scholarly journals Discrete element analysis of the mechanical properties of deep-sea methane hydrate-bearing soils considering interparticle bond thickness

2017 ◽  
Vol 345 (12) ◽  
pp. 868-889 ◽  
Author(s):  
Mingjing Jiang ◽  
Jie He ◽  
Jianfeng Wang ◽  
Yaping Zhou ◽  
Fangyuan Zhu
Keyword(s):  
Mechanical Properties ◽  
Deep Sea ◽  
Methane Hydrate ◽  
Discrete Element ◽  
Element Analysis ◽  
Interparticle Bond

Discrete Element Method Analysis of Mechanical Properties of Railway Ballast during Tamping Process under Different Amplitude

2012 ◽  
Vol 233 ◽  
pp. 224-227 ◽  
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Xue Jun Wang ◽  
Bo Yan
Keyword(s):  
Mechanical Properties ◽  
Discrete Element Method ◽  
Simulation Analysis ◽  
Discrete Element ◽  
Practical Experience ◽  
Field Trials ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Element Method

Railway ballast tamping operations is an important work in the line maintenance and repair operations, the selection of tamping parameter is usually dependent on field trials and practical experience, for the mechanical properties of railway ballast is difficult to measure and describe. This paper creates discrete element analysis model of railway ballast using the discrete element method, the numerical simulations are carried out to study the mechanical properties of railway ballast during tamping process. We focus on the influence of amplitude during tamping process; an optimal amplitude of the simulation analysis is obtained and compared with the recommended amplitude of Plasser & Theurer Company, it is found that the two amplitudes accord. This result verifies the correct validity of the discrete element analysis model of railway ballast during tamping process.

scholarly journals Investigations of Mechanical Properties of API P110 Steel Casing Tubes Operated in Deep-Sea Sour Condensate Well Conditions

2020 ◽  
Vol 27 (3) ◽  
pp. 121-129
Author(s):  
Yao Zilin ◽  
Wang Yu ◽  
Yang Xuefeng ◽  
Gao Anping ◽  
Zhang Rong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Strength ◽  
Yield Strength ◽  
Deep Sea ◽  
Performance Model ◽  
Continuous Change ◽  
Element Analysis ◽  
Equivalent Yield

AbstractDue to the complexity of the marine environment, in deep-sea drilling, all kinds of strings are corroded by different deep-sea conditions for a long time, accompanied by high temperature and high pressure, which lead to the continuous change of mechanical properties of materials. In order to solve the problem that the material mechanical parameters cannot be accurately described in the performance analysis of the casing, deep-sea simulated corrosion and material damage experiments of P110 material were carried out in this paper. Mass loss and tensile experiments on corrosion-damaged test pieces were conducted under different corrosion experimental periods. The changes in mechanical properties of the material were analyzed. Equations of the variation of the equivalent yield strength and the equivalent tensile strength were obtained. The results show that the equivalent yield strength and the equivalent tensile strength decrease with the increase of the weight loss rate. Based on the experimental results and finite element analysis, a method for establishing the material corrosion model was proposed in this paper. The deep-sea drilling corrosion performance model of P110 material was established, which greatly reduced the error caused by the material uniformity assumption in finite element analysis. This paper provides a theoretical basis for the analysis of reliability and life of P110 materials in wells.

scholarly journals Molecular Dynamics Simulation of the Effects of Methane Hydrate Phase Transition on Mechanical Properties of Deep-Sea Methane Hydrate-Bearing Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yanmei Zhang ◽  
Jian Zhang ◽  
Guoxun Li ◽  
Changda Sun ◽  
Yalin Luan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Molecular Dynamics ◽  
Deep Sea ◽  
Methane Hydrate ◽  
Free Water ◽  
Dynamics Simulation ◽  
Soil Particles ◽  
Hydrate Phase ◽  
Excess Pore

In this paper, the methane hydrate phase transition process in deep-sea methane hydrate-bearing soil under heating and compression was simulated by the molecular dynamics method. The evolution of deep-sea methane hydrate-bearing soil’s microstructure, system energy, intermolecular interaction energy, and radial distribution function during heating and compression was investigated. The micromechanism of the influence of the methane hydrate phase transition on the mechanical properties of deep-sea methane hydrate-bearing soil was analyzed. The results demonstrated that the methane hydrate dissociation starts from both sides to the middle and the void spaces between the soil particles had nearly no change during the heating process. For the compression process, the methane hydrate on both sides and the middle dissociated at the same time, and the void spaces became smaller. The methane hydrate phase transition on the effects of mechanical properties of the deep-sea methane hydrate-bearing soil is mainly caused by three aspects. (1) the dissociation of methane hydrate incurs the decrease of methane hydrate saturation. The free water and methane molecules generated cannot migrate in time and thus lead to the increase of excess pore water press and excess pore gas press. (2) The dissipated energy causes the decrease of the effective stress between the soil particles. (3) Due to the methane hydrate decomposition, the free water molecules increase, which reduces the friction of soil particles.

Discrete Element Method Analysis of Mechanical Properties of Railway Ballast during Tamping Process under Different Vibration Frequency

2012 ◽  
Vol 190-191 ◽  
pp. 369-372
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Xue Jun Wang ◽  
Bo Yan
Keyword(s):  
Mechanical Properties ◽  
Discrete Element Method ◽  
Vibration Frequency ◽  
Simulation Analysis ◽  
Discrete Element ◽  
Field Trials ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Element Method

Railway ballast tamping operations is an important work in the line maintenance and repair operations, the selection of tamping parameter is usually dependent on field trials and practical experience, for lack of theoretical basis. This paper creates discrete element analysis model of railway ballast using the discrete element method, the numerical simulations are carried out to study the mechanical properties of railway ballast during tamping process. We focus on the influence of vibration frequency during tamping process; an optimal vibration frequency of the simulation analysis is obtained and compared with the recommended vibration frequency of Plasser & Theurer Company, it is found that the two vibration frequencies accord. This result verifies the correct validity of the discrete element analysis model of railway ballast during tamping process.

