Gopinath Thamilselvan | Toronto Metropolitan University (original) (raw)
Address: Richmond Hill, Ontario, Canada
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Papers by Gopinath Thamilselvan
Ever increasing demand for composite materials in the aerospace industry has lead composite manuf... more Ever increasing demand for composite materials in the aerospace industry has lead composite manufacturers to develop numerous innovations in the field of manufacturing. Composites play an important role in engine components and high-speed jet crafts where weight saving materials that can sustain high temperatures, with little reduction in performance are desired. A cost effective in-house novel manufacturing technique aimed at producing high glass transition temperature (Tg) composite panels on par with autoclave manufacturing technology has been designed and built. The designed compression molding system is integrated with an oven, to cater the need for high temperature and high pressure manufacturing system which can be a potential alternative for autoclaves in terms of fabricating panels for structural testing. Quality of the panel was demonstrated by conducting ultimate tensile test, fatigue test and microscopic examination results. High temperature mechanical testing was also c...
A novel idea of combining two kinds of electro-mechanical couplings to build Active Flutter Suppr... more A novel idea of combining two kinds of electro-mechanical couplings to build Active Flutter Suppression (AFS) strategy for composite structures is presented. The commercially available MFC and a newly proposed shear actuated fiber composite (SAFC) are considered. MFC induces normal strains and SAFC can be made to couple the transverse shear strains. A four noded plate element is employed to build the clamped-free active laminated plate with four MFC and SAFC each. The stiffness, mass, actuator and sensor matrices are obtained from the electro-mechanical coupling analysis. The open loop flutter velocity is computed using the linear aerodynamic panel theory (DLM). Further, the structural and unsteady aerodynamic matrices are represented in state-space form to build the aero-servo-elastic plant. Presently, the unsteady aerodynamics is approximated using a rational polynomial approach. A Linear Quadratic Gaussian control is designed to perform the closed loop flutter calculations. The actuation authority is maintained same through applied control voltage, while evaluating the performance of MFC and SAFC. The results have significantly encouraged the concept of simultaneously targeting the normal and shear strains of aeroelastically excited modes through electromechanical couplings to build an efficient active flutter suppression system.
Nonlinear normal modes, which are defined as a nonlinear extension of the concept of linear norma... more Nonlinear normal modes, which are defined as a nonlinear extension of the concept of linear normal modes, are a rigorous tool for nonlinear modal analysis. The objective of this paper is to demonstrate that the computation of nonlinear normal modes and of their oscillation frequencies can now be achieved for complex, real-world aerospace structures. The application considered in this study is the airframe of the Morane-Saulnier Paris aircraft. Ground vibration tests of this aircraft exhibited softening nonlinearities in the connection between the external fuel tanks and the wing tips. The nonlinear normal modes of this aircraft are computed from a reduced-order nonlinear finite element model using a numerical algorithm combining shooting and pseudo-arclength continuation. Several nonlinear normal modes, involving, e.g., wing bending, wing torsion, and tail bending, are presented, which highlights that the aircraft can exhibit very interesting nonlinear phenomena. Specifically, it is shown that modes with distinct linear frequencies can interact and generate additional nonlinear modes with no linear counterpart.
Ever increasing demand for composite materials in the aerospace industry has lead composite manuf... more Ever increasing demand for composite materials in the aerospace industry has lead composite manufacturers to develop numerous innovations in the field of manufacturing. Composites play an important role in engine components and high-speed jet crafts where weight saving materials that can sustain high temperatures, with little reduction in performance are desired. A cost effective in-house novel manufacturing technique aimed at producing high glass transition temperature (Tg) composite panels on par with autoclave manufacturing technology has been designed and built. The designed compression molding system is integrated with an oven, to cater the need for high temperature and high pressure manufacturing system which can be a potential alternative for autoclaves in terms of fabricating panels for structural testing. Quality of the panel was demonstrated by conducting ultimate tensile test, fatigue test and microscopic examination results. High temperature mechanical testing was also c...
A novel idea of combining two kinds of electro-mechanical couplings to build Active Flutter Suppr... more A novel idea of combining two kinds of electro-mechanical couplings to build Active Flutter Suppression (AFS) strategy for composite structures is presented. The commercially available MFC and a newly proposed shear actuated fiber composite (SAFC) are considered. MFC induces normal strains and SAFC can be made to couple the transverse shear strains. A four noded plate element is employed to build the clamped-free active laminated plate with four MFC and SAFC each. The stiffness, mass, actuator and sensor matrices are obtained from the electro-mechanical coupling analysis. The open loop flutter velocity is computed using the linear aerodynamic panel theory (DLM). Further, the structural and unsteady aerodynamic matrices are represented in state-space form to build the aero-servo-elastic plant. Presently, the unsteady aerodynamics is approximated using a rational polynomial approach. A Linear Quadratic Gaussian control is designed to perform the closed loop flutter calculations. The actuation authority is maintained same through applied control voltage, while evaluating the performance of MFC and SAFC. The results have significantly encouraged the concept of simultaneously targeting the normal and shear strains of aeroelastically excited modes through electromechanical couplings to build an efficient active flutter suppression system.
Nonlinear normal modes, which are defined as a nonlinear extension of the concept of linear norma... more Nonlinear normal modes, which are defined as a nonlinear extension of the concept of linear normal modes, are a rigorous tool for nonlinear modal analysis. The objective of this paper is to demonstrate that the computation of nonlinear normal modes and of their oscillation frequencies can now be achieved for complex, real-world aerospace structures. The application considered in this study is the airframe of the Morane-Saulnier Paris aircraft. Ground vibration tests of this aircraft exhibited softening nonlinearities in the connection between the external fuel tanks and the wing tips. The nonlinear normal modes of this aircraft are computed from a reduced-order nonlinear finite element model using a numerical algorithm combining shooting and pseudo-arclength continuation. Several nonlinear normal modes, involving, e.g., wing bending, wing torsion, and tail bending, are presented, which highlights that the aircraft can exhibit very interesting nonlinear phenomena. Specifically, it is shown that modes with distinct linear frequencies can interact and generate additional nonlinear modes with no linear counterpart.