Fatigue Strength of Socket Welds Repaired by Structural Weld Overlay: Reference ASME Section XI Code Case N-666

2005 ◽  
Author(s):  
Steve McCracken
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Fatigue Strength ◽  
Fatigue Testing ◽  
Element Model ◽  
Weld Overlay ◽  
Weld Residual Stress ◽  
Asme Code ◽  
Vibration Fatigue

ASME Code Case N-666 provides alternative rules for repair of a cracked and leaking small bore socket weld by installation of a structural weld overlay [1]. The crack is not removed but is encapsulated and sealed under the weld overlay. Vibration fatigue testing reported by the Electric Power Research Institute (EPRI) demonstrates that socket welds repaired by the method specified in ASME Code Case N-666 have equivalent or better fatigue strength compared to standard socket welds. This paper investigates fatigue test data and fracture mechanics analyses for standard socket welds and compares this to the vibration fatigue strength exhibited by overlay repaired socket welds. A relationship based on fatigue testing of a standard socket weld with root defects was proposed by Japanese researchers to correlate the reduction in fatigue strength with increasing root defect size. This relationship is compared to an EPRI finite element model that was developed to evaluate the stress intensity factor at the root of a standard socket weld. A correction factor is proposed for estimation of the stress intensity factor at the crack tip of a socket weld repaired by weld overlay. The correction factor is derived from a three-dimensional solution for straight pipe with an inside surface circumferential crack and from the finite element model for standard sized socket welds. Finally, weld residual stress analyses reported by Japanese researchers for standard socket welds are compared to weld residual stress data from recent thermal-mechanical finite element analyses for overlay repaired socket welds. The threshold for fatigue crack propagation and the influence of weld residual stress is presented to explain the high vibration fatigue strength exhibited by socket welds repaired by the method of Code Case N-666.

Numerical Simulation of the Effects of Preheating on Electron Beam Additive Manufactured Ti-6Al-4V Build Plate

2016 ◽  
Vol 879 ◽  
pp. 274-278 ◽  
Author(s):  
Jun Cao ◽  
Philip Nash
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Finite Element ◽  
Electron Beam ◽  
Cross Section ◽  
Element Model ◽  
Normal Direction ◽  
Thermal Residual Stresses ◽  
Longitudinal Residual Stress ◽  
Middle Cross Section

In an earlier study, a 3-D thermomechanical coupled finite element model was built and experimentally validated to investigate the evolution of the thermal residual stresses and distortions in electron beam additive manufactured Ti-6Al-4V build plates. In this study, an investigation using this robust and accurate model was focused on an efficient preheating method, in which the electron beam quickly scanned across the substrate to preheat the build plate prior to the deposition. Various preheat times, beam powers, scan rates, scanning paths and cooling times (between the end of current preheat scan/deposition layer and the beginning of the next preheat scan/deposition layer) were examined, and the maximum distortion along the centerline of the substrate and the maximum longitudinal residual stress along the normal direction on the middle cross-section of the build plate were quantitatively compared. The results show that increasing preheat times and beam powers could effectively reduce both distortion and residual stress for multiple layers/passes components.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

Reelability Assessment of Adhesively Bonded Mechanically Lined Pipe

2021 ◽  
Author(s):  
Grégory Alexandre Toguyeni ◽  
Jens Fernandez-Vega ◽  
Richard Jones ◽  
Martin Gallegillo ◽  
Joachim Banse
Keyword(s):  
Finite Element ◽  
Adhesive Layer ◽  
Element Model ◽  
Curing Temperature ◽  
Sensitivity Analyses ◽  
Adhesively Bonded ◽  
Element Analysis ◽  
Physical Test ◽  
Weld Overlay ◽  
Outer Pipe

