scholarly journals Engineering Studies on Joint Bar Integrity: Part I — Field Surveys and Observed Failure Modes

2014 ◽  
Author(s):  
David Y. Jeong ◽  
Radim Bruzek ◽  
Ali Tajaddini
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Structural Integrity ◽  
Transportation Systems ◽  
Finite Element Analyses ◽  
Research Project ◽  
Field Surveys ◽  
Technology Center ◽  
Survey Team ◽  
Engineering Studies

This paper is the first of a two-part series describing a research project, sponsored by the Federal Railroad Administration (FRA), to study the structural integrity of joint bars. In Part I of this series, observations from field surveys conducted on revenue service track are presented. Automated and visual inspections of rail joints were conducted to identify defective joint bars. Detailed information and measurements were collected at various joint locations. The survey team consisted of personnel from ENSCO, Inc. and Transportation Technology Center, Inc. (TTCI), working in cooperation with staff from participating railroads. Part II of this series describes the development of finite element analyses of jointed rail, which is being carried out by the Volpe National Transportation Systems Center (Volpe Center).

Engineering Studies on Joint Bar Integrity: Part II — Finite Element Analyses

2014 ◽  
Author(s):  
Michael E. Carolan ◽  
David Y. Jeong ◽  
A. Benjamin Perlman
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Structural Response ◽  
Relative Effect ◽  
Structural Performance ◽  
Finite Element Analyses ◽  
Field Surveys ◽  
Engineering Studies ◽  
Toe Angle ◽  
Support Conditions

This paper is the second in a two-part series describing research sponsored by the Federal Railroad Administration (FRA) to study the structural integrity of joint bars. In Part I, observations from field surveys of joint bar inspections conducted on revenue service track were presented [1]. In this paper, finite element analyses are described to examine the structural performance of rail joints under various loading and tie-ballast support conditions. The primary purpose of these analyses is to help interpret and understand the observations from the field surveys. Moreover, the finite element analyses described in this paper are applied to conduct comparative studies and to assess the relative effect of various factors on the structural response of jointed rail to applied loads. Such factors include: discrete tie support (i.e. supported joint versus suspended joint with varying spans between effective ties), bolt pattern (four versus six bolts), initial bolt tension, and easement. In addition, results are shown for 90 lb rail joined with long-toe angle bars compared to 136 lb rail joined with standard short-toe joint bars.

Failure Analysis of Thinned Wall Elbows Under Excessive Seismic Loading

2002 ◽  
Author(s):  
Masaki Shiratori ◽  
Yoji Ochi ◽  
Izumi Nakamura ◽  
Akihito Otani
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Local Buckling ◽  
Seismic Loading ◽  
Cycle Fatigue ◽  
Finite Element Analyses ◽  
Residual Thickness ◽  
Limited Period

A series of finite element analyses has been carried out in order to investigate the failure behaviors of degraded bent pipes with local thinning against seismic loading. The sensitivity of such parameters as the residual thickness, locations and width of the local thinning to the failure modes such as ovaling and local buckling and to the low cycle fatigue damage has been studied. It has been found that this approach is useful to make a reasonable experimental plan, which has to be carried out under the condition of limited cost and limited period.

Integrity Assessment of Subsea Pipeline Dent / Buckle Using ILI Data

2019 ◽  
Author(s):  
Gurumurthy Kagita ◽  
Gudimella G. S. Achary ◽  
Mahesh B. Addala ◽  
Balaji Srinivasan ◽  
Penchala S. K. Pottem ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Failure Modes ◽  
Structural Integrity ◽  
Mechanical Damage ◽  
Metal Loss ◽  
Stress Concentrations ◽  
Subsea Pipeline ◽  
Integrity Assessment ◽  
Finite Element Software

