanotube, functional grading and the nature of temperature variation on bending, buckling and free vibration characteristics. It is found that bending deflection reduces with increase in volume fraction of the CNT except for unsymmetrical functional graded beam. The static bending deflection and deformed shape of the beams are significantly influenced by the nature of temperature field. The critical buckling temperature of the beam with symmetric CNT distribution (where CNTs concentration is far from the neutral axis) is greater than other beams under different temperature fields and its value is less when the beams are exposed to uniform temperature rise above ambient temperature compared to other non-uniform temperature variations. However, the critical buckling temperature is not increasing significantly with increase in volume fraction of the CNT. The fundamental buckling mode shape is not sensitive to the nature of temperature variation but bending amplitude of the buckling mode shape is significantly influenced by functional grading of CNT and volume fraction of the CNT. The natural frequency of the beams reduces significantly with increase in temperature and the free vibration mode shapes are not influenced by temperature rise, nature of temperature variation and volume fraction of the CNT. � 2013 IMechE.
Bending, buckling and free vibration characteristics of FG-CNT-reinforced polymer composite beam under non-uniform thermal load
(SAGE Publications Ltd, 2015) Mayandi, K.; Jeyaraj, P.
Bending, buckling and free vibration behaviors of functionally graded (FG) carbon nanotube (CNT)-reinforced polymer composite beam under different non-uniform thermal loads have been analyzed using finite element method. Extended rule of mixture is used to obtain effective material property of the composite. Four different types of FG beam exposed to four different assumed one-dimensional temperature distributions along the length of the beam are analyzed. Parameters studies are carried out to investigate influences of the volume fraction of the carbon nanotube, functional grading and the nature of temperature variation on bending, buckling and free vibration characteristics. It is found that bending deflection reduces with increase in volume fraction of the CNT except for unsymmetrical functional graded beam. The static bending deflection and deformed shape of the beams are significantly influenced by the nature of temperature field. The critical buckling temperature of the beam with symmetric CNT distribution (where CNTs concentration is far from the neutral axis) is greater than other beams under different temperature fields and its value is less when the beams are exposed to uniform temperature rise above ambient temperature compared to other non-uniform temperature variations. However, the critical buckling temperature is not increasing significantly with increase in volume fraction of the CNT. The fundamental buckling mode shape is not sensitive to the nature of temperature variation but bending amplitude of the buckling mode shape is significantly influenced by functional grading of CNT and volume fraction of the CNT. The natural frequency of the beams reduces significantly with increase in temperature and the free vibration mode shapes are not influenced by temperature rise, nature of temperature variation and volume fraction of the CNT. Â© 2013 IMechE.
Buckling and Dynamic Behavior of Non-Uniformly Heated Cylindrical Panels
(National Institute of Technology Karnataka, Surathkal, 2018) Bhagat, Vinod; Jeyaraj, P.; Murigendrappa, S. M.
