Experimental study and numerical simulation of inerter-based systems

2022 ◽  
pp. 107754632110573
Author(s):  
Yi-lin Zheng ◽  
Lu-yu Li
Keyword(s):  
Seismic Waves ◽  
Nonlinear Models ◽  
Simulation Models ◽  
Inertial Mass ◽  
Theoretical Models ◽  
Shaking Table ◽  
Test Results ◽  
Single Degree Of Freedom ◽  
Mass Damper ◽  
Simulation And Experiment

Based on a single degree of freedom system, the inerter principles of an inertial mass damper and clutch inerter damper are introduced. The motion equations of the systems are derived, and the rotational speed and damping are considered. In addition, a reducer is innovatively combined with clutch inerter damper to significantly improve the inertance. Accordingly, an innovative reducer clutch inerter damper is proposed. Shaking table experiments are carried out on the uncontrolled inertial mass damper, clutch inerter damper, and reducer clutch inerter damper structures under the inputs of harmonic and seismic waves. Simulation models of the four types of structures are developed, and the validity of the theoretical models is verified by a comparison between the simulation and experiment. Moreover, the nonlinear models of clutch inerter damper and reducer clutch inerter damper are discussed. Finally, according to the test results, the vibration reduction effects of the three inerters are analyzed, and the reasons why they are different from the ideal clutch inerter damper are also explained. The results show that clutch inerter damper, especially reducer clutch inerter damper, has a good vibration damping performance.

Energy analysis and optimization of inerter-based systems

2021 ◽  
pp. 107754632098773
Author(s):  
Yi-Lin Zheng ◽  
Lu-Yu Li ◽  
Tian-Jiao Zhang
Keyword(s):  
Inertial Mass ◽  
Structural Vibration ◽  
Optimal Parameters ◽  
Control Effect ◽  
Basic Principles ◽  
Single Degree Of Freedom ◽  
Structural Vibration Control ◽  
Total Input ◽  
Optimal Value ◽  
Mass Damper

This article introduces the basic principles of four kinds of inerters applied for structural vibration control including a traditional inertial mass damper and ideal clutch inerter damper. The clutch inerter damper with all damping (clutch inerter damper_all damped) and clutch inerter damper with partial damping (clutch inerter damper_part damped) are distinguished in detail. First, a series of energy indexes are defined for further analysis. Second, the control effect of displacement for the uncontrolled structure and the four inerter-based single-degree-of-freedom systems are compared. Finally, considering the total input energy ( E1) and the invalid damping energy ( ECID_ric) as the effective indexes, combined with a large number of numerical simulation results, the variation rules of the two energy indexes with respect to two key parameters (inertia mass ratio and additional damping) are summarized, and the optimal parameters are proposed. The effectiveness of the optimal value is verified by displacement comparison.

Influence of changing environment conditions on the development of shrinkage strain and the expansion coefficient of large concrete specimens

2019 ◽  
Author(s):  
Dominik Suza ◽  
Johann Kollegger ◽  
Harald S. Müller
Keyword(s):  
Shrinkage Strain ◽  
Theoretical Models ◽  
Test Results ◽  
Current Standard ◽  
Operating Life ◽  
Changing Environment ◽  
Temperature And Humidity ◽  
Bridge Structures ◽  
Standard Models ◽  
Creep And Shrinkage

<p>The standard creep and shrinkage strain measurements of concrete are usually conducted in a laboratory with constant temperature and humidity with a low variation. The creep and shrinkage measurements are conducted over a few months with the expectation that small concrete specimens can sufficiently describe the evolution of the rheology effects on a large multi-span bridge in the course of its operating life.</p><p>The monitoring of real bridge structures shows the actual progression of the deflections and concrete strains. Unfortunately the evaluation and interpretation of the measured values is complicated. The idea of the scientific Creep &amp; Shrinkage project was to combine the two described situations (laboratory experiments and monitoring of real bridge structures) creating an experimental setup which would benefit from the advantages of both approaches.</p><p>In order to achieve conformity of the measured test results with those of theoretical models (MC 2010, EC) it was necessary to upgrade the current models to include the effects of changing temperature and humidity. Within this paper the upgrade of the current standard models to include changing environment conditions will be elaborated, in addition to an explanation of the method used to separate shrinkage strains from the temperature strains from the measured data. The measured concrete expansion coefficients will also be discussed.</p>

scholarly journals Inertial mass damper for vibration control of cable with sag

2018 ◽  
Vol 39 (3) ◽  
pp. 749-760 ◽  
Author(s):  
Zhi-Hao Wang ◽  
Hui Gao ◽  
Bu-qiao Fan ◽  
Zheng-Qing Chen
Keyword(s):  
Inertial Mass ◽  
Damping Coefficient ◽  
Stay Cables ◽  
Modal Damping ◽  
Optimal Damping ◽  
Mass Damper ◽  
Negative Effect ◽  
Supplemental Damping ◽  
Antisymmetric Vibrations ◽  
General Dynamic

It has been theoretically predicted that superior supplemental damping can be generated for a taut cable with an inertial mass damper. This paper extends previous studies to investigate the effect of the cable sag on the efficiency of an inertial mass damper. The general dynamic characteristics of an inclined sag cable with an inertial mass damper installed close to the cable end are theoretically investigated. The parametric analysis of the inertial mass and the damping coefficient of the inertial mass damper are conducted to evaluate the control performance of the cable with different sags. The results show that the inertial mass damper can alleviate the negative effect induced by the cable sag, and the cable sag can even increase modal damping ratios provided by the inertial mass damper. Sags of stay cables used in actual bridges only affect nearly symmetric vibrations of cables, while having little impact on nearly antisymmetric vibrations. The effect of cable sags will reduce the optimal damping coefficient and inertial mass of the inertial mass damper for the first symmetric mode of the cable.

