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Dynamic-based model for calculating the boulder impact force in debris flow

Journal of Mountain Science 2024年第6期21卷 1930-1940页

作者： YANG Chaoping ZHANG Shaojie YIN Yueping YANG Hongjuan WEI Fangqiang State Key Laboratory of Mountain Hazards and Engineering Resilience Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610299China University of Chinese Academy of Sciences Beijing 100049China China Institute of Geological Environment Monitoring Beijing 100081China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China Chongqing School University of Chinese Academy of SciencesChongqing 400714China

The boulder impact force in debris flow is generally calculated by static methods such as the cantilever beam ***,these methods cannot describe the dynamic scenario of boulder collision on structures,so the inertia and damping effects of the structures are not involved causing an overestimation on the boulder impact *** order to address this issue,a dynamic-based model for calculating the boulder impact force of a debris flow was proposed in this study,and the dynamic characteristics of a cantilever beam with multiple degrees of freedom under boulder collision were *** using the drop-weight method to simulate boulders within debris flow,seven experiments of drop-weight impacting the cantilever beam were used to calibrate the error of the dynamicbased *** indicate that the dynamic-based model is able to reconstruct the impact force history on the cantilever beam during impact time and the error of dynamic-based model is 15.3%in calculating boulder impact force,significantly outperforming the cantilever beam model’s error of 285%.Therefore,the dynamic-based model can overcome the drawbacks of the static-based models and provide a more reliable theoretical foundation for the engineering design of debris flow control structures.

关键词： Debris flow impact force Boulder collision Dynamic-based model Engineering design

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Effects of process parameters on periodic impact force exerting on cutting tool in ultrasonic vibration-assisted oblique turning

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Advances in Manufacturing 2022年第3期10卷 411-427页

作者： Long-Xu Yao Zhan-Qiang Liu Qing-Hua Song Bing Wang Yu-Kui Cai School of Mechanical Engineering Shandong UniversityJinan 250061People's Republic of China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education/Key National Demonstration Center for Experimental Mechanical Engineering Education Jinan 250061People's Republic of China

During ultrasonic vibration-assisted machining,the large impact force induced by tool-workpiece reengagement(TWR)is an important factor that affects tool ***,mechanical analysis into process factors that affect the impact force and their influencing mechanisms are ***,a prediction model for the instantaneous cutting force during both TWR and the stable turning process,which depends on the process parameters and material properties,is firstly proposed based on the kinematic and dynamic analysis of ultrasonic vibration-assisted oblique turning(UVAOT).The results calculated using the developed cutting force model agree well with the experimental results presented in the ***,the linear change law of the instantaneous cutting force with cutting time during the actual TWR is clarified using the proposed *** effect of the UVAOT process parameters on the average impact force during the periodic TWR process is discussed,and the influence mechanism is analyzed from the perspective of mechanics.A positive linear correlation is discovered between the feed speed and average impact *** ultrasonic amplitude and cutting speed do not significantly affect the average impact force of the new sharp cutting *** findings are consistent with the experimental observations of tool chipping and are applicable to select process parameters for reducing tool chipping during UVAOT.

关键词： Kinematics Dynamics Ultrasonic vibrationassisted oblique turning(UVAOT) impact force Cutting force

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Firmness measurement of peach by impact force response

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第12期10卷 883-889页

作者： Yong-wei WANG Jun WANG Chong YAO Qiu-jun LU Department of Biosystems Engineering Zhejiang University Hangzhou 310029 China

The impact force response of a peach impacting on a metal flat-surface was considered as nondestructive determination of firmness. The objectives were to analyze the effect of firmness, drop height, fruit mass, and impact orientation on the impact force parameters, and to establish a relationship between the impact force parameter and firmness. The effect of fruit firmness, drop height and fruit mass on the impact force parameters (coefficient of restitution, percentage of energy absorbed, and coefficient of force-time) was evaluated. The study found that the coefficient of restitution, percentage of energy absorbed, and force-time impact coefficient were significantly affected by fruit ripeness, but not affected by drop height, impact position (fruit cheek), and mass. The percentage of absorbed energy increased with ripeness, while the force-time impact coefficient and coefficient of restitution decreased with ripeness. Relationships were obtained between the three impact characteristic parameters (force-time impact coefficient, coefficient of restitution, and percentage of energy absorbed) and peach firmness using a polynomial model (R2=0.932), S model (R2=0.910), and exponential model (R2=0.941), respectively.

