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To achieve less than 50 N soft-landing using magneto-rheological fluid (MRF) damper, a novel small-MRF damper has been developed. First, we design a new outer electromagnetic coil comparing with traditional inner coil structure, which can obtain miniature damper easily and control the magnetic field conveniently. Second, we apply silicon steel rath...
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Context 1
... obtain soft-landing characteristics of the MRF damper, a test-bed was established as shown in Fig. 2. The test-bed consists of pressure sensor, data acquisition card, current con- troller, motion guide and controller, and computer system. The MRF damper was fixed on the motion guide. When the guide moves at a certain speed, the MRF damper hits pressure sen- sors. Pressure sensor is YDL-1H piezoelectric force sensor made in China, ...
Context 2
... performance. The rea- son is that magnetization effect of MRF is in a gradual state with linear current, which is dynamically coupled with mechanical movement, thereby eliminating the impact. In order to confirm the effectiveness of the proposed approach, we compared our testing results with that of the tra- ditional MRF damper as shown in Fig. 20. It indicates that the new MRF damper can achieve 50 N or less loading force com- paring to 100 N or above loading force from traditional method (when the current is set to 0.2 and 0.4 A, which are driven by a constant current source, loading force of traditional method is 102 and 130 N, respectively, and impact force reaches to 135 ...
Citations
... Bouc Wenn model and Hyperbolic Tangent model parameters give a detail account about post yield behaviour of MRD [16]. When a MR Fluid undergoes shear deformation during seismic application, Shear thinning, and shear thickening will occurs [17]. Due to this inaccurate prediction of Damper force at higher velocities may occur. ...
... Exposing to a magnetic field, MRF fluid exhibits changing viscosity and thus, provides a damping force to the element. In micro-level, applying a magnetic field to the MRF polarizes the ferromagnetic particles and form chain-like links in the carrier fluid [11][12][13][14]. This phenomenon leads to a fast reaction in fluid viscosity in the order of milliseconds. ...
The stability and integrity of structures under indeterminant external loadings, particularly earthquakes, is a vital issue for the design and safe operation of marine and offshore structures. Over the past decades, many structural control systems, such as viscous-based systems, have been developed and embedded in marine and offshore structures, particularly oil platforms to maintain the stability and mitigate the seismic hazards. Rapid improvement in intelligent materials, including shape memory alloys (SMAs) and Magnetorheological fluid (MRF), have led to the design and development of efficient structural control elements. The present work aims to establish a framework for the structural control element in which the controllability of magnetorheological fluid and su-perelasticity effect of shape memory alloy have been combined to generate a new structural control element with an ability to dissipate a significant amount of energy while controlling the inter-element displacement in marine structures. The dynamic responses of a simplified 2DOF structure equipped with structural control elements have been conducted using the Open System for Earthquake Engineering Simulation (OpenSees). A comparison between the present SMA-MRF-based and the viscous-based systems has been performed. IIt is seen that the activated SMA-MRF-based control system in a wide range of the loading frequency spectrum decreases the maximum inter-story displacements of the frame as well as drift ratios. A comparison between the most common stability control element and the present system for seismic conditions has been conducted.
... Some studies on smaller MR dampers have been included in the Refs. [26][27][28][29]. ...
This study proposes a model for describing magnetorheological (MR) fluid dynamic behavior. Experimental research was conducted to validate the model that represents the dynamic behavior of the MR fluid. MR fluid composed of 35 % carbonyl iron and 65 % silicon oil was used. In the experimental setup, sinusoidal excitation was applied to MR fluid under various frequencies while applying various currents, and the experimental data, including displacement, velocity, time and force, were recorded. Proposed model was described and details of the model explained. Force was predicted from the model by using computer software and approximated to experimental force. The error between the predicted results from the model and the measured data was calculated. After the experiments and optimization, the proposed model was compared with extended Bingham and viscoelastic-plastic models. After the analysis, it was seen that the proposed model coincides with other models in the literature. This novel model is practical to use in many engineering applications.
