Browsing by Author "Murigendrappa, S.M."

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A Bottom-Up Optimization Approach for Friction Stir Welding Parameters of Dissimilar AA2024-T351 and AA7075-T651 Alloys
(Springer New York LLC barbara.b.bertram@gsk.com, 2017) Anil Kumar, K.S.; Murigendrappa, S.M.; Kumar, H.
In the present study, optimum friction stir weld parameters such as plunge depth, tool rotation speed and traverse speed for butt weld of dissimilar aluminum alloy plates, typically 2024-T351 and 7075-T651, are investigated using a bottom-up approach. In the approach, optimum FSW parameters are achieved by varying any one parameter for every trial while remaining parameters are kept constant. The specimens are extracted from the friction stir-welded plates for studying the tensile, hardness and microstructure properties. Optimum friction stir weld individual parameters are selected based on the highest ultimate tensile strength of the friction stir-welded butt joint specimens produced by varying in each case one parameter and keeping the other two constant. The microstructure samples were investigated for presence of defects, grain refinement at the weld nugget (WN), bonding between the two materials and interface of WN, TMAZ (thermomechanically affected zone) of both advancing and retreating sides of the dissimilar joints using optical microscopy and scanning electron microscopy analyses. In the experimental investigations, the optimum FSW parameters such as plunge depth, 6.2 mm, rotation speed, 650 rpm and traverse speed of 150 mm/min result in ultimate tensile strength, 435 MPa, yield strength, 290 MPa, weld joint efficiency, 92% and maximum elongation, 13%. The microstructure of optimized sample in the WN region revealed alternate lamellae material flow pattern with better metallurgical properties, defect free and very fine equiaxed grain size of about 3-5 µm. © 2017, ASM International.
A comparison of different methods for determination of coupling factor and velocity response of coupled plates
(2013) Pankaj, A.C.; Sastry, S.; Murigendrappa, S.M.
Coupling loss factors (CLF) and velocity responses has been computed for two plates joined in a 'L' junction configuration using Statistical Energy Analysis. The analyses have been carried out to study the effects of internal loss/damping factor on the coupling factors. The effects of plate widths on the coupling factors and velocity responses at high frequencies has also been studied. The statistical energy parameters have been computed using analytical wave approach, finite element method and Free-SEA software. The studies have revealed that the coupling factor computed by the wave approach is independent of the internal loss factor as compared to the values computed using finite element method, wherein CLF increases linearly as the internal loss factor varies from a zero value, followed by a transition region and converges to the values obtained by the analytical wave approach and remains insensitive to changes at higher values of damping. The results obtained from the studies signify the effects of internal loss/damping factor and plate widths on proper selection and usage of the above mentioned methods for the estimation of coupling factors and velocity responses using statistical energy approach. © Vibroengineering.
An experimental evaluation of the microstructure, mechanical and functional fatigue properties of the boron-doped Cu-Al-Be SMA wires
(Elsevier Ltd, 2021) Singh, R.K.; Biswas, P.; Murigendrappa, S.M.; Kattimani, S.
An experimental evaluation of the microstructure, mechanical and functional fatigue properties of the Cu-11.70Al-0.45Be doped with Bx (x = 0.05, 0.10, 0.12, and 0.14 wt%) SMA wires has been carried out. The experiments were performed to investigate microstructure, phase/precipitates, and transformation temperatures for both as-cast and wire samples. Furthermore, tensile properties, shape recovery ratio, and functional fatigue evaluation have also been carried out for the wire samples. The investigation shows that the addition of the minor amount of boron and secondary processes involved during the specimen preparation induced excellent grain refinement. The addition of boron decreased transformation temperatures; however, there was not a considerable change observed due to the secondary process. It was observed that tensile properties increases with the boron addition, and complete shape recovery was observed for all the selected alloys. Finally, functional fatigue tests were conducted under constant stress condition and observed that the number of cycles until the failure has increased and more distance recovery was achieved with an increase in boron doping. © 2021
An investigation on the properties of boron modified Cu–Al–Be polycrystalline shape memory alloys
(Elsevier Ltd, 2020) Bala Narasimha, G.; Murigendrappa, S.M.
