scholarly journals HIGH SPEED VIDEOMETRIC MONITORING OF ROCK BREAKAGE

2018 ◽  
Vol IV-2 ◽  
pp. 17-24
Author(s):  
J. Allemand ◽  
M. R. Shortis ◽  
M. K. Elmouttie
Keyword(s):  
High Speed ◽  
Impact Testing ◽  
Frame Rate ◽  
Sufficient Evidence ◽  
Video Frame ◽  
Rock Breakage ◽  
Impact Location ◽  
Drop Weight ◽  
Weight Impact ◽  
The Impact

Estimation of rock breakage characteristics plays an important role in optimising various industrial and mining processes used for rock comminution. Although little research has been undertaken into 3D photogrammetric measurement of the progeny kinematics, there is promising potential to improve the efficacy of rock breakage characterisation. In this study, the observation of progeny kinematics was conducted using a high speed, stereo videometric system based on laboratory experiments with a drop weight impact testing system. By manually tracking individual progeny through the captured video sequences, observed progeny coordinates can be used to determine 3D trajectories and velocities, supporting the idea that high speed video can be used for rock breakage characterisation purposes. An analysis of the results showed that the high speed videometric system successfully observed progeny trajectories and showed clear projection of the progeny away from the impact location. Velocities of the progeny could also be determined based on the trajectories and the video frame rate. These results were obtained despite the limitations of the photogrammetric system and experiment processes observed in this study. Accordingly there is sufficient evidence to conclude that high speed videometric systems are capable of observing progeny kinematics from drop weight impact tests. With further optimisation of the systems and processes used, there is potential for improving the efficacy of rock breakage characterisation from measurements with high speed videometric systems.

scholarly journals Experimental and Numerical Simulation Studies of RC Beams under the Actions of Equal Energy Impact Loads

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xiwu Zhou ◽  
Xiangyu Wang ◽  
Runcheng Zhang ◽  
Wen Zhang
Keyword(s):  
Impact Velocity ◽  
Impact Force ◽  
Impact Testing ◽  
Rc Beams ◽  
Finite Element Software ◽  
Equal Energy ◽  
Drop Weight ◽  
Weight Impact ◽  
The Impact ◽  
Peak Value

In this study, two groups of RC beams were subjected to low-speed drop weight impact test by using the domestic advanced ultrahigh heavy-duty drop weight impact testing machine system. The main aspects studied are the influence of the combination of different impact velocity and mass on the dynamic response and local and global damage change of RC beam under the same impact energy. Next, the numerical model considering material strain rate is established using ABAQUS finite element software to verify and expand the experimental results. The results show the following: (1) under the condition of equal energy, the peak value of impact force measured in this experiment increases with the increase of impact velocity, yet the mid span displacement and rebar strain first increase and then decrease. In addition, when the impact velocity is 2.25 m/s and the impact mass is 400 kg, the beam has the most serious damage; (2) compared with the mass, the impact velocity has more obvious effects on the peak value of cumulative impact force, mid span displacement, and rebar strain; (3) with the decrease of the impact velocity (the increase of the mass), the local damage of the beam is gradually weakened and the overall damage is gradually exacerbated. The failure mode of the beam is transformed from local punching shear failure to overall static failure type.

The effect of microwave pretreatment on impact crushing of lead-zinc ore

2021 ◽  
Vol 118 (5) ◽  
pp. 501
Author(s):  
Yulong Liu ◽  
Dexin Ding ◽  
Wenguang Chen ◽  
Nan Hu ◽  
Lingling Wu ◽  
...  
Keyword(s):  
Energy Input ◽  
Impact Test ◽  
Characteristic Parameters ◽  
Microwave Pretreatment ◽  
Drop Weight ◽  
Lead Zinc ◽  
Weight Impact ◽  
Impact Crushing ◽  
The Impact ◽  
The Relationship

The relationship between energy input and particle size of ore samples after crushing and effect of microwave pretreatment on impact crushing of lead-zinc ore were studied by drop weight impact test. The results showed that the lead-zinc ore became softer and had higher degree of crushing after microwave pretreatment. Compared with continuous microwave pretreatment, pulsed microwave pretreatment could improve the drop weight impact crushing efficiency of lead-zinc ore. When the specific comminution energy were 5 kW h/t, 10 kW h/t respectively, the crushing characteristic parameters t10 were 60.42% and 67.46% respectively by continuous microwave. But the values of t10 were increased to 68.64% and 75.88% respectively after pulsed microwave radiation under same microwave power and time. In addition, water quenching could more promote the impact crushing efficiency of lead-zinc ore after microwave irradiation.

