Crack Propagation Modeling and Crack Arrestor Design for X120

2006 ◽  
Author(s):  
Andrea Fonzo ◽  
Andrea Meleddu ◽  
Massimo Di Biagio ◽  
Gianluca Mannucci ◽  
Giuseppe Demofonti ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Wall Thickness ◽  
Full Scale ◽  
Operating Conditions ◽  
Experimental Results ◽  
Finite Element Code ◽  
Pipeline Steels ◽  
Propagation Modeling

The new, higher grade pipeline steels provide an opportunity to reduce pipeline costs by enabling a shift to higher pressure at reasonable wall thickness. However, these higher operating stresses place greater demands on the pipeline, particularly when a running fracture is considered. Several studies have shown that intrinsic arrest cannot be counted on for these grades under all operating conditions. In such cases, crack arrestors will be needed. This paper presents results obtained using CSM’s proprietary PICPRO® finite element code to predict the performance of crack arresters on X120 pipes, and shows that the predictions agree well with full-scale experimental results obtained in arrestor trials.

Full-Scale Wrinkling Tests and Analyses of Large Diameter Corroded Pipes

1998 ◽  
Author(s):  
Marina Q. Smith ◽  
Daniel P. Nicolella ◽  
Christopher J. Waldhart
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Axial Compression ◽  
Wall Thickness ◽  
Full Scale ◽  
Operating Conditions ◽  
Material Behavior ◽  
Combined Loading ◽  
Longitudinal Bending ◽  
Full Scale Tests

The aging of pipeline infrastructures has increased concern for the integrity of pipelines exhibiting non-perforating wall loss and settlement induced bending. While pressure based guidelines exist which allow pipeline operators to define operational margins of safety against rupture (e.g.; ANSI/ASME B31-G and RSTRENG (Battelle, 1989)), reliable procedures for the prediction of wrinkling in degraded pipes subjected to combined loading are virtually non-existent. This paper describes full-scale testing and finite element investigations performed in support of the development of accurate wrinkling prediction procedures for the Alyeska Pipeline Service Company. The procedures are applicable to corroded pipes subjected to combined loading such as longitudinal bending, internal pressure, and axial compression. During the test program, full-scale 48-inch diameter sections of the trans-Alaska pipeline were subjected to internal pressure and loads designed to simulate longitudinal bending from settlement, axial compression from the transport of hot oil, and the axial restraint present in buried pipe. Load magnitudes were designed based on normal and maximum operating conditions. Corrosion in the pipe section is simulated by mechanically reducing the wall thickness of the pipe. The size and depth of the thinned region is defined prior to each test, and attempts to bound the dimensions of depth, axial length, and hoop length for the general corrosion observed in-service. The analytical program utilizes finite element analyses that include the nonlinear anisotropic material behavior of the pipe steel through use of a multilinear kinematic hardening plasticity model. As in the tests, corrosion is simulated in the analyses by a section of reduced wall thickness, and loads and boundary constraints applied to the numerical model exactly emulate those applied in the full-scale tests. Verification of the model accuracy is established through a critical comparison of the simulated pipe structural behavior and the full-scale tests. Results of the comparisons show good correlation with measurements of the pipe curvature, deflections, and moment capacity at wrinkling. The validated analysis procedure is subsequently used to conduct parameter studies, the results of which complete a database of wrinkling conditions for a variety of corrosion sizes and loading conditions.