Effect of microalloying of boron (B) i.e., 0.02–0.15 wt% and the variation of composition of Al and Be from 11.3 to 11.9 wt% and 0.41–0.44 wt% respectively, has been investigated on the grain refinement and shape memory properties of polycrystalline Cu–Al–Be shape memory alloy. The tests have been carried out for microstructure, morphology, phases, crystal structure, phase transformation temperatures and shape recovery ratio. The investigation results in boron has strong impact on grain refinement with minimal addition, followed by Al and Be. AlB2 acts as heterogeneous nucleation site in grain refinement and it increases with increase in B and Al. Transformation temperatures increases with boron up to 0.08 wt% and then decreases, whereas increase in Al and Be decreases the temperatures. Doping and increasing of boron up to 0.15 wt% exhibits complete shape recovery, whereas Be < 0.42 wt% and Al < 11.8 wt% exhibits poor recovery ratio. © 2020 Elsevier B.V.
Buckling and dynamic characteristics of a laminated cylindrical panel under non-uniform thermal load
(Techno Press technop2@chollian.net, 2016) Bhagat, V.; Jeyaraj, J.; Murigendrappa, S.M.
Buckling and free vibration behavior of a laminated cylindrical panel exposed to non-uniform thermal load is addressed in the present study. The approach comprises of three portions, in the first portion, heat transfer analysis is carried out to compute the non-uniform temperature fields, whereas second portion consists of static analysis wherein stress fields due to thermal load is obtained, and the last portion consists of buckling and prestressed modal analyzes to capture the critical buckling temperature as well as first five natural frequencies and associated mode shapes. Finite element is used to perform the numerical investigation. The detailed parametric study is carried out to analyze the effect of nature of temperature variation across the panel, laminate sequence and structural boundary constraints on the buckling and free vibration behavior. The relation between the buckling temperature of the panel under uniform temperature field and non-uniform temperature field is established using magnification factor. Among four cases considered in this study for position of heat sources, highest magnification factor is observed at the forefront curved edge of the panel where heat source is placed. It is also observed that thermal buckling strength and buckling mode shapes are highly sensitive to nature of temperature field and the effect is significant for the above-mentioned temperature field. Furthermore, it is also observed that the panel with antisymmetric laminate has better buckling strength. Free vibration frequencies and the associated mode shapes are significantly influenced by the non-uniform temperature variations. © 2016 Techno-Press, 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 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 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 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
Characterisation of fatigue delamination growth in plain woven hybrid laminated composites subjected to Mode-I loading
(Elsevier B.V., 2024) Suman, M.L.J.; Murigendrappa, S.M.; Kattimani, S.
Effect of similar and dissimilar crack plane interface configuration on fatigue delamination growth in plain woven hybrid composite laminates under Mode-I has been investigated. Constant displacement amplitude fatigue testing with displacement ratio of 0.1 was carried out on 3 configurations of plain woven glass/carbon epoxy composite laminates. A power law like fit between recorded delamination length and corresponding cycle was used to predict crack length for each of the cycle. Delamination growth rate,da/dN is computed by differentiating the expression of power-law like fit. The obtained crack growth rate for each of the specimens were plotted with respect to two normalised functions, G^Imax=GImax(a)/GIR(a) where GImax is maximum mode-I energy release rate and GIR(a) is the interlaminar fracture toughness resistance and ΔG^Ieff=G^Imax-G^Imin2 as crack driving parameters computed on the basis of Modified Beam Theory (MBT) and Valvo's mode partition method (MPV) are used in Paris relation to quantify delamination propagation. It is observed that the exponent values predicted by MBT method for G^Imax is lower as compared to ΔG^Ieff. Whereas, exponent values predicted for G^Imax is higher as compared to ΔG^Ieff predicted by MPV method. The higher the exponent value, the higher is the sensitivity of the model leading to uncertainties in the crack growth prediction. Also, it is to be noted that cyclic loading effect is when both GImax and GImin is considered, the use of ΔG^Ieff as crack driving parameter to quantify delamination propagation is justified. Secondly, MBT