Abstract A solution to prevent liner wrinkling in Mechanically Lined Pipes (MLP) with a standard 3.0mm thick liner during reeling, without the use of pressurisation, has been developed in the form of the GluBi® lined pipe. The liner being adhesively bonded to the outer pipe, its integrity is maintained despite the global plastic strain applied by the installation method. This new linepipe product has been qualified for offshore use through testing accompanied by a detailed Finite Element Analysis programme to fully capture the pipe and adhesive behaviours under and range of temperatures and loading conditions. The objective of this analysis program was to investigate the reelability of the GluBi® pipe. The instalability was defined as the capability of the pipe to tolerate cyclic plastic deformation representative of a typical pipeline installation by reeling without the formation of wrinkling of the CRA liner, and to maintain the integrity of the adhesive layer, particularly near the weld overlay at the pipe ends. Important areas of the GluBi® pipe design are the pipe extremities, particularly the transition between the liner and the weld overlay length. A detailed Finite Element model of the pipe was created. It captured all stages of the pipe manufacturing: pipe lining, hydrostatic expansion, adhesive curing, overlay weld deposition and reeling simulation. The pipe modelled was 312.1mm OD × 19.7mm WT SMLS 450 with a nominal 3.0mm thick Alloy 625 liner. An important validation work was performed to obtain a precise material response of the adhesive layer between liner and outer pipe. The adhesive mechanical properties were thus assessed in shearing and peeling over a range of temperatures covering all possible manufacturing and installation conditions. The model's elements and adhesive property modelling were validated against physical test results. Sensitivity analyses were done on the adhesive curing temperature, the geometry of the adhesive transition between the liner and the overlay weld at the pipe ends and on the liner thickness. The model was subjected to reeling simulation corresponding to Subsea 7's reel-lay vessels. The liner's integrity post reeling was assessed according to a range of acceptance criteria. These studies made it possible to establish parameter ranges for the safe installation of the linepipe.

Use of DNVGL-RP-C203 for Determining the Fatigue Capacity of Connectors

2021 ◽  
Author(s):  
Anthony Muff ◽  
Anders Wormsen ◽  
Torfinn Hørte ◽  
Arne Fjeldstad ◽  
Per Osen ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Experimental Testing ◽  
High Strength ◽  
Element Model ◽  
Fatigue Analysis ◽  
Full Scale ◽  
The Finite Element Model

Abstract Guidance for determining a S-N based fatigue capacity (safe life design) for preloaded connectors is included in Section 5.4 of the 2019 edition of DNVGL-RP-C203 (C203-2019). This section includes guidance on the finite element model representation, finite element based fatigue analysis and determination of the connector design fatigue capacity by use of one of the following methods: Method 1 by FEA based fatigue analysis, Method 2 by FEA based fatigue analysis and experimental testing and Method 3 by full-scale connector fatigue testing. The FEA based fatigue analysis makes use of Appendix D.2 in C203-2019 (“S-N curves for high strength steel applications for subsea”). Practical use of Section 5.4 is illustrated with a case study of a fatigue tested wellhead profile connector segment test. Further developments of Section 5.4 of C203-2019 are proposed. This included acceptance criteria for use of a segment test to validate the FEA based fatigue analysis of a full-scale preloaded connector.

scholarly journals X-ray nanodiffraction analysis of stress oscillations in a W thin film on through-silicon via

2016 ◽  
Vol 49 (1) ◽  
pp. 182-187 ◽  
Author(s):  
J. Todt ◽  
H. Hammer ◽  
B. Sartory ◽  
M. Burghammer ◽  
J. Kraft ◽  
...  
Keyword(s):  
Thin Film ◽  
Residual Stress ◽  
Finite Element ◽  
Diffraction Data ◽  
Element Model ◽  
Stress Distributions ◽  
Through Silicon Via ◽  
X Ray ◽  
Tangential Stresses ◽  
Stress Components

Synchrotron X-ray nanodiffraction is used to analyse residual stress distributions in a 200 nm-thick W film deposited on the scalloped inner wall of a through-silicon via. The diffraction data are evaluated using a novel dedicated methodology which allows the quantification of axial and tangential stress components under the condition that radial stresses are negligible. The results reveal oscillatory axial stresses in the range of ∼445–885 MPa, with a distribution that correlates well with the scallop wavelength and morphology, as well as nearly constant tangential stresses of ∼800 MPa. The discrepancy with larger stress values obtained from a finite-element model, as well as from a blanket W film, is attributed to the morphology and microstructural nature of the W film in the via.

