Vibration Characteristic Evaluation of Nonlinear Vibration Systems With Gaps Considering Energy Dissipation by Collision

2005 ◽  
Author(s):  
Masanori Shintani ◽  
Hiroyuki Ikuta ◽  
Hiroyuki Shume
Keyword(s):  
Nonlinear Vibration ◽  
Analytical Model ◽  
Damping Ratio ◽  
Experimental Results ◽  
Experimental Result ◽  
Vibration Characteristic ◽  
Random Waves ◽  
Restoring Force ◽  
Dissipation Energy ◽  
Experimental Apparatus

This paper deals with nonlinear vibration of a continuum system with gaps under random waves considered collision phenomena. In order to investigate this nonlinear vibration characteristic, experiments are made with an experimental apparatus consisting of a nonlinear vibration system. A 2.3mm thick plate is used for the collision phenomena experiments. Moreover, an analytical model of the cubic equation is proposed based on the restoring force characteristics in the experiments. This analytical model is used for the simulation analysis, and the results are compared with the experimental results. However, the Root- Mean- Square (R.M.S.) values of the response acceleration of the analytical results are larger than R.M.S. values of the response acceleration of the experimental result. The difference of these results indicates that energy is dissipated in the collision phenomena. Then, the coefficient of restitution by the collision phenomenon between mass and plate is measured from the experiments. In the analysis, the dissipation energy is replaced with an equivalent damping ratio. The simulations are calculated by using this modified analysis. Consequently, the simulation results agree well with the experimental results.

Study on Nonlinear Vibration of Continuum System With Gaps Considering Energy Dissipated by Collision

2004 ◽  
Author(s):  
Masanori Shintani ◽  
Hiroyuki Ikuta ◽  
Tadashi Kotera
Keyword(s):  
Kinetic Energy ◽  
Nonlinear Vibration ◽  
Analytical Model ◽  
Experimental Results ◽  
Thin Plates ◽  
Random Waves ◽  
Restoring Force ◽  
Collision Effect ◽  
Experimental Apparatus ◽  
Energy Dissipated

This paper deals with nonlinear vibration of a continuum system with gaps under random waves considered collision phenomena. In order to investigate this nonlinear vibration characteristic, experiments are carried out with an experimental apparatus consisting of a nonlinear vibration system. Moreover, an analytical model of the cubic equation is proposed based on the restoring force characteristics in the experiments. This analytical model is used for the simulation analysis, and its results are compared with the experimental results. However, the results show differences between thick plates and thin plates in the root-mean-square (R.M.S.) value of the response acceleration and the transfer function. The ratio of the kinetic energy of the experimental results and the simulation results is investigated. Consequently, energy is dissipated in the experiments. It is found that the energy dissipated by collision phenomena causes these results. In order to measure the coefficient of restitution by the collision phenomena between the plate and the mass, an experimental apparatus for the collision effect is made. Experiments are carried out with this apparatus. The experimental results agree with part of the results of the ratios of kinetic energy. It is clear that the analytical model in consideration for the energy dissipated by the collision effect is required.

Evaluation of Energy Absorption in Nonlinear Vibration System With Gaps

2005 ◽  
Author(s):  
Masanori Shintani ◽  
Hiroyuki Ikuta ◽  
Hajime Takada
Keyword(s):  
Nonlinear Vibration ◽  
Energy Absorption ◽  
Analytical Model ◽  
Random Waves ◽  
Vibration System ◽  
Restoring Force ◽  
Acceleration Level ◽  
Experimental Apparatus ◽  
Input Acceleration ◽  
Nonlinear Vibration System

This paper deals with nonlinear vibration characteristics of a continuum system with collision phenomena under random waves with gaps. In order to investigate such a nonlinear vibration characteristic, an experimental apparatus consisting of a nonlinear vibration system was made. Moreover, we propose an analytical model based on the restoring force characteristics of the experiments. In this report, the size of the gap between a mass and a plate is set to 0.5mm or 1.0mm. For this experimental model we also propose an analytical model. We use plates of 1.6mm thickness in the collisions both in the experiment and the analysis. The analytical model is based on an elasto-plasticity solid model. When considering the coefficients of restitution or energy absorption, the experimental results nearly agree with the analytical results [10]. We found that the rate of a collision changes with the size of the gap at each input acceleration level. As the gap size widens, energy absorption decreases for each input acceleration level. Consequently, in order to increase the energy absorption, it becomes necessary to increase the rate of the collision.

