scholarly journals Numerical Simulation of Pipeline Deformation Caused by Rockfall Impact

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Jie Zhang ◽  
Zheng Liang ◽  
Chuanjun Han
Keyword(s):  
Plastic Strain ◽  
Impact Crater ◽  
Oil And Gas ◽  
Incidence Angle ◽  
Impact Angle ◽  
The Finite Element Method ◽  
Pipeline Transportation ◽  
Impact Condition ◽  
Plastic Strain Zone ◽  
Eccentric Impact

Rockfall impact is one of the fatal hazards in pipeline transportation of oil and gas. The deformation of oil and gas pipeline caused by rockfall impact was investigated using the finite element method in this paper. Pipeline deformations under radial impact, longitudinal inclined impact, transverse inclined impact, and lateral eccentric impact of spherical and cube rockfalls were discussed, respectively. The effects of impact angle and eccentricity on the plastic strain of pipeline were analyzed. The results show that the crater depth on pipeline caused by spherical rockfall impact is deeper than by cube rockfall impact with the same volume. In the inclined impact condition, the maximum plastic strain of crater caused by spherical rockfall impact appears when incidence angleαis45°. The pipeline is prone to rupture under the cube rockfall impact whenαis small. The plastic strain distribution of impact crater is more uneven with the increasing of impact angle. In the eccentric impact condition, plastic strain zone of pipeline decreases with the increasing of eccentricityk.

Gradient of Soil Constitutive Model

2010 ◽  
Vol 168-170 ◽  
pp. 1126-1129
Author(s):  
Wen Xu Ma ◽  
Ying Guang Fang
Keyword(s):  
Plastic Strain ◽  
Strain Gradient ◽  
Soil Analysis ◽  
Natural Material ◽  
Flow Rule ◽  
The Finite Element Method ◽  
Gradient Effect ◽  
Non Local ◽  
Associated Flow Rule ◽  
Plastic Strain Gradient

For the soil is a very complex natural material, significant strain gradient effect exist in soil analysis. Based on the "gradient" phenomenon, we add the plastic strain gradient hardening item into the traditional Cambridge yield surface. By using the consistency conditions and associated flow rule, we get the explicit expression of plastic strain gradient stiffness matrix. And the finite element method of plastic strain gradient is also shown in this article. Plastic strain gradient is actually a phenomenological non-local model containing microstructure information of the material. It may overcome the difficulties in simulating the gradient phenomenon by traditional mechanical model.

Strain-based fatigue life analysis of pipelines with external defects under cyclic internal pressure

2020 ◽  
pp. 030932472095756
Author(s):  
Hojjat Gholami ◽  
Shahram Shahrooi ◽  
Mohammad shishehsaz
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Plastic Strain ◽  
Internal Pressure ◽  
Oil And Gas ◽  
Isotropic Hardening ◽  
Element Simulation ◽  
Life Analysis ◽  
Fatigue Life Analysis ◽  
Pipe Geometry

Gouge and dent are common mechanical defects in oil and gas pipelines. These defects with plastic strain cause stress concentration in the pipelines. Plastic strain is dependent on initial deformation and spring-back behavior of materials. Therefore, they reduce the fatigue life of pipelines. In this paper, the strain-base fatigue life analysis is investigated in pipelines with smooth dent or combination smooth dent and gouge defects under cyclic internal pressure. For this purpose, elastic-plastic multilinear isotropic hardening finite element simulation was used to investigate the effects of various factors, such as residual stress of dent, amplitude internal pressure, pipe geometry, gouge geometry, and smooth dent geometry on stress concentration factor (SCF). Finally, a new method is proposed for predicting the fatigue life of pipelines with uniform dent and uniform dent and gouge combination defects. The model is presented based on the Smith-Watson-Topper (SWT) criterion. A set of fatigue life test specimens with various pipe materials, size and geometry were prepared and tested. The specimens carried a smooth dent, as well as a combination of smooth dent and gouge defects, results of which were collected to validate those obtained based on the proposed model. The results of the predicted tests using the developed formula showed a good correlation to practical experiments.

