scholarly journals Study of Passive Protective Net Protecting the Rockfall Caused by Open-Pit Blasting on High and Steep Slope

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhiyu Zhang ◽  
Qingyun Qian ◽  
Jianguo Wang ◽  
Haoshan Liu ◽  
Ke Liang ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Impact Force ◽  
Impact Resistance ◽  
Steep Slope ◽  
Interaction Time ◽  
Open Pit ◽  
Buffer Time ◽  
The Impact ◽  
Impulse Force ◽  
High And Steep Slope

In order to prevent rockfall caused by open-pit blasting on the high and steep slope and ensure that the passive protective net structure has sufficient impact resistance, the mechanism of blasting flyrock causing rockfall is analyzed by using ANSYS/AUTODYN to establish the model of rockfall and passive protective net; at the same time, the influences of protective net size, rockfall kinetic energy, and rockfall size to the protective effect were also studied. The results show that under the condition of the same rockfall kinetic energy and rockfall size, the larger the size of the protective net, the longer the buffer time, and the impact force that net can sustain is greater; by assuming the protective net size and rockfall size to be a constant, the greater the rockfall kinetic energy, the less the interaction time between rock and net, and the greater the impulse force that net can suffer; similarly, by keeping the protective net size and the kinetic energy of rockfall to be a constant, it is found that the larger the size of the rockfall, the larger the interaction area and longer interaction time with the net, and the less net will be disrupted; the protective net used in the mine can intercept the rockfall caused by flyrock in blasting process effectively and ensure the safety of villager at the foot of the mountain.

scholarly journals Sandwich panel with in-plane honeycombs in different Poisson's ratio under low to medium impact loads

2021 ◽  
Vol 60 (1) ◽  
pp. 145-157
Author(s):  
Yi Luo ◽  
Ke Yuan ◽  
Lumin Shen ◽  
Jiefu Liu
Keyword(s):  
Poisson’S Ratio ◽  
Sandwich Panel ◽  
Impact Force ◽  
Impact Resistance ◽  
Poisson's Ratio ◽  
Compression Performance ◽  
Post Impact ◽  
Local Impact ◽  
Collapse Behavior ◽  
The Impact

Abstract In this study, a series of in-plane hexagonal honeycombs with different Poisson's ratio induced by topological diversity are studied, considering re-entrant, semi-re-entrant and convex cells, respectively. The crushing strength of honeycomb in terms of Poisson's ratio is firstly presented. In the previous research, we have studied the compression performance of honeycomb with different negative Poisson's ratio. In this study, a comparative study on the local impact resistance of different sandwich panels is conducted by considering a spherical projectile with low to medium impact speed. Some critical criteria (i.e. local indentation profile, global deflection, impact force and energy absorption) are adopted to analyze the impact resistance. Finally, an influential mechanism of Poisson's ratio on the local impact resistance of sandwich panel is studied by considering the variation of core strength and post-impact collapse behavior.

scholarly journals Study on the Impact Resistance of Metal Flexible Net to Rock fall

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Gaosheng Wang ◽  
Yunhou Sun ◽  
Ao Zhang ◽  
Lei Zheng ◽  
Yuzheng Lv ◽  
...  
Keyword(s):  
Finite Element ◽  
Impact Force ◽  
Impact Resistance ◽  
Time History ◽  
Rock Fall ◽  
Fe Model ◽  
Element Analysis ◽  
Inclination Angles ◽  
Fall Protection ◽  
The Impact

Based on experiments and finite element analysis, the impact resistance of metal flexible net was studied, which can provide reference for the application of metal flexible net in rock fall protection. The oblique (30 degrees) impact experiment of metal flexible net was carried out, the corresponding finite element (FE) to the experiment was established, and the FE model was verified by simulation results to the experimental tests from three aspects: the deformation characteristics of metal flexible net, the time history curves of impact force on supporting ropes, and the maximum instantaneous impact force on supporting ropes. The FE models of metal flexible nets with inclination angles of 0, 15, 30, 45, 60, and 75 degrees were established, and the impact resistance of metal flexible nets with different inclination angles was analyzed. The research shows that the metal flexible net with proper inclination can bounce the impact rock fall out of the safe area and prevent rock fall falling on the metal flexible net, thus realizing the self-cleaning function. When the inclination angle of the metal flexible net is 15, 30, and 45 degrees, respectively, the bounce effect after impact is better, the remaining height is improved, the protection width is improved obviously, and the impact force is reduced. Herein, the impact force of rock fall decreases most obviously at 45 degrees inclination, and the protective performance is relatively good.

scholarly journals Effective Formula for Impact Damping Ratio for Simulation of Earthquake-induced Structural Pounding