Study on Analytical Model of Nonlinear Vibration for Elastic Plates With Gaps Under Random Waves

2004 ◽  
Vol 126 (4) ◽  
pp. 504-509 ◽  
Author(s):  
Masanori Shintani ◽  
Manabu Hamai
Keyword(s):  
Nonlinear Vibration ◽  
Analytical Model ◽  
Force Characteristic ◽  
Solid Model ◽  
Random Waves ◽  
Elastic Plates ◽  
Analysis Model ◽  
Restoring Force ◽  
Elasto Plasticity ◽  
Force Characteristics

In this paper, an analytical model for the nonlinear elastic-plastic vibration for long plates with gaps subjected to random vibrations is considered. The nonlinear vibration is caused by the collision phenomena between a mass through a gap and plates with thickness of 0.5, 0.6, and 0.8 mm. An elastic perfectly plastic solid material is assumed in some cases, which adds another aspect to the nonlinear behavior of the system. The material characteristic of the steel is assumed to be an elasto-plasticity solid model. A restoring force characteristic is obtained as the nonlinear vibration of a cubic equation for 0.5, 0.6, and 0.8 mm, the thickness of the plates by experiments. Now the analytical model is proposed by the elasto-plasticity solid model. The relation between the displacement and the force is described by a complicated equation. The curve from the analytical model is called a deflection curve. The results by the analytical model are compared with the results by the experimental model. The restoring force characteristics by the analysis agree with those of the experiment. The restoring force characteristics of the analysis are described using cubic equations. The simple analysis model for evaluation of the vibration characteristic of the nonlinear vibration system, which performs collision vibration with gaps, is proposed by elasto-plasticity solid model in this paper. The results of this proposed analytical model agree with the experimental results better than the results of the minimum of error of square.

An Evaluation of a Two-Phase Damping Model on Tube Bundles Subjected to Two-Phase Cross Flow

2010 ◽  
Author(s):  
W. G. Sim ◽  
Njuki W. Mureithi
Keyword(s):  
Analytical Model ◽  
Mass Flux ◽  
Damping Ratio ◽  
Cross Flow ◽  
Experimental Results ◽  
Water Mixture ◽  
Two Phase ◽  
Phase Damping ◽  
Tube Bundles ◽  
Damping Model

The analytical model (Sim; 2007), to predict the two-phase damping ratio for upward cross-flow through horizontal tube bundles, has been evaluated. The damping model was formulated, based on Feenstra’s model (2000) for void fraction and various models (homogeneous, Levy, Martinelli-Nelson and Marchaterre) for two-phase friction multiplier. The analytical results of drag coefficient on a cylinder and two-phase Euler number were compared with the experimental results by Sim-Mureithi (2010). The factor, a relation between frictional pressure drop and the hydraulic drag coefficients, could be determined by considering experimental results. The two-phase damping ratios, given by the analytical model, were compared with existing experimental results. It was found that the model, based on Marchaterre’s model, is suitable for air-water mixture while the Martinelli-Nelson’s model for steam-water and Freon mixtures. The two-phase damping ratio is independent on pitch mass flux for air-water mixture, but it is more or less influenced by the mass flux for steam-water/Freon(134) mixtures. The two-phase damping ratios, given by the present model, agree well with experimental results for a sufficiently wide range of pitch mass ratio, quality and p/d ratios.

scholarly journals Investigation of Dynamic Responses and Vibration Serviceability of Temporary Grandstands by a 3 DOF Interaction Model due to Swaying Motion

2022 ◽  
Vol 2022 ◽  
pp. 1-32
Author(s):  
Jian Yuan ◽  
Suhui Yu ◽  
Cong Liu ◽  
Chengqiang Gao ◽  
Wei Wang ◽  
...  
Keyword(s):  
Damping Ratio ◽  
Force Plate ◽  
Interaction Model ◽  
Reference Value ◽  
Experimental Results ◽  
Shaking Table ◽  
Dynamic Responses ◽  
Random Waves ◽  
Lateral Direction ◽  
Structural Dynamic

