Prediction of the dynamic characteristics of an elastically supported full-size flat plate from those of its complete-similitude scale model

2006 ◽  
Vol 84 (3-4) ◽  
pp. 102-114 ◽  
Author(s):  
Jia-Jang Wu
Keyword(s):  
Flat Plate ◽  
Dynamic Characteristics ◽  
Scale Model ◽  
Full Size ◽  
Elastically Supported

Interaction Between the Underwater Explosion Bubble and the Structure

2008 ◽  
Author(s):  
A. M. Zhang ◽  
X. L. Yao ◽  
D. Y. Shi ◽  
J. Li
Keyword(s):  
Free Surface ◽  
Flat Plate ◽  
Dynamic Characteristics ◽  
Potential Flow ◽  
Underwater Explosion ◽  
Wall Pressure ◽  
Severe Damage ◽  
Plastic Structure ◽  
Pressure Peak ◽  
Great Damage

Based on the potential-flow assumption, BEM is applied to simulate the dynamic characteristics of underwater explosion bubble near boundaries and solve the interaction of bubble and elastic-plastic structure by coupling with FEM. A complete 3D program of underwater bubble analysis (UBA) is developed and the calculated error is within 10%. With this program, flat plate, cylinder and other simple structures are analyzed; the damages caused by retarded flow, pulsating pressure and jet and other loads on the structures are calculated, including different cases with free surface or without free surface. Results show that bubbles can cause great damage, and the specific cases can even cause greater damage. From the wall pressure and the stress curves of typical elements on the structure, it can be seen that the pressure peak occurs when the bubble collapses, which proves that the pressures caused by the bubble’s collapse and jet can result in great structure’s severe damage. It can provide reference for the research on the dynamic characteristics. The research in this paper aims to provide references for the correlated research on the dynamics of the underwater bubble.

Effect of wind gusts on the dynamics of railway vehicles running on a curved track

2017 ◽  
Vol 232 (4) ◽  
pp. 1103-1120 ◽  
Author(s):  
Wonhee You ◽  
Hyukbin Kwon ◽  
Joonhyuk Park ◽  
Yujeong Shin
Keyword(s):  
Dynamic Characteristics ◽  
Wind Tunnel Test ◽  
Simulation Software ◽  
Scale Model ◽  
Railway Vehicle ◽  
Wind Gust ◽  
Railway Vehicles ◽  
Wind Gusts ◽  
Pitch Moment ◽  
Curved Track

Due to global warming, there is an increasing number of wind gusts that affect the stability of railway vehicles. A railway vehicle running on a curved track during a wind gust is subjected to multiple forces simultaneously, which include the centrifugal force and forces exerted by the wind gust and cant, and they significantly affect the vehicle’s dynamic characteristics as well as its safety. The forces increase the vibration of carbodies and the risk of derailment and overturning of cars; the effect is worse on irregular tracks. In order to review the phenomenon in detail, a 1/20 scale model of a railway vehicle was built to measure the aerodynamic coefficients in five directions—side force, lift force, roll moment, pitch moment, and yaw moment—through a wind tunnel test. The data collected were applied as external forces to a full-scale railway vehicle model traveling on a curved track. Using a multibody simulation software program, SIMPACK, a railway vehicle was modeled, which was then used in the simulation of the dynamic characteristics and safety of vehicles while traveling on a curved track during a wind gust. Using the actual measured track data from the curved zone, a comparison was made on the dynamic characteristics of the car traveling, with and without a wind gust, on a curved track with a railway curve radius of 599 m; also, the difference was analyzed with the direction of the wind gust blowing from inside and toward the center of curvature. The results showed that in the presence of a wind gust blowing from outside the curvature with an average speed of 25 m/s it is advisable to stop train services on grounds of safety.

Theoretical design and experimental verification of a 1/50 scale model of a quayside container crane

2011 ◽  
Vol 226 (6) ◽  
pp. 1644-1662 ◽  
Author(s):  
Y L Jin ◽  
Z G Li
Keyword(s):  
Dynamic Characteristics ◽  
Large Scale ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Scale Model ◽  
Engineering Structures ◽  
Scaled Model ◽  
Container Crane ◽  
Comparison Results ◽  
Quayside Container Crane

An effective way to study the dynamic performances and seismic behaviours of large-scale engineering structures is using a scale model. This article aims to develop a geometric-scaled model of the 1/50 for a quayside container crane such that the dynamic characteristics of the prototype can be accurately predicted from the relevant features of this scale model. To this end, a detailed design process for the main components of a 1/50 scale model of the quayside container crane was first presented according to the similitude law. Then, a hammering modal test and the Ling dynamic system shaking table test were successively carried out to obtain the dynamic characteristics of this 1/50 scale model. Furthermore, the experimental results were compared with the computed results of the prototype obtained from numerical simulation and they showed a fairly good agreement. From the comparison results, it can be seen that the model design is instructive enough to provide some valuable information and practical use for professionals and researchers involved in the design of large-scale port facilities.

Experimental Study of Mechanical Pipe Snubber Seismic Behavior

1997 ◽  
Vol 119 (3) ◽  
pp. 384-388 ◽  
Author(s):  
D. K. Nims ◽  
J. M. Kelly
Keyword(s):  
Experimental Study ◽  
Dynamic Characteristics ◽  
Seismic Behavior ◽  
Full Scale ◽  
Hysteretic Behavior ◽  
Scale Model ◽  
Piping System ◽  
Complicated Pattern ◽  
Seismic Tests ◽  
Input Motion

A series of seismic tests of mechanical snubbers on a full-scale model piping system provided a unique opportunity for detailed scrutiny of snubber seismic behavior on an actual piping system. The observed snubber behavior is a complicated pattern of braking and releasing, drag and drift, and the dynamic characteristics of the snubber, as well as the input motion, play a role in the response of the snubber. The snubbers were effective in limiting pipe displacements. Relative accelerations across the snubber were larger than expected. Snubber hysteretic behavior was irregular. Results from this testing are important in understanding snubber behavior, evaluating snubber performance, and in assessing alternatives to snubbers.

