Comparing Fatigue Strength From Full Scale Blade Tests With Coupon-Based Predictions

In order to get a deeper understanding of the blade-to-blade variations and to determine the statistical distribution of the fatigue strength of rotor blades, 37 small rotor blades have been tested in static and fatigue loading. The blades are 3.4 m commercially available blades adapted to the needs of the project. In addition to these blade tests, coupons of the blade material have been tested. The tests have encompassed static flapwise bending tests, flapwise fatigue tests at two different sections of the blade, and edgewise fatigue tests. Since some blades could be re-used after a first test, a total number of 42 blade tests has been carried out in three different testing laboratories. The blades showed large deformation, development of creep and stiffness reduction. After correction for these phenomena, the fatigue strength of the blades was predicted very well by the classical Goodman relation using the well-known slope parameter of 10.

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Comparing Fatigue Strength From Full Scale Blade Tests With Coupon-Based Predictions

ASME 2002 Wind Energy Symposium ◽

10.1115/wind2002-21 ◽

2002 ◽

Author(s):

Hans van Leeuwen ◽

Don van Delft ◽

John Heijdra ◽

Henk Braam ◽

Eric Jo̸rgensen ◽

...

Keyword(s):

Fatigue Strength ◽

Large Deformation ◽

Fatigue Loading ◽

Fatigue Tests ◽

Full Scale ◽

Rotor Blades ◽

Slope Parameter ◽

Bending Tests ◽

Testing Laboratories ◽

Identical Material

In order to get a deeper understanding of the blade to blade variations and to determine the statistical distribution of the fatigue strength of rotor blades, 37 small rotor blades have been tested in static and fatigue loading. The blades are 3.4 m commercially available blades adapted to the needs of the project. Next to these blade tests, also coupons of identical material have been tested. The tests have encompassed static flapwise bending tests, flapwise fatigue tests at two different sections of the blade and edgewise fatigue tests. Since some blades could be re-used after a first test, a total number of 42 blade tests has been carried out in three different testing laboratories. The blades showed large deformation and development of creep. After correction for these phenomena, the fatigue strength of the blades seemed very good predictable with the classical Goodman relation using the well known slope parameter of 10.

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Elucidation of the High Cycle Fatigue Damage Mechanism of Modified 9Cr-1Mo Steel at Elevated Temperature

Volume 9: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2015-53341 ◽

2015 ◽

Cited By ~ 1

Author(s):

Takuya Murakoshi ◽

Motoyuki Ochi ◽

Ken Suzuki ◽

Hideo Miura

Keyword(s):

Fatigue Strength ◽

High Cycle Fatigue ◽

Elevated Temperatures ◽

Surface Hardness ◽

Diffraction Method ◽

Fatigue Loading ◽

Damage Mechanism ◽

Fatigue Tests ◽

Electron Back Scatter Diffraction ◽

Cycle Fatigue

Modified 9Cr-1Mo steel is one of the heat-resistant steels developed for steam generator in a FBR (Fast Breeder Reactor). When it is used in a FBR, the lifetime of the steel under HCF (High Cycle Fatigue) and V-HCF (Very-High Cycle Fatigue) caused by flow-induced vibration has to be considered for assuring its long-term reliability up to 1011 cycles. Since previous studies showed that the fatigue limit did not appear up to 108 cycles, it is necessary to investigate the fatigue strength of this alloy in cycles higher than 108 cycles. In this study, in order to clarify high cycle fatigue strength and fracture mechanism of the modified 9Cr-1Mo steel, the change of the lath martensitic strengthening structure was observed in detail on the surface of specimens fractured by rotary bending fatigue tests by using EBSD (Electron Back-Scatter Diffraction) method. The Kernel Average Misorientation (KAM) value obtained from the EBSD analysis was used for the quantitative evaluation of the change of the lath martensitic texture. It was found that the average KAM values clearly decreased on the surface areas of the fractured specimens after the application of 107-108 cycles of fatigue loading at temperatures higher than 550°C. This result indicates that degradation of the lath martensitic texture occurred around the surface of specimens tested at the temperature higher than 550°C. In order to quantitatively evaluate the decrease of its strength, a hardness test was performed at room temperature by using a nanoindentation method. It was confirmed that the surface hardness of specimens decreased drastically in the specimens fractured at temperatures higher than 550°C. From these results, it was concluded that the effective 0.2%-proof stress decreased during the fatigue tests by the degradation of the lath martensitic texture caused by the fatigue loading at elevated temperatures. Further analyses are indispensable for explicating the damage mechanism more in detail.

