scholarly journals Experimental Study on Rockfall Mechanism of Platy Rock on a Complex Slope

2020 ◽  
Vol 10 (8) ◽  
pp. 2849
Author(s):  
Xiaohui Liao ◽  
Qi Ouyang ◽  
Haiyang Liu ◽  
Juanjuan Sun ◽  
Xueliang Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Slope Angle ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Rock Fall ◽  
Restitution Coefficient ◽  
Hazard Control ◽  
Before And After ◽  
Control Work

The rock fall trajectory and its mechanisms are the most difficult to predict, owing to the complexity of the slope and the Irregular shape of falling rocks. To acquire a better knowledge of the rock fall mechanism of platy rock and to investigate the influence of various impact parameters, a comprehensive physical model experimental study was undertaken based on 3D printing technology using a high-speed camera and specially developed block release system. Based on the experimental results, the effects of the slope angle on the stopping position, the instantaneous kinetic energy and collision position of platy rock block were analyzed. Meanwhile, the effects of movement forms of platy rock before and after collision on the normal coefficient of restitution and the tangent coefficient of restitution were discussed. It is observed that rock fall trajectory depends not only on slope material characteristics, slope angle but also on factors related to the platy block (weight, size and shape). The experimental results showed the value of restitution coefficient exceeding 1 has an important relation with the combination of various movement forms (including the flip motion) and the change of movement forms of platy rock before and after the collision. A new feasible experimental method for research and prevention of rock fall disaster was put forward. It would be important and helpful to the geo-hazard control work.

Experimental Study of Turbulent Macroinstabilities in an Agitated System with Axial High-Speed Impeller and with Radial Baffles

1996 ◽  
Vol 61 (6) ◽  
pp. 856-867 ◽  
Author(s):  
Oldřich Brůha ◽  
Ivan Fořt ◽  
Pavel Smolka ◽  
Milan Jahoda
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
High Speed ◽  
Experimental Results ◽  
Turbulent Regime ◽  
Frequency Of Occurrence ◽  
Visualization Method ◽  
Entire Flow

The frequency of turbulent macroinstability occurrence was measured in liquids agitated in a cylindrical baffled vessel. As it has been proved by preceding experimental results of the authors, the stochastic quantity with frequency of occurrence of 10-1 to 100 s-1 is concerned. By suitable choosing the viscosity of liquids and frequency of impeller revolutins, the region of Reynolds mixing numbers was covered from the pure laminar up to fully developed turbulent regime. In addition to the equipment making it possible to record automatically the macroinstability occurrence, also the visualization method and videorecording were employed. It enabled us to describe in more detail the form of entire flow field in the agitated system and its behaviour in connection with the macroinstability occurrence. It follows from the experiments made that under turbulent regime of flow of agitated liquids the frequency of turbulent macroinstability occurrence is the same as the frequency of the primary circulation of agitated liquid.

Experimental Study of a Variable Pressure Damper on Automotive Valve Motion

1996 ◽  
Author(s):  
Jin-Jang Liou ◽  
Grodrue Huang ◽  
Wensyang Hsu
Keyword(s):  
Experimental Study ◽  
Friction Coefficient ◽  
Friction Force ◽  
High Speed ◽  
Experimental Results ◽  
Variable Pressure ◽  
Friction Forces ◽  
Valve Spring ◽  
Valve Motion

Abstract A variable pressure damper (VPD) is used here to adjusted the friction force on the valve spring to investigate the relation between the friction force and the valve bouncing phenomenon. The friction force on the valve spring is found experimentally, and the corresponding friction coefficient is also determined. Dynamic valve displacements at different speeds with different friction forces are calibrated. Bouncing and floating of the valve are observed when the camshaft reaches high speed. From the measured valve displacement, the VPD is shown to have significant improvement in reducing valve bouncing distance and eliminating floating. However, experimental results indicate that the valve bouncing can not be eliminated completely when the camshaft speed is at 2985 rpm.

