Energy Dissipation of Damper Rings for Thin-Walled Gears

2019 ◽  
Author(s):  
Zichao Li ◽  
Yanrong Wang ◽  
Xianghua Jiang ◽  
Hang Ye ◽  
Weichao Yang
Keyword(s):  
Energy Dissipation ◽  
Contact Surface ◽  
Strain Difference ◽  
Damping Ratio ◽  
Harmonic Balance Method ◽  
Axial Direction ◽  
Relative Displacement ◽  
Axial Displacement ◽  
Hysteresis Curve ◽  
Thin Walled

Abstract When the gear generates a nodal mode shape vibration, there are two directions of possible relative displacement between the corresponding points on the contact surface of the damper ring and the damper groove, which are circumferential direction and axial direction respectively. In this paper, the relative displacement of the damper ring and the damper groove are considered in two directions, and the calculation method of energy dissipation is proposed. When the nodal vibration occurs in the gear, due to the existence of the strain difference between the damper ring and the damper groove on the contact surface, circumferential slip of partial area would occur. The energy dissipation in one vibration cycle is accurately determined by analytical solution. Since the aviation gears are mostly thin-walled structures, the axial displacement is large when resonance occurs. Based on the discrete damper ring model which considers interaction between every segment of the ring, the first-order harmonic balance method is used to calculate the axial displacement of the damper ring under the given gear rim amplitude. And then the hysteresis curve area of each discrete segment on the contact surface is summed to obtain energy dissipation in one vibration cycle. In this paper, based on the energy method, the damping effect of the damper ring is predicted. The damping ratio curve obtained by energy dissipation in two directions is compared and analyzed. The occurrence conditions of the two directions of possible relative displacement and the influence of the damper ring parameters on both situations are summarized.

scholarly journals Design and Experimental Study on Shock-Absorbing Steel Bar with Limit Function for Bridges

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Zhaoguang Li ◽  
Ri Gao ◽  
Wei Jia
Keyword(s):  
Energy Dissipation ◽  
Damping Ratio ◽  
Hysteresis Curve ◽  
Limit Function ◽  
Viscous Damping ◽  
Initial Stiffness ◽  
Equivalent Viscous Damping ◽  
Steel Bar ◽  
Steel Bars ◽  
Equivalent Viscous Damping Ratio

The existing research on shock-absorbing steel bars is only limited to simply supported beam bridge. In order to expand the application of shock-absorbing steel bars to other fields, this paper develops a novel shock-absorbing steel bar with limit function, and it is suitable for continuous beam bridges. The structure and working mechanism of the shock-absorbing steel bar are analyzed. Three sets of specimens of the shock-absorbing steel bar are fabricated and then repeatedly loaded by the designed quasistatic loading device, in order to investigate their seismic performance parameters, including hysteresis curve, skeleton curve, and initial stiffness and equivalent viscous damping ratio. The results show that when the displacement of the specimen exceeds the initial gap, it enters the stage of energy dissipation and has a stable hysteresis curve and good fatigue resistance. Besides, the shock-absorbing device has a high initial stiffness and can provide stable bearing capacity after yielding. The equivalent viscous damping ratio reflects that the designed shock-absorbing steel bar has good energy dissipation capacity.

Experimental Study on the Effect of Moisture Content on Hysteretic Behavior of Reinforced Concrete Columns

2018 ◽  
Vol 12 (1) ◽  
pp. 47-61
Author(s):  
Wenjuan Lv ◽  
Baodong Liu ◽  
Ming Li ◽  
Lin Li ◽  
Pengyuan Zhang
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Moisture Content ◽  
Early Stage ◽  
Damping Ratio ◽  
Concrete Columns ◽  
Hysteretic Behavior ◽  
Cyclic Test ◽  
Experimental Result ◽  
Reinforced Concrete Columns

Background: For reinforced concrete structures under different humid conditions, the mechanical properties of concrete are significantly affected by the moisture content, which may result in a great change of the functional performance and bearing capacity. Objective: This paper presents an experiment to investigate the influence of the moisture content on the dynamic characteristics and hysteretic behavior of reinforced concrete column. Results: The results show that the natural frequency of reinforced concrete columns increases quickly at an early stage of immersion, but there is little change when the columns are close to saturation; the difference between the natural frequencies before and after cyclic test grows as the moisture content rises. The damping ratio slightly decreases first and then increases with the increase of moisture content; the damping ratio after the cyclic test is larger than before the test due to the development of the micro-cracks. Conclusion: The trend of energy dissipation is on the rise with increasing moisture content, although at an early stage, it decreases slightly. According to the experimental result, a formula for the moisture content on the average energy dissipation of reinforced concrete columns is proposed.