Today, curved panels especially cylindrical and conical are considered as a backbone of numerous engineering structures. Knowledge of buckling and dynamic behavior of structures over a range of temperature is essential for their better design. Most of the studies carried out on heated panels are based on uniform temperature distribution assumption. However, in real life application, the cylindrical panels employed in structures are exposed to non-uniform temperature variation due to the location of the heating source and thermal boundary conditions. In the present study, the thermal buckling strength of the non-uniformly heated metallic panel predicted numerically is validated experimentally using in-house developed experimental set-up. Further studies are extended to investigate the effect of non-uniform temperature variation on buckling strength and free vibration characteristics of metallic, laminated composite, and functionally graded carbon nanotube (FGCNT) reinforced polymer composite, cylindrical panels using the finite element method. Finally, the optimization of a non-uniformly heated laminated cylindrical panel against thermal buckling strength and fundamental natural frequency is also carried out. Typical variation of temperature-deflection plot for different temperature fields is obtained experimentally and further, inflection point method is used to predict the critical buckling temperature from temperature-deflection plot. Experimental studies are further extended to analyze the influence of geometrical parameters and structural boundary constraints on critical buckling temperature. Experimentation results reveal that the location of the heat source and resulting non-uniform ivtemperature field influences the thermal buckling strength significantly. Among three cases examined in experimentation for the position of heat source, minimal buckling strength is observed when the heater is located at the center of the panel while maximum buckling strength is observed when the heater is located at the forefront curved edge. It is also found that aspect ratio and structural boundary constraints play a major role in deciding the buckling strength of the panel. From the numerical studies carried out on non-uniformly heated panels, a relation known as magnification factor is established to evaluate the buckling strength of non-uniformly heated cylindrical panels knowing the buckling strength of uniformly heated panels. Among five cases investigated for the position of heat source, the highest magnification factor is observed for a panel with the heat source located at the forefront curved edge. It is observed that the free vibration mode shapes of the panel change significantly with increase in elevated temperature. The changes are observed in terms switching of modes with a significant change in modal indices. With the rise in temperature, nodal and anti-nodal positions of a particular free vibration mode shape are shifting towards the location where the intensity of the heat source is high and structural stiffness is low. It is found that for a stiffer panel, the buckling strength of the laminated and FG-CNT composite panels with temperature-dependent elastic properties is significantly lesser than that of the panels with temperature independent elastic properties. Panel with maximum area exposed to a peak temperature of particular non-uniform temperature fields shows lowest buckling strength. Functional grading of CNTs with more amount of CNTs located close to top and bottom of the panel (FG-X) results in higher buckling strength and free vibration frequencies compared to those panel with maximum CNTs distribution near the mid-plane. Free vibration frequencies of non-uniformly heated FG-CNT panel with temperature dependent properties is observed to decrease drastically with elevated temperature compared to the panel with temperature independent properties. Variation vin frequencies observed in a pre-stressed panel with temperature dependent and independent properties is more significant in stiffer panels. Irrespective of temperature dependent and independent properties, shifting of nodal and anti-nodal lines and change of modal indices are also observed at elevated temperature. Well-known and generally acknowledged optimization technique, particle swarm optimization is employed for the optimization of thermal buckling strength of laminated composite panels exposed to five different temperature fields. Two different optimization approach like single objective optimization approach and multiobjective optimization approach are employed. In single objective optimization, the panel is exposed known temperature field whereas, in multi-objective optimization, the panel is exposed to unknown temperature fields when in-service. It is found from the analysis that the variation in the optimum buckling strength of non-uniformly heated panels is more significant at lower curvature ratio. Whereas, variation in the optimum fiber orientation under different temperature fields is significant at higher curvature ratio. Multi-objective optimization approach has proved to be superior to that of single objective optimization approach when panels are exposed to the unpredictable thermal environment. Further, studies are carried out on optimization of both thermal buckling strength and fundamental free vibration frequency of heated panels using particle swarm optimization in conjunction with the artificial neural network. Multiobjective design index (MODI) has been derived for the panel considering buckling strength and fundamental frequency as objectives for optimization. It is found that MODI of the cylindrical panels under thermal load is complex and significantly influenced by the temperature fields, lamination scheme, in-plane boundary constraints, elevated temperature and geometric parameters. It is also observed that the MODI of the panel can be maximized by optimizing laminate orientations. Further, it is observed that panel with lamination scheme of (θ°/–θ°/θ°/–θ°)S gives higher value of MODI compared to other lamination schemes considered.
Buckling and Dynamic Characteristics of Non-Uniformly Heated FGCNT Polymer Nanocomposite Plate
(National Institute of Technology Karnataka, Surathkal, 2017) George, Nivish; Jeyaraj, P.; Murigendrappa, S. M.
