Study on the Air Damping of the Movable Armature

2013 ◽  
Vol 562-565 ◽  
pp. 1397-1401
Author(s):  
Ben Dong Liu ◽  
Jia Hui Yang ◽  
Yu De Wu
Keyword(s):  
Mathematical Model ◽  
Mean Free Path ◽  
Air Gap ◽  
Damping Coefficient ◽  
Mems Devices ◽  
Damping Force ◽  
Small Vibration ◽  
Damping Characteristics ◽  
Air Damping ◽  
The Mathematical Model

The distance of air gap is much larger than the mean free path of gas molecules for MEMS devices with small vibration. The nonlinear Reynolds equation can be transformed into linear Reynolds Eq. based on this condition and under certain assumptions. Then the mathematical model of damping of the movable armature is established with the linear Renault equation. The damping characteristics of the movable armature are studied based on the damping force mathematical model. The relation of damping coefficient and the dimensions of movable armature, the dimensions of air gap are analyzed. The research in this paper provides references for the design and analysis of the damping coefficient of the MEMS devices with small vibration.

Damping characteristics of a magneto-rheological damper with dual independent controllable ducts

2021 ◽  
pp. 1045389X2110188
Author(s):  
Jianqiang Yu ◽  
Xiaomin Dong ◽  
Tao Wang ◽  
Zhengmu Zhou ◽  
Yaqin Zhou
Keyword(s):  
Dynamic Range ◽  
Fluid Flows ◽  
Mr Damper ◽  
Viscous Damping ◽  
The Novel ◽  
The Finite Element Method ◽  
Damping Force ◽  
Damping Characteristics ◽  
Magneto Rheological ◽  
The Mathematical Model

This paper presents the damping characteristics of a linear magneto-rheological (MR) damper with dual controllable ducts based on numerical and experimental analysis. The novel MR damper consisting of a dual-rod cylinder system and a MR valve is used to reduce the influences of viscous damping force and improve dynamic range. Driven by the dual-rod cylinder system, MR fluid flows in the MR valve. The pressure drop of the MR valve with dual independent controllable ducts can be controlled by tuning the current of two independent coils. Based on the mathematical model and the finite element method, the damping characteristics of the MR damper is simulated. A prototype is designed and tested on MTS machine to evaluate its damping characteristics. The results show that the working states and damping force of the MR damper can be controlled by the two independent coils.

Dynamic Modelling and Analysis of Rectangle-Shaped Plastic-Coated Slideways in Machine Tools

2011 ◽  
Vol 50-51 ◽  
pp. 37-41
Author(s):  
Jian Fu Zhang ◽  
Zhi Jun Wu ◽  
Ping Fa Feng ◽  
Ding Wen Yu
Keyword(s):  
Mathematical Model ◽  
Machine Tools ◽  
Vibration Mode ◽  
Dynamic Modelling ◽  
Rigid Bodies ◽  
Theoretical Research ◽  
Damping Characteristics ◽  
Vibration Properties ◽  
Stiffness And Damping ◽  
The Mathematical Model

The plastic-coated slideways have been widely used for form-generating movement in machine tools. Its dynamic behavior plays an important role in the vibration properties of the whole machine. In this work, according to the situation that researches on this subject were rather insufficient, a theoretical research was analyzed concerning the stiffness and damping characteristics of rectangle-shaped plastic-coated slideways. The mathematical model was firstly suggested especially based on the assembly of the saddle and worktable. Both stiffness and damping characteristics on vertical and horizontal directions were theoretically determined. To derive the governing motion equation of the slideway system, the carriage and rail were considered as rigid bodies and connected with a series of spring and damping elements at the joint face. Moreover, through the Lagrange’s approach, the frequencies of the carriage at vertical, pitching, yawing and rolling vibration mode were identified.

Research on Damping Properties of Seperated and Manually Adjustable Shock Absorber Oriented to Damping Matching

2013 ◽  
Vol 694-697 ◽  
pp. 36-40 ◽  
Author(s):  
Da Feng Song ◽  
Gong Ke Yang ◽  
Chun Xiao Du
Keyword(s):  
Mathematical Model ◽  
Structural Changes ◽  
Shock Absorber ◽  
Structural Parameters ◽  
Characteristic Curve ◽  
Bench Test ◽  
Damping Properties ◽  
Damping Characteristics ◽  
Test Use ◽  
The Mathematical Model

