Finite Element Modeling and Quantification of Mechanical Damage Severity in Pipelines

2016 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Finite Element ◽  
Oil And Gas ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Mechanical Damage ◽  
Failure Behavior ◽  
Element Analysis ◽  
Fea Model ◽  
Transmission Pipeline ◽  
Element Type

Mechanical damage is one of the major threats to oil and gas transmission pipeline integrity, which has been the case now for decades. Although much work has been done in that context, due to the complexity of its effects mechanical damage severity remains difficult to quantify. Thus, work continues to better understand the failure mechanism and develop the means to screen damage severity. The present paper adopts a validated elastic-plastic finite element analysis (FEA) model to simulate mechanical dents in pipelines and to quantify the effects of damage through a broad parametric study. This considers the need for three-dimensional FEA models and the effects of FEA element type, soil constraint condition, indenter type, pipeline grade and initial pipe pressure on dent response. The FEA model is also used to assess the minimum wall thickness for which a dent has the minimal effect on pipeline integrity. Finally, application of the proposed FEA model is illustrated by successfully predicting the failure behavior of a dent in a full-scale fatigue test involving a modern pipeline steel.

Structural Integrity Assessment Criteria and Service Life Prediction of Cold Wrinklebends

2012 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Finite Element ◽  
Service Life ◽  
Structural Integrity ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Computation Time ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Fea Model ◽  
Hardening Models

Three-dimensional elastic-plastic finite element analysis (FEA) is performed in this paper to simulate the complicated stresses and deformation of wrinklebends in a pipeline from its bending formation to operation under cyclic loading. Three plastic hardening models (isotropic, kinematic and combined isotropic/kinematic) are discussed and used in FEA of wrinklebend response that considers strain hardening and Bauschinger effects. The FEA simulation is carried out first for an elbow held at constant pressure while subject to cyclic bending, which serves as a benchmark case. The results show that the three hardening models lead to very different outcomes. Comparable FEA simulations are then developed for wrinklebends under cyclic pressure. Detailed parametric analysis is considered, including finite-element type, element sensitivity, computation time, and material input data. Based on those results viable nonlinear FEA model is developed as the basis to quantify wrinklebend response under service-like conditions. Based on the FEA results, fatigue damage is quantified using the Smith, Watson and Topper (SWT) parameter, and thereafter a damage criterion is proposed to predict the fatigue life of a wrinklebend under the pressure cycles of 72%–10% of SMYS for typical X42 pipeline steel. The results show that the wrinkle aspect ratio H/L is a key parameter to control the service life of a wrinklebend.

Finite Element Study of the Cutting Mechanics of the Three Dimensional Rock Turning Process

2015 ◽  
Author(s):  
Demeng Che ◽  
Jacob Smith ◽  
Kornel F. Ehmann
Keyword(s):  
Finite Element ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Polycrystalline Diamond ◽  
Close Correlation ◽  
Experimental Results ◽  
Failure Behavior ◽  
Fe Model ◽  
Gas Drilling ◽  
Cutting Mechanics

The unceasing improvements of polycrystalline diamond compact (PDC) cutters have pushed the limits of tool life and cutting efficiency in the oil and gas drilling industry. However, the still limited understanding of the cutting mechanics involved in rock cutting/drilling processes leads to unsatisfactory performance in the drilling of hard/abrasive rock formations. The Finite Element Method (FEM) holds the promise to advance the in-depth understanding of the interactions between rock and cutters. This paper presents a finite element (FE) model of three-dimensional face turning of rock representing one of the most frequent testing methods in the PDC cutter industry. The pressure-dependent Drucker-Prager plastic model with a plastic damage law was utilized to describe the elastic-plastic failure behavior of rock. A newly developed face turning testbed was introduced and utilized to provide experimental results for the calibration and validation of the formulated FE model. Force responses were compared between simulations and experiments. The relationship between process parameters and force responses and the mechanics of the process were discussed and a close correlation between numerical and experimental results was shown.