method does not account for the mode-mixity arising due to hybrid material configuration as in the case of Local Symmetry Fatigue (LSF) and Asymmetry Fatigue (ASF) specimens. Hence, results in higher exponent as compared to MPV method. On the other side, the G^Imax and ΔG^Ieff computed on the basis of MPV method is the pure Mode-I component deduced from the total energy release rate of mode-mixity. The equations of curve fitting is very much the same for Simple Symmetry Fatigue (SSF) specimens indicating that MBT and MPV methods predict pure Mode-I behaviour for symmetric configuration for delamination growth under fatigue Mode-I loading. From the composite laminate configuration point of view, LSF specimens have higher exponents as compared to ASF and SSF specimens indicating, local symmetry configuration laminates are highly sensitive to the small uncertainties and results in unstable crack growth. Comparison of results of all hybrid composite laminates shows that the normalised functions of G^Imax and ΔG^Ieff as crack driving parameters computed on the basis of MPV method is able to capture the effect of interlayers and stacking effect on the delamination growth in hybrid plain woven composites in fatigue loading and MPV method is found to be not sensitive to G^Imax and ΔG^Ieff for displacement ratio of 0.1. © 2023 Elsevier Ltd
Detection of damage in spot welded joints using a statistical energy analysis-like approach
(2017) Pankaj, A.C.; Shivaprasad, M.V.; Murigendrappa, S.M.
Vibration-based damage detection has been frequently used for low frequency problems. However, there are situations where the damage, like connections of structures with spot welds, mainly affects the highest modes. Energybased approaches such as Statistical Energy Analysis (SEA) is one of the most widely used methods for high frequency analysis that is well-suited for periodic structures. The present work studies the damage detection of joints based on statistical energy analysis-like principles using apparent coupling factors to predict velocity/acceleration responses and detect damage in the spot welds located at various positions on a sub-system (spot-welded plate configurations). Apparent coupling factors have been derived for four cases of spot-welded plates and used further to predict the velocity/acceleration responses using the statistical energy analysis like (SEAL) approach for an assembly of three subsystems (three plates lap joined by spot-welds) for all the possible combinations. The results are discussed, compared, and validated by experimentation and finite element simulations for a healthy and damaged configuration. A database of the predicted values using the SEAL approach for the remaining combinations has been compared with values obtained from finite element simulations. The proposed SEAL-based approach can be effectively applied as a simulation tool to locate the damaged joint in an assembly of subsystems for future use.
Detection of damage in spot welded joints using a statistical energy analysis-like approach
(International Institute of Acoustics and Vibrations P O Box 13 Auburn AL 36831, 2017) Pankaj, A.C.; Shivaprasad, M.V.; Murigendrappa, S.M.
Vibration-based damage detection has been frequently used for low frequency problems. However, there are situations where the damage, like connections of structures with spot welds, mainly affects the highest modes. Energybased approaches such as Statistical Energy Analysis (SEA) is one of the most widely used methods for high frequency analysis that is well-suited for periodic structures. The present work studies the damage detection of joints based on statistical energy analysis-like principles using apparent coupling factors to predict velocity/acceleration responses and detect damage in the spot welds located at various positions on a sub-system (spot-welded plate configurations). Apparent coupling factors have been derived for four cases of spot-welded plates and used further to predict the velocity/acceleration responses using the statistical energy analysis like (SEAL) approach for an assembly of three subsystems (three plates lap joined by spot-welds) for all the possible combinations. The results are discussed, compared, and validated by experimentation and finite element simulations for a healthy and damaged configuration. A database of the predicted values using the SEAL approach for the remaining combinations has been compared with values obtained from finite element simulations. The proposed SEAL-based approach can be effectively applied as a simulation tool to locate the damaged joint in an assembly of subsystems for future use.
Determination of apparent coupling factors for adhesive bonded acrylic plates using SEAL approach
(2018) Pankaj, A.C.; Shivaprasad, M.V.; Murigendrappa, S.M.