关键词： Firmness Peach impact force Coefficient of restitution Percentage of absorbed energy

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APPROXIMATE　FORMULASOF　impact　force　FOR　NORMAL　impact　OF　A　FINITE　ELASTIC　BEAM　OF　ELASTIC　FOUNDATION　BY　A　FINITE　ROD

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Applied Mathematics and Mechanics(English Edition) 1996年第1期17卷 45-52页

作者：任文敏黄剑敏陈文 Department of Engineering Mechanics Qinghua University Beijing P. R. China

The normal impact of an elastic initially static beam of finite length on an elastic foundation by a finite elastic rod with initial velocity is investigated in this paper. The approximate formulas for the impact forc... 详细信息

关键词： impact force elastic wave Galerkin principle

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impact force Attenuation Process during Landing in Simulated Parachute Jumping

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Journal of Medical Colleges of PLA 1987年第3期 286-290页

作者：冯文树刘铁汉何扬举简进章范建伟 Department of Aviation Biodynamics Fouth Military Medical College Xi’an

Under the simulating of parachute jumping,the landing impact forceson the segments of the human body of three parachuters were studied with thehelp of high-speed photography and theoretical *** results show:(1)There was an attenuation process of the impact forces on the body segments.(2)The impact force on the body segments and the peak of the impact force on the feetat the time from 0.08 to 0.26 s attenuated by 40.6-64.1% as compared with thoseat 0.08s.(3)The attenuation curve of the peak of the impact force on the feet isclose to the curve of its regression equation.

关键词： parachute jumping aviation medicine biomechanics impact force impact time

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Reconstruction of impact force of mechanical press in time domain

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Journal of Southeast University(English Edition) 2011年第4期27卷 400-404页

作者：何鹏程贾方东南大学机械工程学院南京211189

To overcome the difficulty in directly measuring the impact force of a mechanical press, the inverse theory is employed to reconstruct the impact force from the corresponding response data in time domain. The nature of ill-posedness of impact force reconstruction is explored through singular value decomposition （SVD） and the Tikhonov regularization is utilized to deal with the ill-posedness, in which the optimal parameter is chosen in light of the L-curve criterion and the generalized cross- validation （GCV）. The experimentally measured strain responses of upper and lower dies of the press are chosen as source data for impact force reconstruction, and the corresponding numerical results are compared with the experimental measurements, which verifies the effectiveness of the reconstruction method.

关键词： mechanical press impact force reconstruction inverse problem regularization

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Protective effect of retaining wall on rock avalanche:A case study of Nayong rock avalanche in China

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Journal of Mountain Science 2024年第4期21卷 1215-1230页

作者： WANG Zhongfu SHI Fengge HE Siming ZHANG Xusheng WANG Jingying LIU Enlong North China University of Water Resources and Electric Power Zhengzhou 450046China Hunan Provincial key Laboratory of key Technology on Hydropower Development Changsha 410014China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China College of Water Resource and Hydropower Sichuan UniversityChengdu 610065China

Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they ***,barrier structures constructed along the path of a rock avalanche can partially mitigate the magnitudes and consequences of such catastrophic *** selected a rock avalanche in Nayong County,Guizhou Province,China as a case to study the effect of the location and height of a retaining wall on the dynamic characteristics of rock avalanche by using both actual terrain-based laboratory-model tests and coupled PFC3D-FLAC3D numerical *** findings demonstrate that a retaining wall can largely block a rock avalanche and its protective efficacy is significantly influenced by the integrity of the retaining *** numerical simulation can serve as a powerful tool for analyzing the interaction between a rock avalanche and a retaining wall,facilitating precise observations of its deformation and *** impact-curve characteristics of the retaining wall depend upon whether or not the rock avalanche-induced destruction is taken into *** location of the retaining wall exerts a greater influence on the outcome compared to the height and materials of the retaining wall,while implementing a stepped retaining-wall pattern in accordance with the terrain demonstrates optimal efficacy in controlling rock avalanche.