Nature of temperature variation influences buckling and dynamic behaviour of structures under thermal load. However, studies on buckling and dynamic behaviour of non-uniformly heated structures are very limited. In present work, influence of non-uniform temperature variation on buckling strength of beams made of aluminium and laminated glass-epoxy materials are investigated experimentally. A novel experimental set-up, built in-house, is developed to perform this investigation. The load vs deflection curve obtained experimentally is used to predict the thermal buckling strength using inflection point method. Non-linear finite element analysis, considering the initial geometric imperfection, has been carried out to compare the experimentally obtained typical load-deflection curve. Experimental and numerical results revealed that critical buckling temperature of the non-uniformly heated beam greatly differs from the uniformly heated beam. It is also observed that different locations of heat source and resulting non-uniform temperature variations influence the critical buckling temperature significantly depending on the location of heat source. With the confidence gained from the results obtained from experimental investigation, a detailed numerical investigation is carried out on Functionally Graded Carbon Nanotube (FG-CNT) reinforced polymer composite plate to obtain the influence of non-uniform heating on the buckling, free vibration and forced vibration response. The effective material constants of the plate are obtained using the extended rule of mixture along with efficiency parameters of the CNT (to include geometry-dependent material properties). Influence of boundary conditions, iiaspect ratio, functional grading of the CNT, non-uniform heating on thermal buckling, free and forced vibration behaviour of the heated plate are analysed. The acoustic response of the plate is analysed by solving the Rayleigh integral. It is observed that temperature fields and functional grading of CNTs influences the critical buckling temperature of the plates. Further, nature of functional grading showed significant change in buckling mode shapes irrespective of the boundary conditions. The first few natural frequencies of the plate under thermal load decreases as the temperature increases and they are influenced significantly by the nature of temperature field. The free vibration modes of the rectangular plates are sensitive to the nature of temperature field whenever there is a free edge associated with the boundary condition. It is observed that, the plates with FG-X type CNT distribution showed better thermal buckling strength and free vibration characteristics in comparison to other types of functional grading. The resonant amplitude of vibration and acoustic response are significantly influenced by the nature of different functional grading and rise in thermal load. This reflects in the band wise calculation of sound power also which recommends the CNT functional grading with X distribution along the thickness direction for lower frequency level. Considerable increase in sound power level has been observed with increase in thermal load in the lower frequency range due to the variation in the stiffness associated with the plate. Similar variation in vibroacoustic response has been observed with increase in the CNT loading also.
Buckling and dynamic responses of 3D printed nanocomposites and their graded variants
(Elsevier Ltd, 2023) Kumar, S.; Ramesh, M.R.; Jeyaraj, P.; Doddamani, M.
The experimental and numerical investigations are carried out for buckling and vibration of 3D printed functionalized MWCNTs/HDPE based nanocomposite (NC) and their functionally graded nanocomposite (FGNC) variants. Pcr(critical buckling load) is computed through MBC (modified budiansky criteria) and DTM (double tangent method) techniques. It is observed that Pcr of the 3D printed NCs and FGNCs increases with the functionalized MWCNTs content. The Pcr values for the NCs (H0.5-H5) computed using DTM and MBC increased in the range of 16–79%, while for FGNC-1 (H0.5-H1-H3) and FGNC-2 (H1-H3-H5), the Pcr increased from 54 to 91% compared to HDPE. Further, it is observed that the natural frequency of the NCs and FGNCs increases with the functionalized MWCNTs loading while decreases with rise in compression. The natural frequency of the NCs (H0.5-H5) and FGNCs increased up to 41% than HDPE. The highest Pcr and the natural frequency is noted for H5 and FGNC-2 prints. The experimental and numerical results showed good agreement. © 2023 Elsevier Ltd
Buckling and Free Vibration Behavior of a Temperature Dependent FG-CNTRC Cylindrical Panel under Thermal Load
(2018) Bhagat, V.; Jeyaraj, P.; Murigendrappa, S.M.