Abstract Mechanical damage in subsea pipelines in the form of local dents / buckles due to excessive bending deformation may severely threaten their structural integrity. A dent / buckle has two significant effects on the pipeline integrity. Notably, residual stresses are set up as result of the plastic deformation and stress concentrations are created due to change in pipe geometry caused by the denting / buckling process. To assess the criticality of a dent / buckle, which often can be associated with strain induced flaws in the highly deformed metal, integrity assessment is required. The objective of this paper is to evaluate the severity of dent / buckle in a 48” subsea pipeline and to make the rerate, repair or replacement decision. This paper presents a Level 3 integrity assessment of a subsea pipeline dent / buckle with metal loss, reported in in-line inspection (ILI), in accordance with Fitness-For-Service Standard API 579-1/ASME FFS-1. In this paper, the deformation process that caused the damage (i.e. dent / buckle) with metal loss is numerically simulated using ILI data in order to determine the magnitude of permanent plastic strain developed and to evaluate the protection against potential failure modes. For numerical simulation, elastic-plastic finite element analyses (FEA) are performed considering the material as well as geometric non-linearity using general purpose finite element software ABAQUS/CAE 2017. Based on the numerical simulation results, the integrity assessment of dented / buckled subsea pipeline segment with metal loss has been performed to assess the fitness-for-service at the operating loads.

Simplified Assessment of Studs Allowing for Low Constraint Conditions

2017 ◽  
Author(s):  
P. James ◽  
C. Madew ◽  
M. Jackson
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Structural Integrity ◽  
High Stress ◽  
Pressure Vessels ◽  
Materials Testing ◽  
Screw Thread ◽  
Surface Point ◽  
Finite Element Analyses ◽  
Supporting Materials

Defect tolerance assessments are carried out to support the demonstration of structural integrity for high integrity components such as nuclear reactor pressure vessels. These assessments often consider surface-breaking defects and assess Stress Intensity Factors (SIFs) at both the surface and deepest points. This can be problematic when there is a high stress at the surface, for example due to the stress concentration at the root of a screw thread. In the past this has led to the development of complex and costly 3D finite element analyses to calculate more accurate SIFs, and still resulting in small apparent limiting defect sizes based on initiation at the surface point. Analysis has been carried out along with supporting materials testing, to demonstrate that the increased SIF at the surface point is offset by a reduction in crack-tip constraint, such that the material exhibits a higher apparent fracture toughness. This enables a more simplistic assessment which reduces the effective SIF at the surface such that only the SIF at the deepest point needs to be considered for many defects. This then leads to larger calculated limiting defect sizes. This in turn leads to a more robust demonstration of structural integrity, as the limiting defect sizes are consistent with the capability of non-destructive examination techniques. An overview of the supporting materials testing is provided in an accompanying paper. The accompanying paper details how it was not possible to demonstrate the required material response with conventional tests, such as those using shallow-notched bend specimens. Instead it was necessary to develop modified specimens in which semi-elliptical defects were introduced into a geometry which replicated the notch acuity at the root of a screw thread. These tests were used to quantify the stud materials sensitivity to constraint. Conventional three-point bend tests were also seen to confirm these values. A series of R6 constraint modified assessments have been considered to understand the benefit from including a loss of constraint, particularly when assessing the surface breaking SIF. This has necessitated a series of complex finite element analyses to define the elastic SIF as well as the elastic constraint parameter, T-Stress, T. Further verification analyses have also been performed to determine the equivalent elastic-plastic J and Q parameters. These have been used to provide guidance on how best to assess surface breaking defects within studs. This has shown that the increased perceived toughness at the surface location means that under the majority of conditions, the assessment can simply be based upon the SIF at the depth location using high constraint fracture toughness. This paper provides an overview of the process undertaken to provide simplified guidance on assessing defects within studs that allows benefit from constraint loss.

Numerical Simulations of Stiffened Panels under Compressive Loads and Structural Analyses of Midship Section

2012 ◽  
Author(s):  
Evangelos Koutsolelos
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Structural Integrity ◽  
Finite Element Analyses ◽  
Structural Components ◽  
Ship Structures ◽  
Stiffened Panels ◽  
Compressive Loads

In this paper, structural integrity of ship structures is discussed using Finite Element analyses. Buckling behaviors of shell structural components are investigated taking into account geometric and material nonlinearities. Recommendations are made to Naval Architects based on tools developed throughout the research.