Dynamic Analysis of Thin Glass Under Ball Drop Impact With New Metrics

2013 ◽  
Author(s):  
Liang Xue ◽  
Claire R. Coble ◽  
Hohyung Lee ◽  
Da Yu ◽  
Satish Chaparala ◽  
...  
Keyword(s):  
High Speed ◽  
Impact Testing ◽  
Image Correlation ◽  
Thin Glass ◽  
Fea Model ◽  
Wear And Tear ◽  
Local Measurements ◽  
Drop Impacts ◽  
Global And Local ◽  
The Impact

Response of brittle plate to impact loads has been the subject of many research studies [1–7]. Specifically, glass presents a wide variety of applications in daily life, and helps to protect the displays of smartphones, tablets, PCs, and TVs from everyday wear and tear. Therefore, the necessity of glass to resist scratches, drop impacts, and bumps from everyday use leads to the importance of investigation of the glass response under dynamic impact loading. The ball drop test has been applied in the past, specifying an energy threshold as a prediction metric. Use of energy as the key parameter in impact testing is limited, since it does not account for the time spent in contact during the impact event. This study attempts to establish a reliable metric for impact testing based on a momentum change threshold. The deformation and the strain of the glass will be obtained by the Digital Image Correlation (DIC) system, while the rebound velocity will be measured with the high speed cameras. The global and local measurements are conducted to verify the accuracy of the experimental results. Finally, the FEA model is developed using ANSYS/LS-DYNA to provide a comprehensive understanding of the dynamic response of the glass. Excellent correlation in deflection is obtained between the measurements and predictions.

scholarly journals Drop-weight impact ignition of CL-20 crystals caused by trapped gases: A high-speed photographic study

2020 ◽  
Vol 1 (2) ◽  
pp. 117-122
Author(s):  
Chuanguo Chai ◽  
Jianming Zhang ◽  
Shaojun Yu ◽  
Jinjiang Xu ◽  
Qian Yu ◽  
...  
Keyword(s):  
High Speed ◽  
Drop Weight ◽  
Trapped Gases ◽  
Weight Impact

Drop-weight impact testing for the study of energy absorption in automobile crash boxes made of composite material

2020 ◽  
pp. 146442072095281
Author(s):  
N Nasir Hussain ◽  
Srinivasa Prakash Regalla ◽  
Yendluri V Daseswara Rao ◽  
Tatacipta Dirgantara ◽  
Leonardo Gunawan ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Energy Absorption ◽  
Impact Testing ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Plastic ◽  
Fiber Reinforced Plastic ◽  
Drop Weight ◽  
Glass Fiber Reinforced ◽  
Reinforced Plastic ◽  
Weight Impact

There is an ever-increasing demand in the automotive sector to continuously improve the performance and reduce cost through weight reduction in the structure of the vehicle. In the present scenario, it is also necessary to meet the standards set by crash safety regulating authorities in various parts of the world. In automobiles, the crash box is placed in the anterior region to absorb the impact energy in the event of an accident. Glass fiber reinforced plastic crash boxes have a high strength-to-weight ratio and also are good in energy absorption, particularly useful in this scenario. In this paper, the effectiveness of different triggers in combination with various geometries is investigated for Glass fiber reinforced plastic crash boxes using drop-weight impact testing. A trigger is a geometric irregularity introduced in the crash box design to alter the energy as well as force levels by modifying the deformation mode under loading. Comparison of change in force level, absorption of impact energy, specific energy absorption values was performed for composite crash boxes made of various types of cross-sectional geometries along with multiple patterns of triggers. Force versus displacement (F–D) curves are drawn for all the cases of the glass fiber reinforced plastic crash boxes to understand the behavior of each combination formed with various types of geometries and triggers, under impact loading. Strength-to-weight ratio was considered as the deciding factor for the comparisons to know the best and worst cases of the crash boxes made of different cross-sections along with various trigger types. This study provides detailed insights into the drop-weight impact testing procedure including the preparation of specimens, setting up the drop-weight impact test, preparation of specimen clamps, safety precautions involved, data acquisition from the test and its processing.

scholarly journals Experimental Investigation on the Impact Resistance of Carbon Fibers Reinforced Coral Concrete

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4000 ◽  
Author(s):  
Bing Liu ◽  
Jingkai Zhou ◽  
Xiaoyan Wen ◽  
Jianhua Guo ◽  
Xuanyu Zhang ◽  
...  
Keyword(s):  
Weibull Distribution ◽  
Carbon Fibers ◽  
Impact Test ◽  
Concrete Strength ◽  
Impact Resistance ◽  
Initial Crack ◽  
Drop Weight ◽  
Weight Impact ◽  
The Impact ◽  
Two Parameter