... The total damping force could be decomposed into a controllable force due to the controllable yield stress , an uncontrollable force , and a friction [25,26]. According to the parallel-plate Bingham model [27,28], the damping force of the MRF damper can be expressed as ...
Magnetorheological fluid (MRF) damper is one of the most promising semiactive devices for vibration control. In this paper, a shear-valve mode MRF damper for pipeline vibration control is proposed. The dynamic model and the state equation of the pipeline are established and the linear quadratic regulator (LQR) is used to generate the optimal damping force of MRF damper. The design concept considering the structure and the electromagnetic properties simultaneously is discussed in detail. A mathematical model of the relation between shear stress and control current based on interpolation method is established. Finite element analysis (FEA) software COMSOL is selected to simulate the magnetic field and electromagnetism-thermal field of the MRF damper. A computational method based on the simulation model is established to calculate the shear stress. In order to reduce the magnetic leakage, a method of adding magnetism-insulators at both ends of the piston head is presented. The influence of control current, displacement, and velocity on mechanical performance of the proposed MRF damper is experimentally investigated. The test results show that the performance of the MRF damper is basically identical with the theoretical prospective and the simulation conclusions, which proves the correctness and feasibility of this design concept.
... The superhydrophobic surface is expected to be an adaptable and efficient method for reducing human labor and saving water during the cleaning of MR fluid, and may have potential of applications in the precise analysis of complex suspensions. electromagnetic recoil damping systems [1][2][3]. Besides, the MR fluid mixed with abrasive particles can be used as a working medium in magnetorheological finishing (MRF) which is a damage-free machining process applied in optical lens manufacturing [4,5]. However, MR fluid is a non-colloidal suspension system which consists of dispersion ...
Magnetorheological (MR) fluid is a well-established controllable smart material for fabricating electromagnetic functional components and for magnetorheological finishing. However, the water and labor consumption in cleaning work could seriously reduce its efficiency. Superhydrophobic surface has been widely used in self-cleaning applications owing to its excellent anti-wetting property. In this work, superhydrophobic surface was adopted to prevent the microparticles from adhering to the solid surface, in order to realize the easy washing of MR fluid. The superhydrophobic surface showed water-repellency when MR fluid contact angles exceeded 150°. The bouncing phenomena of the MR fluid were observed even though the carbonyl iron powders concentration was up to 70 vol%. Additionally, the mechanical durability and robustness of prepared surface were satisfactory during the sandpaper polishing process and MR fluid wear tests. Moreover, excellent self-cleaning properties can be obtained by changing micropowders scale from millimeter to nanometer and MR fluid—a complex suspension system. The superhydrophobic surface is expected to be an adaptable and efficient method for reducing human labor and saving water during the cleaning of MR fluid, and may have potential of applications in the precise analysis of complex suspensions.
... acing with the global, customer driven, and dynamic market, wafer manufacturers have to keep high on-time delivery to keep high reputation as original equipment manufacturers [1,2]. The wafer foundry must evaluate if the order can be fulfilled before the due date expected by the customer. ...
