Browsing by Author "Saini, R.S.S."

Now showing 1 - 4 of 4

Design of bypass rotary vane magneto rheological damper for prosthetic knee application
(International Conference on Adaptive Structures and Technologies, 2019) Saini, R.S.S.; Kumar, H.; Chandramohan, S.; Sujatha, S.
In this paper, a bypass rotary vane type magneto rheological (MR) damper suitable for prosthetic knee application is designed. The torque and angular velocity requirements of the normal human knee are used as design limits. In the proposed design, the rotary vane chamber and the MR valve are connected by hydraulic cables and ports and are designed separately. The rotary vane chamber is designed based on the cross-sectional size limits of the normal human knee, while the MR valve is designed with the objective of obtaining the maximum on-state damping torque, minimum weight, and minimum off-state torque. Â© copyright Environment and Climate Change Canada.
Design of twin-rod flow mode magneto rheological damper for prosthetic knee application
(American Institute of Physics Inc. subs@aip.org, 2019) Saini, R.S.S.; Kumar, H.; Chandramohan, S.; Sujatha, S.
In the present study, a twin-rod magneto rheological (MR) damper working in flow mode is designed. The piston core, annular fluid gap, outer sleeve, and the outer cylinder forms the magnetic flow path. A nonlinear constrained optimization problem is formulated to obtain the geometric dimensions of the piston assembly. The flow mode equations of the damper and the electromagnetic circuit design equations, assuming constant magnetic field links are coupled together to form an optimization problem. The design torque and angular velocity requirements of the normal human knee are converted to damping forces and linear velocity using the knee and damper geometry based on the previous study. The damping force design constraints and the constraints related to current requirements and magnetic field saturation are imposed. The obtained optimum dimensions of the piston assembly yielded an off state damping force of 56.8 N and a maximum on-state damping force of 1582 N at a current of 1.6 A for a design velocity of 0.1 m/s. Magnetostatic analysis of the piston assembly using the optimized dimensions is performed which showed that the annular gap is exposed to a field of 0.6 T, as assumed and the piston core is subjected to a field of 1.8 T which is below the saturation limit of the core material. Â© 2019 Author(s).
Determination of optimal magnetorheological fluid particle loading and size for shear mode monotube damper
(Springer Verlag service@springer.de, 2019) Acharya, S.; Saini, R.S.S.; Kumar, H.
Magnetorheological (MR) fluids belong to a class of controllable fluids, and the composition and concentration of its components govern its magnetorheological properties. In this study, an optimum particle loading (or mass fraction) and size of iron particles in MR fluid for use in a shear mode monotube MR damper were determined based on the damping force and off-state viscosity of synthesized MR fluid samples. Initially, the morphological and magnetic properties of carbonyl iron particles were characterized. Six MR fluid samples were prepared composed of combination of three different particle loadings and two sizes of iron particles. Magnetorheological tests were conducted on these samples to determine the flow curves at off-state and on-state magnetic field conditions. Herschel–Bulkley model was used for mathematical representation of flow curves at different magnetic fields and to determine their dynamic yield stress. Further, a shear mode monotube MR damper with accumulator was designed by using optimization technique for desired dynamic range and damping force. Magnetostatic analysis was performed to determine the magnetic field strength generated in the shear gap at different currents. The damping force was calculated for synthesized MR fluids based on their dynamic yield stress corresponding to the magnetic field strength in the shear gap. Analysis of variance was performed to analyse the significance of independent factors on the damping force and off-state viscosity of MRF. The optimal particle loading and size which yielded maximum damping force with minimum off-state viscosity were determined using a multi-objective genetic algorithm. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.
Optimal design and analyses of t-shaped rotor magnetorheological brake
(Institute of Physics Publishing helen.craven@iop.org, 2019) Acharya, S.; Saini, R.S.S.; Kumar, H.
Magnetorheological (MR) brakes, belonging to the class of electromagnetic brakes, have a potential to replace conventional hydraulic brakes owing to reversible, rapidly controllable torque characteristics. In this study, T-shaped rotor MR brake was considered due to their higher braking torque capability and compactness compared to other configurations of brake. Optimal design of the brake was performed considering brake rotor radius, rotor thickness, flange length, casing thickness, coil height and coil width. Magnetostatic analyses were performed for different combinations of parameters of the brake dimensions to compute the magnetic flux density generated in the MR fluid region and the torque ratio and mass were calculated. The optimum dimensions of the brake were determined based on maximization of torque ratio and minimization of mass of the brake using multi-objective Genetic algorithm optimization technique. Further, magnetostatic analyses of the T-rotor brake with optimal dimensions were performed and torque characteristics were compared with those obtained for brake with simple disk rotor. It was concluded that T-rotor brake produces higher braking torque compared to simple disk rotor type MR brake for similar dimensions. Â© 2019 IOP Publishing Ltd. All rights reserved.