In this study, the impact resistance of coral concrete with different carbon fiber (CF) dosages subjected to drop-weight impact test was investigated. For this purpose, three concrete strength grades (C20, C30, C40) and six CF dosages (0.0%, 0.3%, 0.6%, 1.0%, 1.5%, and 2.0% by weight of the binder) were considered, and a total of 18 groups of carbon fibers reinforced coral concrete (CFRCC) were cast. For each group, eight specimens were tested following the drop-weight impact test suggested by CECS 13. Then, the two-parameter Weibull distribution theory was adopted to statistically analyze the variations in experimental results. The results indicated that the addition of CFs could transform the failure pattern from obvious brittleness to relatively good ductility and improve the impact resistance of coral concrete. Moreover, the impact resistance of CFRCC increases with the CF dosage increasing. The statistical analysis showed that the probability distribution of the blow numbers at the initial crack and final failure of CFRCC approximately follows the two-parameter Weibull distribution.

The ignition of a thin layer of explosive by impact

1974 ◽  
Vol 338 (1612) ◽  
pp. 77-93 ◽  
Keyword(s):  
Pressure Drop ◽  
Thin Layer ◽  
High Speed ◽  
Large Scale ◽  
Flow Speed ◽  
Thin Layers ◽  
Drop Weight ◽  
Flow Speeds ◽  
Show Evidence ◽  
Weight Impact

The behaviour of thin layers of solid materials under drop-weight impact is studied with the aid of high-speed photographic and pressure-measuring techniques. Photographic sequences taken with a high-speed framing camera show that explosive materials suffer large-scale deformation before initiation of explosion. The sample may undergo plastic flow in bulk, show evidence of partial fusion, and even (with PETN) melt completely. There is also evidence of Munroe jetting and instability of flow of material at the anvil/layer interfaces. The flow speed of the sample during these processes is considerable and may reach 300 m/s. When ignition of the layer occurs it does so at a small number of local hot spots, following which rapid combustion develops at speeds of 200-700 m/s. Strain-gauge measurements show that the pressures attained during drop-weight impact are typically 0.5-1 GPa (5–10 kbar) and the duration of impact 300–500 μs. In the course of impact of a thin layer of granular material a sharp pressure drop may occur, frequently from several hundred MPa down to zero. With an explosive layer, ignition occurs immediately following the instant of the pressure drop. The sudden fall in pressure is due to mechanical failure of the sample, and correlation of the two experiments shows that this is the cause of the very high flow speeds attained during impact. On the basis of these results a possible mechanism of ignition is suggested.

Full scale field testing of temporary rockfall protection measures

2020 ◽  
Author(s):  
Axel Volkwein ◽  
Florian Hofstetter ◽  
Marc Hauser
Keyword(s):  
High Speed ◽  
Minimum Weight ◽  
Field Tests ◽  
Front Surface ◽  
Frame Rate ◽  
Slope Surface ◽  
Retention Capacity ◽  
Protection Measures ◽  
The Impact ◽  
Rockfall Protection

<p>Temporary rockfall protection measures are often implemented by using so-called steel palisades. Such elements can described as a steel surface that is supported perpendicular to the slope surface. In the present case, several sheet piling sections are welded onto a steel frame to form an area 1.5m high and 3m long. At the lateral edges of the surface, steel sections, welded together to form a triangle, create the support of the front surface, so that one side of the triangle is parallel to the impact surface and another side is parallel to the slope surface. At the corners close to the ground, massive steel spikes allow penetration into the ground. The weight of a palisade is about 900kg. An example of such a palisade can be found in [1].</p><p>The above barriers are in usage since many years. However, their rockfall energy retention capacity has never been evaluated yet. For that reasons, the Swiss Federal Railways launched a project for a deeper understanding of the performance of the palisades; for an adequate selection of the protection measures and a reliable risk analyses with respect to the variety of rockfall events that can be expected at a specific construction site and might cause failure of a structure.</p><p>Failure limits of the palisades are expected regarding the following failure scenarios:</p><ul><li>tilting of the barrier over the valley side steel spikes</li> <li>displacement of the barrier due to insufficient action of the steel spikes</li> <li>failure of the front surface</li> </ul><p>In this contribution, the above mechanisms are evaluated by means of 1:1 field tests.  A detailed analysis of performance and failure states will be provided. Furthermore, potential solutions for simple but effective reinforcement of the barriers are discussed.</p><p>The field tests were carried out on a slope inclined at an angle of about 30 degrees. Test blocks with a minimum weight of 240kg are thrown onto the palisades with the help of a forestry cableway reaching impact speeds of up to 25m/s. The impact energies vary from 12 to 100 kJ. Impact location and impact speed are determined by means of laterally taken high-speed video records with a frame rate of up to 1000fps and a resolution of 800x600pxs. Furthermore, the accelerations in the test body were measured at 1000Hz and – for some of the tests - the acting anchorage forces at 5000Hz.</p><p> </p>

Sign in / Sign up

Export Citation Format

Share Document