A Fundamental Study of the Interaction of Residual Stress and Applied Loading on Fracture

2010 ◽  
Author(s):  
C. J. Aird ◽  
M. J. Pavier ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Field ◽  
Crack Closure ◽  
Applied Load ◽  
Element Model ◽  
Residual Stress Field ◽  
Fundamental Study ◽  
Analytical Expression ◽  
Applied Loading

This paper presents the results of a fundamental finite-element based study of the crack-closure effects associated with combined residual and applied loading. First, an analytical expression for a representative two-dimensional residual stress field is derived. This residual stress field contains a central compressive region surrounded by an equilibrating tensile region. The analytical expression allows the size and shape of the field to be varied along with the magnitude of the residual stress. The residual stress field is then used as a prescribed initial stress field in a finite element model, in addition to a far field applied load. By introducing cracks of increasing length into these models, charts of stress-intensity-factor versus crack length are produced for different relative magnitudes of residual stress and applied load and for different sizes and shape of the residual stress field. These charts provide insight into the way in which crack-tip conditions evolve with crack growth under conditions of combined residual and applied loading and also enable conditions of crack closure and partial closure to be identified.

Research on the Effects of Welding Sequence on Welding Residual Stress of High-Speed Train Based on SYSWELD

2011 ◽  
Vol 399-401 ◽  
pp. 1806-1811
Author(s):  
Yong Hong Chen ◽  
Peng Chen ◽  
Ai Qin Tian
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
High Speed ◽  
Element Model ◽  
Welding Residual Stress ◽  
High Speed Train ◽  
Distribution Law ◽  
Element Analysis ◽  
Welding Sequence ◽  
Maximum Residual Stress

The finite element model of the roof of aluminum high-speed train was established, double ellipsoid heat source was employed, and heat elastic-plastic theory was used to simulate welding residual stress of the component under different welding sequence based on the finite element analysis software SYSWELD. The distribution law of welding residual stress was obtained. And the effects of the welding sequence on the value and distribution of residual stress was analyzed. The numerical results showed that the simulation data agree well with experimental test data. The maximum residual stress appears in the weld seam and nearby. The residual stress value decreases far away from the welding center. Welding sequence has a significant impact on the final welding residual stress when welding the roof of aluminum body. The side whose residual stress needs to be controlled should be welded first.

Fatigue Assessment of Welded Joints Taking Into Account Effects of Residual Stress

2010 ◽  
Author(s):  
Nur Syahroni ◽  
Stig Berge
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Fatigue Testing ◽  
International Association ◽  
Hot Spot ◽  
Mean Stress ◽  
Element Analysis ◽  
Structural Rules ◽  
Fatigue Design

Residual stress may have a significant effect on the fatigue strength of welded joints. As a non-fluctuating stress, it has an effect similar to that of the mean stress. Recently the International Association of Ship Classification Societies (IACS) has issued Common Structural Rules (CSR) for respectively tankers (IACS 2006a) and bulk carriers (IACS 2006b). The effect of mean stress in fatigue design is taken into account in both sets of rules. However, the treatment is quite different, in particular with regard to residual stress and shakedown effects. In the present paper a comparative study of fatigue design procedures of the IACS rules is reported, with emphasis on residual stress effects. Testing was carried out with longitudinal attachment welds in the as-welded condition. The initial residual stress was measured by a sectioning method using strain gages. Hot spot stress was determined experimentally by strain gauges and numerically by finite element analysis using different types of elements. Fatigue testing was carried out and SN-curves were plotted according to the relevant stress as specified by the rules. In order to investigate the shake-down effect of residual stress, testing was performed for several pre-load conditions which could be taken to represent maximum load levels in a load history. The aim of the study is to contribute towards better understanding of the effect of residual stress and shakedown on fatigue strength of welded joints.

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