Fatigue Assessment of Aluminum Ship Details by Hotspot Stress Approach

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Bård Wathne Tveiten ◽  
Stig Berge ◽  
Xiaozhi Wang
Keyword(s):  
Finite Element ◽  
Hot Spot ◽  
Experimental Tests ◽  
Fatigue Tests ◽  
Stress Range ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Fatigue Assessment ◽  
Modeling Techniques

This paper presents a robust methodology for fatigue assessment of aluminum ship details using a hot-spot stress range approach. A series of fatigue tests of a typical aluminum ship detail was carried out to obtain a design S–N curve. The test detail was analyzed by the finite element method using several modeling techniques and element types. The results from both experimental tests and finite element analysis are discussed. Recommendations on the procedure of fatigue assessment of aluminum ships including S–N curve to be used are also presented.

Fatigue Assessment of Aluminum Ship Details by Hot-Spot Stress Approach

2011 ◽  
Author(s):  
Ba˚rd Wathne Tveiten ◽  
Stig Berge ◽  
Xiaozhi Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Hot Spot ◽  
Fatigue Tests ◽  
Stress Range ◽  
Extrapolation Methods ◽  
The Finite Element Method ◽  
Hot Spot Stress ◽  
Fatigue Assessment ◽  
Modeling Techniques

This paper presents a robust methodology for fatigue assessment of aluminum ship details using a hot-spot stress range approach. A series of fatigue tests of a typical aluminum ship detail was carried out to obtain a design S-N curve. The test detail was analyzed by the finite element method (FEM) using several modeling techniques and element types. Recommendations are given on finite element modeling practice, extrapolation methods and design S-N curves.

scholarly journals Use of 3D Scan of Weld Joint in Finite Element Analysis and Stochastic Analysis of Hot-Spot Stresses in Tubular Joint for Fatigue Life Estimation

2019 ◽  
Author(s):  
Mikkel L. Larsen ◽  
Vikas Arora ◽  
Marie Lützen ◽  
Ronnie R. Pedersen ◽  
Eric Putnam
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Welded Joints ◽  
Hot Spot ◽  
Strain Range ◽  
Fe Model ◽  
Design Codes ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Weld Toe

Abstract Several methods for modelling and finite element analysis of tubular welded joints are described in various design codes. These codes provide specific recommendations for modelling of the welded joints, using simple weld geometries. In this paper, experimental hot-spot strain range results from a full-scale automatically welded K-node test are compared to corresponding finite element models. As part of investigating the automatically welded K-joint, 3D scans of the weld surfaces have been made. These scans are included in the FE models to determine the accuracy of the FE models. The results are compared to an FE model with a simple weld geometry based on common offshore design codes and a model without any modelled weld. The results show that the FE model with 3D scanned welds is more accurate than the two simple FE models. As the weld toe location of the 3D scanned weld is difficult to locate precisely in the FE model and as misplacement of strain gauges are possible, stochastic finite element modelling is performed to analyse the resulting probabilistic hot-spot stresses. The results show large standard deviations, showing the necessity to evaluate the hot-spot stress method when using 3D scanned welds.

Theoretical Analysis and Experimental Verification of the Stress Concentration Factor at the Steel Tube-Welded Hollow Sphere Connection Node

2016 ◽  
Vol 851 ◽  
pp. 739-744
Author(s):  
Bo Li ◽  
Hong Gang Lei ◽  
Xu Yang
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Theoretical Analysis ◽  
Hollow Sphere ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Hot Spot ◽  
Steel Tube ◽  
Element Analysis ◽  
Hot Spot Stress

In this paper, the author uses ANSYS, the software of finite element analysis, to establish the finite element model, the hot spot stress value of different connection structures of steel tube-welded hollow sphere under uniaxial elongation has been analyzed, the theoretical stress concentration factor of this joint has been obtained. Through the static test on the four typical test-piece, 26 steel tube-welded hollow spherical nodes in total, the actually measured stress concentration factor of the joints has been obtained. The theoretical analysis basically coincides with the law of stress concentration factor obtained from the test results.

scholarly journals Parametric design and Finite Element Analysis of metallic tanks transporting dangerous goods

2018 ◽  
Vol 188 ◽  
pp. 04003
Author(s):  
Konstantinos Sykaras ◽  
Michail Malikoutsakis ◽  
Minas Loulas ◽  
Athanassios Mihailidis
Keyword(s):  
Finite Element ◽  
Parametric Design ◽  
Hot Spot ◽  
Analytical Calculation ◽  
Automated Analysis ◽  
Surface Model ◽  
International Institute ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Dangerous Goods