Accurate prediction of cycle time (CT) plays an important role in the promises of a good delivery-time for semiconductor manufacturers. However, the CTs of wafer lots are difficult to forecast since they are influent by a lot factors (e.g. workload for every machine). The identification of key factors (called CT-related) can not only improve the prediction performance, but also facilitate the control of CT, which is of particular significance. This paper focuses on gathering subtle variables into the candidate variables set along with the further analysis which is required in the correlation analysis between various candidate factors and CTs of wafer lots. The candidates set is first constructed to collect all factors that may affect wafer lots’ cycle time. Then, a regression-based model is proposed to select CT-related variables, which consists of three parts: Discretization, adaptive logistic regression-based correlation analysis, and CT-related factor selection. Subsequently, a parallel computation model is implemented to forecast the CTs of wafer lots. In the numerical experiments, 108 CT-related factors stood out from 774 candidates and replaced 6 global factors (used as reference) to predict CTs of wafer lots. The results indicated that the proposed approach had higher accuracy than linear regression and BPN in CT forecasting in large scale data analysis. IEEE
... Li and Thoroddsen (2013) experimentally studied the factors affecting the climbing velocity and found that the speed of the fastest droplets is limited by inertia following their emergence at the cone tip; further, Guo and Tang (2015) experimentally found that cactus spines can transport the liquid droplet upward with a maximum velocity of approximately 1.17 m/s. Being able to eventually design, optimize using simulation models, and fabricate tapered pillars with similar functionality is essential to large-scale fabrication (Chu and Liu 2008;Madou 2011;Li et al. 2015). ...
Directional liquid transport has significant domestic and industrial applications. Theoretically, tapered objects can transport a liquid droplet horizontally or along a small slant angle: Many biomaterials have already demonstrated this ability. However, spontaneously transporting liquid in the vertical direction has been challenging. In this study, a numerical model was developed to simulate the transporting process and design inverted tapered pillars. The range of acceptable parameters for the pillar’s geometry was obtained. When the taper angle, the diameter of the bottom end of the pillar, and the contact angle of the liquid are less than 10°, 80 μm, and 54.5°, respectively, then liquid may be transported upward spontaneously. An experimental setup for fabricating the pillars was also developed and presented. With this setup, the designed pillars were successfully fabricated by the gradient electrochemical corrosion method and enhanced its wettability by the electrochemical modification method. The fabricated pillars were then experimentally validated, showing that they can spontaneously transport a micrometer-scale droplet upward. These results may provide a new and systematic way to design and fabricate a tool for high-efficiency liquid transport.
... Microelectronics packaging technology is the leading industry in the microelectronics, moreover, high-speed dispensing technology is the key to realize the industrialization [1][2][3][4][5]. Based on the advancing requirement of dispensing precision and dispensing efficiency, the dispensing technology has been changed from the traditional contact dispensing to non-contact jetting dispensing, which has a series of advantages such as no vertical displacement, wide dispensing range and high efficiency [6][7][8][9][10][11]. ...
... With the development of microsystems and micro-machine, new demand of microminiature damping device is generated. [10][11][12][13] For example, bonding pressure of microelectronics packaging equipment needs to be applied to the stable load of 5N, [14][15][16][17][18] and damping force of micro-mechanical damping system is only 20N. 19,20 Recently, some small MRF dampers are developed, such as the RD-1097-01X damper is the smallest commercial damper, whose force is still 100N. ...
In order to realize small loading and small damping, a mini Magneto-rheological fluid (MRF) damper is suggested by using new method of outer coils, and its physical model is established firstly. It was found that the landing force is only 1.74∼8N, the landing force is the third-order function with the current by polynomial fitting of the experimental data, which shows a force-current model. The results of force-displacement and force-velocity indicate that it has nonlinear hysteretic damping characteristics. Based on the new mini-mode principle and the damping characteristics, an improved nonlinear dynamics model is proposed, and its parameter expressions are obtained by parameter identification and regression fitting. Model curves fit well with experimental curves, and the improved model has fully demonstrated the dynamic characteristics of the mini-MRF damper. It will provide scientific method and physical model for the small MRF damper development.
... TSV technology presents a number of significant advantages compared with previous packaging technologies, such as better performance, lower power consumption, lower cost, smaller size and more functionality of future electronic products [6][7][8]. TSV based 3D IC packaging mainly consists of via formation, via filling, wafer thinning and chip stacking [9][10][11][12], and Cu is one of the most commonly used materials to fill TSV [13][14][15][16]. Due to large mismatch in the Coefficient of Thermal Expansion (CTE) between Cu via and Si substrate of TSV, significant thermal stress will be induced under the thermal load [17,18]. ...