Experimental and finite element study on the single-layer reticulated composite joints

2020 ◽  
Vol 23 (10) ◽  
pp. 2174-2187
Author(s):  
Liang Zheng ◽  
Cheng Qin ◽  
Hong Guo ◽  
Dapeng Zhang ◽  
Mingtan Zhou ◽  
...  
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Wall Thickness ◽  
Great Influence ◽  
Single Layer ◽  
Experimental Results ◽  
Steel Pipe ◽  
Cover Plate ◽  
Element Analysis

In this article, a new type of reticulated joint, named the steel–concrete composite reticulated shell joint, is proposed. The proposed reticulated shell joint consists of an inner circular steel pipe, an outer circular steel pipe, a steel cover plate, and internal concrete. Five test specimens were tested under axial compression. The variable study included the wall thickness of the inner and outer circular steel pipes and the radius of the inner circular steel pipe. The test specimens exhibited a high bearing capacity and good plastic deformation ability under axial compression. The test results show that the wall thickness of the outer circular steel pipe and the radius of the inner circular steel pipe have a great influence on the bearing capacity of the steel–concrete composite reticulated shell joint, while the wall thickness of the inner circular steel pipe has little influence on the bearing capacity of the steel–concrete composite reticulated shell joint. Based on the test of the steel–concrete composite reticulated shell joints under axial load, the three-dimensional nonlinear finite element model was used to analyze the mechanical properties of the steel–concrete composite reticulated shell joints under axial compression. The results of the finite element analysis showed good agreement with the experimental results. The formula for calculating the bearing capacity of the joint is derived. By comparing with the experimental results, the calculated results are basically consistent with the experimental results.

Thermal Mechanical Crack Growth Rate of a High Strength Nickel Base Alloy

1986 ◽  
Vol 108 (2) ◽  
pp. 396-402 ◽  
Author(s):  
D. A. Wilson ◽  
J. R. Warren
Keyword(s):  
Crack Propagation ◽  
Crack Growth ◽  
Base Alloy ◽  
High Strength ◽  
Operating Conditions ◽  
Thermally Induced ◽  
Propagation Modeling ◽  
Computer Based ◽  
Mechanical Crack ◽  
Nickel Base

An understanding of thermal mechanical fatigue (TMF) crack propagation is fundamental to the application of fracture mechanics to gas turbine components. Typical operating conditions for a cooled turbine disk rim consist of a complex mechanical history and an associated variable amplitude thermal history. While thermally induced stress gradients are commonly incorporated in the mechanical history, the effects of thermal cycling on crack growth must be addressed in an appropriate fatigue model. A current computer-based empirical crack propagation modeling system has demonstrated effectiveness under isothermal conditions and can be readily expanded to include thermal-mechanical effects. The existing isothermal models were developed from an extensive data base and describe crack growth over a broad range of temperature and loading conditions. Building on this established system, a model of thermal-mechanical crack growth is being developed.

scholarly journals On Longitudinal Propagation of a Ductile Fracture in a Buried Gas Pipeline: Numerical and Experimental Analysis

2000 ◽  
Author(s):  
G. Berardo ◽  
P. Salvini ◽  
G. Mannucci ◽  
G. Demofonti
Keyword(s):  
Finite Element ◽  
Ductile Fracture ◽  
Driving Force ◽  
Fracture Propagation ◽  
Full Scale ◽  
Finite Element Code ◽  
Line Pipe ◽  
Real Phenomenon ◽  
Buried Gas Pipeline ◽  
Soil Pipe

The work deals with the development of a finite element code, named PICPRO (PIpe Crack PROpagation), for the analysis of ductile fracture propagation in buried gas pipelines. Driving force estimate is given in terms of CTOA and computed during simulations; its value is then compared with the material parameter CTOAc, inferred by small specimen tests, to evaluate the toughness of a given line pipe. Some relevant aspects are considered in the modelling with the aim to simulate the real phenomenon, namely ductile fracture mechanism, gas decompression behaviour and soil backfill constraint. The gas decompression law is calculated outside the finite element code by means of experimental data from full-scale burst tests coupled with classical shock tube solution. The validation is performed on the basis of full-scale propagation experiments, carried out on typical pipeline layouts, and includes verification of global plastic displacements and strains, CTOA values and soil-pipe interaction pressures.

scholarly journals Development and Validation of Overpressure Response Model in Steel Tunnels Subjected to External Explosion