Enhancement of acoustic absorption of a rigidly backed poroelastic plate with periodic elliptic inclusions

2019 ◽  
Vol 33 (30) ◽  
pp. 1950367
Author(s):  
Hongbo Zhang ◽  
Bilong Liu
Keyword(s):  
Material Properties ◽  
Composite Plate ◽  
Incidence Angle ◽  
Major Axis ◽  
Acoustic Energy ◽  
Absorption Peak ◽  
Acoustic Absorption ◽  
The Finite Element Method ◽  
Solid Materials ◽  
Low Frequencies

Perfect acoustic absorption is an important issue for a lot of applications. In this paper, a rigidly backed poroelastic plate with periodic elliptic inclusions is proposed to achieve perfect acoustic absorption at low frequencies by using the finite element method (FEM) with the porous material considered as fluid and solid materials. The absorption of the acoustic energy in such a composite plate resulting from viscous and thermal losses is enhanced by the resonances of the inclusions and energy trapping between the upper part of the poroelastic plate and the inclusion at low frequencies. The influence of the geometry, the incidence angle and the material properties on the absorption coefficient are investigated in detail. Our results show that increasing the major axis of the inclusion, the first absorption peak is pushed to lower frequencies and its value is first increased upto one and then it is decreased. The major axis is the most important parameter to tune the absorption peak, when the thickness is not changed. Once the major axis is determined, perfect acoustic absorption persists even if other parameters are changed. The reported results pave the way for the design of absorption devices which could be used to solve the major issue of noise control.

The case for shared infrastructure to unlock onshore resources

2020 ◽  
Vol 60 (2) ◽  
pp. 431
Author(s):  
Kai C. Eberspaecher
Keyword(s):  
Oil And Gas ◽  
Barriers To Entry ◽  
Pipeline Transportation ◽  
General Development ◽  
Current State ◽  
Capital Assets ◽  
Strategic Review ◽  
Resource Policy ◽  
The Uk ◽  
Shared Infrastructure

This paper outlines the current state of the upstream industry for smaller oil and gas developers in Australia’s mature onshore basins. In particular, a strategic review of the market landscape based on Porter’s Five Forces model is undertaken from a junior exploration company’s perspective with a focus on barriers to market entry, such as access to infrastructure, capital, assets and expertise. In the strategic framework context, the paper examines the opportunities to break down natural monopolistic structures and barriers to entry across incumbent producers, pipeline transportation companies and contractors. It also investigates potential changes in resource policy dealing with access to infrastructure and general development requirements. In its analysis, the importance of junior explorers to extend the longevity of mature basins by looking at other petroleum provinces around the globe is highlighted. Examples in North America (onshore) and the UK (offshore) are used to showcase approaches in assisting smaller companies converting resources into reserves. In its conclusion, the paper demonstrates qualitatively how shared infrastructure, coopetition and incorporating renewables can be game changers for junior explorers in unlocking further resources and new prospects in the Australian onshore hydrocarbon provinces. The paper also calls for further coordination between companies, industry bodies and government under an improvement framework to ensure continued success.

Effect of Interference on Stress and Strain Distribution on the Spherical Sealing Cup of a PIG in Dented Pipeline

2019 ◽  
Author(s):  
Hang Zhang ◽  
Jinhui Dong ◽  
Can Cui ◽  
Ningsheng Liao
Keyword(s):  
Strain Distribution ◽  
Optimization Design ◽  
Oil And Gas ◽  
Model Simulation ◽  
Outer Edge ◽  
Stress And Strain ◽  
Pipeline Transportation ◽  
Pipeline Inspection ◽  
Simulation Results ◽  
Stress And Strain Distribution

Abstract Regular pigging operation of the pipeline inspection gauges (PIGs) is crucial for pipeline transportation. However, the PIG is often stuck when it runs in the oil and gas pipeline due to the interaction between spherical sealing cup and dent inside the pipe. The stress and strain distribution of the outer edge of the spherical sealing cup can provide a reference to the problem of understanding the blockage. In this study, numerical simulation of a PIG with spherical sealing cups runs through a pipe with dented wall is presented using MSC Marc 2016. Effects of the interference (δ) of the spherical sealing cup on the stress and strain distribution on the outer edge of the cup were discussed based on the model. Simulation results indicate that the smaller the thickness of the spherical sealing cup, the greater the effect of the interference of the cup on the stress. And the thickness of the cup should not be too small, an example of the failure of pigging due to the small thickness of the cup and the increase in the interference is given. The conclusions obtained in this study can contribute to the optimization design of the PIGs.