Geosciences ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 347 ◽  
Author(s):  
Seyed Mohammad Khatami ◽  
Hosein Naderpour ◽  
Rui Carneiro Barros ◽  
Anna Jakubczyk-Gałczyńska ◽  
Robert Jankowski
Keyword(s):  
Kinetic Energy ◽  
Impact Force ◽  
Damping Ratio ◽  
Dissipated Energy ◽  
Force Model ◽  
Single Collision ◽  
Structural Pounding ◽  
Impact Forces ◽  
The Impact ◽  
Impact Damping

Structural pounding during earthquakes may cause substantial damage to colliding structures. The phenomenon is numerically studied using different models of collisions. The aim of the present paper is to propose an effective formula for the impact damping ratio, as a parameter of the impact force model used to study different problems of structural pounding under seismic excitations. Its accuracy has been verified by four various approaches. Firstly, for the case of collisions between two structural elements, the dissipated energy during impact has been compared to the loss of kinetic energy. In the second stage of verifications, the peak impact forces during single collision have been analyzed. Then, the accuracy of different equations have been verified by comparing the impact force time histories for the situation when a concrete ball is dropped on a rigid concrete surface. Finally, pounding between two structures during earthquakes has been studied. The results of the analysis focused on comparison between dissipated and kinetic energy show relatively low errors between calculated and assumed values of the coefficient of restitution when the proposed equation is used. In addition, the results of the comparison between experimentally and numerically determined peak impact forces during single collision confirm the effectiveness of the approach. The same conclusion has been obtained for the whole impact time history for collision between a ball and a rigid surface. Finally, the results of the comparative analysis, conducted for pounding between two structures during an earthquake, confirm the simulation accuracy when the proposed approach is used. The above conclusions indicate that the proposed formula for impact damping ratio, as a parameter of impact force model for simulation of earthquake-induced structural pounding, is very effective and accurate in numerical simulations in the case of different scenarios.

scholarly journals Numerical Investigation on Dynamic Response of RC T-Beams Strengthened with CFRP under Impact Loading

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 890
Author(s):  
Huiling Zhao ◽  
Xiangqing Kong ◽  
Ying Fu ◽  
Yihan Gu ◽  
Xuezhi Wang
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Reaction Force ◽  
Impact Resistance ◽  
Structural Response ◽  
Element Model ◽  
Strengthening Effect ◽  
Strengthened Beam ◽  
Simulation Results ◽  
The Impact

To precisely evaluate the retrofitting effectiveness of Carbon Fiber Reinforced Plastic (CFRP) sheets on the impact response of reinforced concrete (RC) T-beams, a non-linear finite element model was developed to simulate the structural response of T-beams with CFRP under impact loads. The numerical model was firstly verified by comparing the numerical simulation results with the experimental data, i.e., impact force, reaction force, and mid-span displacement. The strengthening effect of CFRP was analyzed from the section damage evaluation. Then the impact force, mid-span displacement, and failure mode of CFRP-strengthened RC T-beams were studied in comparison with those of un-strengthened T-beams. In addition, the influence of the impact resistance of T-beams strengthened with FRP was investigated in terms of CFRP strengthening mode, CFRP strengthening sizes, CFRP layers and FRP material types. The numerical simulation results indicate that the overall stiffness of the T-beams was improved significantly due to external CFRP strips. Compared with the un-strengthened beam, the maximum mid-span displacement of the CFRP-strengthened beam was reduced by 7.9%. Additionally, the sectional damage factors of the whole span of the CFRP-strengthened beam were reduced to less than 0.3, indicating that the impact resistance of the T-beams was effectively enhanced.

Initial response mechanism and local contact stiffness analysis of the floating two-stage buffer collision-prevention system under ship colliding

2021 ◽  
pp. 136943322098610
Author(s):  
Kai Lu ◽  
Xu-Jun Chen ◽  
Zhen Gao ◽  
Liang-Yu Cheng ◽  
Guang-Huai Wu
Keyword(s):  
Kinetic Energy ◽  
Impact Force ◽  
Contact Stiffness ◽  
Impact Angle ◽  
Bridge Pier ◽  
Two Stage ◽  
Collision Prevention ◽  
Prevention System ◽  
The Impact ◽  
Depth Curves

