Browsing by Author "Roychowdhury S."

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    An Anisotropic Hyperelastic Inflated Toroidal Membrane in Lateral Contact with Two Flat Rigid Plates
    (2022) Sahu S.; Roychowdhury S.
    The present paper studies the contact problem of an inflated toroidal nonlinear anisotropic hyperelastic membrane laterally pressed between two flat rigid plates. The material is assumed to be homogeneous, and an anisotropic term is included in the incompressible Mooney�Rivlin hyperelastic model. Initially, two annular-shaped flat membranes, bonded at both equators, are considered in an undeformed state, which results in a toroidal geometry upon uniform internal pressurization. The contact problem of the inflated torus laterally pressed between two flat parallel plates is solved. Two different contact conditions, namely frictionless contact and no-slip contact, are considered within the contact region. The enclosed amount of gas within the inflated membrane is considered to be constant during the solution of the contact problem, which is solved in a quasi-static manner. In the case of no-slip contact, the stretch locking has been observed, and the frictionless contact causes the free flow of material points. The membrane�s stiffness increases with increasing anisotropic, material, and geometric parameters depicted in the force versus displacement curve under contact conditions. � 2022, The Chinese Society of Theoretical and Applied Mechanics.
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    Static and dynamic analysis of a hyperelastic toroidal air-spring structure
    (2025) Sahu S.; Roychowdhury S.
    The present work proposes a novel toroidal air-spring model consisting of two cylindrical elastomeric membranes unlike conventional convoluted air-spring with one rubber bellow. The membranes are attached with two annular plates at top and bottom in circumferential direction, forming a closed space in between. With internally pressurizing the setup, the inflated bellow in the shape of a toroidal air-spring structure is formed. The static and dynamic analysis of the air-spring model is performed under transverse loading on top plate. The static analysis is carried out by compressing the air-spring to different suspension heights, assuming adiabatic compression of the enclosed air. The conditions for impending wrinkling, its prevention measures by choosing suitable design parameters, and the effect using cord-reinforced membranes are explored. The dynamic study under harmonic forcing is performed using the method of assumed modes coupled with a perturbation technique to solve the Eigenvalue problem of the discretized membrane structure. The radial asymmetric perturbations are included in the formulation to explore the symmetry breaking during dynamic study. The Eigen frequencies of the structure are obtained for different inflation pressures of the air-spring. Interestingly, a frequency veering phenomenon is observed between a few Eigen modes associated with closely spaced natural frequencies, where the possibility of mode swapping exists. The forced vibration analysis around a few Eigen frequencies shows beating like responses. The stiffness of the proposed air-spring is found to be linear under both static and dynamic conditions, which is inline with the stiffness nature of the convectional convoluted air-springs. � 2024 Elsevier Masson SAS