Apparent coupling loss factors (CLF) and velocity responses has been computed for two lap joined adhesive bonded plates using finite element and experimental statistical energy analysis like approach. A finite element model of the plates has been created using ANSYS software. The statistical energy parameters have been computed using the velocity responses obtained from a harmonic forced excitation analysis. Experiments have been carried out for two different cases of adhesive bonded joints and the results have been compared with the apparent coupling factors and velocity responses obtained from finite element analysis. The results obtained from the studies signify the importance of modeling of adhesive bonded joints in computation of the apparent coupling factors and its further use in computation of energies and velocity responses using statistical energy analysis like approach. � 2018 Author(s).
Determination of apparent coupling factors for adhesive bonded acrylic plates using SEAL approach
(American Institute of Physics Inc. subs@aip.org, 2018) Pankaj, A.C.; Shivaprasad, M.V.; Murigendrappa, S.M.
Apparent coupling loss factors (CLF) and velocity responses has been computed for two lap joined adhesive bonded plates using finite element and experimental statistical energy analysis like approach. A finite element model of the plates has been created using ANSYS software. The statistical energy parameters have been computed using the velocity responses obtained from a harmonic forced excitation analysis. Experiments have been carried out for two different cases of adhesive bonded joints and the results have been compared with the apparent coupling factors and velocity responses obtained from finite element analysis. The results obtained from the studies signify the importance of modeling of adhesive bonded joints in computation of the apparent coupling factors and its further use in computation of energies and velocity responses using statistical energy analysis like approach. Â© 2018 Author(s).
Determination of coupling factors for adhesive-bonded plates
(Asian Research Publishing Network arpn@arpnjournals.com, 2016) Pankaj, A.C.; Murigendrappa, S.M.
Adhesive bonding has gained importance in structural bonding in aircraft industry as an alternative method of joining materials together over the more conventional joining methods. It is gaining interest due to the increasing demand for joining similar or dissimilar structural components, mostly within the framework of designing light weight structures. In this present study, a finite element model of a structure, consisting of two Acrylic/Perspex plates joined by an adhesive has been modeled using ANSYS software. Comparisons have been made for the computed coupling factors and velocity responses for the adhesive bonded plates using finite element method and analytical wave approach of the same plates for a line junction at the joint. The results obtained from the studies signify the importance of modeling of adhesive joints in computation of the coupling factors and its further use in computation of energies and velocity responses using statistical energy approach as compared to the values obtained using analytical wave approach for a continuous line junction. Coupling factors have been computed from the velocity responses for the adhesive bonded plates using finite element method and compared with the values obtained from the analytical wave approach for the same plates with a line junction at the joint. © 2006-2016 Asian Research Publishing Network (ARPN).
Development of an in-house MATLAB code for finite element analysis of composite beam under static load
(2019) Patil, P.R.; Ahire, A.S.; Suman, M.L.J.; Murigendrappa, S.M.
The focus of this work is to develop an in-house finite element (FE) code using programming software, MATLAB for analysing composite beam subjected to tensile loading. The composite beams are modelled by using two dimensional quadrilateral plane elements. The computed results obtained from developed code are validated by experimentally as per standard ASTM D3039M-14 and commercially available finite element tool, ABAQUS (V2016). The fabricated composite beams made up of plain woven glass epoxy with eight plies using vacuum bag technique. The computed results obtained from in-house FE code are in good agreement with the experimental and ABAQUS simulated results. Further, the developed code has the capability to support post processing in the form of graphical representation. � 2018 Author(s).
Development of an in-house MATLAB code for finite element analysis of composite beam under static load
(American Institute of Physics Inc. subs@aip.org, 2019) Patil, P.R.; Ahire, A.S.; Suman, M.L.J.; Murigendrappa, S.M.
The focus of this work is to develop an in-house finite element (FE) code using programming software, MATLAB for analysing composite beam subjected to tensile loading. The composite beams are modelled by using two dimensional quadrilateral plane elements. The computed results obtained from developed code are validated by experimentally as per standard ASTM D3039M-14 and commercially available finite element tool, ABAQUS (V2016). The fabricated composite beams made up of plain woven glass epoxy with eight plies using vacuum bag technique. The computed results obtained from in-house FE code are in good agreement with the experimental and ABAQUS simulated results. Further, the developed code has the capability to support post processing in the form of graphical representation. Â© 2018 Author(s).