Due to the availability of limited literature on functionally graded porous circular beams, the static deformation and free vibration analysis of simply supported functionally graded porous circular beams considering the effects of even and uneven porosities are presented in this paper. The Navier type closed-form solutions are obtained for both static and vibration problems within the framework of the higher-order hyperbolic circular beam theory. The theory considers the effects of transverse shear deformation and rotary inertia. The theory satisfies the transverse shear-stress free boundary conditions at the upper and lower surfaces of the beam. The circular beam is made up of the functionally graded material in which material characteristics vary across the thickness direction using the power-law technique which has been adjusted to approximate the porosity effects with even and uneven distributions. A dynamic version of the virtual work principle is employed to derive the governing differential equations of motion, which are then solved analytically using the Navier solution technique. The non-dimensional values of displacements, stresses, and fundamental frequencies are presented for various values of the power-law index ( p i ), the radius of curvature ( R ), porosity volume fraction (α), and type of porosity distribution (even and uneven). The present results are compared in few problems with existing literature and found in good agreement with those. This study also highlights some new results for the reference of future researchers, especially on circular beams. 

On the static deformation and frequency analysis of functionally graded porous circular beams

Abstract Magnetorheological (MR) dampers with bypass arrangements and combined annular-radial fluid flow channels have shown superior performance compared to conventional MR dampers with single annular/radial fluid flow gaps. Achieving a higher controllable dynamic force range with low off-state but high on-state damping force is yet a significant challenge for developing MR dampers for high payload ground vehicle suspensions. This paper presents the conceptual design, fabrication, and experimental characterization of a mid-sized large-capacity MR damper equipped with a compact annular-radial MR fluid bypass valve. Extensive experimental tests were conducted to investigate the dynamic characteristics of the proposed MR damper considering wide ranges of excitation frequency, loading amplitude, and electrical current. The equivalent viscous damping and the dynamic range were calculated as functions of loading conditions considered. The proposed damper initially realized the maximum dynamic range and damping force of 2.3 and 5.54 kN, respectively. With MR valve design modifications, the maximum dynamic range and damping force were substantially increased, reaching 5.06 and 6.61 kN, respectively. The effectiveness of the proposed MR damper was subsequently identified by comparing its dynamic range with other conventional MR dampers in previous studies. The results confirmed the superior performance of the proposed MR damper and its potential application for highly adaptive suspension systems for off-road wheeled and tracked vehicles. 

https://iopscience.iop.org/article/10.1088/1361-665X/ac9a16/pdf

Development and experimental characterization of a large-capacity magnetorheological damper with annular-radial gap

\n In this research work, graphite flake has been used as an additive in magnetorheological (MR) fluid to improve its thermal and tribological performance. MR fluids with varying amounts of graphite flakes (0.5, 1, 2, 3, 4, and 5 wt%) are prepared to show effective thermal and tribological performance. A test rig is developed with a DC motor, torque sensor, and MR clutch operated in a shear mode to test the torque transmission. Results show the lubrication effects of graphite flakes in the MR fluid. Torque transmission is improved in on-state and off-state using graphite flakes-based MR fluid as compared with conventional MR fluid. Heating of the MR clutch is also reduced with the graphite flakes-based MR fluid. Wear marks and damages are decreased significantly with the increased amount of graphite flakes as found in surface roughness tests. Scanning electron microscopy and energy-dispersive spectroscopy are used to characterize the worn surfaces. This research provides information about the effectiveness of graphite flakes in the MR clutch to improve the device’s performance.