Structural Integrity Assessment of Steam Generator Tube by the Use of Heterogeneous Finite Element Method

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Xinjian Duan ◽  
Michael J. Kozluk ◽  
Sandra Pagan ◽  
Brian Mills
Keyword(s):  
Finite Element ◽  
Steam Generator ◽  
Failure Modes ◽  
Structural Integrity ◽  
Fretting Wear ◽  
Defect Depth ◽  
Steam Generator Tube ◽  
Integrity Assessment ◽  
Failure Pressure ◽  
Steam Generator Tubes

Aging steam generator tubes have been experiencing a variety of degradations such as pitting, fretting wear, erosion-corrosion, thinning, cracking, and denting. To assist with steam generator life cycle management, some defect-specific flaw models have been developed from burst pressure testing results. In this work, an alternative approach; heterogeneous finite element model (HFEM), is explored. The HFEM is first validated by comparing the predicted failure modes and failure pressure with experimental measurements of several tubes. Several issues related to the finite element analyses such as temporal convergence, mesh size effect, and the determination of critical failure parameters are detailed. The HFEM is then applied to predict the failure pressure for use in a fitness-for-service condition monitoring assessment of one removed steam generator tube. HFEM not only calculates the correct failure pressure for a variety of defects, but also predicts the correct change of failure mode. The Taguchi experimental design method is also applied to prioritize the flaw dimensions that affect the integrity of degraded steam generator tubes such as the defect length, depth, and width. It has been shown that the defect depth is the dominant parameter controlling the failure pressure. The failure pressure varies almost linearly with defect depth when the defect length is greater than two times the tube diameter. An axial slot specific flaw model is finally developed.

scholarly journals Structural Integrity of Conventional and Modified Railroad Bearing Adapters for Onboard Monitoring

2014 ◽  
Author(s):  
Joseph Montalvo ◽  
Alexis Trevino ◽  
Arturo A. Fuentes ◽  
Constantine M. Tarawneh
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Element Model ◽  
Operating Conditions ◽  
Finite Element Analyses ◽  
Distribution Maps ◽  
Bearing Condition Monitoring ◽  
Monitoring Applications ◽  
Railroad Bearing ◽  
The Impact

This paper presents a detailed study of the structural integrity of conventional and modified railroad bearing adapters for onboard monitoring applications. Freight railcars rely heavily on weigh bridges and stations to determine cargo load. As a consequence, most load measurements are limited to certain physical railroad locations. This limitation provided an opportunity for an optimized sensor that could potentially deliver significant insight on bearing condition monitoring as well as load information. Bearing adapter modifications (e.g. cut-outs) were necessary to house the sensor and, thus, it is imperative to determine the reliability of the modified railroad bearing adapter, which will be used for onboard health monitoring applications. To this end, this study quantifies the impact of the proposed modifications on the adapter structural integrity through a series of experiments and finite element analyses. The commercial software Algor 20.3TM is used to conduct the stress finite element analyses. Different loading scenarios are simulated with the purpose of obtaining the conventional and modified bearing adapter stresses during normal and abnormal operating conditions. This information is then used to estimate the lifetime of these bearing adapters. Furthermore, this paper presents an experimentally validated finite element model which can be used to attain stress distribution maps of these bearing adapters in different service conditions. The maps are also useful for identifying areas of interest for an eventual inspection of conventional or modified railroad bearing adapters in the field.

scholarly journals Rotation Stiffness Investigation of Spatial Joints with End-Plate Connection

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Shizhe Chen ◽  
Jianrong Pan ◽  
Zhan Wang ◽  
Chao Zhou
Keyword(s):  
Finite Element ◽  
Mechanical Behaviour ◽  
Failure Modes ◽  
Reference Method ◽  
Calculation Model ◽  
Finite Element Analyses ◽  
Spatial Coupling ◽  
End Plate ◽  
Rotation Stiffness ◽  
Plate Connections

Spatial joints with end-plate connections show significant spatial coupling effects under spatial loading. Mechanical behaviour and failure modes of these spatial joints differ from those of planar joints. This study involved experiments and finite element analyses with respect to planar joints with end-plate connections under static load. The numerical results agreed well with the experimental data, and this verified the adequacy of the finite element analyses. Then, finite element models of the spatial interior joint, exterior joint, and corner joint were established to analyse the difference between the mechanical behaviour of spatial joints and planar joints. The component method was used to analyse components contributing to the initial stiffness of spatial joints. An initial rotation stiffness calculation model of spatial joints was proposed based on the deformation of joints. The findings indicated that results of the calculation models were in good agreement with those of the finite element analyses, and this proved that the calculation model proposed in this study could act as a reference method.

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