Review of FE-Based Fatigue Evaluation Methods for the Rib to Floorbeam Welds in Orthotropic Bridge Decks

2014 ◽  
Vol 627 ◽  
pp. 337-340
Author(s):  
Wouter de Corte ◽  
Arne Jansseune
Keyword(s):  
Evaluation Method ◽  
Hot Spot ◽  
Bridge Decks ◽  
High Stress ◽  
International Institute ◽  
Element Analysis ◽  
Stress Evaluation ◽  
Linear Elastic ◽  
Mesh Density ◽  
Fatigue Evaluation

Complex welded structures such as bridges are very often designed with the help of FE analysis. However, one should remain cautious when using such an analysis, since the results are mesh sensitive, with especially the mesh density and the element type influencing the results. In addition, these results are in most cases retrieved in hot spot areas with high stress gradients, where the maximum stress even cannot be correctly determined with linear elastic finite element analysis. For that reason, a stress evaluation method is required to obtain relevant stress levels that can be directly related to fatigue detailing. The most complete set of stress evaluation recommendations is given in the Recommendations for Fatigue Design of Welded Joints and Components from the International Institute of Welding. Nevertheless, several authors have recently commented on the difficulties regarding the application of these methods for the rib to floorbeam welds in orthotropic bridge decks. This paper provides findings for this type of connections based on both shell and solid model analysis and relates these findings to work from other authors.

Fatigue Failure Analysis Using the Theory of Critical Distance

2011 ◽  
Vol 462-463 ◽  
pp. 663-667 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail
Keyword(s):  
Stress Concentration ◽  
Fatigue Failure ◽  
Notch Root ◽  
High Stress ◽  
Critical Distance ◽  
Future Research ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Elastic Fracture

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.

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.

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.

scholarly journals FATIGUE LIFE ANALYSIS OF RAIL-WELDS USING LINEAR ELASTIC FRACTURE MECHANICS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mequanent M. Alamnie ◽  
Yalelet Endalemaw
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Fatigue Cracks ◽  
High Stress ◽  
Fatigue Cracking ◽  
Linear Elastic Fracture Mechanics ◽  
Frequency Interval ◽  
Element Analysis ◽  
Linear Elastic ◽  
Elastic Fracture

The initiation and growth of fatigue cracking is mainly due to high stress concentration, heterogeneity and poor quality of weld. The detection and rectification of such weld defects are major concerns of rail network managers to reduce potential risk of rail breaks and derailments. To estimate the fatigue life of welded joints and to analyze the progress of fatigue cracks, a fracture mechanics-based analysis and fatigue models were developed using Finite Element Analysis. The initial flaw is obtained from a sample weld using ultrasonic flaw detecting machine test. Linear Elastic Fracture Mechanics (LEFM) approach based on the Paris law was applied to determine critical crack size and the number of cycles to failure using FRANC3D software. The inspection interval of rail welds before fracture (failure) was suggested based on reliability and life cycle analysis that correspond with minimum overall cost and frequency interval. It is recommended that fracture-based models in combination with reliability analyses can be a sustainable infrastructure decision-making algorithm.

A Simplified Fatigue Assessment Method for ASME VIII-2

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jun Shen ◽  
Mingwan Lu ◽  
Heng Peng ◽  
Yinghua Liu ◽  
Zhiwei Chen
Keyword(s):  
Evaluation Method ◽  
Failure Modes ◽  
Economic Cost ◽  
Material Design ◽  
Assessment Method ◽  
Element Analysis ◽  
Design Factor ◽  
Screening Criteria ◽  
Detailed Assessment ◽  
Fatigue Evaluation

Abstract Fatigue is one of the most common and important failure modes in pressure vessel. ASME VIII-2 provides three screening criterion and three detailed assessment method for fatigue failure. With the decrease of material design factor and the extension of fatigue curve to high cycle, the applicable scope of the three screening criteria become relatively smaller and the economic efficiency is also reduced. Meanwhile, the three fatigue evaluation methods given in ASME VIII-2 Code are all based on detailed numerical calculations (such as finite element analysis (FEA)). Both economic cost and requirements of technical personnel of engineers are higher. In this paper, a simplified fatigue evaluation method is proposed, which gives simple implementation procedures and relatively conservative fatigue evaluation results. Compared with the screening criteria method A, the main advantage is that the scope of its application is wider, that is: (1) the number of significant load cycle can be considered is extended from 1000 to 105; (2) there is no upper limit to the range of pressure fluctuation, which is 20% in method A. Compared with the screening criteria method B, the main advantage is that this method is much simpler and for most materials, design fatigue curves are not required during calculation and evaluation. Compared with the three detailed assessment methods given in ASME VIII-2, this method is very convenient and does not require detailed FEA. The method proposed in this paper can simplify the evaluation process of fatigue analysis in a certain range and provide a more cost-effective engineering assessment method.