On the basis of the structure characteristics of the seperated manually adjustable damper and its working principles, establish the shock absorber mathematical model, at the same time, get test data and curves of seperated manually adjustable shock absorber damping characteristics by bench test. Use MATLAB to simulate the characteristic curve of the speed of the shock absorber based on the mathematical model. The simulation curves and experimental curves were compared to verify the correctness and accuracy of the model. Further simulation and analysis affect of parts of structural changes on the damping characteristics. In order to provide a theoretical basis to structural parameters designing and vehicle damping matching.

scholarly journals A High-Efficiency Energy Harvesting By Using Hydraulic Electromagnetic Regenerative Shock Absorber

2020 ◽  
Author(s):  
Muhammad Yousaf Iqbal ◽  
Zhifei Wu ◽  
Khalid Mahmood
Keyword(s):  
Mathematical Model ◽  
Energy Harvesting ◽  
Shock Absorber ◽  
Mechanical Energy ◽  
Excitation Frequency ◽  
National Standard ◽  
Damping Force ◽  
Damping Characteristics ◽  
Simulation Results ◽  
Regenerative Shock Absorber

Abstract This article intends a hybrid energy harvesting shock absorber design which comprehends energy harvesting of automobile suspension vibration dissipation. A mathematical model of the energy harvesting prototype is established, and simulation results show that the dissipation energy can be recovered by varying the feed module, thereby got the damping forces ratio at different compression and extension stroke. The energy conversion from hydraulic energy to mechanical energy mainly then mechanical energy converted into electrical energy furthermore we can rechange our battery from this recovered energy. The advanced mathematical model and prototype proposed maximum ride comfort meanwhile recovered the suspension energy and fuel saving. This article shows the simulation results verifying it with prototype test results. The damping force of expansion stroke is higher than the damping force of compression stroke. The damping characteristics curves and speed characteristics curves verify the validity by simulation and prototyping damper at different amplitudes of off-road vehicles. The Hydraulic Electromagnetic Regenerative Shock Absorber (HESA) prototype characteristic is tested in which 65 watts recovered energy at 1.67 Hz excitation frequency. So, 14.65% maximum energy recovery efficiency got at 20 mm rod diameter and 8 cc/rev motor displacement. The damping characteristics of the HESA prototype examined and it has ideal performance as the standard requirements of the National Standard QC/T 491–1999.

A new type of damper combining eddy current damping with rack and gear

2020 ◽  
pp. 107754632093711
Author(s):  
Yafeng Li ◽  
Shouying Li ◽  
Jianzhong Wang ◽  
Zhengqing Chen
Keyword(s):  
Eddy Current ◽  
Permanent Magnets ◽  
Air Gap ◽  
Damping Coefficient ◽  
Apparent Mass ◽  
Damping Force ◽  
Equivalent Damping ◽  
Eddy Current Damping ◽  
New Type ◽  
Equivalent Damping Coefficient

A new type of damper combining eddy current damping with rack and gear, which can simultaneously export damping and inertial forces, is proposed. Eddy current damping with rack and gear is supposed to be installed between the building superstructure and foundation to mitigate the seismic response of the building. First, the concept of eddy current damping with rack and gear is introduced in detail and its apparent mass and equivalent damping coefficient are both theoretically investigated. Second, a prototype of eddy current damping with rack and gear is manufactured, and a series of tests on the prototype are carried out to verify its structural parameters. The experimental and theoretical results of the apparent mass of the prototype agree well with each other. The experimental result of the equivalent damping coefficient of the prototype is slightly lower than the numerical results obtained from COMSOL Multiphysics and its maximum relative differences are 11.3% and 13.6% for α = 0° and 45°, respectively. Third, detailed parametric studies on the damping force, including the effects of the thickness of the conductor plate, air gap, and number and location of permanent magnets, are conducted. The results show that the damping force keeps a linear relationship with velocity if it is lower than 0.15 m/s, and with the increase of the velocity, a strong nonlinear relationship between the damping force and the velocity is observed. The available maximum damping force can be increased by decreasing the thickness of the conductor plate and the air gap, increasing the number of permanent magnets. There is an optimal location about the permanent magnets for the available maximum damping force. In addition, the hysteretic curves of the eddy current damping with rack and gear obtained from the test indicate that the ability of energy dissipation is considerable.

