scholarly journals Research on the Wing-Type Antiscour Device of Pier Based on Scour Test and Numerical Simulation

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Yan Wang ◽  
Xiaoli Shen ◽  
Jinchao Chen ◽  
Zhejiang Chen ◽  
Jing Liu
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Local Scour ◽  
Simulation Test ◽  
Protection Effect ◽  
Front End ◽  
Type Device ◽  
Inclination Angles ◽  
The Impact ◽  
Sediment Carrying Capacity

In order to reduce the local scour before the antiscour device of piers, this paper proposed an improvement on a “V-type” device. That was to say, wing plates were set on the surface of the “V-type” device to enhance the diversion and reduce the local scour. To explore the protection effect of the modified device, the inclination angles of the wing plates were set to three angles, and the scour characteristics around the device were studied through the flume scour test and numerical simulation test. The results showed that the wing plates can reduce the impact force of the diving flow which was at the front end of the protective device. Besides, they could also disturb the flow around both sides of the device and weaken its sediment carrying capacity. Thus, the local scour around the device was effectively reduced. Especially, when the wing plates were 30°, the performance of reducing the local scour was the best.

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.

Numerical Simulation Analysis of Collision between Ship and Steel Sheet Pile Quay-Wall

2015 ◽  
Vol 744-746 ◽  
pp. 1175-1179 ◽  
Author(s):  
Peng Liu ◽  
Hong Wang ◽  
Chao Zhu
Keyword(s):  
Numerical Simulation ◽  
Steel Sheet ◽  
Impact Force ◽  
Simulation Analysis ◽  
Sheet Pile ◽  
Time Curve ◽  
Finite Element Software ◽  
Quay Wall ◽  
Force Time ◽  
The Impact

The impact process of 50000t ship and steel sheet pile bulkhead is simulated by finite element software ANSYS/LS-DYNA. This article acquires the impact force-time curve, equivalent force-time curve of steel sheet pile and the pressure-time curve of breast wall. Comparing the impact force of numerical simulation with the result of ship-bridge collision specifications, and general rules and characteristics are obtained. At the same time, put forward some measures to prevent the damage of wharf structure under the ship of large velocity impact, which provide theoretical references during the design, maintenance, and transformation of similar wharf.

scholarly journals Theoretical Analysis of Rockfall Impacts on the Soil Cushion Layer of Protective Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Xing Wang ◽  
Yongxu Xia ◽  
Tianyue Zhou
Keyword(s):  
Numerical Simulation ◽  
Energy Conservation ◽  
Penetration Depth ◽  
Impact Force ◽  
Theoretical Method ◽  
Cavity Expansion ◽  
Rockfall Hazards ◽  
Protective Structures ◽  
Cushion Layer ◽  
The Impact

During the Wenchuan Earthquake, with a magnitude of 5.12, collapses and rockfall hazards persisted for a long time after the initial investigations carried out by research fellow S. M. He and his team at the scene of the disaster in October 2008. It is possible that additional incidents of rockfalls in large quantities may continue in the same areas over the next ten to fifteen years. Furthermore, in the vast mountainous region of western China, the topographic relief is evident, and earthquakes occur frequently. Therefore, it is difficult to effectively defend against rockfall hazards. When designing protective structures, the key issue is the analysis of the mechanical response mechanism of the soil cushion layer of the upper cushion when subjected to the impact of rockfall. As such, a theoretical method was used to perform such an analysis. The cavity expansion and energy conservation model were adopted. Analytical solutions for the impact force and penetration depth were then derived. Furthermore, the impact force and penetration depth of rockfall were studied with the LS-DYNA software to obtain values for the impact forces and the penetration depth. Finally, the reliability of the theoretical method was evaluated using the cavity expansion, energy conservation, numerical simulation, Hertz, Japanese, Swiss, Australian, B. S. Guan, tunnel manual, and subgrade methods based on an engineering model. The results show that the cavity expansion and the energy conservation methods yielded consistent results. Meanwhile, the cavity expansion and the energy conservation methods also yielded consistent results with the numerical simulation, Japanese (obtained by laboratory experiment), Swiss (obtained by laboratory experiment), and Australian (obtained by field experiment) methods. The relevant methods and conclusions shall therefore be applied to the design of rockfall protection structure in future investigations.

