Displacement Consideration for a Ductile Propagating Fracture in Line Pipe

1974 ◽  
Vol 96 (4) ◽  
pp. 318-322 ◽  
Author(s):  
A. K. Shoemaker ◽  
R. F. McCartney
Keyword(s):  
Driving Force ◽  
Driving Forces ◽  
Pipe Wall ◽  
Shear Fracture ◽  
Crack Tip ◽  
Complex Problem ◽  
Empirical Correlations ◽  
Line Pipe ◽  
Velocity Of Propagation ◽  
Propagating Shear

To date, the technically complex problem of arriving at an analysis for a running shear fracture in a gas-transmission line pipe has been primarily viewed by investigators in terms of an energy balance that involves empirical correlations of data. In contrast, in the present paper, the problem is reviewed in terms of the forces, masses, and time involved in the fracturing event and the resultant accelerations, velocities, and displacements with respect to (1) the forces driving the crack, (2) the pipe-wall ductility resisting the driving forces, and (3) the manner in which the crack arrests. Special attention is given to the effects of backfill on these events. On the bases of the data available, it is proposed that the displacements developed by the driving force are the result of the acceleration developed by the pressure acting on the flaps behind the crack. The driving force developed by the flaps results in forces which open the crack. For a constant velocity of propagation, the time for this flap displacement corresponds to the time for the pipe-wall thinning at the crack tip, which is controlled by the pipe-wall ductility. Thus, pipe-wall ductility can limit the speed of the crack. At a low crack speed, sufficient radial displacement of the flaps behind the crack occurs to cause the crack to turn in a helical path and arrest. Finally, the backfill significantly decreases the driving force and thus reduces the pipe-wall ductility necessary for arrest. Therefore, considerations of the displacements which occur during a propagating shear fracture indicate that the time and forces required for thinning the material at the crack tip, which is essentially governed by the ductility of the pipe wall, limit the speed of the crack.

Pipe Deformation During a Running Shear Fracture in Line Pipe

1974 ◽  
Vol 96 (4) ◽  
pp. 309-317 ◽  
Author(s):  
K. D. Ives ◽  
A. K. Shoemaker ◽  
R. F. McCartney
Keyword(s):  
Circumferential Strain ◽  
Shear Fracture ◽  
Large Diameter ◽  
Crack Tip ◽  
Local Pressure ◽  
Pipe Length ◽  
Line Pipe ◽  
Iron And Steel ◽  
Pressure Transducers ◽  
Propagating Shear

Under sponsorship of the American Iron and Steel Institute, U. S. Steel Research has been conducting full-scale burst tests of large-diameter submerged-arc-welded line pipe to determine the toughness required to arrest running shear fractures for different design conditions. As part of that program, the pipe were instrumented with crack detectors, strain gages, and pressure transducers to determine the crack velocities and the actual pipe deformation and strain fields associated with the shear fracture propagating along the top of the pipe. This paper summarizes the test data that document the manner in which the pipe deforms during this type of crack propagation. The data show that for a propagating shear fracture, each of four different locations along the pipe length (relative to the crack tip) has a distinctive type of pipe deformation. For a location many pipe diameters ahead of the crack tip, the circumferential strain first decreases because of flexural waves associated with the initiation process and then continues to decrease in proportion to the local gas decompression; however, the longitudinal strain continuously increases because of a longitudinal “tongue” of tensile straining on the top of the pipe caused by pressure-induced opening of the flaps of the pipe on both sides of the fracture behind the crack tip. At a distance about two diameters ahead of the crack tip, the pipe cross section becomes oval, and in the presence of this deformation the strain field is no longer determined by the local pressure; in fact, the circumferential strain is near zero at a distance two diameters ahead of the crack. The oval pipe shape ahead of the crack tip is caused by the venting of the gas behind the crack tip which creates a downward reactive force on the bottom portion of the pipe. Opening at the crack tip is the result of tensile straining caused by circumferential and radial displacement of the flaps behind the crack tip. Thus it is believed that the action of the pipe-wall flaps behind the crack tip provides the primary force driving the crack down the top of the pipe.

Subcritical crack growth and crack tip driving forces in relation to material resistance

2017 ◽  
Vol 35 (4-5) ◽  
pp. 251-265 ◽  
Author(s):  
Kuntimaddi Sadananda ◽  
Kiran N. Solanki ◽  
Asuri K. Vasudevan
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Driving Force ◽  
Subcritical Crack Growth ◽  
Driving Forces ◽  
Crack Tip ◽  
Crack Arrest ◽  
Internal Stresses ◽  
Continuous Growth ◽  
Elastic Plastic

AbstractBasic concepts, related to the crack tip driving forces in relation to the material resistance, are analyzed for the elastic and elastic-plastic crack growth condition. This defines the crack initiation and growth conditions, as well as for crack arrest. Environment provides an additional driving force, thereby reducing the mechanical driving force required for the crack to grow. It is shown that (a) crack initiation and its growth are inseparable and (b) the magnitude of the applied and/or internal stresses; their gradients are also important for initiation and continuous growth of a crack. Elastic-plastic crack growth is also analyzed using the discrete dislocation models. The results show that its behavior is similar to that of an elastic crack. These concepts are valid for all subcritical crack growth. Mechanical and mechanical equivalent of chemical forces are defined for estimating the life prediction of a component in service. Failure diagrams are defined based on the extension of classical Kitagawa-Takahashi diagram that bridges the behavior of smooth and fracture mechanics specimens. Connections between crack initiation, growth, arrest, and overload fracture are established via these failure diagrams. Application of these diagrams for engineering components in service is outlined for diagnostic and prognostic purposes.

