Faculty Publications
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Item 3D printing of fly ash-based syntactic foams(Elsevier, 2021) Doddamani, M.; Gupta, N.In addition to the ease of fabrication using a wide range of forming processes, thermoplastic polymers are recyclable, which is a strong driving force behind their industrial applications. This chapter deals with manufacturing thermoplastic matrix lightweight composites called syntactic foams (SFs) using in the fused filament fabrication 3D printing process. High-density polyethylene (HDPE) is used as the matrix material and fly ash cenospheres are used as the filler. The development of SFs with cenospheres serves a dual purpose of beneficial utilization of industrial waste fly ash and a reduction in the component cost. Hollow fly ash cenospheres are mixed with HDPE to form a cenosphere/HDPE blend, which is extruded in the form of filaments for commercial 3D printers. Single-screw extruder parameters are optimized to develop eco-friendly SF filaments with minimum cenosphere fracture and homogeneous mixing of constituents. Fly ash-based SFs are successfully 3D printed for mechanical characterization and their properties are observed to be comparable to injection molded specimens of the same compositions. 3D printing of industrial components is successfully demonstrated with potential weight saving capabilities of 8% in addition to reduced polymer consumption to the tune of 4.64 million tons globally per year. © 2022 Elsevier Inc. All rights reserved.Item Thermal Buckling of 3D Printed Auxetic Core Sandwich Beams(Springer, 2025) Dattam, V.K.; Pitchaimani, J.; Doddamani, M.Experimental investigation carried out on the thermal deflection behavior of 3D printed poly lactic acid sandwich beams possessing positive, negative, and zero Poisson’s ratio cellular cores is presented. Using a fused deposition modelling based 3D printer, sandwich beams were fabricated and investigated for thermal buckling under different heating conditions. Influence of Poisson’s ratio of the core and orientation of the beam on thermal buckling were also studied. It is found that Poisson's ratio of the core influences the thermal deflection of the beams remarkably. The sandwich beam having a vertically oriented core with zero Poisson's ratio exhibited superior buckling resistance compared to the other two cases. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.Item A comprehensive review on 3D printing advancements in polymer composites: technologies, materials, and applications(Springer Science and Business Media Deutschland GmbH, 2022) Jagadeesh, P.; Madhu, M.; Rangappa, S.M.; Karfidov, K.; Gorbatyuk, S.; Khan, A.; Doddamani, M.; Siengchin, S.3D printing is a constantly expanding technology that represents one of the most exciting and disruptive production possibilities available today. This technology has gained global recognition and garnered considerable attention in recent years. However, technological breakthroughs, particularly in the field of material science, continue to be the focus of research, particularly in terms of future advancements. The 3D printing techniques are employed for the manufacturing of advanced multifunctional polymer composites due to their mass customization, freedom of design, capability to print complex 3D structures, and rapid prototyping. The advantages of 3D printing with multipurpose materials enable solutions in challenging locations such as outer space and extreme weather conditions where human involvement is not possible. Each year, numerous research papers are published on the subject of imbuing composites with various capabilities such as magnetic, sensing, thermal, embedded circuitry, self-healing, and conductive qualities by the use of innovative materials and printing technologies. This review article discusses the various 3D printing techniques used in the manufacture of polymer composites, the various types of reinforced polymer composites (fibers, nanomaterials, and particles reinforcements), the characterization of 3D printed parts, and their applications in a various industries. Additionally, this review discussed the limitations of 3D printing processes, which may assist future researchers in increasing the utility of their works and overcoming the shortcomings of previous works. Additionally, this paper discusses processing difficulties, anisotropic behavior, stimuli-responsive characteristics (shape memory and self-healing materials), CAD constraints, layer-by-layer appearance, and void formation in