Application of structural integrity assessment procedure on an axle pin of a wind turbine

2017 ◽  
Vol 40 (8) ◽  
pp. 1284-1294 ◽  
Author(s):  
N. Gubeljak ◽  
M. Cvetic ◽  
Ž. BOŽIĆ ◽  
J. Predan
Keyword(s):  
Wind Turbine ◽  
Structural Integrity ◽  
Assessment Procedure ◽  
Integrity Assessment

Acoustic Emission for Structural Integrity Assessment of Wind Turbine Blades

2014 ◽  
pp. 369-382 ◽  
Author(s):  
Nikolaos K. Tsopelas ◽  
Dimitrios G. Papasalouros ◽  
Athanasios A. Anastasopoulos ◽  
Dimitrios A. Kourousis ◽  
Jason W. Dong
Keyword(s):  
Acoustic Emission ◽  
Wind Turbine ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Integrity Assessment

Estimation of Through-Wall Cracking Frequency of RPV Under PTS Events Using PFM Analysis Method for Identifying Conservatism Included in Current Japanese Code

2014 ◽  
Author(s):  
Kazuya Osakabe ◽  
Koichi Masaki ◽  
Jinya Katsuyama ◽  
Genshichiro Katsumata ◽  
Kunio Onizawa
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Crack Initiation ◽  
Structural Integrity ◽  
Probabilistic Approach ◽  
Pressure Vessels ◽  
Assessment Procedure ◽  
Analysis Method ◽  
Integrity Assessment ◽  
The U.S

To assess the structural integrity of reactor pressure vessels (RPVs) during pressurized thermal shock (PTS) events, the deterministic fracture mechanics approach prescribed in Japanese code JEAC 4206-2007 [1] has been used in Japan. The structural integrity is judged to be maintained if the stress intensity factor (SIF) at the crack tip during PTS events is smaller than fracture toughness KIc. On the other hand, the application of a probabilistic fracture mechanics (PFM) analysis method for the structural reliability assessment of pressure components has become attractive recently because uncertainties related to influence parameters can be incorporated rationally. A probabilistic approach has already been adopted as the regulation on fracture toughness requirements against PTS events in the U.S. According to the PFM analysis method in the U.S., through-wall cracking frequencies (TWCFs) are estimated taking frequencies of event occurrence and crack arrest after crack initiation into consideration. In this study, in order to identify the conservatism in the current RPV integrity assessment procedure in the code, probabilistic analyses on TWCF have been performed for certain model of RPVs. The result shows that the current assumption in JEAC 4206-2007, that a semi-elliptic axial crack is postulated on the inside surface of RPV wall, is conservative as compared with realistic conditions. Effects of variation of PTS transients on crack initiation frequency and TWCF have been also discussed.

Improvements to the Fracture Assessment of Welds Using FITNET Fitness for Service Assessment Procedure

2005 ◽  
Author(s):  
Mustafa Koc¸ak ◽  
Eduard Seib ◽  
Afshin Motarjemi
Keyword(s):  
Laser Beam ◽  
Structural Integrity ◽  
High Strength ◽  
Assessment Procedure ◽  
Welded Structures ◽  
Integrity Assessment ◽  
Friction Stir ◽  
Funded Project ◽  
Aluminum And Magnesium Alloys ◽  
Welding Processes

