In this paper, an exoskeleton for human knee is proposed. This design is based on the magnetorheological (MR) fluid theory and its application on vibration damper. The damper is analyzed and developed to suit the human motion. The motor torque is optimized that the knee torque is smallest as possible. After formulating the equations related to motor torque, external forces on human leg and damper force, the design is undertaken followed by optimization using ANSYS APDL software. The objective function in this software is concentrated on maximal damping force of damper (supporting 30% force when human foot lands on the ground).
Magnetorheological (MR) fluid is smart material that behaves differently with an applied magnetic field. MR brake consists of the fluid with a magnetic source to produce sufficient torque for the braking application. This paper takes the multidisc MR brake with a new approach to produce more uniform magnetic field using the Helmholtz coil setup and placing the other coils inside of the braking discs. The system is optimized for the resulting torque that can be used within the leg exoskeleton for walking support.
In this paper, magneto-rheological (MR) mount for a cabin of heavy equipment vehicles is designed for improving vibration isolation in both low and high frequency domains. The proposed mount consists of two principal parts of mount, rubber part and MR fluid path. The rubber part of existed mount and spring are used to change the stiffness and frequency characteristics for low vibration frequency range. The MR fluid path is a valve type structure using flow mode. In order to control the external magnetic field, a solenoid coil is placed in MR mount. Magnetic intensity analysis is then conducted to optimize dimensions using computer simulation. Experimental results show that magnetic field can reduce low frequency vibration. The results presented in this work indicate that proper application of MR fluid and rubber characteristic to devise MR mount can lead to the improvement of vibration control performance in both low and high frequency ranges.
The technologies related to saving energy/or green vehicles are actively researched. In this tendency, the problem for reducing exhausted gas is in development with various ways. Those efforts are directly related to the operation of engine which emits exhausted gas. The auto start/stop of vehicle engine when a vehicle stop at road is currently as a main stream of vehicle industry resulting in reducing exhausted gas. However, this technology automatically turns on and off engine frequently. This motion induces vehicle engine to transmit vibration of engine which has large displacement, and torsional impact to chassis. These vibrations causing uncomfortable feeling to passengers are transmitted through the steering wheel and the gear knob. In this work, in order to resolve this vibration issue, a new proposed magnetorheological (MR) fluid based engine mount (MR mount in short) is presented. The proposed MR mount is designed to satisfy large damping force in various frequency ranges. It is shown that the proposed mount can have large damping force and large force ratio which is enough to control unwanted vibrations of engine start/stop mode.
In this paper, a new innovative modified high-loaded magneto-rheological fluid (MR in short) damper-mount is presented. The proposed damper-mount is designed based on two modes of MR fluid such as flow mode and shear mode, and it includes two separated electric coil for establishing magnetic field. The damping force of the damper-mount is analyzed based on the difference pressure between upper chamber and lower chamber. After analyzing the mathematical function of damping force, the proposed mount is optimized following the maximal damping force by using ANSYS software. Besides, there is a laboratorial MR fluid using in this optimization such as plate-like fluid MRF140. Results of optimization show that the requirement of damping force is obtain and the saturation of materials is in range of limitation.
In this paper, a damage detection method based on a combination of wavelet analysis and an interval type-2 fuzzy logic system (IT-2FLS) is proposed. Firstly, synthesizing IT-2FLSs as a data-driven model is proposed. The structure is then divided into elements and excited to be vibrated to measure vibration signal. Average quantity signal of wavelet transform coefficient (AQWTC) of vibration signal with a used-scale-sheet is established. The IT-2FLS is utilized to identify the structure at its undamaged time via AQWTC signal. At each surveying time, AQWTC at each element is calculated to estimate difference of corresponding AQWTCs between two cases: undamaged status and the status at the checked time. By applying the AQWTC’s contrast at two these times, a damage coefficient is described which is used to estimate status of the structure. Besides, in order to predict structure’s status, the time-series prediction using the IT-2FLS and the calculated damage coefficient are also presented. The effectiveness of the proposed method is demonstrated by experiment via data sources measured from dynamic response of a real structure.
In this paper, a new type of magnetorheological fluid (MRF) mount is proposed. This design is based on the well-known of two modes of MRF such as flow mode and shear mode. These modes are applied in the design which includes two components: MR mount for controlling vertical vibrations, and MR brake for controlling horizontal vibrations. The structure of MR valve is applied in design mount part, while the disk type of structure is employed in design brake part. These structures contribute to the initial requirements such as small structure, high damping force and high braking force. The theoretical analysis for the design is undertaken followed by design optimization using ANSYS ADPL software. The objective functions are concentrated on maximal damping force for MR mount and maximum braking force for MR brake. As traditional design, rubber mount is used in the proposed design for suffering static loads. It has been shown through computer simulation that the initial requirements with high damping force and high braking force have been successfully achieved.