printed composites. Eventually, the promise of maturing technology is discussed, along with recommendations for research activities that are desperately required to realize the immense potential of operational 3D printing. © 2022, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.Item Dynamic mechanical analysis of 3D printed eco-friendly lightweight composite(Elsevier Ltd, 2020) Doddamani, M.Dynamic mechanical analysis (DMA) is conducted on 3D printed eco-friendly environmentally pollutant fly ash cenosphere/HDPE lightweight composite. Cenospheres with varying volume % are mixed with HDPE, filament extruded and fed to FDM based 3D printer. Higher crystallinity % is observed in prints compared to respective filaments owing to differential cooling rates in extrusion and printing. Crystallinity drops with cenosphere addition owing to pseudo lubricating effect. The crystallinity of prints is higher than their respective filaments. Storage (E?), loss modulus (E?), and damping (Tan ?) increase with increasing cenosphere content in printed lightweight composite. HDPE with 60 by volume % of cenospheres registered higher values, implying the potential of eco-friendly 3D printed lightweight composite to be utilized for weight-sensitive structures. © 2020 Elsevier LtdItem Mechanical behaviour of 3D printed lightweight nano-composites(Bentham Science Publishers, 2021) Doddamani, M.Background: The nanoclay (NC) and Glass Micro Balloons (GMB) based reinforced polymer composites are explored extensively through traditional processing methods. NC shows substantial enhancement in mechanical properties. Polymer composites developed by reinforcing GMB fillers provide a substantial reduction in weight, which is essential in the marine, aerospace, and au-tomotive field. In this study, an attempt is made by developing polymer nanocomposites by reinforcing NC and GMB particles. Objective: The paper deals with 3-dimensional printing (3DP) of lightweight Nanocomposite Foam (NF) developed by mixing nanoclay (NC) and glass micro balloons (GMB) in high-density polyethylene (HDPE). The NF blend is prepared by keeping NC at 5 weight %. Subsequently, GMBs are added by volume (20-60%) to NC/HDPE blend to realize lightweight NFs. Methods: The lightweight feedstock filaments are developed by extruding the blends using a single screw extruder. The extruded NF filaments are used as input in a 3D printer to print NFs. The density of extruded filaments and prints is measured. The printed NFs are subjected to tensile and flexu-ral testing. Results and Conclusion: With an increase in GMB loading, the density of both filaments and prints decreases. Compared to neat HDPE, printed NFs show ~30% weight-reducing potential. The tensile, flexural modulus and strength increases with GMB loading. NFs exhibited superior mechanical performance as compared to HDPE and NC/HDPE. Further, the property map reveals that the 3D-printed NFs show superior tensile, flexural modulus, and strength in comparison with injection and compression-molded foams. © 2021 Bentham Science Publishers.Item Compressive response of 3D printed graded foams(Elsevier B.V., 2021) Dileep, B.; Doddamani, M.The syntactic foams are widely used in aeronautics, underwater vehicle structures, and oil drilling applications. These foams are being extensively utilized in naval applications wherein they are subjected to the compressive forces that are depth-dependent. Developing graded foams with better compressive behavior using three-dimensional printing (3DP) permits realizing complex geometrical structures with numerous advantages compared to conventional processing routes. The present work deals with 3DP of syntactic foams and their graded configuration by embedding (20, 40, and 60 vol%) glass microballoons (GMBs) in high density polyethylene (HDPE). It is noted that the modulus increases with the filler content. Specific properties of the graded foams exhibited superior response as compared to neat HDPE. Among functionally graded foams (FGFs), FGF-2 (20–40–60) showed the highest modulus and yield strength. FGFs exhibited better energy absorption among all the tested samples. GMBs are observed to be intact, and a seamless interface is seen in micrographs of 3D printed graded foams, making them candidate materials for lightweight structural applications. © 2021Item Recycling potential of MWCNTs/HDPE nanocomposite filament: 3D printing and mechanical characterization(Springer, 2023) Kumar, S.; Ramesh, M.R.; Doddamani, M.Fused filament fabrication (FFF) based additive manufacturing (AM) process is a widely used and emerging manufacturing process for polymer-based products. The recycled filaments are realized through wastage generated while extruding the constant diameter feedstock filament, which is otherwise dumped in landfills or incinerated, releasing hazardous and toxic gases that influence the ecological environment. The wastage of these filaments can be eliminated by recycling and reusing them, addressing materials circular economy effectively, presented in this paper. The functionalized MWCNT reinforced HDPE (high-density polyethylene) nanocomposite (NC) is realized through a brabender, which is further used for filament extrusion. The waste/unrecycled (W/UR) and the recycled filaments are checked for quality. The density of the recycled filaments increases compared to the W/UR filament in each extrusion pass. The crystallinity and tensile properties of the recycled filaments increase compared to the W/UR filament with each additional extrusion cycle. Further, these filaments are used for 3D printing, and investigated for density, XRD and tensile tests. It is observed that the density, crystallinity and tensile properties of the recycled prints increase compared to the W/UR print. The tensile strength and modulus of 1 × , 2 × and 3 × prints are 63.82, 67.11 and 67.76%, and 45.63, 55.34 and 97.81% respectively, higher than those of the W/UR print. The highest tensile strength and modulus are observed for 3 × print which is 67.76 and 97.81% respectively, higher than those of the W/UR print. 3D prints exhibited enhanced performance as compared to their respective filaments. Finally, the present tensile results are mapped on a property chart, and compared with the available HDPE composites. © 2023, Springer Nature Japan KK, part of Springer Nature.Item Investigation on hardness, impact, and compression responses of additively manufactured functionally graded nanocomposites(Elsevier Ltd, 2023) Kumar, S.; Ramesh, M.R.; Doddamani, M.Functionally graded nanocomposites (FGNCs) are fabricated using 3D printing for hardness, impact and compression investigations with different wt. % (0.5⟶H0.5, 1⟶H1, 3⟶H3, 5⟶H5) of functionalized MWCNTs in high-density polyethylene (HDPE). Further, they are extruded as feedstock filament for 3D printing. The hardness, impact strength, and compressive properties increase while the energy absorption decreases with a % increase in the functionalized MWCNTs. The highest hardness, impact strength, compressive moduli, and strength observed for FGNC-2 (H1⟶H3⟶H5) are 76.80, 119.99, 61.14, and 11.56%, respectively, higher than HDPE. The betterment in the mechanical properties is attributed to the strengthening and stiffening effects due to the homogeneous distribution of the functionalized MWCNTs in HDPE. The FGNC-2 exhibited the highest mechanical properties, and can be used in various applications wherein variational stiffness is required. © 2023 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 LtdItem Buckling behavior of non-uniformly heated 3D printed plain and functionally graded nanocomposites(John Wiley and Sons Inc, 2023) Kumar, S.; Ramesh, M.R.; Jeyaraj, J.; Powar, S.; Doddamani, M.The functionalized multi-walled carbon nanotubes (MWCNTs) (0.5–5 wt.%) are compounded with high density polyethylene (HDPE), and, subsequently, used for extruding nanocomposite filaments to fabricate nanocomposites (NCs) and functionally graded nanocomposites (FGNCs) through 3D printing. The 3D printed NCs are investigated for coefficient of thermal expansion (CTE), and buckling under different non-uniform temperature distributions (case-1: left edge heating, case-2: centre heating, and case-3: left and right edge heating). A significant reduction in CTE is observed with MWCNT addition and gradation. The highest reduction in CTE is observed for H5 (5 wt.% of MWCNT in HDPE) NC and H1 ⟶ H3 ⟶ H5 (FGNC-2) among the NCs and the FGNCs. It is noted that Tcr (critical buckling temperature) is highest for case-3 and lowest for case-2. The highest deflection is noticed in case-2, while no significant difference is observed in case-1 and case-3 heating conditions. It is also observed that Tcr increases with gradation and MWCNTs addition. The H5 NC and FGNC-2 exhibited the highest Tcr among the NCs and FGNCs, respectively. The maximum deflection is noticed for HDPE, whereas the minimum deflection is noticed for FGNC-2 and H-5 NC among the tested samples. The results also revealed that Tcr is very sensitive to type of heating. © 2023 Society of Plastics Engineers.