Faculty Publications
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Item Mechanical behavior of 3D printed syntactic foam composites(Elsevier Ltd, 2020) Bharath, H.S.; Sawardekar, A.; Waddar, S.; Jeyaraj, J.; Doddamani, M.A three-dimensional printed (3DP), polymer based syntactic foams are developed using hollow glass micro balloons (GMB) dispersed in high density polyethylene (HDPE). This work presents the buckling and vibration response of 3D printed foams subjected to axial compression. The buckling load is estimated using Modified Budiansky Criteria (MBC) and Double Tangent Method (DTM) through the load–deflection plots. The first three natural frequencies and their mode shapes are computed as a function of axial compressive load. It is noted that the natural frequency reduces with an increase in axial compressive load. It is also observed that with an increase in GMB %, the natural frequencies and critical buckling load increases. In mode-1, the natural frequency decreases in pre-buckling regimes and increases exponentially in post-critical loading conditions. Analytical solutions obtained from the Euler-Bernoulli-beam theory are compared with experimental results. It is noted that the fundamental frequency approaches zero when the axial load is equal to the critical load. The critical buckling load is estimated through the vibration correlation technique and compared with the results obtained using DTM and MBC methods. The property map is plotted for buckling load against the density of various composites. © 2020 Elsevier LtdItem Influence of axial compressive loads on buckling and free vibration response of surface-modified fly ash cenosphere/epoxy syntactic foams(SAGE Publications Ltd info@sagepub.co.uk, 2018) Waddar, S.; Jeyaraj, P.; Doddamani, M.This work deals with experimental buckling and free vibration behavior of silane-treated cenosphere/epoxy syntactic foams subjected to axial compression. Critical buckling loads are computed from compressive load–deflection plots deduced using universal testing machine. Further, compressive loads are applied in the fixed intervals until critical loading point on different set of samples having similar filler loadings to estimate natural frequency associated with the first three transverse bending modes. Increasing filler content increases critical buckling load and natural frequency of syntactic foam composites. Increasing axial compressive load reduce structural stiffness of all the samples under investigation. Syntactic foams registered higher stiffness compared to neat epoxy for all the test loads. Similar observations are noted in case of untreated cenosphere/epoxy foam composites. Silane-modified cenosphere embedded in epoxy matrix registered superior performance (rise in critical buckling load and natural frequencies to the tune of 23.75% and 11.46%, respectively) as compared to untreated ones. Experimental results are compared with the analytical solutions that are derived based on Euler–Bernoulli hypothesis and results are found to be in good agreement. Finally, property map of buckling load as a function of density is presented by extracting values from the available literature. © The Author(s) 2018.Item 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.Item 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 LtdItem 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