Use of Finite Element Analysis for Stud Pre-Tension Determination of Large Diameter Integral Flanges With Ring Joint Gaskets

2010 ◽  
Author(s):  
Upali Panapitiya ◽  
Haoyu Wang ◽  
Syed Jafri ◽  
Paul Jukes
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Oil And Gas ◽  
Large Diameter ◽  
Three Dimensional ◽  
Oil And Gas Industry ◽  
Element Analysis ◽  
Axial Forces ◽  
Three Dimensional Finite Element

Large diameter integral steel flanges are widely used in many applications in the oil and gas industry. The flanges of nominal pipe sizes, 26-inch and above with ring-joint gaskets as specified in ASME B 16.47 Standard, are used in the offshore applications for the transportation of oil and gas from production facilities. These pipelines require flanged connections at end terminations, mid-line tie-ins and expansion loops. The conventional design of large diameter steel flanges is based on one-dimensional analytical methods similar to the procedure in ASME VIII Boiler and Pressure Vessel Code, Division 1 Appendix 2. The effects of axial forces and bending moments are approximated by calculating an equivalent pressure. This usually results in conservative designs for the large flanges because it estimates the required stud pre-tension based on the assumption that the gasket will be unloaded entirely to a minimum stress, whereas only a small section of the gasket is subjected to low stress. This technical paper presents the quasi-static, nonlinear, and three-dimensional finite element models of large diameter steel flanged joint for the determination of stud pre-tension and change of stud tension under various loading conditions. The finite element analysis results are compared with the results obtained by using the equivalent pressure method and flange “Joint Diagram”.

Finite Element Analysis on Drilling of Unidirectional Carbon Fiber Reinforced Plastic (CFRP)

2013 ◽  
Vol 455 ◽  
pp. 228-231 ◽  
Author(s):  
Yan Li He ◽  
Guo Peng Zhang ◽  
Jun Peng Xue
Keyword(s):  
Finite Element ◽  
Carbon Fiber ◽  
Thrust Force ◽  
Three Dimensional ◽  
Failure Behavior ◽  
Drilling Process ◽  
Fe Model ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
Carbon Fiber Reinforced

Various kinds of damage may occur during the drilling of carbon fiber reinforced polymer composite (CFRP). To review the mechanism of CFRP drilling, a three-dimensional macro-mechanical finite element (FE) model was constructed for CFRP drilling based on FE software tool Abaqus. The workpiece was modeled as equivalent homogenous anisotropic material (EHAM) with elastic-failure behavior. Three-dimensional Hashin criterion was used to predict the material failure. The material was implemented in user subroutine VUMAT. The drilling process was analyzed and the thrust force with respect to cutting conditions was evaluated. The simulation shows that thrust force increase with feed rates while decrease with spindle speed, as agrees with experiment.

Generalized Equations of Motion for the Dynamic Analysis of Elastic Mechanism Systems

1984 ◽  
Vol 106 (4) ◽  
pp. 243-248 ◽  
Author(s):  
D. A. Turcic ◽  
Ashok Midha
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Single Type ◽  
Generalized Equations ◽  
Element Analysis ◽  
Beam Elements ◽  
Elastic Mechanism ◽  
Element Type

Until recently, vibration effects have generally been neglected in the design of high-speed machines and mechanisms. This has been primarily due to the complexity of the mathematical analysis of mechanisms with elastic links. With the advent of high-speed computers and structural dynamics techniques, such as finite element analysis, this is no longer regarded as such a formidable task. To date, with few exceptions, the analysis of elastic mechanism systems have been limited to a single type of mechanism (i.e., a four-bar or slider-crank) modeled with a small number of simple finite elements (usually beam elements). This paper develops the generalized equations of motion for elastic mechanism systems by utilizing finite element theory. The derivation and final form of the equations of motion provide the capability to model a general two- or three-dimensional complex elastic mechanism, to include the nonlinear rigid-body and elastic motion coupling terms in a general representation, and to allow any finite element type to be utilized in the model. A discussion of a solution method, applications, as well as an experimental investigation of an elastic four-bar mechanism will be presented in subsequent publications.

Three-dimensional finite element analysis of the effects of anisotropy on bone mechanical properties measured by nanoindentation

2004 ◽  
Vol 19 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Z. Fan ◽  
J.Y. Rho ◽  
J.G. Swadener
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Cortical Bone ◽  
Three Dimensional ◽  
Indentation Modulus ◽  
Element Analysis ◽  
Fea Model ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

A three-dimensional finite element analysis (FEA) model with elastic–plastic anisotropy was built to investigate the effects of anisotropy on nanoindentation measurements for cortical bone. The FEA model has demonstrated a capability to capture the cortical bone material response under the indentation process. By comparison with the contact area obtained from monitoring the contact profile in FEA simulations, the Oliver–Pharr method was found to underpredict or overpredict the contact area due to the effects of anisotropy. The amount of error (less than 10% for cortical bone) depended on the indentation orientation. The indentation modulus results obtained from FEA simulations at different surface orientations showed a trend similar to experimental results and were also similar to moduli calculated from a mathematical model. The Oliver–Pharr method has been shown to be useful for providing first-order approximations in the analysis of anisotropic mechanical properties of cortical bone, although the indentation modulus is influenced by anisotropy.