Notch Ductilities of Rich Natural Gas Transmission Line Pipes for Arresting Propagating Shear Fracture

1987 ◽  
Vol 109 (1) ◽  
pp. 2-8 ◽  
Author(s):  
E. Sugie ◽  
M. Matsuoka ◽  
T. Akiyama ◽  
K. Tanaka ◽  
Y. Kawaguchi
Keyword(s):  
Natural Gas ◽  
Crack Velocity ◽  
Shear Fracture ◽  
High Strength ◽  
Velocity Curve ◽  
Research Committee ◽  
Velocity Change ◽  
Charpy Test ◽  
Line Pipe ◽  
Propagating Shear

High Strength Line Pipe Research Committee organized by The Iron and Steel Institute of Japan carried out two full-scale burst tests on X70 line pipes, 48 in. o.d. × 0.720 in. w.t., with rich natural gas as the pressurizing gas. A theoretical investigation which gives the crack velocity change in terms of the crack velocity curve and the gas decompression velocity curve is presented, and the theoretical predictions and the experimental results are in good agreement. The developed method can predict the required notch ductilities obtained from Charpy test and DWTT in order to arrest a propagating shear fracture according to the type of gas, design stress and acceptable fracture length in the pipeline.

Shear Fracture Arrestability of Controlled Rolled Steel X70 Line Pipe by Full-Scale Burst Test

1984 ◽  
Vol 106 (1) ◽  
pp. 55-62 ◽  
Author(s):  
E. Sugie ◽  
H. Kaji ◽  
T. Taira ◽  
M. Ohashi ◽  
Y. Sumitomo
Keyword(s):  
Shear Fracture ◽  
High Strength ◽  
Full Scale ◽  
Research Committee ◽  
Line Pipe ◽  
Iron And Steel ◽  
Propagation Behavior ◽  
Velocity Relationship ◽  
On Line ◽  
Propagating Shear

The High Strength Line Pipe Research Committee organized by the Iron and Steel Institute of Japan has conducted five full-scale burst tests on line pipe of 48 in. o.d. × 0.720 in. w.t. (wall thickness) and grade X70 under pressure of 80 percent SMYS with air: 1) to study the influence of separation on the arrestability of shear fracture, and 2) to obtain the material criterion for arresting the propagating shear fracture. Test pipes of Charpy V notch energy from 80 to 290J with different amount of separation, were produced from both controlled rolled steels and quenched and tempered steels. These research projects clarified that the separation of material itself did not influence the crack propagation behavior and its arrestability. Furthermore, the material criterion for arresting the shear fracture was analyzed by the pressure-velocity relationship counterbalancing the crack velocity curve and gas decompression curve.

Cracks Loaded by Rolling Contact - Influence of Plasticity around the Crack

2016 ◽  
Vol 258 ◽  
pp. 221-224 ◽  
Author(s):  
Werner Daves ◽  
Michal Kráčalík
Keyword(s):  
Finite Elements ◽  
Driving Force ◽  
Driving Forces ◽  
Crack Tip ◽  
Rolling Contact ◽  
Shear Cracks ◽  
Sliding Contacts ◽  
Crack Driving Force ◽  
Non Linear ◽  
The Common

For the description of cracks in rolling/sliding contacts many overlapping interactions has to be regarded and most of them are non-linear phenomena. This paper emphasis the aspect of plasticity around cyclically loaded shear cracks which is omitted very often in the common literature. It is shown that this plasticity can be calculated and regarded in computed crack driving forces; however, the problem is not solved after doing this. It is a first estimate only to regard the crack driving force calculated in the finite elements surrounding the crack tip as a relevant measure.

scholarly journals Driving forces on dislocations: finite element analysis in the context of the non-singular dislocation theory

2021 ◽  
Author(s):  
Xiandong Zhou ◽  
Christoph Reimuth ◽  
Peter Stein ◽  
Bai-Xiang Xu
Keyword(s):  
Finite Element ◽  
Dislocation Loop ◽  
Driving Force ◽  
Complex Geometry ◽  
Driving Forces ◽  
Singular Solutions ◽  
Dislocation Model ◽  
Configurational Force ◽  
Element Analysis ◽  
Dislocation Configuration

AbstractThis work presents a regularized eigenstrain formulation around the slip plane of dislocations and the resultant non-singular solutions for various dislocation configurations. Moreover, we derive the generalized Eshelby stress tensor of the configurational force theory in the context of the proposed dislocation model. Based on the non-singular finite element solutions and the generalized configurational force formulation, we calculate the driving force on dislocations of various configurations, including single edge/screw dislocation, dislocation loop, interaction between a vacancy dislocation loop and an edge dislocation, as well as a dislocation cluster. The non-singular solutions and the driving force results are well benchmarked for different cases. The proposed formulation and the numerical scheme can be applied to any general dislocation configuration with complex geometry and loading conditions.