2020 ◽  
Vol 10 (18) ◽  
pp. 6166 ◽  
Author(s):  
Cheng-Wei Hung ◽  
Hsin-hung Lai ◽  
Bor-Cherng Shen ◽  
Pin-Wen Wu ◽  
Tai-An Chen
Keyword(s):  
Finite Element ◽  
Numerical Results ◽  
Experimental Results ◽  
Response Model ◽  
Finite Element Code ◽  
Scaled Distance ◽  
Development And Validation

This study employed C4 explosives to evaluate the overpressure response in steel tunnels subjected to external explosions. The explosive scaled distance of the C4 charge from 2.15 to 3.26 m/kg1/3 was evaluated by experiments and the hydrodynamic finite element code LS-DYNA. The numerical results are in agreement with the experimental results. A simple way to estimate the overpressure in steel tunnels was proposed in this paper. The proposed methodology is both useful and efficient and can be further developed for designing protection for military structures and other facilities against explosion.

Dynamic Apparatus for CTOA Measurement in Pipeline Steels

2008 ◽  
Author(s):  
Avigdor Shtechman ◽  
Christopher McCowan ◽  
Rony Reuven ◽  
Elizabeth Drexler ◽  
Philippe Darcis ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Fracture Mode ◽  
High Speed ◽  
Crack Propagation Rate ◽  
Full Scale ◽  
Opening Angle ◽  
Test Machine ◽  
Hydraulic Test ◽  
Pipeline Steels ◽  
Initial Results

When a crack initiates and propagates in a pressurized pipe, the only thing that might stop this high-velocity event is the release of internal pressure (decompression), resulting in a deceleration in the crack-propagation rate. This deceleration can be achieved through the use of crack arrestors, or the ability of the pipeline material to resist ductile fracture. To evaluate the resistance to crack growth, the crack tip opening angle (CTOA) is used. Recent articles on the CTOA of pipeline steels at quasi-static rates with modified double cantilever beam specimens (MDCB), and at dynamic displacements rates by use of drop weight tear testing have provided data to support this need. These laboratory results from the literature, compared with results of full-scale tests, indicate that details of the fracture mode depend on the rate of fracture. To further study the dependence among the rate, fracture mode, and CTOA, a dynamic test apparatus was designed to perform CTOA testing of MDCB specimens, so that comparisons to quasi-static and full-scale results could be made. This new apparatus consists of a 500 kN uniaxial hydraulic test machine capable of stand-alone displacement rates of 300 mm/s, and a disc spring apparatus that is used to further accelerate the testing displacement rate. Initial results of the testing show that full slant fracture mode is observed at the highest rates tested for X65 and X100 steels. Maximum crack velocities approaching 10 m/s were recorded with highspeed photography. CTOA measurements were typically made at a position about 30 mm ahead of the pre-fatigue crack, over a distance of about 15 mm in the steady-state crack propagation regime. In this paper, we describe the high-speed apparatus, discuss the relationship among specimen configuration, crack speed, and CTOA, and present initial results on X65 and X100 pipeline steels.

Influences of Blank Holding Force on Stamping of Large Ellipsoidal Heads Based on Simulation

2012 ◽  
Vol 217-219 ◽  
pp. 2097-2100 ◽  
Author(s):  
Zheng Zhi Luo ◽  
Jing Zeng ◽  
Jin Peng Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Wall Thickness ◽  
Computational Efficiency ◽  
Adaptive Mesh ◽  
Element Model ◽  
Experimental Results ◽  
Forming Quality ◽  
Sheet Stamping ◽  
Blank Holding Force

Ellipsoidal heads is a important composition of railways tank car. Sheet stamping process is a common method used for manufacturing ellipsoidal heads. An accurate and efficient finite element model was developed for analysis and prediction of ellipsoidal heads forming quality, with different degrees of reduction deformation at different binder forces considered, and self-adaptive mesh were adopted to improve computational efficiency and quality. And the results of simulation was validated by experimental results. Based on this finite element model, the distributions of stress, strain and wall thickness during this process were obtained.

Sign in / Sign up

Export Citation Format

Share Document