Recent developments of the advanced welding processes such as laser beam welding (LBW), solid state friction stir welding (FSW) and hybrid welding, numbers of advanced structures are being designed and constructed in industries such as aerospace, power generation, oil and gas transmission and transportation. Development of new structural aluminum and magnesium alloys as well as high strength steels provide further possibilities for the welded structures in similar and dissimilar (material-mix) configurations. Consequently, there is an increasing demand for “Fitness-for-Service” (FFS) assessment of those advanced welded structures by considering the specific features of these weld joints (such as narrow weld width, high strength mis-match, etc.). In year 1999, Structural Integrity Assessment Procedure SINTAP has been developed for analysis of flaws to avoid fracture within the European Commission funded project SINTAP. Recently, the European Community funded project FITNET in the form of a Thematic Network (TN) organisation has started to review the existing FFS procedures and develop an updated, unified and verified European FITNET FFS Procedure to cover structural integrity analysis to avoid failures due to fracture, fatigue, creep and corrosion. This new FFS Procedure has adopted the SINTAP approach for assessing of the welded structures. This paper describes the FITNET FFS weld assessment route and also aims to demonstrate suitability of weld joint assessment route of the FITNET FFS Procedure in prediction of the critical conditions of various advanced welded joints containing flaw. The welded specimens used in this work cover conventional multi-pass welded Inconel-718 turbine blade (T-joint), center cracked wide plates of electron beam welded 13% Cr supermartensitic stainless steel, laser beam welded shipbuilding C-Mn steel and aluminum alloy. The results are showing that the weld strength mismatch analysis option of the FITNET FFS is conservative and degree of conservatism is similar to the analysis options for the homogeneous materials. This provides confidence in the use of the FITNET FFS procedure for assessing of the structural significance of flaws in welded structures.

Implications of Cleavage Fracture Criteria for Structural Integrity Assessment of RPV Steels

2010 ◽  
Author(s):  
S. J. Lewis ◽  
C. E. Truman ◽  
D. J. Smith
Keyword(s):  
Cleavage Fracture ◽  
Structural Integrity ◽  
Strain History ◽  
Assessment Procedure ◽  
Load History ◽  
Safe Operation ◽  
Local Approach ◽  
Integrity Assessment ◽  
Rpv Steel ◽  
Current Assessment

To accurately assess the safe operation of structures containing defects, it is necessary to consider the influences of previous load cycles on crack propagation. A number of current assessment codes contain advice to account for strain history and residual stress, but are generally known to be highly conservative which may potentially result in the unnecessary and expensive repair or replacement of infrastructure. This paper considers the results of previous investigations into cleavage fracture of an A533b RPV steel to determine the accuracy of the widely used R6 structural integrity assessment procedure for fracture following significant load history. The levels of conservatism associated with a number of assessment methods are discussed and compared with experimental data. The general trends suggested an improvement in assessment accuracy may be obtained by using local approach methods, compared to crack tip failure parameters. It is noted however that all the methods used produced some unsafe estimates of failure load, which is felt to be related to an over estimate of the characteristic material toughness.

Reliability-Based Derivation of Partial Safety Factor for Structural Integrity Assessment

2008 ◽  
Author(s):  
Shuo Pan ◽  
Jianping Zhao
Keyword(s):  
Safety Factor ◽  
Fracture Mode ◽  
Structural Integrity ◽  
Research Work ◽  
Random Variables ◽  
Assessment Procedure ◽  
Safety Factors ◽  
Integrity Assessment ◽  
Partial Safety Factor ◽  
Partial Safety Factors

When there are uncertainties in the input random variables, or scatter in the material properties, probabilistic assessment is a useful tool for decision making in the field of safety analysis. The partial safety factor (PSF) method was aimed on ensuring that the failure probability did not exceed a target value. In order to be conservative the input value for each random variable during the assessment procedure should be multiplied by the partial safety factors. So it is essentially a deterministic assessment using conservative values of the input random variables and a relatively simple and independent method of assessing failure probabilities using R6 failure assessment diagram. The application of partial safety factors is an important breakthrough of assessment in structures containing defects. In recent years, sets of PSFs for load, defect size, fracture toughness and yield stress had been given in two standards, BS7910 and API579. However, the recommended PSFs in both standards were larger than the original PSFs in PD6493 which was replaced by BS7910. It is therefore a new method of calculating PSFs should be found to prove which is more appropriate and convenient for engineering application. In the case of the partial safety factor method target reliabilities in the range from 0.001 to 0.00001 were considered and new series of PSFs were derived from the results of reliability analysis for the linear elastic fracture mode and elastic-plastic fracture mode. After comparing with the PSFs in BS7910 and API 579, it is concluded that the partial safety factors were generally conservative compared to our research work.

scholarly journals Structural integrity assessment of floating offshore wind turbine support structures