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.

scholarly journals Design and analysis of demolition robot arm based on finite element method

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985396 ◽  
Author(s):  
Jiong Li ◽  
Yu Wang ◽  
Kai Zhang ◽  
Zhiqiao Wang ◽  
Jiaxing Lu
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Impact Force ◽  
Second Order ◽  
Robot Arm ◽  
Element Analysis ◽  
Front End ◽  
The Finite Element Analysis ◽  
The Impact ◽  
Ansys Workbench

As a novel robot which mainly engages in the demolition and transformation of various concrete buildings, the demolition robot has developed rapidly in recent years. The impact force is mainly produced by the breaking hammer installed in the front end of the arm. As the most important part of a demolition robot, the boom arm is mainly composed of four parts including a supporting arm, a main arm, a fore arm, and a breaking hammer system. In this article, a mechanical model of the boom arm is established, and the finite element analysis obtaining the first four-order natural frequencies and modes is carried out in ANSYS Workbench. The results reveal that the resonation can be easily stimulated when a hydraulic breaking hammer is at the second-order frequency. The mounting block of the hydraulic breaking hammer, the hinge parts of the supporting arm, and the main arm are easily deformed or damaged in the Y direction by analyzing the deformation in three directions of the second-order mode. After the structure optimization, the vibration characteristics of the two parts are significantly enhanced, which provides a theoretical basis for optimizing the prototype and gives a reference in the experimental modes.

Design of Experiment, Approximate Model and Optimization of a Muzzle Brake

2011 ◽  
Vol 295-297 ◽  
pp. 2563-2567
Author(s):  
Kun Jiang ◽  
Hao Wang
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Latin Hypercube Sampling ◽  
Approximate Model ◽  
Shape Parameters ◽  
Analysis Process ◽  
Surface Method ◽  
Brake Performance ◽  
Set Up ◽  
The Impact

The approximate model of the muzzle brake performance was set up and evaluated to simplify the analysis process. LHS(Latin Hypercube Sampling) and numerical simulation of inviscid muzzle flow field were applied to obtain some samples of the muzzle brake performance. The performance was weighted with the impact force on the muzzle brake. Then RSM(Response Surface Method) was adopted to get the approximate model of the muzzle brake performance to establish a mapping of muzzle brake shape parameters and the impact force. In the end GA(Genetic Algorithm) was applied to perform the optimization of the muzzle brake shape parameters with the approximate model.

Numerical Simulation of Bird Strike Damage on Jet Engine Fan Blade

2004 ◽  
Author(s):  
Kazuo Shimamura ◽  
Tadashi Shibue ◽  
Donald J. Grosch
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Bird Strike ◽  
Soft Body ◽  
Jet Engine ◽  
Fan Blade ◽  
The Impact ◽  
Interaction Problem ◽  
Numerical Simulation Technique ◽  
Good Agreement

Aircraft jet engine should be designed to keep the required performance against for the event of foreign object ingestion, such as bird-strike. For the purpose to realize highly efficient and more advanced design of fan blade of jet engine, a numerical simulation technique for bird-strike problem has developed. Good agreement was obtained between simulation results and the soft body impact tests described in this paper. It was also shown that bird-strike problem has to be recognized as a fluid-structure interaction problem, because the impacted bird behaves like fluid and the impact force is highly influenced by the deformation of fan blade.

An experimental comparison of the pedestrian safety performances of a spring actuator and a pyrotechnic actuator for deploying an active hood lift system

2017 ◽  
Vol 231 (7) ◽  
pp. 973-983 ◽  
Author(s):  
Tae-Hoon Lee ◽  
Gun-Ha Yoon ◽  
Je-Won Kang ◽  
Seung-Bok Choi
Keyword(s):  
Impact Force ◽  
Pedestrian Safety ◽  
Safety Performance ◽  
Experimental Comparison ◽  
Passenger Vehicle ◽  
Protection Effect ◽  
Working Principle ◽  
Deployment Time ◽  
The Impact ◽  
System Time