Effect of Skirts on the Lateral Capacity of Mudmats in Soft Clay

2013 ◽  
Author(s):  
Jianchun Cao ◽  
Luo Yang
Keyword(s):  
Finite Element ◽  
Lateral Displacement ◽  
Soft Clay ◽  
Three Dimensional ◽  
Soil Mass ◽  
Element Analysis ◽  
Lateral Capacity ◽  
Fea Model ◽  
Rate Of Increase ◽  
Three Dimensional Finite Element

This paper presents the development of a three-Dimensional Finite Element Analysis (3D FEA) model using Finite Element Code PLAXIS 3D to investigate the skirt’s effect on the lateral capacity of a mudmat in soft clay. It is found that, for a skirted mudmat, 1) the stiffness of skirts had an influence on the mobilization of its ultimate lateral capacity; 2) the required lateral displacement to mobilize the ultimate lateral capacity was about 1% of its width; 3) the lateral capacity is proportional to skirt depth under a soft clay condition with a linearly increasing strength; 4) the ultimate lateral capacity can also be increased by adding internal skirts, but the rate of increase becomes less prominent with the increase of internal skirt number; 5) an empirical formula in ISO19901-4 [5] was confirmed to conservatively estimate the lateral capacity of a skirted mudmat. Moreover, the influence of skirt on the involved soil mass was discussed.

Behavior of NPS30 Pipe Subject to Denting Load

2014 ◽  
Author(s):  
Hossein Ghaednia ◽  
Kyle Gerard ◽  
Sudip Bhattacharjee ◽  
Sreekanta Das
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Petroleum Products ◽  
Lateral Loads ◽  
Element Analysis ◽  
Engineering Research ◽  
Three Dimensional Finite Element

Pipeline is the common mode for transporting oil, gas, and various petroleum products. Structural integrity of oil and gas transmission pipelines is often threatened by external interferences such as concentrated lateral loads and as a result, a failure of the pipeline may occur due to “mechanical damages”. Sometime, this load may not cause immediate rupture of pipes; rather form a dent which can reduce the pressure capacity of the pipeline. A dent is a localized defect in the pipe wall in the form of a permanent inward plastic deformation. This kind of defect is a matter of serious concern for the pipeline operator since a rupture or a leak may occur. Accordingly, an extensive experimental study is currently underway at the Centre for Engineering Research in Pipelines (CERP), University of Windsor on 30 inch (762 mm) diameter and X70 grade pipes with D/t of 90. The aim of this research is to examine the influence of various parameters such as dent shape and service pressure on strain distributions of dented pipe. Also, three-dimensional finite element models were developed and validated for determining strains underneath the indenter. The load-deformation behavior of pipes subject to this type of lateral denting load obtained from experimental study and finite element analysis is discussed in this paper. In addition, distributions of important strains in and around the dent obtained from the study are also discussed.

Improvements to the ASME B31.8 Dent Strain Equations

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Chike Okoloekwe ◽  
Nikko Aranas ◽  
Muntaseer Kainat ◽  
Doug Langer ◽  
Sherif Hassanien ◽  
...  
Keyword(s):  
Strain Distribution ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Element Analysis ◽  
Fea Model ◽  
Global View ◽  
Current Implementation ◽  
Gas Products ◽  
External Forces

Pipelines used to transport oil and gas products are often subjected to external forces during its construction or operation, which can result in the formation of dents in the pipe. Various pipeline codes have stipulations on how a dent's severity can be ascertained in order to prioritize repairs. The most prominent being the depth-based criterion, which determines the severity of a dent by its depth. The depth-based criterion fails to consider the fact that the geometry of the dent can result in high strain concentration and eventually lead to integrity issues at the dented region. Alternatively, the strains associated with the dent can be an indicator of the dent's severity. Nonmandatory codified equations are available for evaluating the strains at the dented region of the pipe. The current implementation of these equations might fail to capture the strains that are not aligned with the most severe deformation profile of the dent and as such a global view of the strain distribution of the dented profile would be more informative as per the localized strain distribution. The study presented herein is the implementation of ASME B31.8 formulations together with the suggested modifications to evaluate the three-dimensional (3D) strain state of the dented pipe. The strain distributions obtained are compared against the strains predicted by finite element analysis (FEA) model. The correlation in the predicted strains indicates the possibility of the rapid and concise strain based characterization of dented pipes with the proposed technique.

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