An experimental study of high-speed rotor supported by air bearings: test RIG and first experimental results

2006 ◽  
Vol 39 (8) ◽  
pp. 839-845 ◽  
Author(s):  
Guido Belforte ◽  
Terenziano Raparelli ◽  
Vladimir Viktorov ◽  
Andrea Trivella ◽  
Federico Colombo
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Experimental Results ◽  
Air Bearings ◽  
Test Rig

Experimental Study of Kick up Phenomenon in Thermosonic Wire-Bonding

2012 ◽  
Vol 160 ◽  
pp. 77-81
Author(s):  
Jing Jing Tian ◽  
Lei Han
Keyword(s):  
Image Processing ◽  
Experimental Study ◽  
High Speed ◽  
Gold Wire ◽  
Wire Bonding ◽  
Processing Method ◽  
Experimental Results ◽  
High Speed Camera ◽  
Depth Study ◽  
Thermosonic Wire Bonding

Kick-up phenomenon during looping is an important factor in thermosonic wire bonding. In this study, the loping process during wire bonding was recorded by using high-speed camera, and wire profiles evolution was obtained from images sequence by image processing method. With a polynomial fitting, the wire loop profiling was described by the curvature changing, and kick-up phenomenon on gold wire was found between the instant of 290th frame(0.0537s) to 380th frame (0.0703s), the change of curvature is divided into three phases, a looping phase, a mutation phase and a kick-up phase. While in the kick-up phase, the kick up phenomenon is the most obvious. These experimental results were useful for in-depth study of kick-up phenomenon by simulation.

Experimental Study on the Response Characteristics of Oilcans under High-Velocity Fragment Impact

2012 ◽  
Vol 510 ◽  
pp. 500-506
Author(s):  
Chang Hai Chen ◽  
Xi Zhu ◽  
Hai Liang Hou ◽  
Li Jun Zhang ◽  
Ting Tang
Keyword(s):  
Experimental Study ◽  
High Velocity ◽  
High Speed ◽  
Room Temperature ◽  
Experimental Results ◽  
Fuel Oil ◽  
High Speed Camera ◽  
Response Characteristics ◽  
Fuel Oils ◽  
The Impact

To explore the deflagration possibility of the warship cabin filled with fuel oil under impact of high-speed fragments in the condition of room temperature, experiments were carried out employing the small aluminium oilcans filled with fuel oil. Response processes of the oilcans were observed with the help of a high-speed camera. The disintegration as well as flying scattering of the oilcans were analyzed. The reasons for atomization of the fuel oils were presented. Finally, the deflagration possibility of warship oil cabin was analyzed. Results show that the pressure inside the oilcan is quite great under the impact of the high-speed fragment, which makes the oilcan disintegration and flying scattering. Simultaneously, fuel oils inside the oilcans are atomized quickly followed by ejected in front and back directions. Under the same condition as in present tests, deflagration will not occur for fuel oils used by warships. Experimental results will provide valuable references for the deflagration analysis of warship fuel oil cabins subjected to the impact of high-velocity fragments.

scholarly journals Effect of laser deweighting on properties of ZL205A aluminum alloy

2021 ◽  
Vol 2137 (1) ◽  
pp. 012033
Author(s):  
Guang Li ◽  
Zhipeng Wei ◽  
Junlong Wang ◽  
Yangyang Zhang ◽  
Chen Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Aluminum Alloy ◽  
Surface Morphology ◽  
Pulse Laser ◽  
Process Parameters ◽  
Experimental Results ◽  
Matrix Properties ◽  
Before And After ◽  
The Matrix

Abstract In this paper, a nanosecond fiber pulse laser is used to carry out the experimental study on laser weight removal of ZL205A aluminum alloy gyro rotor. By optimizing the process parameters of laser weight removal, better surface morphology was obtained. The effects of surface roughness, metallographic structure and hardness of samples before and after laser deweighting were analyzed. The experimental results show that the laser weight removal does not affect the matrix properties of ZL205A aluminum alloy. The laser de-weight technology is suitable for the balance of ZL205A aluminum alloy gyro rotor.

Experimental study on oblique water entry of projectiles

2016 ◽  
Vol 30 (28) ◽  
pp. 1650348 ◽  
Author(s):  
Chenggong Zhao ◽  
Cong Wang ◽  
Yingjie Wei ◽  
Xiaoshi Zhang ◽  
Tiezhi Sun
Keyword(s):  
Experimental Study ◽  
Impact Velocity ◽  
High Speed ◽  
Transition Point ◽  
Water Entry ◽  
High Speed Photography ◽  
Initial Water ◽  
Before And After ◽  
Velocity Attenuation ◽  
Cavity Evolution

An experimental study of oblique water entry of projectiles with different noses has been conducted using high-speed photography technology. The images of the initial water entry impact, cavity evolution, and the closure and shedding of vortices of cavity are presented in the paper. The results reveal that for high-speed oblique water entry (the initial impact velocity [Formula: see text][Formula: see text]50 m/s), the cavity attached to the projectile is symmetrical and free from the influence of gravity. The shedding of the water–vapor–air mixture in the tail of the cavity produces vortices which disappear in the rear of the projectile trajectory. Particular attention is given to the velocity attenuation of the projectile after water entry. The results show that there is a transition point at the time corresponding to the surface seal of the cavity during the velocity attenuation after oblique water entry, and the rates of velocity attenuation are different before and after this transition point. Additionally, the chronophotography of the cavity evolution shows that the time when the surface seal of the cavity occurs decreases with the increase of the initial impact velocity of the projectile.