关键词： Rock avalanche Laboratory model test Retaining wall PFC^(3D) FLAC^(3D) impact force

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Impulse force reductions and their effects on WBV exposures in high impact shovel loading operations

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International Journal of Mining Science and Technology 2018年第3期28卷 423-435页

作者： Danish Ali Samuel Frimpong Mining & Nuclear Engineering Department Missouri University of Science and Technology

When shovels load the dump trucks with over 100-ton passes under gravity dumping conditions, they will create a large impact force on the dump truck body which generates high frequency shock waves which expose the operators to whole body vibrations （WBV）. The main cause of such truck vibrations is the large impact force due to the gravity dumping of large tonnage passes. Therefore a rigorous mathematical model has been developed for the impact force containing all the necessary factors upon which it depends. Latter, a thorough analysis shows that percentage reduction of 7.19%, 9.40%, 13.27%, 14.8%, 17.30% and 18.13% can he achieved by reducing the dumping distance to 6.33 m, 6.0 m, 5.5 m, 5.33 m, 5.0 m and 4.9 m, respectively, as compared to when the dumping distance was 7.33 m. Even more reduction in the magnitude of impact force can he observed if the shovel pass gets divided into more than two sub-passes. Therefore, these models can he used to figure out the number of sub-passes into which a single ore pass can he divided and/or the extent to which the dumping distance can he reduced which would reduce the impact force significantly enough to obtain safer yet economic operations.

关键词： impact force HISLO Mathematical modeling Dumping distance Shovel ore sub-passes

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Macro-phenomenological high-strain-rate elastic fracture model for ice-impact simulations

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Chinese Journal of Aeronautics 2023年第3期36卷 146-160页

作者： Jiang FAN Qinghao YUAN Fulei JING Guangchen BAI Xiuli SHEN School of Energy and Power Engineering Beihang UniversityBeijing 100191China Beijing Key Laboratory of Aero-Engine Structure and Strength Beijing 100191China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100191China Aero-Engine Academy of China Aero Engine(Group)Corporation of ChinaBeijing 101304China

The ice impact can cause a severe damage to an aircraft’s exposed structure,thus,requiring its *** numerical simulation represents an effective method to overcome this *** establishment of the ice material model is ***,ice is not a common structural material and exhibits an extremely complex material *** material models of ice reported so far are not able to accurately simulate the ice behavior at high strain *** study proposes a novel high-precision macro-phenomenological elastic fracture model based on the brittle behavior of ice at high strain *** developed model has been compared with five reported models by using the smoothed particle hydrodynamics method so as to simulate the ice-impact process with respect to the impact speeds and ice *** important metrics and phenomena(impact force history,deformation and fragmentation of the ice projectile and deflection of the target)were compared with the experimental data reported in the *** findings obtained from the developed model are observed to be most consistent with the experimental data,which demonstrates that the model represents the basic physics and phenomena governing the ice impact at high strain *** developed model includes a relatively fewer number of material ***,the used parameters have a clear physical meaning and can be directly obtained through ***,no adjustment of any material parameter is needed,and the consumption duration is also *** advantages indicate that the developed model is suitable for simulating the iceimpact process and can be applied for the anti-ice impact design in aviation.

关键词： Crack propagation Elastic fracture High strain rate Ice impact impact force Material model

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Study of damage to a high concrete dam subjected to underwater shock waves

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Earthquake Engineering and Engineering Vibration 2014年第2期13卷 337-346页

作者： Lu Lu Li Xin Zhou Jing Faculty of Architecture and Civil Engineering Huaiyin Institute of Technology The State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology

To study the effect of a strong underwater shock wave on a concrete dam, this research aims to improve hammer impact methods in model tests. Six 1:200 scale models were designed and tested under distributed impact loads. A device was deployed for a direct measurement of the impact force at the upstream face of the dams. The model dam bases were anchored to prevent displacement. The experimental results indicate that the top part of the concrete dam is a weak zone, and the impact failure initiates with a fracture on the top of the dam. The peak value of impact stress increases when the second crack appears in the concrete dam from the upstream face to the downstream face. And, the level of the second crack in the dam body is lower as the peak value of impact stress increases. In this study, dynamic analysis was conducted by calculating the results to verify the effectiveness of a device to directly measure the impact force. This method may be used to approximately forecast the damage of concrete dam and may also be useful in other engineering applications.

关键词： underwater shock wave hammer impact impact force high concrete gravity dam forecast damage

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