A floating two-stage buffer collision-prevention system (FTBCPS) has been proposed to reduce the impact loads on the bridge pier in this paper. The anti-collision process can be mainly divided into two stages. First, reduce the ship velocity and change the ship initial moving direction with the stretching and fracture of the polyester ropes. Second, consume the ship kinetic energy with the huge damage and deformation of the FTBCPS and the ship. The main feature of the FTBCPS lies in the first stage and most of the ship kinetic energy can be dissipated before the ship directly impacts on the bridge pier. The contact stiffness value between the ship and the FTBCPS can be a significant factor in the first stage and the calculation method of it is the focus of this paper. The contact force, the internal force and the general equation of motion have been given in the first part. The structure model of the ship and the FTBCPS are then established in the ANSYS Workbench. After that, 38 typical load cases of the ship impacting on the FTBCPS are conducted in LS-DYNA. The reduction processes of the ship kinetic energy and the ship velocity in different load cases have been investigated. It can be summarized that the impact angle and the ship initial velocity are the main factors in the energy and velocity dissipation process. Moreover, the local impact force-depth curves have also been studied and the impact angle is found to be the only significant factor on the ship impact process. Next, the impact force-depth curves with different impact angles are fitted and the contact stiffness values are accordingly calculated. Finally, the impact depth range, the validity of the local simulation results and the consistency of the fitted stiffness value are verified respectively, demonstrating that the fitted stiffness values are applicable in the global analysis.

The Low-Velocity Impact Response of Sandwich Panels

2010 ◽  
Vol 168-170 ◽  
pp. 1149-1152
Author(s):  
Xiao Xiong Zha ◽  
Hong Xin Wang
Keyword(s):  
Impact Force ◽  
Energy Levels ◽  
Impact Resistance ◽  
Sandwich Panels ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Weight Impact ◽  
The Impact

The low velocity impact response of sandwich panels at different energy levels has been investigated by conducting drop-weight impact tests using an instrumented falling-weight impact tower. Impact parameters like maximum impact force and the extent of the damage were evaluated and compared for different types of sandwich panels. Finite elements simulations have been undertaken using the LS-DYNA software; the results of FE simulations have a good agreement with the experiments. It shows that, the impact force increased with thickness of face-sheets and foam core, the extent of the damage increased with the impact energy, sandwich panels with steel face sheet has a good impact resistance in comparison with sandwich panel with aluminum face sheets.

Impact Indentation Properties and Interfacial Strength of Ceramic Coatings

2010 ◽  
Vol 654-656 ◽  
pp. 1972-1977
Author(s):  
Yi Wang Bao ◽  
Kun Ming Li ◽  
De Tian Wan ◽  
Xue Qiang Cao
Keyword(s):  
Impact Force ◽  
Steel Substrate ◽  
Impact Resistance ◽  
Interfacial Strength ◽  
Ceramic Coatings ◽  
Impact Angle ◽  
Zro2 Coating ◽  
Aluminum Substrates ◽  
The Impact ◽  
Peak Impact Force

Spherical impact indentation tests with different impact angles (90°, 60°, 45°, and 30°) were carried out to understand the impact resistance and interfacial adhesion of zirconia (ZrO2) ceramic coating on steel and aluminum substrates, respectively. A linear rail with an adjustable impact angle was used to guide the slipping impact head to impact the specimen. It is found that the peak impact force for surface damage decreases but the contact indentation becomes longer with decreasing impact angle. Under almost the same peak impact force, the smaller the impact angle, the higher the impulse. The experimental results indicate that the ZrO2 coating on steel substrate has higher impact resistance than that on the aluminum substrate. The cross bonded test results show that ZrO2 coating on both steel and aluminum substrates exhibit excellent interfacial tensile and shear strength.

scholarly journals Experimental Research on the Mechanical Performance of the Bolted Rock under Lateral Impact Load: Effect of Prestress, Body Material, and Anchorage Style

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yongzheng Wu ◽  
Yukai Fu ◽  
Denyun Hao ◽  
Gangye Guo
Keyword(s):  
Axial Force ◽  
Impact Force ◽  
Impact Load ◽  
Impact Resistance ◽  
Time History ◽  
Full Length ◽  
Lateral Impact ◽  
Impact Peak ◽  
Action Time ◽  
The Impact

In order to reveal the impact mechanical properties and their key influencing factors of the bolted rock under the lateral impact load, through the lateral drop hammer impact test, the time-history curve of impact force, axial force of the bolt, and surface strain of the sample under different combination types of influencing factors is obtained, and the whole process of deformation and failure of the bolted rock is recorded. The test results show that the material of the bolt has a significant influence on the impact force and axial force of the bolt. There is a positive correlation between bolt strength and impact peak and impact attenuation slope and a negative correlation between bolt strength and impact action time. The effect of prestress on the impact resistance of the bolted rock was also evaluated by the test which suggested that prestress of the bolt can significantly reduce both impact time and bolt axial force of the bolted rock but has limited effect on the impact force. It was also found that the time-history curve of the impact force of anchoring rock mass had significant difference with full-length anchoring and nonanchoring. Compared with the nonanchoring bolt, the full-length anchored rock mass has a larger impact peak and shorter action time, which means that the impact resistance of the full-length bolted rock has a certain degree of weakening. Through scientific research, determining the reasonable bolt material, prestress value, and anchorage style can improve the impact resistance of the sample.

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