A CRASHWORTHINESS SIMULATION FOR A LIGHT AIRCRAFT CONSTRUCTED OF COMPOSITE MATERIALS

2015 ◽  
Vol 39 (4) ◽  
pp. 829-843 ◽  
Author(s):  
Pu-Woei Chen ◽  
Kuan-Jung Chen
Keyword(s):  
Composite Material ◽  
Aluminum Alloy ◽  
Composite Materials ◽  
Fiber Composite ◽  
Impact Angle ◽  
The Finite Element Method ◽  
Dynamic Impact ◽  
Carbon Fiber Composite ◽  
Impact Speed ◽  
Impact Simulations

This study analyzes the crashworthiness of a light aircraft that is constructed from composite materials. The finite element method is employed to conduct dynamic impact simulations on carbon fiber composite fuselages. The results show that the safe impact speed for an aluminum alloy cockpit crashed at a 30° impact angle is 9.59 m/s, but a cockpit made of composite material can withstand a speed greater than 18.05 m/s. The safe impact angle for an aluminum alloy cockpit is 16.56°, but that for a composite cockpit is 84.9°. The safety crash zone for a composite material cockpit is 160% greater than that for an aluminum alloy cockpit.

scholarly journals Investigation of hydrate slurry flow behaviors in deep-sea pipes with different inclination angles

2019 ◽  
Vol 74 ◽  
pp. 48 ◽  
Author(s):  
Shupeng Yao ◽  
Yuxing Li ◽  
Wuchang Wang ◽  
Guangchun Song ◽  
Zhengzhuo Shi ◽  
...  
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Gas Hydrate ◽  
Oil And Gas ◽  
Pipeline Transportation ◽  
Slurry Flow ◽  
Initial Particle ◽  
Initial Particle Size ◽  
Inclination Angles ◽  
Slurry Transport

The marine area is the main direction of the development of oil and gas resources in the world. The pipeline transportation technology of natural gas hydrate slurry plays an important role in the exploitation of marine oil and gas and the exploitation of marine gas hydrate resources. In order to study the influence of pipe inclination on pipeline transportation, population balance model based on hydrate particle aggregation dynamics was coupled with the Eulerian–Eulerian two-fluid multiphase flow model to simulate the flow behaviors of hydrate slurry flow in pipes with different inclination angles. In the study, three variables of inclination, flow rate and initial particle size were considered. The results show that tilted pipes are beneficial to hydrate slurry transport rather than harmful. Meanwhile, higher flow rates and lower initial particle sizes are beneficial for promoting the flow safety of hydrate slurry transport. However, the flow pressure drop of the hydrate slurry increases with the increase of the flow rate and the decrease of the initial particle size, which is not conducive to the economics of mining. The research results in this paper can provide reference for the research of hydrate slurry flow safety and parameter guidance for hydrate solid fluidized mining.

Diffraction-Based Investigation Methods in Analysing Plastic Strain Zone Underneath Fracture Surface

2019 ◽  
pp. 97-110
Author(s):  
S.A. Naprienko ◽  
P.N. Medvedev ◽  
A.N. Raevskikh ◽  
M.A. Popov
Keyword(s):  
Fracture Surface ◽  
Plastic Strain ◽  
Texture Analysis ◽  
Electron Backscatter Diffraction ◽  
Pole Density ◽  
Two Phase ◽  
X Ray ◽  
Imaging Geometry ◽  
Investigation Methods ◽  
Plastic Strain Zone

We used samples of the ВТ41 two-phase titanium alloy to estimate the relationship between testing temperature, KCV fracture toughness values, width of the plastic strain zone and its formation specifics. We developed an efficient method of estimating the plastic strain zone width, based on a special X-ray imaging geometry enabling a high degree of locality for measuring variations in the X-ray line broadening when moving away from the fracture surface. We studied material texture close to the fracture zone and at a distance from it, which allowed us to detect the specifics of grain reorientation, in particular, texture diffusion and an increase in the concentration of basal and prismatic planes parallel to the fracture surface as a result of plastic strain and dislocation saturation. We hypothesise that pole density in the [0001] region grows due to the [1012]-oriented grain slip, while in the region around [1010] pole density grows due to slip of the grains whose orientation is close to [1120]. We verified our X-ray texture analysis data by texture analysis via electron backscatter diffraction (EBSD).

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