Present study deals with the buckling and free vibration behavior of functionally graded carbon-nanotubes reinforced composite (FG-CNTRC) cylindrical panel exposed to uniform thermal load. Stresses setup due to thermal load and temperature dependent properties influences the buckling and free vibration behavior of the heated structures. Approach employed in the present study consists of static analysis to compute thermal stresses, eigen-value buckling analysis to compute critical buckling temperature and finally modal analysis, taking thermal stresses into account. Influence of different CNTs grading pattern, CNTs volume fraction, geometric parameters, boundary constraints and temperature dependent properties on the buckling strength are investigated. It is observed that hybrid CNTs distribution pattern gives comparatively higher buckling strength and free vibration frequencies. Investigation on free vibration characteristics of the FG-CNTRC panel at elevated temperature signifies that the decline in free vibration frequencies is very drastic at a temperature close to buckling temperature along with temperature dependent properties. c 2017 Elsevier Ltd. All rights reserved. � 2018 Elsevier Ltd.
Buckling and Free Vibration Behavior of a Temperature Dependent FG-CNTRC Cylindrical Panel under Thermal Load
(Elsevier Ltd, 2018) Bhagat, V.; Jeyaraj, P.; Murigendrappa, S.M.
Present study deals with the buckling and free vibration behavior of functionally graded carbon-nanotubes reinforced composite (FG-CNTRC) cylindrical panel exposed to uniform thermal load. Stresses setup due to thermal load and temperature dependent properties influences the buckling and free vibration behavior of the heated structures. Approach employed in the present study consists of static analysis to compute thermal stresses, eigen-value buckling analysis to compute critical buckling temperature and finally modal analysis, taking thermal stresses into account. Influence of different CNTs grading pattern, CNTs volume fraction, geometric parameters, boundary constraints and temperature dependent properties on the buckling strength are investigated. It is observed that hybrid CNTs distribution pattern gives comparatively higher buckling strength and free vibration frequencies. Investigation on free vibration characteristics of the FG-CNTRC panel at elevated temperature signifies that the decline in free vibration frequencies is very drastic at a temperature close to buckling temperature along with temperature dependent properties. c 2017 Elsevier Ltd. All rights reserved. Â© 2018 Elsevier Ltd.
Buckling and free vibration behavior of cenosphere/epoxy syntactic foams under axial compressive loading
(ASTM International, 2018) Waddar, S.; Jeyaraj, P.; Doddamani, M.; Gupta, N.
The buckling and free vibration behavior of cenosphere/epoxy syntactic foams under axial compressive loading are investigated experimentally in this work. The buckling load is obtained from the load-deflection curve based on the Double Tangent Method (DTM) and Modified Budiansky Criteria (MBC). Furthermore, the influence of an axial compression load on the natural frequencies associated with the first three transverse bending modes is analyzed. Finally, the buckling loads predicted using DTM and MBC are compared to the buckling load calculated based on the vibration correlation technique. It is observed that the buckling loads predicted through the three different methods are in close agreement. The experimental results revealed that the buckling load and natural frequency of the syntactic foams increase with the cenosphere volume fraction. It is observed that the natural frequencies reduce with increases in the axial compression load for all the modes. However, a rapid increase in the fundamental frequency is observed when the compressive load is near and beyond the critical buckling load. © © 2018 by ASTM International.
Buckling and Free Vibration Characteristics of a Uniformly Heated Isotropic Cylindrical Panel
(2016) Bhagat, V.; Jeyaraj, P.; Murigendrappa, S.M.
In this paper buckling and free vibration characteristics of an isotropic cylindrical panel subjected to uniform temperature rise has been investigated using finite element method. The procedure involves the determination of critical buckling temperature, which is followed by modal analysis considering pre-stress due to the thermal field in the cylindrical panel. Detailed studies are carried out to analyze the influence of curvature ratio, thickness ratio and aspect ratio on the critical buckling temperature and free vibration behavior of an isotropic cylindrical panel. It has been found that as the curvature ratio and the thickness ratio increases the thermal buckling strength of the cylindrical panel decreases. It has also been found that free vibration frequencies reduce with an increase in temperature and the reduction is more significant for the lowest frequency mode. It is observed that free vibration mode shapes at ambient temperature changes with an increase in temperature. � 2016 The Authors.