This research experimentally investigates the pedestrian safety performance of an active hood lift system of a passenger vehicle by adopting two different actuators: a spring actuator and a pyrotechnic actuator (gunpowder). After briefly introducing the working principle of the active hood lift system with the two different actuators, experiments to measure the deployment time of the system are carried out to evaluate the pedestrian safety. Subsequently, headform impact tests on the hood are performed to generate the impact force, and hence the mitigation of pedestrian injuries is investigated for the two different actuators. By comparing the measured performances obtained from both actuators, it is shown that the pyrotechnic actuator can provide a faster deployment system time. It is also identified that the spring actuator can provide a better safety performance for protecting adult pedestrians, whereas the safety performance of the pyrotechnic actuator is relatively low. Consequently, the pyrotechnic actuator is redesigned and manufactured to improve its safety performance and tested again. Then, it is shown that the modified pyrotechnic actuator can provide a better protection effect for an adult pedestrian than the spring actuator can.

Analysis and Numerical Simulation on Dynamic Response of Buried Pipeline Caused by Rock Fall Impaction

2012 ◽  
Author(s):  
Hongyuan Jing ◽  
Qinglu Deng ◽  
Jianbin Hao ◽  
Bing Han ◽  
Liangliang Li
Keyword(s):  
Numerical Simulation ◽  
Dynamic Response ◽  
Cross Section ◽  
Impact Force ◽  
Equivalent Stress ◽  
Rock Fall ◽  
Major Influence ◽  
Buried Pipeline ◽  
Stress Concentration Region ◽  
The Impact

Theoretical analysis methods are discussed to estimate additional stresses of shallow buried oil and gas pipeline caused by rock fall impaction. The process of impaction is simulated using finite elements software, in the model a 1 m3 square shape falling hard rock impacts soil ground upright of pipe with a vertical velocity, and dynamic response of pipeline is analyzed. The impact force, soil additional stresses, pipe displacement and additional stresses in the impaction process are studied. The effect of pipeline buried depth and rock velocity to the impaction also discussed. Results show that the impaction process is very short and the duration is about 10−3∼10−2s. The maximum impact force has approximately direct ratio with the velocity of rock. The additional vertical stress in soil caused by impaction load has a stress concentration region near the surface of pipe, and its distribution has the similar pattern with that in static load, but has a faster attenuation from the impaction center to sidewall. The most dangerous pipe cross-section appears in the underside of impaction center, and the maximum additional equivalent stress appears in the top of the cross-section, and has an approximately direct ratio with the velocity of rock if other impaction conditions are confirmed. The buried depth of pipeline has major influence to impaction. Large thickness of soil cover has marked effect on improve the protection of pipeline. According the study, shallow buried pipeline has weak defense to rock fall. The additional internal force and stress of pipeline caused by impaction of rock fall can be approximately estimated using theoretical methods or numerical simulation.

scholarly journals Full-Scale Impact Test and Numerical Simulation of a New-Type Resilient Rock-Shed Flexible Buffer Structure

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Z. X. Yu ◽  
L. Zhao ◽  
L. P. Guo ◽  
Y. P. Liu ◽  
C. Yang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Impact Test ◽  
Impact Force ◽  
Full Scale ◽  
Dynamic Responses ◽  
Construction Costs ◽  
Braking Distance ◽  
Cushion Layer ◽  
The Impact ◽  
Buffer Structure

Rock sheds have been widely used to protect against rockfall. Traditionally, a cushion layer is placed on the top of a rock shed to reduce the impact force and dissipate energy. However, heavy cushion layers lead to high dead loads and increased construction costs. This paper discusses the concept of an impact-resilient flexible buffer structure. On the basis of that concept, it also proposes a buffer structure mainly composed of springs, ring nets, spring rods, and support ropes, which can be used to replace the traditional cushion layer on a shed for rockfall protection. Full-scale impact tests were conducted to study the impact-resilient characteristic of the structure combined with numerical simulation. The dynamic responses of the buffer structure, including force, deformation, and energy dissipation, were analysed in depth. Finally, parametric numerical simulations of 33 models were conducted; the spring stiffness of these models ranged from 300 kN/m to 1500 kN/m; the impact energy ranged from 100 kJ to 2000 kJ. Moreover, simple approaches for estimating the impact force and braking distance of the buffer structure were proposed and verified using measured data obtained from the impact test.

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