Hysteretic damping characteristics of a mechanical tensioner: Modeling and experimental investigation

2018 ◽  
Vol 233 (7) ◽  
pp. 1890-1902 ◽  
Author(s):  
Hao Zhu ◽  
Yumei Hu ◽  
Yangjun Pi ◽  
Weidong Zhu
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Damping Characteristics ◽  
Hysteretic Damping ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
The Mathematical Model

The aim of this article is to investigate hysteretic damping characteristics of a typical tensioner used in engine accessory drive systems. An experiment device is developed to measure the friction coefficients of three contact pairs within the tensioner. Statistic results of test data show that the friction coefficient is linearly dependent on normal forces, and thus a linear function is used to describe it. An exact mathematical model and an accurate three-dimensional finite element model are proposed in this study to calculate the relationship of friction torque and rotation angle as well as the damping characteristics of the tensioner. The mathematical model and three-dimensional finite element model are verified through an experiment. Comparison indicates that both the mathematical and finite element model can accurately predict the working torque of the tensioner during operation process, while the finite element model has better accuracy in predicting the damping characteristics than the mathematical model.

The Mathematical Model of Crane Hoisting Mechanism

2013 ◽  
Vol 477-478 ◽  
pp. 315-320 ◽  
Author(s):  
Wei He ◽  
Zhe Kun Li ◽  
Zhen Yu Wang ◽  
An Liu
Keyword(s):  
Mathematical Model ◽  
Theoretical Basis ◽  
Theoretical Method ◽  
Virtual Prototype ◽  
Damping Coefficient ◽  
Stiffness Coefficient ◽  
Contact Type ◽  
Resistance Torque ◽  
Virtual Prototype Technology ◽  
The Mathematical Model

Established the mathematical model of hoisting mechanism based on the theory of vibration, through experimental and theoretical method obtained system stiffness coefficient, damping coefficient, finally calculated reel resistance torque. According to the mathematical model, the hoisting mechanism is simulated and analyzed by using virtual prototype technology, it provide a theoretical basis for design of non-contact type weighing sensor.

scholarly journals Modelling and Analysis of a Magnetorheological Damper with Nonmagnetized Passages in Piston and Minor Losses

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Guojie Li ◽  
Ze-Biao Yang
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Mr Damper ◽  
Magnetorheological Damper ◽  
Damping Force ◽  
Mr Fluid ◽  
Pressure Drops ◽  
Viscous Loss ◽  
Minor Losses ◽  
The Mathematical Model

This work aims to establish the mathematical model with the high effectiveness in predicting the damping force of an MR damper with nonmagnetized passages in piston. The pressure drops due to viscous loss, MR effect, and the minor losses at the inlet and outlet of passages are considered in the mathematical model. The widely reported Bingham model is adopted to describe the mechanical property of MR fluid. The mechanical behaviours of the MR damper are experimentally evaluated under different excitations and current. The yield stress of MR fluid with respect to the current applied to piston coil is obtained by finite element analysis in Ansoft Maxwell 14.0. The proposed model is validated by comparing the simulated damping characteristics with the measured data under various currents applied to the piston coil. The simulated results are also compared with those obtained from the mathematical model without the pressure drop due to the minor losses at the inlet and outlet of passages. The comparisons show that the proposed mathematical model can yield more accurate predictions of damping force. This indicates that the pressure drop due to the minor losses is significant and nonnegligible. The nonlinearity of force-velocity characteristics is discussed. In order to quantitatively explain the necessity of taking the minor losses into account for modelling the MR damper, the proportion of pressure drop due to the minor losses to the total pressure drop is investigated and discussed. Pressure drops due to the minor losses and viscous loss are also investigated and discussed. At last, the proposed mathematical model is used to analyse the working principle of nonmagnetized passages.

Dynamic Response of Two-Disk Systems With Friction and Misalignment

1998 ◽  
Author(s):  
Ahmed Anabtawi ◽  
Kambiz Farhang
Keyword(s):  
Mathematical Model ◽  
Dynamic Response ◽  
Contact Stiffness ◽  
Stick Slip ◽  
Torsional Response ◽  
Damping Characteristics ◽  
Disk Friction ◽  
Stiffness And Damping ◽  
The Mathematical Model ◽  
Friction Induced Vibration

Abstract Friction induced vibration and noise pose one of the most challenging problems. The complexity of the friction system arises due to the nonlinear nature of friction phenomena and that of contact stiffness and damping. This paper presents a mathematical model for studying the dynamic response of two-disk friction system in the presence of misalignment. The contact stiffness and damping characteristics of the system are represented in the axial as well as the torsional directions. In addition, the axial and torsional responses of the system are coupled by assuming dependency between the torsional response and the normal force between the two disks. Using the mathematical model, various scenarios are examined to study the effect of misalignment. These include cases of symmetric and asymmetric actuation forces as well as forces applied at unequal actuation times. The results suggest that asymmetry in actuation forces has negligible effect on stick-slip behavior of the system.

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