Faculty Publications
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Item Nonlinear buckling and free vibration analysis of auxetic graphene origami composite beams under nonuniform thermal environment(Taylor and Francis Ltd., 2025) Shashiraj; Pitchaimani, J.; Kattimani, S.This study examines the thermo-mechanical behavior of auxetic metamaterial beams enhanced by graphene origami (GOri) under spatially varying nonuniform temperature distributions (SVTD). Utilizing Timoshenko beam theory considering von-Kármánn type nonlinear strain–displacement relationship, GOri beams are modeled as layered structures. The Ritz method is employed to solve equilibrium equations, analyzing the impact of GOri distribution patterns, content, and folding degree on post-buckling and vibration paths. The effects of five SVTDs, three end conditions, and three GOri distribution patterns on buckling, post-buckling behavior, and nonlinear free vibration characteristics are explored. Findings reveal that the parabolic temperature distribution with peak temperatures at beam ends (P-MAE) results in higher critical temperatures and nonlinear free vibration frequencies. This research provides crucial insights into the design and optimization of GOri-enabled metamaterial structures in complex thermal environments, highlighting the significant influence of nonuniform temperature distributions along the beam’s length. © 2024 Taylor & Francis Group, LLC.Item Non-linear transient vibration response of graphene origami enhanced metamaterial beams under spatially-varying temperature distributions(Elsevier Ltd, 2025) Shashiraj; Pitchaimani, J.; Kattimani, S.Understanding the dynamic behavior of advanced materials under varying conditions is crucial for the development of resilient and efficient structural systems. This research investigates the non-linear transient response of auxetic metamaterial beams enhanced with graphene origami under spatially varying non-uniform thermal environment. Using Timoshenko beam theory with von-Kármánn type non-linear strain–displacement relations, graphene origami beams are modeled as layered structures. The equilibrium equations are solved using the Ritz method, with a focus on how different graphene origami distribution patterns, content levels, and folding degrees influence the transient response under various time-dependent forces. Non-linear motion equations are solved using the Newmark-Beta method. This study evaluates the impact of five distinct non-uniform temperature distributions, seven types of time-dependent loadings, three boundary conditions, and three configurations of graphene origami distribution on the vibration characteristics. Results indicate that parabolic temperature distributions with peak temperatures at the beam ends lead to substantially decreased dynamic deflections. This research provides valuable insights into the structural dynamics of graphene origami-enhanced metamaterial beams within complex thermal environments, highlighting the considerable influence of spatial temperature variations along the length of the beam. © 2025Item Investigation of dielectric properties and shore hardness of 3D-printed PLA core sandwich disc with functional ceramics surface cladding(KeAi Publishing Communications Ltd., 2025) Senthil Murugan, S.S.; Kattimani, S.; Bharadwaj, N.Poly-lactic acid (PLA), a popular biodegradable polymer for 3D printing, has limited dielectric strength and surface hardness, restricting its use in advanced electronic and structural applications. Existing enhancement methods are often complex or yield inconsistent results. Therefore, a straightforward and scalable approach is necessary to enhance the properties of 3D-printed PLA. This study aims to explore the enhancement of the dielectric and surface hardness of printed PLA discs through surface cladding using nano-functional ceramics and graphene for next-generation multifunctional applications. PLA discs were fabricated via Fused Deposition Modelling (FDM) and subsequently cladded using hand layup with Araldite resin as a binder. Cladding materials included cobalt ferrite (CF), barium titanate (BTO), and graphene (Gr), individually and in combinations. Dielectric properties—capacitance, impedance, dielectric constant, dielectric loss, dissipation factor, and AC conductivity—were analyzed using an impedance analyzer, while surface hardness was measured using a Shore-D durometer. Results revealed that cladding led to uniform particle dispersion with effective surface bonding, improved dielectric performance, and significantly enhanced surface hardness. The CF + BTO + Gr combination exhibited superior dielectric behaviour, balancing high polarization with low energy dissipation, while BTO contributed to an enhanced dielectric constant and graphene improved charge transfer. All cladded samples showed frequency-dependent dielectric responses, with stability at higher frequencies. The highest surface hardness was achieved with CF + BTO, attributed to rigid, uniform reinforcement. © 2025 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltdé This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/Item Non-linear thermal stability and free vibration behavior of sandwich beams with auxetic re-entrant aluminum cores and graphene origami-enhanced facings(Elsevier Ltd, 2025) Shashiraj; Pitchaimani, J.; Kattimani, S.Revolutionizing advanced sandwich structures, this study delves into the non-linear thermal stability behavior and free vibration characteristics of auxetic aluminum re-entrant core sandwich beams enhanced with graphene origami (GOri) metamaterial facings, subjected to spatially varying thermal environment. The sandwich beams are modeled as layered structures incorporating complex geometric non-linearities, using a higher-order shear deformation framework and non-linear strain–displacement kinematics based on von Kármán assumptions. The governing equations of motion are addressed through the Ritz formulation, enabling an in-depth investigation of how variations in graphene origami layout, concentration, and fold geometry within the face sheets influence the structural performance. Additionally, the influence of various core Poisson's ratio configurations-negative (NPR), zero (ZPR), and positive (PPR)-along with the effects of core angle and thickness ratio, are systematically explored. The results highlight that core topology critically influences post-buckling resistance and non-linear vibrational characteristics. Furthermore, the integration of graphene origami significantly enhances stiffness and structural stability, demonstrating its potential for next-generation aerospace, automotive, and high-performance engineering applications. To the best of the authors’ knowledge, this is the first study to explore the coupled effects of auxetic re-entrant aluminum cores and graphene origami-enhanced facings on the non-linear thermal and dynamic behavior of sandwich beams. © 2025 Elsevier Ltd