Verification of Alternative Criteria for Shakedown Evaluation Using Flat Head Vessel

2002 ◽  
Author(s):  
Seiji Asada ◽  
Norimichi Yamashita ◽  
Asao Okamoto ◽  
Isoharu Nishiguchi
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Evaluation Method ◽  
Three Dimensional ◽  
Evaluation Criteria ◽  
Strain Range ◽  
Element Analysis ◽  
Plastic Strain Range ◽  
Stress Evaluation ◽  
Elastic Shakedown

Alternative stress evaluation criteria suitable for Finite Element Analysis (FEA) proposed by Okamoto et al. [1] have been studied by the Committee on Three Dimensional Finite Element Stress Evaluation (C-TDF) in Japan. Thermal stress ratchet criteria in plastic FEA are now under consideration. Two criteria are proposed: evaluating variations in plastic strain increments and evaluating variations in the elastic core region. To verify the validity of these criteria, calculations were performed for several typical models in C-TDF [2]. This paper shows calculations and evaluation results of a Flat Head Vessel for shakedown. To study shakedown criteria for gross structural discontinuity, a flat head vessel is surveyed. The flat head vessel consists of a stiff flat head and a shell and is subjected internal pressure and thermal cycle. The elastic shakedown area and the plastic area are compared and plastic strain increments are surveyed. A shakedown evaluation method based on distribution of elastic-plastic strain range is proposed.

Technical Bases for Alternative Stress Evaluation Criteria in Japan Based on Partial Inelastic Analyses

2004 ◽  
Author(s):  
Seiji Asada ◽  
Asao Okamoto ◽  
Isoharu Nishiguchi ◽  
Mitsuru Aoki ◽  
Yasuhide Asada
Keyword(s):  
Finite Element Analysis ◽  
Evaluation Criteria ◽  
Cyclic Loads ◽  
Collapse Load ◽  
Element Analysis ◽  
Stress Evaluation ◽  
Inelastic Analysis ◽  
Plastic Analysis ◽  
Load Analysis ◽  
Fatigue Evaluation

An Alternative Stress Evaluation Criteria suitable for Finite Element Analysis using inelastic analysis has been developed. The Alternative Criteria prescribes evaluations for Primary Loads, Cyclic Loads and Fatigue. Collapse load analysis is used for the evaluation of Primary Loads. The evaluation for Cyclic Loads consists of Shakedown Evaluation and Thermal Ratchet Evaluation. The 2xY method is applied to Simplified Elastic-Plastic Analysis in Fatigue Evaluation. In this paper, the major technical bases of these evaluations are described.

Acoustic Fatigue Evaluation of Branch Connections

2014 ◽  
Author(s):  
Dan Lin ◽  
Ajay Prakash ◽  
Philip Diwakar ◽  
Bertito David
Keyword(s):  
Maximum Stress ◽  
High Stress ◽  
Acoustic Energy ◽  
Mitigation Measures ◽  
Element Analysis ◽  
Acoustic Frequency ◽  
High Stress Concentration ◽  
Fatigue Evaluation ◽  
Acoustic Fatigue ◽  
Vibration Damage

High acoustic energy is known to cause vibrations in pipes, and in some severe cases acoustic induced vibration can lead to fatigue failure at branch connections with high stress concentration. Industry guidelines suggest using mitigation measures such as fabricated full wrap-around reinforcement pad (re-pad) or Sweepolet fittings at branch connections. Effectiveness of these mitigation measures is evaluated via a finite element analysis of four types of branch connections; (i) Sockolet, (ii) Sockolet with 2″ wide partial re-pad, (iii) Sockolet with full wrap-around re-pad, and (iv) Sweepolet. Four distinct acoustic frequency ranges (1/3 octave bands) with associated sound pressure levels are used as the excitation source. Maximum stress levels in the main header pipe at the branch tie-in are monitored to assess the potential for vibration damage. Of the four branch connections, Sockolet with full wrap-around re-pad is found to be least susceptible to damage, followed by the Sweepolet. Unreinforced Sockolet is most susceptible to damage, and the Sockolet with partial re-pad is only marginally better.

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