Excessive vibration of temporary grandstand by the crowd has lateral rhythmic motions, which attracted increasing attention in the recent years. This paper focuses on experiments where a temporary grandstand occupied by 20 participants is oscillated by a shaking table with a series of random waves and the crowd-induced rhythmic swaying motions at lateral direction, respectively. The dynamic forces that were induced by participants who have swayed at 0.5–1.8 Hz are recorded by a tri-axial human biomechanics force plate. A new relationship between the annoyance rate and structural acceleration at logarithmic coordinate is investigated and proposed, and the swaying load model is given. Based on these experimental results, a simplified three-degree-of-freedom lumped dynamic model of the joint human–structure system is reinterpreted. Afterwards, combined with a feasible range of crowd/structural dynamic parameters, a series of interaction models are analyzed, the vibration dose value (VDV) of the structure is obtained and discussed, and the notable parameters for interaction model are predicted. The experimental results show that the lateral serviceability limit is 1.29 m/s1.75 and the upper boundary is 2.32 m/s1.75. The dynamic response of model indicated that the VDV of structure will be decreased with increasing the mass of static crowd and damping ratio of the dynamic crowd. The max response of the model is α ≤ 0.6, f2 = 1.8 Hz or α > 0.6, f2 = 1.5 Hz or f1 = 2.5–3.5 Hz. It may be used as a reference value in vibration safety and serviceability assessment of TDGs, to estimate realistically the vibration response on the occasions when the crowds are swaying.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

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.

scholarly journals Generalized analytical model based on harmonic coupling for hybrid plasmonic modes: comparison with numerical and experimental results

2015 ◽  
Vol 23 (21) ◽  
pp. 27376 ◽  
Author(s):  
Mitradeep Sarkar ◽  
Jean-François Bryche ◽  
Julien Moreau ◽  
Mondher Besbes ◽  
Grégory Barbillon ◽  
...  
Keyword(s):  
Analytical Model ◽  
Experimental Results ◽  
Model Based

Convective Losses From Cavity Solar Receivers—Comparisons Between Analytical Predictions and Experimental Results

1983 ◽  
Vol 105 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. M. Clausing
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Analytical Model ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Refined Model ◽  
Wall Area

Cavity solar receivers are generally believed to have higher thermal efficiencies than external receivers due to reduced losses. A simple analytical model was presented by the author which indicated that the ability to heat the air inside the cavity often controls the convective loss from cavity receivers. Thus, if the receiver contains a large amount of inactive hot wall area, it can experience a large convective loss. Excellent experimental data from a variety of cavity configurations and orientations have recently become available. These data provided a means of testing and refining the analytical model. In this manuscript, a brief description of the refined model is presented. Emphasis is placed on using available experimental evidence to substantiate the hypothesized mechanisms and assumptions. Detailed comparisons are given between analytical predictions and experimental results. Excellent agreement is obtained, and the important mechanisms are more clearly delineated.

scholarly journals Mathematical modelling of the overflowing cylinder experiment

2003 ◽  
Vol 474 ◽  
pp. 275-298 ◽  
Author(s):  
P. D. HOWELL ◽  
C. J. W. BREWARD
Keyword(s):  
Free Surface ◽  
Surfactant Concentration ◽  
Dynamic Properties ◽  
Vertical Cylinder ◽  
Surfactant Solution ◽  
Surface Concentration ◽  
Experimental Results ◽  
Surface Velocity ◽  
Experimental Apparatus ◽  
Finite Distance

The overflowing cylinder (OFC) is an experimental apparatus designed to generate a controlled straining flow at a free surface, whose dynamic properties may then be investigated. Surfactant solution is pumped up slowly through a vertical cylinder. On reaching the top, the liquid forms a flat free surface which expands radially before over flowing down the side of the cylinder. The velocity, surface tension and surfactant concentration on the expanding free surface are measured using a variety of non-invasive techniques.A mathematical model for the OFC has been previously derived by Breward et al. (2001) and shown to give satisfactory agreement with experimental results. However, a puzzling indeterminacy in the model renders it unable to predict one scalar parameter (e.g. the surfactant concentration at the centre of the cylinder), which must be therefore be taken from the experiments.In this paper we analyse the OFC model asymptotically and numerically. We show that solutions typically develop one of two possible singularities. In the first, the surface concentration of surfactant reaches zero a finite distance from the cylinder axis, while the surface velocity tends to infinity there. In the second, the surfactant concentration is exponentially large and a stagnation point forms just inside the rim of the cylinder. We propose a criterion for selecting the free parameter, based on the elimination of both singularities, and show that it leads to good agreement with experimental results.

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