Buckling and Free Vibration Characteristics of a Uniformly Heated Isotropic Cylindrical Panel
(Elsevier Ltd, 2016) Bhagat, V.; Jeyaraj, P.; Murigendrappa, S.M.
In this paper buckling and free vibration characteristics of an isotropic cylindrical panel subjected to uniform temperature rise has been investigated using finite element method. The procedure involves the determination of critical buckling temperature, which is followed by modal analysis considering pre-stress due to the thermal field in the cylindrical panel. Detailed studies are carried out to analyze the influence of curvature ratio, thickness ratio and aspect ratio on the critical buckling temperature and free vibration behavior of an isotropic cylindrical panel. It has been found that as the curvature ratio and the thickness ratio increases the thermal buckling strength of the cylindrical panel decreases. It has also been found that free vibration frequencies reduce with an increase in temperature and the reduction is more significant for the lowest frequency mode. It is observed that free vibration mode shapes at ambient temperature changes with an increase in temperature. Â© 2016 The Authors.
Buckling and free vibration of nonuniformly heated functionally graded carbon nanotube reinforced polymer composite plate
(World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2017) George, N.; Jeyaraj, P.; Murigendrappa, S.M.
Buckling and free vibration behavior of functionally graded carbon nanotube reinforced polymer composite plate subjected to nonuniform temperature fields have been investigated using finite element approach. The effective material constants of the plate are obtained using the extended rule of mixture along with efficiency parameters of the carbon nanotube (to include geometry-dependent material properties). Influence of boundary conditions, aspect ratio, functional grading of the carbon nanotube, nonuniform thermal loading on thermal buckling and free vibration behavior of the heated plate are analyzed. It is observed that temperature fields and functional grading are influenced on the critical buckling temperature of the plates. Further, nature of functional grading showed significant change in buckling mode shapes irrespective of the boundary conditions. The first few natural frequencies of the plate under thermal load decreases as the temperature increases and they are influenced significantly by the nature of temperature field. Variations in free vibration mode shapes of the square plates found with not significant change as temperature increases. However, free vibration modes of the rectangular plates are sensitive to the nature of temperature field whenever there is a free edge associated with the boundary condition. Influence of functional grading on the free vibration mode shapes is not significant in contrast with the free vibration natural frequencies. The magnitude of free vibration natural frequencies of functional grade-X type carbon nanotube reinforcement showed higher in comparison with other two types of reinforcements considered here. © 2017 World Scientific Publishing Company.
Buckling and free vibrations behaviour through differential quadrature method for foamed composites
(Elsevier B.V., 2023) Duryodhana, D.; Waddar, S.; Bonthu, D.; Jeyaraj, P.; Powar, S.; Doddamani, M.
The current work focuses on predicting the buckling and free vibration frequencies (fn) of cenosphere reinforced epoxy based syntactic foam beam under varying loads. Critical buckling loads (Ncr) and fn are predicted using the differential quadrature method (DQM). Ncr and fn have been calculated for beams of varying cenosphere volume fractions subjected to axial load under clamped-clamped (CC), clamped-simply (CS), simply-simply (SS), and clamped-free (CF) boundary conditions (BC′s). Upon increasing the cenosphere volume fraction, Ncr and fn of syntactic foam composites increases. These numerical outcomes are compared with the theoretical values evaluated through the Euler-Bernoulli hypothesis and further compared with experimental outcomes. Results are observed to be in precise agreement. The results of the DQM numerical analysis are given out for the different BC′s, aspect ratios, cenosphere volume fractions, and varying loads. It is perceived that depending on the BC′s, the type of axial varying loads and aspect ratios has a substantial effect on the Ncr and fn behaviour of the syntactic foam beams. A comparative study of the obtained results showed that the beam subjected to parabolic load under CC boundary conditions exhibited a higher buckling load. © 2023 The Authors
Buckling and vibration behavior of a non-uniformly heated isotropic cylindrical panel
(Techno-Press, 2016) Bhagat, V.S.; Jeyaraj, P.; Murigendrappa, S.M.