2020 ◽  
Vol 208 ◽  
pp. 107487
Author(s):  
Behrooz Tafazzoli Moghaddam ◽  
Ali Mahboob Hamedany ◽  
Jessica Taylor ◽  
Ali Mehmanparast ◽  
Feargal Brennan ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Structural Integrity ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Support Structures ◽  
Floating Offshore Wind Turbine ◽  
Integrity Assessment

Structural Integrity Assessment of Weldments at High Temperature: A Proposed New Approach for R5

2008 ◽  
Author(s):  
N. G. Smith ◽  
D. W. Dean ◽  
M. P. O’Donnell
Keyword(s):  
High Temperature ◽  
Fatigue Damage ◽  
Structural Integrity ◽  
Fatigue Crack Initiation ◽  
Current Approach ◽  
Assessment Procedure ◽  
New Approach ◽  
Integrity Assessment ◽  
Creep Fatigue ◽  
Match Effect

The majority of problems associated with the structural integrity of components, particularly those operating at high temperature, are associated with welds. The R5 procedures provide a comprehensive methodology for the assessment of structures operating within the high temperature creep regime. This includes advice on the modifications required to the basic procedure to account for weldments in creep-fatigue crack initiation assessments. The current approach is based on the use of a Fatigue Strength Reduction Factor (FSRF) which has a value according to the particular class of welded joint. The FSRF affects the calculation of creep and fatigue damage. However, the current approach can be excessively conservative for as-welded weldments which are the main type of weldments in plant. This paper outlines the proposed changes to R5, which seek to achieve the following objectives: • to simplify and clarify the current advice for creep-fatigue initiation assessments of weldments, whilst maintaining a conservative assessment procedure; • to have a robust procedure which can be applied to complex components and loading conditions. The new approach separates the FSRF into two components which are as follows: • the geometric strain enhancement due to the weldment geometry (if applicable) and the material mis-match effect between parent material and weld metal, which is called the Weld Strain Enhancement Factor (WSEF), and • the fatigue endurance reduction effect due to the presence of small imperfections (e.g. inclusions, porosity, etc.) in the weldment constituent materials, which is called the Weld Endurance Reduction (WER). The WSEF is used to determine the stress at the start of a dwell or hold period and, because it has a lower value than the FSRF (due to the removal of the WER), results in less conservative calculations of creep damage compared to the current procedure, which uses the full FSRF. For fatigue damage predictions, the modified route is broadly similar to the current route, since the combination of the WER and the WSEF in the modified route corresponds to the FSRF used in the current route. Assessments to demonstrate the improved endurance predictions using the proposed new approach have been performed on several creep-fatigue weldment features tests and examples are provided in this paper.

Fracture Assessment of the High Strength Super-Martensitic Stainless Steel Welds by SINTAP Defect Assessment Procedure

2003 ◽  
Author(s):  
A. K. Motarjemi ◽  
M. Koc¸ak ◽  
R. Segar ◽  
S. Riekehr
Keyword(s):  
Stainless Steel ◽  
Carrying Capacity ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Welding Process ◽  
Assessment Procedure ◽  
Load Carrying Capacity ◽  
Deformation And Failure ◽  
Integrity Assessment ◽  
Load Carrying

13% Cr supermartensitic stainless steel is an adequate substitute material for the conventional carbon and duplex stainless steel pipes for mild corrosive environments in the oil and gas industries. By development of these new steel and respective welding technologies, structural integrity analysis of the welded pipes, is essential and a challenging task. Depending on the welding process, filler wire used, the deformation and failure behaviours of the welded pipes could be different. In this study, fitness for service analysis verified with Submerged Arc welded Middle Tension, M(T), plates as well as for the reeling deformation during the pipe-laying process. This was done by applying analysis Levels 0, I, II and III of a recently developed European Structural Integrity Assessment Procedure (SINTAP). The goal was first of all to verify SINTAP’s load-carrying capacity predictions for welded M(T) specimens (wide plates) by comparing them with corresponding experimental data. SINTAP was also used for estimating the maximum tolerable crack size within the base or weld regions under about 2.7% applied strain, which is the strain equal to the reeling process. The estimated load-carrying capacity of the plates were found on the safe side with acceptable conservatism for all the SINTAP analysis Levels.

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