Browsing by Author "Motagondanahalli Rangarasaiah, R."

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Dynamic characterization of hybrid composite material of rotor-bearing support system
(Taylor and Francis Ltd., 2022) Gonsalves, T.H.; Garje Channabasappa, M.K.; Motagondanahalli Rangarasaiah, R.; Joladarashi, S.
In this paper, the dynamic characterization of hybrid composite material of carbon-epoxy sandwiched by steel is presented from the rotor-bearing system perspective. The tensile and flexural strengths of the hybrid material are investigated followed by the detailed damping estimation using modal testing in cantilever mode and dynamic mechanical analysis in double cantilever mode. The experimental characterization results obtained in this work have fundamentally ascertained the mechanical and dynamic behavior of hybrid composite material for the intended application. © 2020 Taylor & Francis Group, LLC.
Hybrid composite shaft of High-Speed Rotor-Bearing System - A rotor dynamics preview
(Bellwether Publishing, Ltd., 2021) Gonsalves, T.H.; Garje Channabasappa, M.K.; Motagondanahalli Rangarasaiah, R.
In this present study, the detailed rotor dynamic evaluation of hybrid composite material rotating shaft of a power turbine high-speed rotor-bearing system is presented. The slender power turbine shaft of front driving turboshaft engine powering the rotorcraft requires a stiffer and lighter material to exhibit better rotor dynamics. Based on the preliminary investigation which predicted substantial rotor dynamic advantages, the laminated composite material shaft is proposed in the compressor section of the rotor-bearing system. To avoid the direct exposure of composite material to the harsh environment of gas turbine engine, hybrid metal fiber form of rotating shaft is employed. The hybrid metal fiber shaft is comprised of a core laminated carbon-epoxy tube sandwiched by steel tubes both inside and outside. The effect of parametric variation in the laminate and length of the hybrid shaft is evaluated and compared with the existing steel shaft. The viscoelastic material damping of carbon-epoxy laminate is also included as a rotating internal damping to evaluate the rotor dynamic instability threshold of the rotor-bearing system. From the analysis, it is found that the combination of metal and fiber-reinforced material can effectively leverage the combined strengths of both materials. © 2020 Taylor & Francis Group, LLC.
Surface design of Mg-Zn alloy temporary orthopaedic implants: Tailoring wettability and biodegradability using laser surface melting
(Elsevier B.V., 2018) Manne, B.; Thiruvayapati, H.; Bontha, S.; Motagondanahalli Rangarasaiah, R.; Das, M.; Balla, V.K.
Magnesium-based alloys have attracted significant attention for biomedical applications due to its biodegradability as well as density and elastic modulus which are close to those of human bone. However, the uncontrolled biodegradation and hydrogen evolution are of major concern. In this work, laser surface melting (LSM) has been carried out to tailor initial corrosion rates of Mg-2.2Zn alloy implants. Melt pool dimensions, microstructure and surface topography of the LSM samples were analysed. The wettability and in vitro degradation characteristics of untreated and treated alloy were compared. LSM resulted in much finer cellular microstructural features than as-cast alloy and the melted region depths between 65 and 115 ?m. Higher treatment depths helped to extend the corrosion protection time by suppressing the corrosion front movement. Polished LSM samples resulted in overall corrosion rates of 0.5–0.62 mm/year which was about 40%–50% reduction compared to the as-cast alloy. Accelerated biomineralisation of the surface via enhancements in the surface energy due to microstructural refinement as well as microstructural homogeneity and Zn enrichment in ?-Mg, favoured improvement of the overall corrosion performance of LSM-treated alloy. © 2018 Elsevier B.V.