Metallic tanks are widely used for the transportation of dangerous goods. Manufacturers utilize standards in conjunction with European legislation concerning the international carriage (ADR and RID) to specify the minimum design and construction requirements. The analysis of the tank’s attachment to the vehicle is not covered by analytical calculation methods, and only the Finite Element stress analysis can be used prior to manufacture. New ADR amendments demand that the certification authorities conduct stringent examinations that the manufacturer has the ability to perform high quality weldings. Applying the structural strength concept implemented in the International Institute of Welding (IIW) guidelines into the calculation is a protracted task. Aiming at speeding up the procedure, a parametric design and an efficient FE analysis is developed for a LGBF tank. Utilizing parametric design offers sufficient overview of the whole structure, while a supplementary surface model is generated to reduce pre-processing time. The tank is subjected to prescribed load cases, while the meshing directives of the structural hot spot stress concept (SHSSC) according to the IIW recommendations are incorporated in the procedure, in order to assess both the static and fatigue strength of the weld details. Using a multi-compartment LGBF tank as a case study, it is shown that the proposed detailed and automated analysis succeeds in reducing the time and effort needed, as well as in allocating the critical spots, substantially increasing the calculation accuracy.

New Data on the Capacity of X-Joints Under Tension and Implications for Codes

2008 ◽  
Author(s):  
Adrian F. Dier ◽  
Philip Smedley ◽  
Gunnar Solland ◽  
Hege Bang
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Hot Spot ◽  
Case Scenario ◽  
Element Analysis ◽  
Worst Case ◽  
Numerical Work ◽  
Hot Spot Stress ◽  
Integrity Assessment ◽  
Existing Structures

This paper reviews available static strength data and presents results of finite element analyses on first crack loads and ultimate loads of X-joints in tension. A critique of existing guidance for such joints is given. An examination of hot spot stress for such joints is presented, together with new capacity formulations based on test data. The new formulations are verified with reference to new data from a finite element analysis. The new capacity formulations will be of interest to regulatory authorities, to designers of new offshore installations and to engineers carrying out assessments of existing structures. It is also expected that the formulations will be considered by code drafting committees, e.g. for API RP2A, ISO 19902 and NORSOK, during code revisions. The paper demonstrates that present guidance is unduly conservative in two respects: (1) high γ joints (i.e. thin-walled chords) in the range 0.7 ≤ β ≤ 0.9 joints (i.e. moderately high brace/chord diameter ratios), and (2) joints with β = 1.0 having low γ. However, it is shown that present guidance may be optimistic for low γ joints with β < 0.9. The new capacity formulations proposed in this paper correct these deficiencies. As one example, the new formulations give an increase of 60% in capacity compared to existing guidance for a joint with β = 1.0 and γ = 10, not untypical of many joints in service. In the near term, the paper may be most appreciated by those involved with structural integrity assessment studies. There have been some recent examples where existing guidance has indicated that some primary structural joints are under-strength. This has prompted extensive numerical work to prove the adequacy of the joints. A worst case scenario would be the implementation of unnecessary offshore strengthening work.

Hot Spot Stress Analysis of Fatigue for Tsing Ma Bridge Critical Members under Traffic Using Finite Element Method

2007 ◽  
Vol 353-358 ◽  
pp. 925-928 ◽  
Author(s):  
Tai Quan Zhou ◽  
Tommy Hung Tin Chan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Hot Spot ◽  
Suspension Bridge ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Traffic Loading ◽  
Tsing Ma Bridge ◽  
Fatigue Evaluation

The suspension bridge has more flexibility and repetitive vehicles produce stress cycles in members. Then fatigue of the member is accumulated with the daily traffic loadings. In order to evaluate the working condition of the Tsing Ma Bridge, the online monitoring health system has been installed in long suspension bridge. The location of the strain sensor is not exactly at the critical member locations. The hot spot stress analysis for critical members is necessary for accurate fatigue evaluation of the bridge. The global finite element analysis of the Tsing Ma Bridge under traffic loading is performed to determine the critical fatigue member locations. A detailed local finite element analysis for the welded connections is performed to determine the hot spot stress of critical fatigue location. As a case for study, the calculated stress concentration factor is combined with the nominal representative stress block cycle to obtain the representative hot spot stress range cycle block under traffic loading from online health monitoring system. The comparison result shows that the nominal stress approach cannot consider the most critical stress of the fatigue damage location and the hot spot stress approach is more appropriate for fatigue evaluation.

Fatigue Analysis of a Thin Cover Plate Structure in a Light Craft

2015 ◽  
Author(s):  
Till Köder ◽  
Berend Bohlmann
Keyword(s):  
Hot Spot ◽  
Gas Metal Arc Welding ◽  
Plate Thickness ◽  
Fatigue Analysis ◽  
Fatigue Tests ◽  
Cover Plate ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Notch Stress ◽  
Metal Arc Welding

Experimental fatigue analysis of a fillet-welded cover plate detail (‘floating frame’) of small and light craft was carried out at Kiel University of Applied Sciences. The structural detail is an intersection of longitudinal deck stiffener and transverse web frame with a plate thickness of 3.5mm and a doubling length of 100mm. Manual gas metal arc welding was used for the production of the 46mm long transverse fillet welds. The load-controlled constant amplitude fatigue tests at stress ratio R = 0 were supported by 3D finite-element analysis based on laser scans of the weld seams. Structural hot-spot stress, stress linearisation and Xiao and Yamada’s 1mm geometrical stress approaches were applied to the specimens as well as the notch stress concept with reference radii rref = 0.05mm and 1.00mm.