Discrete Element Analysis of Hydraulic Fracturing of Methane Hydrate-Bearing Sediments

2021 ◽  
Author(s):  
Yuanxin Yao ◽  
Zehui Guo ◽  
Jiaming Zeng ◽  
Dongliang Li ◽  
Jingsheng Lu ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Methane Hydrate ◽  
Discrete Element ◽  
Element Analysis ◽  
Hydrate Bearing Sediments

scholarly journals Failure Analysis on a Collapsed Flat Cover of an Adjustable Ballast Tank Used in Deep-Sea Submersibles

2019 ◽  
Vol 9 (23) ◽  
pp. 5258
Author(s):  
Fang Wang ◽  
Mian Wu ◽  
Genqi Tian ◽  
Zhe Jiang ◽  
Shun Zhang ◽  
...  
Keyword(s):  
Deep Sea ◽  
Material Selection ◽  
High Strength ◽  
External Pressure ◽  
Element Analysis ◽  
Ballast Tank ◽  
Material Inhomogeneity ◽  
Comprehensive Properties ◽  
Ultimate Cause ◽  
Flat Cover

A flat cover of an adjustable ballast tank made of high-strength maraging steel used in deep-sea submersibles collapsed during the loading process of external pressure in the high-pressure chamber. The pressure was high, which was the trigger of the collapse, but still considerably below the design limit of the adjustable ballast tank. The failure may have been caused by material properties that may be defective, the possible stress concentration resulting from design/processing, or inappropriate installation method. The present paper focuses on the visual inspections of the material inhomogeneity, ultimate cause of the collapse of the flat cover in pressure testing, and finite element analysis. Special attention is paid to the toughness characteristics of the material. The present study demonstrates the importance of material selection for engineering components based on the comprehensive properties of the materials.

scholarly journals Discrete Element Analysis of High-Pressure Zones of Sea Ice on Vertical Structures

2021 ◽  
Vol 9 (3) ◽  
pp. 348
Author(s):  
Xue Long ◽  
Lu Liu ◽  
Shewen Liu ◽  
Shunying Ji
Keyword(s):  
High Pressure ◽  
Sea Ice ◽  
Failure Mode ◽  
Contact Area ◽  
Loading Rate ◽  
Discrete Element ◽  
Offshore Platforms ◽  
Marine Structures ◽  
Element Analysis ◽  
Ice Pressure

In cold regions, ice pressure poses a serious threat to the safe operation of ship hulls and fixed offshore platforms. In this study, a discrete element method (DEM) with bonded particles was adapted to simulate the generation and distribution of local ice pressures during the interaction between level ice and vertical structures. The strength and failure mode of simulated sea ice under uniaxial compression were consistent with the experimental results, which verifies the accuracy of the discrete element parameters. The crushing process of sea ice acting on the vertical structure simulated by the DEM was compared with the field test. The distribution of ice pressure on the contact surface was calculated, and it was found that the local ice pressure was much greater than the global ice pressure. The high-pressure zones in sea ice are mainly caused by its simultaneous destruction, and these zones are primarily distributed near the midline of the contact area of sea ice and the structure. The contact area and loading rate are the two main factors affecting the high-pressure zones. The maximum local and global ice pressures decrease with an increase in the contact area. The influence of the loading rate on the local ice pressure is caused by the change in the sea ice failure mode. When the loading rate is low, ductile failure of sea ice occurs, and the ice pressure increases with the increase in the loading rate. When the loading rate is high, brittle failure of sea ice occurs, and the ice pressure decreases with an increase in the loading rate. This DEM study of sea ice can reasonably predict the distribution of high-pressure zones on marine structures and provide a reference for the anti-ice performance design of marine structures.

scholarly journals Discrete element analysis of the punching behaviour of a secured drapery system: from laboratory characterization to idealized in situ conditions

2021 ◽  
Author(s):  
Antonio Pol ◽  
Fabio Gabrieli ◽  
Lorenzo Brezzi
Keyword(s):  
Mechanical Response ◽  
Steel Wire ◽  
Discrete Element ◽  
Wire Mesh ◽  
Steel Plates ◽  
Loading Conditions ◽  
Element Analysis ◽  
In Situ Conditions ◽  
Wire Meshes

AbstractIn this work, the mechanical response of a steel wire mesh panel against a punching load is studied starting from laboratory test conditions and extending the results to field applications. Wire meshes anchored with bolts and steel plates are extensively used in rockfall protection and slope stabilization. Their performances are evaluated through laboratory tests, but the mechanical constraints, the geometry and the loading conditions may strongly differ from the in situ conditions leading to incorrect estimations of the strength of the mesh. In this work, the discrete element method is used to simulate a wire mesh. After validation of the numerical mesh model against experimental data, the punching behaviour of an anchored mesh panel is investigated in order to obtain a more realistic characterization of the mesh mechanical response in field conditions. The dimension of the punching element, its position, the anchor plate size and the anchor spacing are varied, providing analytical relationships able to predict the panel response in different loading conditions. Furthermore, the mesh panel aspect ratio is analysed showing the existence of an optimal value. The results of this study can provide useful information to practitioners for designing secured drapery systems, as well as for the assessment of their safety conditions.

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