A Critical Study of the Applicability of Rigid-Body Collision Theory

1996 ◽  
Vol 63 (2) ◽  
pp. 307-316 ◽  
Author(s):  
D. Stoianovici ◽  
Y. Hurmuzlu
Keyword(s):  
Rigid Body ◽  
High Speed ◽  
Equations Of Motion ◽  
Coefficient Of Restitution ◽  
Electrical Circuit ◽  
Experimental Results ◽  
Critical Study ◽  
Low Velocity ◽  
Steel Bars ◽  
Body Theory

This article deals with the collision of steel bars with external surfaces. The central issue of the article is the investigation of the fundamental concepts that are used to solve collision problems by using rigid-body theory. We particularly focus on low-velocity impacts of relatively rigid steel bars to test the applicability of these concepts. An experimental analysis was conducted to study the rebound velocities of freely dropped bars on a large external surface. A high-speed video system was used to capture the kinematic data. The number of contacts and the contact time were determined by using an electrical circuit and an oscilloscope. Tests were performed by using six bar lengths and varying the pre-impact inclinations and the velocities of the bars. The experimental results were used to verify the applicability of Coulomb’s law of friction and the invariance of the coefficient of restitution in the class of impacts considered in this study. Then, given the unusual variation the coefficient of restitution as a result of changing pre-impact inclinations, a theoretical model was developed to explain this variation. A discrete model of the bar was used to obtain the equations of motion during impact. Computed and experimental results were compared to establish the accuracy of numerical model. The internal vibrations of the bar and multi impacts between the bar and the surface were found to be two main factors that cause the variation of the coefficient of restitution. Furthermore, a slenderness factor was proposed to identify the subset of collision problems where the coefficient of restitution was invariant to the inclination angle.

Dynamics of a Radially Rotating Beam With Impact, Part 1: Theoretical and Computational Model

1990 ◽  
Vol 112 (1) ◽  
pp. 65-70 ◽  
Author(s):  
A. S. Yigit ◽  
A. G. Ulsoy ◽  
R. A. Scott
Keyword(s):  
Rigid Body ◽  
Computational Model ◽  
Computational Algorithm ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Body Motion ◽  
Momentum Balance ◽  
Rotating Beam ◽  
Before And After ◽  
Simulation Results

A model is presented for the dynamics of a radially rotating beam with impact. The model uses a momentum balance method and a coefficient of restitution, and enables one to predict the rigid body motion as well as the elastic motion before and after impact. A computational algorithm is also developed to implement the model. In Part 2 simulation results will be compared with experimental results to investigate the validity of the model.

scholarly journals Determinação experimental do coeficiente de restituição normal de rochas: aplicação na previsão do alcance de blocos em encostas

2006 ◽  
Vol 29 (2) ◽  
pp. 149-167
Author(s):  
Gilmar Pauli Dias ◽  
Emílio Velloso Barroso
Keyword(s):  
Acoustic Method ◽  
Coefficient Of Restitution ◽  
Rock Fall ◽  
Restitution Coefficient ◽  
Sound Recording ◽  
In Situ Tests ◽  
Sensibility Analysis ◽  
Repeated Impacts ◽  
Gravity Acceleration

Among the several parameters involved in rock fall analisys, the restitution coefficient, which is related to the kinetic energy wasted after repeated impacts of a rocky body against the ground, is probably the most important and most difficult to acquire. There is the necessity of in situ tests where blocks of rocks are thrown down on the slopes. However these tests cannot be performed in places where people or urban equipments could be in risk. In this paper an acoustic method is used for the measurement of the normal restitution coefficient of rocks. This method is very well known by physicists but it has not been applied in the geosciences and engineering areas. It consists in the sound recording of successive impacts of a rock sphere against a smooth rocky surface. The gravity acceleration was back calculated from data obtained in order to verify if precision of the method is suitable. A sensibility analysis of the coefficient of restitution was already carried out simulating real rock fall problems.

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