Analysis of Vibration Caused by Electromagnetic Force on Stator End-Winding of Large Dry Submersible Motor

2013 ◽  
Vol 416-417 ◽  
pp. 428-432
Author(s):  
Li Shan ◽  
Xiao Wei Cheng ◽  
Yong Fang ◽  
Xiao Hua Bao
Keyword(s):  
Electromagnetic Field ◽  
Steady State ◽  
Transition State ◽  
Electromagnetic Force ◽  
Radial Displacement ◽  
Radial Direction ◽  
Axial Direction ◽  
Axial Displacement ◽  
Force Density ◽  
Submersible Motor

This paper investigates the vibration which caused by electromagnetic on the stator end-winding of the large dry submersible motor. Firstly, the electromagnetic field which included transition state and steady state is researched by 3-D FEM. Secondly, the electromagnetic force which lead to vibrations of end-winding is calculated by numerical method, it can be obtained that where endured the largest force density along the slant part of end-winding. Finally, the radial displacement and the axial displacement of the slant part which caused by vibrations is studied, the analysis results show that the axial displacement is larger than the amplitude of radial displacement. It indicates that the slant part of end-winding will be more easily damaged at axial direction than radial direction.

scholarly journals Estimation of Additional Equivalent Damping Ratio of the Damped Structure Based on Energy Dissipation

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Xiuyan Hu ◽  
Qingjun Chen ◽  
Dagen Weng ◽  
Ruifu Zhang ◽  
Xiaosong Ren
Keyword(s):  
Energy Dissipation ◽  
Damping Ratio ◽  
Theoretical Concept ◽  
Estimation Methods ◽  
External Excitation ◽  
Single Degree Of Freedom ◽  
Equivalent Damping ◽  
Seismic Motion ◽  
Practical Engineering ◽  
Energy Dissipation Capacity

In the design of damped structures, the additional equivalent damping ratio (EDR) is an important factor in the evaluation of the energy dissipation effect. However, previous additional EDR estimation methods are complicated and not easy to be applied in practical engineering. Therefore, in this study, a method based on energy dissipation is developed to simplify the estimation of the additional EDR. First, an energy governing equation is established to calculate the structural energy dissipation. By means of dynamic analysis, the ratio of the energy consumed by dampers to that consumed by structural inherent damping is obtained under external excitation. Because the energy dissipation capacity of the installed dampers is reflected by the additional EDR, the abovementioned ratio can be used to estimate the additional EDR of the damped structure. Energy dissipation varies with time, which indicates that the ratio is related to the duration of ground motion. Hence, the energy dissipation during the most intensive period in the entire seismic motion duration is used to calculate the additional EDR. Accordingly, the procedure of the proposed method is presented. The feasibility of this method is verified by using a single-degree-of-freedom system. Then, a benchmark structure with dampers is adopted to illustrate the usefulness of this method in practical engineering applications. In conclusion, the proposed method is not only explicit in the theoretical concept and convenient in application but also reflects the time-varying characteristic of additional EDR, which possesses the value in practical engineering.

A Family of Efficient Sloshing Liquid Dampers for Suppression of Wind-Induced Instabilities

2003 ◽  
Vol 9 (3-4) ◽  
pp. 361-386 ◽  
Author(s):  
V. J. Modi ◽  
A. Akinturk ◽  
W. Tse
Keyword(s):  
Energy Dissipation ◽  
High Efficiency ◽  
Damping Ratio ◽  
Real Life ◽  
Wind Tunnel Test ◽  
Tall Buildings ◽  
Two Phases ◽  
Liquid Dampers ◽  
Obstacle Geometry ◽  
Floating Particles