Numerical Studies on Size Effect Behaviors of Glassy Polymers Based on Strain Gradient Elastoviscoplastic Model

2018 ◽  
Vol 86 (2) ◽  
Author(s):  
Yujun Deng ◽  
Jin Wang ◽  
Peiyun Yi ◽  
Linfa Peng ◽  
Xinmin Lai ◽  
...  
Keyword(s):  
Finite Element ◽  
Size Effect ◽  
Strain Gradient ◽  
Simulation Models ◽  
Theoretical Models ◽  
Deformation Energy ◽  
Glassy Polymers ◽  
Traditional Theory ◽  
Fe Model ◽  
Processing Load

The improvement of the accuracy and efficiency of microforming process of polymers is of great significance to meet the miniaturization of polymeric components. When the nonuniform deformation is reduced to the microscopic scale, however, the mechanics of polymers shows a strong reinforcement behavior. Traditional theoretical models of polymers which have not considered material feature lengths are difficult to describe the size effect in micron scale, and the process simulation models based on the traditional theory could not provide effective and precise guidance for polymer microfabrication techniques. The work reported here proposed strategies to simulate size effect behaviors of glassy polymers in microforming process. First, the strain gradient elastoviscoplastic model was derived to describe the size affected behaviors of glassy polymers. Based on the proposed constitutive model, an eight-node finite element with the consideration of nodes' rotation was developed. Then, the proposed finite element method was verified by comparisons between experiments and simulations for both uniaxial compression and microbending. Finally, based on the FE model, under the consideration of the effect of rotation gradient, the strain distribution, the deformation energy, and the processing load were discussed. These strategies are immediately applicable to other wide-ranging classes of microforming process of glassy polymers, thereby foreshadowing their use in process optimizations of microfabrication of polymer components.

scholarly journals A case report of COVID-19 monitoring in the Austrian professional football league

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Antje van der Zee-Neuen ◽  
Dagmar Schaffler-Schaden ◽  
Jürgen Herfert ◽  
James O´Brien ◽  
Tim Johansson ◽  
...  
Keyword(s):  
Perceived Risk ◽  
National Football League ◽  
Reproduction Number ◽  
Simulation Models ◽  
Subjective Health ◽  
Test Results ◽  
Contact Sport ◽  
Technical Problems ◽  
Sport Teams ◽  
Observation Period

AbstractSince the beginning of the COVID -19 pandemic, many contact sport teams are facing major challenges to safely continue training and competition. We present the design and implementation of a structured monitoring concept for the Austrian national football league. 146 professional players from five clubs of the professional Austrian football league were monitored for a period of 12 weeks. Subjective health parameters, PCR- test results and data obtained from a geo-tracking app were collected. Simulations modelling the consequences of a COVID-19 case with increasing reproduction number were computed. No COVID -19 infection occurred during the observation period in the players. Infections in the nearer surroundings lead to increased perceived risk of infection. Geo tracking was particularly hindered due to technical problems and reluctance of users. Simulation models suggested a hypothetical shut-down of all training and competition activities. A structured monitoring concept can help to continue contact sports safely in times of a pandemic. Cooperation of all involved is essential. Trial registration: ID: DRKS00022166 15/6/2020 https://www.who.int/ictrp/search/en/.

Comparison on Simulation and Experiment of Supply Air through Metro Vehicle Air Conditioning Duct

2010 ◽  
Vol 44-47 ◽  
pp. 1724-1728
Author(s):  
Hong Ge Tao ◽  
Huan Xin Chen ◽  
Jun Long Xie ◽  
Jun Zhi Jiang
Keyword(s):  
Air Conditioning ◽  
Optimization Design ◽  
Simulation Method ◽  
Test Results ◽  
Air Velocity ◽  
Relative Deviation ◽  
Air Volume ◽  
Experiment Validation ◽  
Simulation And Experiment ◽  
Actual Test

CFD technique is often employed to simulate and optimize air duct design, but the corresponding experiment validation in metro vehicle is rare. By taking an independent metro vehicle duct as research object in this paper, supply air through air duct is simulated and compared with the actual test results from the angle of supply air velocity at each outlet and supply air volume through several outlets of air duct. The results show that the relative deviation of simulation and test value of air velocity at most of the outlets are within or near ±20%, which is acceptable for the engineering applications. Moreover, the ratio of supply air volume through several outlets to the corresponding total supply air volume through main air duct or flat duct in the case of simulation is consistent with that in the case of experiment. It can be concluded that numerical simulation method is effective and reliable in air duct optimization design of metro vehicle.

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