Test of Scale Model Post-Tensioned Flat Plate

1977 ◽  
Vol 103 (6) ◽  
pp. 1237-1255
Author(s):  
Ned H. Burns ◽  
Roongroj Hemakom
Keyword(s):  
Flat Plate ◽  
Scale Model ◽  
Post Tensioned

Discussion of “Test of Scale Model Post-Tensioned Flat Plate”

1978 ◽  
Vol 104 (1) ◽  
pp. 242-244
Author(s):  
Harinatha B. Goli ◽  
Hans Gesund
Keyword(s):  
Flat Plate ◽  
Scale Model ◽  
Post Tensioned

Convective Heat Losses From Flat-Plate Solar Collectors in Turbulent Winds

1983 ◽  
Vol 105 (1) ◽  
pp. 80-85 ◽  
Author(s):  
R. J. Kind ◽  
D. H. Gladstone ◽  
A. D. Moizer
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Convective Heat ◽  
Residential Building ◽  
Scale Model ◽  
Solar Collectors ◽  
Single Family ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

This paper presents results for convective heat transfer coefficients on the surface of flat-plate solar collectors mounted on a single-family residential building and exposed to the wind. The results were obtained by testing a 1:32 scale model in highly turbulent nonuniform flows which simulated the natural wind. For full-scale conditions, the heat transfer coefficients are two to three times lower than those given by a commonly used correlation. The coefficients show some sensitivity to wind direction but are insensitive to the characteristics of the wind and to architectural details of the building.

Turn-Up and Turn-Down in Hot Rolling: A Study on a Model Mill Using Plasticine

1972 ◽  
Vol 14 (4) ◽  
pp. 245-254 ◽  
Author(s):  
S. A. E. Buxton ◽  
S. C. Browning
Keyword(s):  
Hot Rolling ◽  
Surface Friction ◽  
Scale Model ◽  
Speed Ratio ◽  
Strain Component ◽  
Full Size ◽  
Plastic Yield ◽  
Steel Slabs ◽  
Work Rolls ◽  
Better Than

Turn-up and turn-down is a phenomenon which occurs in the hot rolling of flat products when the nose of a slab, or the whole slab, curls up or down upon emerging from the rolls and remains deformed unless subsequently straightened. Turn-up and turn-down can be troublesome to production, since it can cause damage to the mill rolls, housing, and run-out tables and can also cause production delays due to the difficulty of re-rolling a deformed slab. The object of this paper is to determine the main factors governing the phenomenon, to obtain quantitative relationships between causes and effects, and to suggest means of preventing curvature occurring. The best approach was considered to be a scale model using plasticine to simulate the hot metal. As a basis for the work, several dimensionless ratios are formed which have to be the same in both model and full size mill, if the model is to be both dynamically and geometrically similar. In the more important dimensionless ratios, account is taken of the plastic yield characteristics of the material, including the rate-of-strain component, of the stresses due to surface friction and gravity, and finally of the ratio of roll speeds. The results are compared with some previous work by others on steel slabs using a full size mill. In all respects, the results agree closely. The most significant factor affecting turn-up and turn-down is the ratio of surface speeds of the two work-rolls. Curvature is proportional to this speed ratio, but slipping at the rolls may modify this relationship. For a given angle of entry, the ratio of torque upon each roll is a function of the speed ratio. Angle of entry has negligible effect on turn-up and turn-down, but has a powerful effect upon the torque ratio. Slip is very undesirable and it appears that the roll surface finish should not be better than necessary if slip is to be avoided. To produce a flat slab, a speed ratio of about 0·97 is required in the model. In practice, this may be achieved either directly by controlling the speed ratio, or indirectly by controlling the torque ratio, provided the angle of entry is constant.

Inherent Characteristic Similarity Analysis on Short Thin-Walled Cylindrical Shell

2014 ◽  
Vol 607 ◽  
pp. 386-392
Author(s):  
Qing Bin Han ◽  
Jian Guo ◽  
Ning Sun ◽  
Zhong Luo
Keyword(s):  
Cylindrical Shell ◽  
Scaling Laws ◽  
Equations Of Motion ◽  
Excitation Frequency ◽  
Dynamic Responses ◽  
Scale Model ◽  
Similarity Analysis ◽  
Prototype System ◽  
Thin Walled ◽  
Elastically Supported

A method for predicting the vibration characteristics of the short thin-walled cylindrical shell was presented by dynamic similarity analysis. Firstly, the similarity conditions between the prototype system and its complete-similitude scale model were derived from their equations of motion. Then, the scaling factors, such as length, radius, thickness, force, and excitation frequency, spring constant and dynamic responses of the cylindrical shell were determined based on the last similarity conditions and the dimensional analysis theory. Free and forced vibration analyses of the elastically supported prototype cylindrical shell and those of its complete-similitude scale model were performed to validate the derived scaling laws, and satisfactory results were obtained.

Prediction of the vibration characteristics of a full-size structure from those of a scale model

2002 ◽  
Vol 80 (18-19) ◽  
pp. 1461-1472 ◽  
Author(s):  
Jia-Jang Wu ◽  
M.P. Cartmell ◽  
A.R. Whittaker
Keyword(s):  
Size Structure ◽  
Vibration Characteristics ◽  
Scale Model ◽  
Full Size
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