Driving forces and structural changes of China as a market provider for Korea

2018 ◽  
Vol 22 (3) ◽  
pp. 194-211 ◽  
Author(s):  
Yongqi Feng ◽  
Tianshu Zhang
Keyword(s):  
Steady State ◽  
Driving Force ◽  
Design Methodology ◽  
Structural Changes ◽  
Driving Forces ◽  
Consumption Expenditure ◽  
Input Output ◽  
Content Type ◽  
Fixed Capital Formation ◽  
The Impact

Purpose The purpose of this paper is to provide a better understanding of the driving forces and structural changes of China as a market provider for Korea. This paper gives the answers for the following questions: How do China’s final demands trigger the growth of its imports from Korea? And what’s the impact of China’s final demands on the import in different industries? Design/methodology/approach Based on the Multi-Regional Input-Output model and World Input-Output Table database, this paper constructs the non-competitive imports input-output (IO) table of China to Korea. According to this table, we can calculate the induced imports coefficient and comprehensive induced import coefficients of China’s four final demands for imports from Korea in the 56 industries in China. Findings Among the four driving forces, the strongest one is changes in inventories and valuables. The impact of final consumption expenditure and fixed capital formation is much lower than that of changes in inventories and valuables, but they have a broader impact for the 56 industries. This paper finds out the China’s import induction of the final demands to Korea peaked in 2005 and 2010 and decreased greatly in 2014, so the position of China as market provider for Korea will no longer rise substantially, contrarily it will be in a steady state. Originality/value First, this paper constructs the non-competitive IO table to analyze the market provider issues between two countries and provides practical ways and methods for studies on the issues of imports and market provider. Second, this paper investigates the different roles of four final demands on driving force of China as market provider for Korea and the structural changes of China as a market provider for Korea among 56 industries from 2000 to 2014.

Study on the Steering Performance of Dual-Motor Drive Track Bulldozer

2013 ◽  
Vol 427-429 ◽  
pp. 133-136
Author(s):  
Qiang Song ◽  
Pu Zeng
Keyword(s):  
Simulation Model ◽  
Dynamic Characteristics ◽  
Driving Force ◽  
Driving Forces ◽  
Small Radius ◽  
Motor Drive ◽  
Matlab Simulink ◽  
Simulation Results ◽  
Two Sides

The driving theory and the dynamic characteristics of small radius steering, medium radius steering and big radius steering is analyzed, and the simulation model is established under Matlab/Simulink. Then the track bulldozers steering performance of the three sheerings is simulated. The results show that, at different steering modes, the running states of the two sides driving motors are not the same, and the track driving forces of the two sides vary widely. The track driving force is great in the small radius steering model, while small in the medium and big radius steering models. The simulation results lay the foundation for dual-motor drive track bulldozers steering performance matching.

scholarly journals The Formation of Deposits on the Walls of the Pores in the Filtering Process

2019 ◽  
Vol 14 (2) ◽  
pp. 15-22
Author(s):  
Yu. A. Taran ◽  
A. V. Kozlov ◽  
A. L. Taran
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Driving Force ◽  
Nonequilibrium Thermodynamics ◽  
Driving Forces ◽  
Solid Particles ◽  
Original Structure ◽  
Small Particles ◽  
Filtration Process ◽  
Filter Unit

The aim of the work is to consider the mechanism of clogging the pores of the filter unit by small particles from the flow of filtrate inside them. Theoretical ideas about the process of filtering with the deposition of small particles from the filtrate on the pore walls and attribution of its fundamentals to restructuring from the original structure to the final structure allow to describe the process of clogging the pores using well studied concepts of known processes with phase transformations (in particular, crystallization). Based on this analogy and the approach to the description of the transformation of the "old" structure into a "new" one in time, using experimental data and their processing we calculated the rate of nucleation of the sediment centers (ωnucl), the linear (υlin) and volumetric rates of sediment plaques growth in the pores of the filter unit at different values of the process driving force, at different pressure difference in the system, and at different concentrations of solid particles in the suspension. Interpolation and extrapolation dependences were obtained for analyzing the mechanisms of sediments formation and growth for determining and calculating these (ωnucl, υlin) rates. Using the concepts of nonequilibrium thermodynamics to assess the influence of the driving forces we studied their influence (changes in the concentration of solid particles in the filtrate suspension and pressure drop across the filtering layer) on the dynamics of the filtration process. Using the data obtained it is possible to find the degree of clogging of through pores, which determines the filtration conditions, the filter septum type, and the filter overall dimensions.

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