Bluff structures in the form of tall buildings, smokestacks, control towers, bridges, etc., are susceptible to vortex resonance and galloping type of instabilities. One approach to vibration control of such systems is through energy dissipation using sloshing liquid dampers. In this paper we focus on enhancing the energy dissipation efficiency of a rectangular liquid damper through the introduction of two-dimensional obstacles as well as floating particles. The investigation has two phases. To begin with, a parametric free vibration study aimed at the optimization of the obstacle geometry is undertaken to arrive at configurations promising increased damping ratio and hence higher energy dissipation. The study is complemented by an extensive wind tunnel test program, which substantiates the effectiveness of this class of damper in suppressing both vortex resonance and galloping type of instabilities. Simplicity of design, ease of implementation, minimal maintenance, reliability as well as high efficiency make such liquid dampers quite attractive for real-life applications.

Nonlinear Dynamics of One-Way Clutches in Belt-Pulley Systems

2003 ◽  
Author(s):  
Farong Zhu ◽  
Robert G. Parker
Keyword(s):  
Nonlinear Dynamics ◽  
Degrees Of Freedom ◽  
Piecewise Linear ◽  
Primary Resonance ◽  
Harmonic Balance Method ◽  
Excitation Amplitude ◽  
Relative Displacement ◽  
Second Primary ◽  
Arc Length ◽  
The One

One-way clutches are frequently used in the serpentine belt accessory drives of automobiles and heavy vehicles. The clutch plays a role similar to a vibration absorber in order to reduce belt/pulley vibration and noise and increase belt life. This paper analyzes a two-pulley system where the driven pulley has a one-way clutch between the pulley and accessory shaft that engages only for positive relative displacement between these components. The belt is modeled with linear springs that transmit torque from the driving pulley to the accessory pulley. The one-way clutch is modeled as a piecewise linear spring with discontinuous stiffness that separates the driven pulley into two degrees of freedom (DOF). The harmonic balance method (HBM) combined with arc-length continuation is employed to illustrate the nonlinear dynamic behavior of the one-way clutch. HBM with arc-length continuation yields the stable and unstable periodic solutions for given parameters. These solutions are examined across a range of excitation frequencies. The results are confirmed by numerical integration and the widely used bifurcation software AUTO. At the first primary resonance, most of the responses are aperiodic, including quasiperiodic and chaotic solutions. At the second primary resonance, the peak bends to the left with classical softening nonlinearity because clutch disengagement decouples the pulley and the accessory over portions of the response period. The dependence on system parameters such as clutch stiffness, excitation amplitude, and inertia ratio between the pulley and accessory is studied to characterize the nonlinear dynamics across a range of conditions.

scholarly journals Development Behavior for Post-Tensioned Self-Centering Steel Connection under Cyclic Loading

2017 ◽  
Vol 3 (3) ◽  
pp. 152-159
Author(s):  
Ahmadreza Torabipour ◽  
M. R. Shiravand
Keyword(s):  
Energy Dissipation ◽  
Numerical Models ◽  
Perfect Match ◽  
High Strength ◽  
Relative Displacement ◽  
Initial Stiffness ◽  
Validation Parameters ◽  
Steel Connection ◽  
Energy Dissipation Capacity ◽  
Post Tensioned

One of the newest steel beam-column joints to replace conventional welded connections, post-tensioned connection steel is with the upper and lower angles. In this connection are high-strength steel strands that parallel beam web and angles between beams and column. Actually high resistance strands and upper and lower angles respectively are provider centralization properties and energy dissipation capacity of the connection. The benefits of post-tensioned steel can be used in connection with the centralization and lack of relative displacement (drift) persistent, stay elastic core components such as connecting beams, columns and fountains connection, appropriate initial stiffness and joint manufacture with materials and traditional skills. . In this study, numerical modelling in Abaqus software, the results of the analysis were compared with the results of laboratory samples and the results showed that the two together are a perfect match. After validation, parameters influential centrist connection then pulled the thick angles in three numerical models were evaluated.  The results show that by increasing the thickness of the angles, increase energy dissipation capacity and ductility connection and the β₁ value does not experience tangible changes with changes in angle thickness.

scholarly journals Study of Mechanical Energy Dissipation by Normal and Decalcified Animals Bones

