Fitrian Imaduddin

Fabrication and viscoelastic characteristics of waste tire rubber based magnetorheological elastomer

In this study, waste tire rubber (WTR) was successfully converted into magnetorheological (MR) elastomer via high-pressure and high-temperature reclamation. The physical and rheological properties of WTR based MR elastomers were assessed for performance. The revulcanization process was at the absence of magnetic fields. Thus, the magnetizable particles were allowed to distribute randomly. To confirm the particle dispersion in the MR elastomer matrix, an observation by scanning electron microscopy was used. The magnetization saturation and other magnetic properties were obtained through vibrating sample magnetometer. Rheological properties including MR effect were examined under oscillatory loadings in the absence and presence of magnetic fields using rotational rheometer. The WTR based MR elastomer exhibited tunable intrinsic properties under presentation of magnetic fields. The storage and loss modulus, along with the loss factor, changed with increases in frequency and during magnetization. Interestingly, a Payne effect phenomenon was seen in all samples during dynamic swept strain testing. The Payne effect was significantly increased with incremental increases in the magnetic field. This phenomenon was interpreted as the process of formation–destruction–reformation undergone by the internal network chains in the MR elastomers.

Simulation Studies of a New Magnetorheological Brake with Difference Gap Size Using Combination of Shear and Squeeze Mode

Magnetorheological (MR) brake contains magnetized particles, which are strong, fast and reversible transform in their rheological properties when applied the magnetic field. There are a few types of modes that have been working on in the fluid such as the shear mode, flow mode, squeeze mode and recently a new mode called the magnetic gradient pinch mode. Commonly, shear modes have been widely investigated and used in MR brakes. Nevertheless, limited focus has been given to the combination of shear and squeeze mode due to the design consideration in MR brake. This paper focuses on the design of MR brake with a difference of fluid gap rather than a single gap in one device by using both modes. In this work, a few design criteria are considered to select the basic automotive MR brake configuration such as material selection, MR fluid selection, working surface area, applied current density, and wire size. Then, a Finite Element Method in 2D simulation is performed to analyse the resulting magnetic circuit within the MR brake configuration. Moreover, the simulated results of the magnetic flux density in the MR fluid are used to predict the torque produced by the combination of shear and squeeze modes. It can be concluded that, the finite element simulation predictions show a good correlation between effect of the current and fluid gap.

Performance prediction of magnetorheological valves under various type of fluid and flux path

The Crude Palm Oil industry has now become the largest agricultural industry in Indonesia. Nevertheless, the growth of CPO industry could also bring negative impacts on the environment if the company does not control their emissions and discharges properly. Life-cycle Assessment (LCA) is one of the tools that can assess the environmental impacts due to CPO production activities. This study aims to assess the potential environmental impacts arising from the CPO production system at Mill J, PT XYZ, Sumatera Island by using Eco-indicator 99. Based on this study, in 2015, the process in plantation and mill contributed to climate change category was 0.013 DALY or after normalized 202 Pt. Meanwhile, the land use category has 395 PDF*m2yr or 30.8 Pt. Meanwhile, all of the other categories were less than 30.8 Pt, hence, the highest impact of this CPO production system is climate change at the activities in industrial estate (fertilizers usage) and industry (emitted from waste water of palm oil mill).Magnetorheological (MR) valve is one of the key components in regulating the control flow of MR fluid flow in MR devices. Due to MR rheological properties enabling magnetic modifications, many MR valve designs have been introduced and are widely utilized in MR devices. The main objective of this article is to compare the pressure drop generated by each types of MR valves. Five different configurations of MR valves were analyzed in this study. To provide a fair comparison, several parameters were fixed; which is the size of the MR valves, gap size, number of coil turns and power consumption. In order to demonstrate the MR valve performance, the pressure drops were calculated based on the mathematical equations derived from MR valve models and the magnetic fields derived from finite element method based software. The results of the simulations were compared to each type of MR valve and, then, discussed.

New Variable Stiffness Damper with Magnetorheological-Based Accumulator Control

This paper introduces a new design of variable stiffness damper using controlled accumulator filled with Magnetorheological (MR) fluids. The originality of the new design is in its capability to offer less consumption of MR fluids than the conventional design of MR damper. The new design does not fill the whole cylinder with MR fluids but only use the accumulator space as the volume compensation control zone with MR fluids. The MR fluids control the compressive movement of the accumulator piston which alter the flow of the hydraulic oil to the accumulator chamber. As a result, the regulated flow of oil to the accumulator chamber will only have a direct effect to the compression stiffness of the damper. The experimental results show that the proposed design is capable to adjust the compression force while maintaining the rebound force of the damper.

A Model of Magnetorheological Grease using Machine Learning Method

Magnetorheological (MR) grease is a promising material to replace MR fluid because the advantage in term of stability and less possibility to leaking. To improve the material properties, an accurate model can be critical for reducing the time and cost of the development process. A model has been developed to predict MR fluid material properties by including the composition. However, the model may need adjustment and cannot predict other essential rheology parameters, such as viscosity, apparent viscosity, shear rate, and shear stress. Therefore, the technical novelty of this paper is to propose a model with composition as one of the inputs using extreme learning machine method. A scoring system is also introduced to quantify the significance of the composition effect toward the MR grease performance. Then, the model is simulated and compared with experimental data. The performance shows high accuracy estimation with normalized root mean square error about 1.25%.

The Changed of Behaviour of MR Fluid in MR Damper after a Long-Term Operation

Magnetorheological (MR) fluid devices are now applied in various applications. Although a lot of studies have been discussed in long-term implementation of MR devices, only few studies have concerned on MR fluid application in valve operation mode, such as at MR valve. The experiments were conducted on a dynamic test machine in a custom MR damper with meandering MR valve. The experiment test was applied at continuous-load in long term-operation with parameters of 20 mm length of stroke, 0.4 Hz of frequency, 0.5 A of applied current and 175,000 cycles. The rheological properties of MR fluid were characterized using rotational and oscillatory shear rheometer. The result showed that the rheological properties of MR fluid changed after applied in long-term operation. The changed of MR fluid also investigated through morphological characteristics using SEM and EDX.

An investigation on the mitigation of end-stop impacts in a magnetorheological damper operated by the mixed mode

This paper presents mitigation behaviour of magnetorheological (MR) damper operated with a mixed working modes. A combination of the shear and squeeze modes is employed in the structure of MR damper to obtain the field-dependent normal yield stress as well as strengthen the squeeze effect. The experimental evaluation shows that when the piston is squeezing the bottom gap from the stroke of 25 to 26 mm, the sudden increase of squeeze force is observed confirming the existence of the mitigation effect. It is also observed that the magnitude of mitigation force is positively correlated with the magnitude of current given to the electromagnet. The measured peak mitigation forces are ranged from 722 N to 1032 N when the electromagnet currents are varied from 0.2 A to 0.8 A, respectively. The variable mitigation effect indicates that the concept can be further discussed as a potential impact protection feature in an MR damper.

Magnetorheological Fluid Characterization and Applications

This chapter provides an overview of the magnetorheological (MR) fluid characteristics especially its operational modes and its application on MR devices such as MR damper, valve, brake, clutch and mount. Four pure MR fluid operational modes and two types of mixed-modes of the MR fluid are explained. Each of these operational modes has a distinct characteristic than can be applicable for a specific system. We describe the structure design of the MR devices and their utilized operational modes. This chapter provides a good knowledge about the MR fluid characteristics and applications.