Thermal and Tribological Performance of Graphite Flake-Based Magnetorheological Fluid Under Shear Mode Clutch

Magnetorheological (MR) dampers with bypass arrangements and combined annular-radial fluid flow channels have shown superior performance compared to conventional MR dampers with single annular/radial fluid flow gaps. Achieving a higher controllable dynamic force range with low off-state but high on-state damping force is yet a significant challenge for developing MR dampers for high payload ground vehicle suspensions. This paper presents the conceptual design, fabrication, and experimental characterization of a mid-sized large-capacity MR damper equipped with a compact annular-radial MR fluid bypass valve. Extensive experimental tests were conducted to investigate the dynamic characteristics of the proposed MR damper considering wide ranges of excitation frequency, loading amplitude, and electrical current. The equivalent viscous damping and the dynamic range were calculated as functions of loading conditions considered. The proposed damper initially realized the maximum dynamic range and damping force of 2.3 and 5.54 kN, respectively. With MR valve design modifications, the maximum dynamic range and damping force were substantially increased, reaching 5.06 and 6.61 kN, respectively. The effectiveness of the proposed MR damper was subsequently identified by comparing its dynamic range with other conventional MR dampers in previous studies. The results confirmed the superior performance of the proposed MR damper and its potential application for highly adaptive suspension systems for off-road wheeled and tracked vehicles.

As known, the aim of this paper is to present the field hysteresis behavior of a BMR actuator via identifying the hysteresis model. In order to realize this purpose, firstly, a BMR actuator is manufactured. The feature of this actuator has two disks which are rotated in opposite direction at the same speed and two coils are placed directly on each side of the housing. The two input signals consisting of velocity and current are applied to the BMR actuator to investigate the characteristic of this actuator. Secondly, a proper Preisach hysteresis model is built with two inputs and one output to estimate the torque of the actuator. Finally, the accuracy and the effectiveness of the model are demonstrated by the errors comparison between the constructed hysteretic curves and the experimental ones

Hysteresis Identification of Bidirectional Magneto-Rheological Actuators Employing Preisach Model

Design and experimental evaluation of a novel bidirectional magnetorheological actuator

In this research, a new 2D-haptic joystick featuring a 2D-gimbal mechanism and two bidirectional magneto-rheological actuators (BMRAs) is designed, manufactured, and experimentally tested. Firstly, a new configuration of proposed 2D-haptic joystick is introduced; then, the BMRAs for force feedback of the haptic joystick are proposed, optimally designed, and experimentally evaluated. The BMRA has two disks rotating in opposite directions at the same speed. The two disks are placed inside a housing which is connected to the gimbal mechanism. The BMRA has two coils placed directly on each side of the housing. A prototype of the whole haptic joystick is then manufactured, and a controller is designed to feedback a required force to the operator. Force feedback performance of the haptic joystick is then experimentally investigated and compared with simulated one.

Performance Evaluation of a 2D-Haptic Joystick Featuring Bidirectional Magneto-Rheological Actuators

The paper aims at introducing an analysis of thin-walled functionally graded sandwich beams for general nonuniform quadrilateral cross-sections. Generally, the materials are assumed to be graded through the thickness following a predefined shape while Poisson’s ratio kept as a constant due to its less domination. The crosssection linearly varies from one end to another end of the beam. In order to relax the difficulties in modeling as well as capturing the behaviors of thin-walled functionally graded beams, a higher-order approach has been applied including warping, coupling distortions as well as Poisson’s distortion. A multi-separated beam on each edge of the cross-section which is an application of the so-called beam-frame-modal method is adopted. Subsequently, the effects of these major importance along with anisotropy of materials are then fully considered. As a consequence, the analysis is able to extensively applied to closed-section beam-shells with different curvatures. In order to illustrate the accuracy and computational efficiency of the method, various examples have been conducted in which the results obtained from finite element package as ABAQUS are employed.

Hiep Dai Le

Papers

Design and experimental evaluation of a novel bidirectional magnetorheological actuator

Performance Evaluation of a 2D-Haptic Joystick Featuring Bidirectional Magneto-Rheological Actuators

General non-uniform quadrilateral cross-sections for thin-walled FG sandwich beams

Design and experimental evaluation a novel magneto-rheological brake with tooth shaped rotor

Development of a novel magnetorheological brake with zigzag magnetic flux path