This study attempts to address the buckling and free vibration characteristics of an isotropic cylindrical panel subjected to non-uniform temperature rise using numerical approach. Finite element analysis has been used in the present study. The approach involves three parts, in the first part non-uniform temperature field is obtained using heat transfer analysis, in the second part, the stress field is computed under the thermal load using static condition and, the last part, the buckling and pre-stressed modal analysis are carried out to compute critical buckling temperature as well as natural frequencies and associated mode shapes. In the present study, the effect of non-uniform temperature field, heat sink temperatures and in-plane boundary constraints are considered. The relation between buckling temperature under uniform and non-uniform temperature fields has been established. Results revealed that decrease (Case (ii)) type temperature variation field influences the fundamental buckling mode shape significantly. Further, it is observed that natural frequencies under free vibration state, decreases as temperature increases. However, the reduction is significantly higher for the lowest natural frequency. It is also found that, with an increase in temperature, nodal and anti-nodal positions of free vibration mode shapes is shifting towards the location where the intensity of the heat source is high and structural stiffness is low. © © 2016 Techno-Press, Ltd.
Buckling and vibration behaviour of syntactic foam core sandwich beam with natural fiber composite facings under axial compressive loads
(Elsevier Ltd, 2019) Waddar, S.; Jeyaraj, P.; Doddamani, M.; Barbero, E.
An experimental study of buckling and dynamic response of cenosphere reinforced epoxy composite (syntactic foam) core sandwich beam with sisal fabric/epoxy composite facings under compressive load is presented. Influence of cenosphere loading and surface modification on critical buckling load and natural frequencies of the sandwich beam under compressive load is presented. The critical buckling load is obtained from the experimental load-deflection data while natural frequencies are obtained by performing experimental modal analysis. Results reveal that natural frequencies and critical buckling load increase significantly with fly ash cenosphere content. It is also observed that surface modified cenospheres enhance natural frequencies and critical buckling load of the sandwich beam under compressive load. Vibration frequencies reduce with increase in compressive load. Fundamental frequency increases exponentially in post-buckling regime. Experimentally obtained load-deflection curve and natural frequencies are compared with finite element analysis wherein results are found to be in good agreement. © 2019 Elsevier Ltd
Buckling Behavior of Non-Uniformly Heated Tapered Laminated Composite Plates with Ply Drop-Off
(World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2018) Ashok, S.; Jeyaraj, P.
The thermal buckling characteristics of non-uniformly heated tapered laminated composites plates with ply drop-off have been investigated numerically. Detailed parametric studies have been carried out for the effects of taper configuration, temperature variation, aspect ratio and structural boundary conditions on critical buckling temperatures and buckling mode shapes. It is found that the nature of taper as well as the applied temperature field have considerable effects on the critical buckling temperatures of laminated composite tapered plates. Square plates buckle at the highest temperature when subjected to the decreasing temperature profile. Additionally, it is noted that Taper B and Taper C plates show the best behavior under buckling for most structural boundary conditions. Moreover, the change in buckling mode shapes with respect to temperature profile and taper configuration is significant for rectangular plates in comparison with square plates. © 2018 World Scientific Publishing Company.
Buckling of non-uniformly heated isotropic beam: Experimental and theoretical investigations
(Elsevier Ltd, 2016) George, N.; Jeyaraj, P.; Murigendrappa, S.M.
Influence of non-uniform heating on critical buckling temperature of an aluminium beam has been investigated experimentally with the help of a novel experimental set-up developed in-house. Non-linear finite element analysis, considering the initial geometric imperfection, has been carried out to compare the experimentally obtained typical load-deflection curve. The linear critical buckling temperature predicted numerically are validated with analytical solutions. Experimental results revealed that critical buckling temperature of the non-uniformly heated beam greatly differs from the uniformly heated beam. It is also observed that the location of heat source and resulting non-uniform temperature variation influences the critical buckling temperature significantly. © 2016 Elsevier Ltd