2019 ◽  
Vol 16 (1) ◽  
pp. 113-119
Author(s):  
Abdul Rauf ◽  
Syed Ismail Ahmad
Keyword(s):  
Energy Dissipation ◽  
Viscoelastic Properties ◽  
Applied Load ◽  
Mechanical Energy ◽  
Maximum Energy ◽  
Hysteresis Curve ◽  
Normal Bone ◽  
Dissipation Of Energy ◽  
Mechanical Energy Dissipation ◽  
Energy Dissipated

The energy dissipated properties of normal and decalcified femur, rib and scapula bones of animals ox and camel have been studied by uniform bending technique. A hysteresis curve has been observed between the elevation in bone and load applied. It is observed that the energy dissipated as calculated from the hysteresis loop for rib is more than that of femur and scapula of ox and camel. It has been observed that the dissipation of energy in normal bone is less than that of decalcified bone under the same condition of applied load. The highest energy dissipation was observed in case of rib bone of camel compared to that of any other bone, rib of camel and scapula of ox dissipates maximum energy than femur bones. The study suggests that this technique is simple, elegant and inexpensive besides accurate in determining viscoelastic properties of bone.

Shock isolation characteristics of a bistable vibration isolator with tunable magnetic controlled stiffness

2021 ◽  
pp. 1-28
Author(s):  
Bo Yan ◽  
Peng Ling ◽  
Yanlin Zhou ◽  
Chuan-yu Wu ◽  
Wen-Ming Zhang
Keyword(s):  
Damping Ratio ◽  
Excitation Amplitude ◽  
Relative Displacement ◽  
Vibration Isolator ◽  
Maximum Acceleration ◽  
Vibration Isolators ◽  
Displacement Ratio ◽  
Shock Isolation ◽  
Maximum Relative Displacement ◽  
Isolation Performance

Abstract This paper investigates the shock isolation characteristics of an electromagnetic bistable vibration isolator (BVI) with tunable magnetic controlled stiffness. The theoretical model of the BVI is established. The maximum acceleration ratio (MAR), maximum absolute displacement ratio (MADR) and maximum relative displacement ratio (MRDR) are introduced to evaluate the shock isolation performance of the BVI. The kinetic and potential energy are observed to further explore the performance of the BVI. The effects of the potential barrier, shape of potential well, damping ratio on the BVI are discussed compared to the linear vibration isolators (LVI). The results demonstrate that the intrawell oscillations and snap-through oscillations are determined by the excitation amplitude and duration time of main pulse. MADR and MRDR of the BVI are smaller than those of the LVI. The maximum acceleration peak amplitude of the BVI is far below that of the LVI, especially when the snap-through oscillation occurs. In brief, the proposed BVI has a better shock isolation performance than the LVI and has the potential to suppress the shock of space structures during the launch and on-orbit deploying process.

Numerical Impact Analysis of Folding-Induced Tubular Thin-walled Energy-dissipating Elements

2021 ◽  
Vol 62 (2) ◽  
pp. 82-92
Author(s):  
Eugenio Ruocco ◽  
Antonia Giovenale ◽  
Danilo Di Giacinto
Keyword(s):  
Energy Dissipation ◽  
Impact Analysis ◽  
Impact Resistance ◽  
Impact Angle ◽  
Galvanized Steel ◽  
Absorption Mechanism ◽  
Induced Folding ◽  
Cold Formed Steel ◽  
Thin Walled ◽  
Scale Experiment

This paper deals with the numerical impact analysis of tubular thin-walled steel-made elements with induced folding for energy dissipation application. The excellent deceleration of the impacting mass of axial collapsing structures favors their use in energy dissipation applications, such as impact resistance and rockfall protection. Dynamic Finite Element analyses have been carried out to evaluate the performance of vertical assemblies of cold-formed steel cell-shaped elements welded on each other to form collapsible tubular elements. In turn, these have been gathered in groups and restrained by galvanized steel wires to create modules. The axial collapse, which is the most effective energy absorption mechanism, has been triggered by shaping the elements' edge as serpentine. In the analysis, several assembly configurations have been subjected to a freefall rhombicuboctahedron-shaped rigid block impact; Falling height, impact angle, and block mass have been varied to investigate their effect on the performance. The numerical results show a good agreement when compared to those obtained through a real-scale experiment.

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