Qualification of the Notch Stress Approach for the Fatigue Assessment of Welded Pressure Equipment and Power Plant Components

2017 ◽  
Author(s):  
Jürgen Rudolph ◽  
Ralf Trieglaff ◽  
René Stößlein ◽  
Fabian Hauser
Keyword(s):  
Test Data ◽  
Welded Joints ◽  
Low Cycle Fatigue ◽  
Hot Spot ◽  
Pressure Vessels ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Fatigue Assessment ◽  
Notch Stress

The fatigue assessment of welded joints in different engineering disciplines is usually based on nominal, structural or notch stresses on one hand (elastic concept using component fatigue curves of load controlled test data) and local strains on the other hand (elasto-plastic concept using material fatigue curves of strain-controlled push-pull test data of un-notched and polished standard specimens). The concepts of the first mentioned group are implemented in widespread standards and recommendations such as [1] to [3]. The fatigue assessment procedure of the European standard for unfired pressure vessels (EN 13445-3, Clause 17 & 18 and related annexes) [4] is currently under revision with one focus on the elaboration of user friendly fatigue assessment options for welded components [5]. The current state of the art focuses on the application of an adapted structural hot spot stress approach to the fatigue assessment of welded pressure equipment [5]. Although this is a significant step forward, the implementation of a notch stress approach can furtherly increase the fatigue assessment options by detailed weld seam analysis. The paper focuses on respective methodological proposals and application examples of typical welded joints. The finite element analysis as part of the procedure has to be harmonized with the requirements of the assessment procedure. Of course, the compatibility of the hot spot stress approach and a notch stress approach has to be guaranteed for individual examples. The direct comparison of the different approaches allows for a qualitative evaluation of methods. The application of an appropriate master fatigue curve FAT100 and the limitations with regard of stress/strain ranges in the low cycle fatigue (LCF) regime as well as the fatigue assessment of welded joints with mild weld toe notches is the subject of special considerations. The latest recommendations of German Welding Society (DVS) [6] constitute a reference for the last two subjects raised.

Numerical Investigation on the Fatigue Behavior of the Multi-Planar Tubular DX-Joint under Combined Loads

2014 ◽  
Vol 1006-1007 ◽  
pp. 11-17
Author(s):  
Gui Jie Liu ◽  
Yu Zhang ◽  
Basit Farooq
Keyword(s):  
Finite Element ◽  
Hot Spot ◽  
Fatigue Behavior ◽  
Combined Loading ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Bending Load ◽  
Weld Toe ◽  
Plane Bending ◽  
Stress Concentration Factors

The stress concentration factors (SCFs) is used in the fatigue design for calculating hot-spot stress. However a major issue can be noted that the majority of research results are focused on the SCF distribution of uni-planar tubular joints subjected to the single basic load. By aiming to find the solution of this problem, the distribution of SCFs at the weld toe of a multi-planar tubular DX-joint which is subjected to the two set of the balanced combined loading components at the end of in-plane braces is studied by the finite element method. Thus it is concluded that for the axial plus in-plane bending load case, hot-spot stress location varies between saddle and crown position; while the location is invariably at the saddle position under combined axial plus out-of-plane bending loads. At last the API RP2A equation for predicting hot-spot stress is used for comparison with the finite element analysis results. Meanwhile the distribution of SCFs is also provided, that information indicates the-hot spot location along the weld toe affects the crack initiation.

Fatigue assessment of a steel truss bridge based on multi-dimensional finite element modelling

2021 ◽  
Author(s):  
Kris Hectors ◽  
Hans De Backer ◽  
Lien Saelens ◽  
Wim De Waele
Keyword(s):  
Finite Element ◽  
Decision Support ◽  
Finite Element Modelling ◽  
Hot Spot ◽  
Hot Spot Stress ◽  
Fatigue Assessment ◽  
Railway Bridges ◽  
Element Modelling ◽  
Railway Traffic ◽  
Steel Truss Bridge

<p>This paper presents a multidimensional finite element modelling approach for the fatigue assessment of welded railway bridges based on a case study of a railway bridge in Belgium. The nominal stress approach of Eurocode 3 is compared to a hot spot stress based fatigue life calculation for the standardized fatigue load models for railway traffic. Hot spot stresses are calculated with an in-house developed framework that allows automated determination of hot spot stresses. It is discussed how this work can fit in a larger decision support system in the scope of structural health monitoring. The presented approach proves to be better for decision support compared to the conventional approach in the Eurocode.</p>

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