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Evaluation of Deformation Behavior in Cu Thin Film under Tensile and Fatigue Loading by X-Ray Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.524-525.807 ◽

2006 ◽

Vol 524-525 ◽

pp. 807-812 ◽

Cited By ~ 3

Author(s):

Yoshiaki Akiniwa ◽

Tsuyoshi Suzuki ◽

Keisuke Tanaka

Keyword(s):

Fatigue Strength ◽

Applied Stress ◽

Deformation Behavior ◽

Stress Measurement ◽

Fatigue Loading ◽

Fatigue Tests ◽

Ray Method ◽

X Ray ◽

Strength Change ◽

Cu Thin Film

Two kinds of electrodeposited copper foils (thickness is 8 and 20 μm) were loaded statically, and the deformation behavior was observed. In-situ X-ray stress measurement was carried out under tensile loading. Fatigue tests were also conducted to observe the effect of the thickness on the fatigue strength. Change in the line broadening with stress cycles was observed to evaluate the fatigue damage. The tensile strength of 8 μm foil was higher than that of 20 μm foil. When the foils were loaded within elastic region, the stress measured by the X-ray method agreed with applied stress. When the plastic deformation occurred, difference between the measured stress and the applied stress became large. The difference of 20 μm foil was larger than that of 8 μm foil. Fatigue strength of 8 μm foil was also higher than that of 20 μm foil. The value of the full width at half maximum, FWHM, increased rapidly at the first cycle, and then the value became nearly constant. Just before fracture, the value increased again. The change in FWHM corresponded to the change in the accumulated ratchet strain.

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Numerical analysis on fatigue behavior of ultrahigh-performance concrete-Orthotropic steel composite bridge deck

Advances in Structural Engineering ◽

10.1177/13694332211064663 ◽

2022 ◽

pp. 136943322110646

Author(s):

Yang Huang ◽

Shiming Chen ◽

Ping Gu

Keyword(s):

Fatigue Strength ◽

Bridge Deck ◽

Fatigue Loading ◽

Element Model ◽

Fatigue Tests ◽

Nominal Stress ◽

Composite Bridge ◽

Steel Composite ◽

Welded Connection ◽

Composite Bridge Deck

Ultrahigh-performance concrete-orthotropic steel composite bridge deck is composed of the orthotropic steel deck and a thin ultrahigh-performance concrete (UHPC) overlayer. In the previous fatigue tests, two typical fatigue failure modes were found and identified. As a supplementary test after fatigue tests, air penetration method is capable of providing a reference to the quantitative and non-destructive damage detection of fatigue damage of UHPC. To further the previous study, a detailed numerical investigation is accomplished through complimentary finite element (FE) analysis. Compared with the solid element model, the refined shell-solid element model can better reflect the mechanical behavior. It is illustrated that the vertical stress can be adopted in assessing the fatigue strength of rib-to-diaphragm welded connection in the field test by means of nominal stress method. The combination of various factors would lead to fatigue shear failure of the short headed-studs. The fatigue strength of rib-to-diaphragm welded connection predicted by the hot spot stress method and the consistent nominal stress (CNS) method can basically meet the requirements of FAT90. The consistent nominal stress method can be used as the optimization method of nominal stress of fatigue detail. It is demonstrated that the fatigue life of UHPC can be estimated by S-N curves of ordinary concrete conservatively. The allowable equivalent maximum stress level can be taken as 0.55 for two million cycles of fatigue loading, and 0.52 for five million cycles of fatigue loading.

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Fatigue Strength Simulation and Prediction of a Turbine Blade

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.627.229 ◽

2014 ◽

Vol 627 ◽

pp. 229-232 ◽

Cited By ~ 1

Author(s):

Milan Růžička ◽

Josef Jurenka ◽

Martin Nesládek ◽

Ján Džugan

Keyword(s):

Fatigue Strength ◽

Fatigue Tests ◽

Multiaxial Fatigue ◽

Rotor Blades ◽

Strength Prediction ◽

Prediction Methods ◽

The Finite Element Method ◽

Pressure Steam ◽

Experimental Approaches ◽

Service Conditions

Fatigue strength prediction methods of blades of a high pressure steam turbine are the main topic of this article. Experimental approaches, as well as use of the experimental results for the verification of the finite element method (FEM) and fatigue models, were performed on two basic levels. First, verification by the fatigue tests of smooth and notched cylindrical specimens under room and service conditions was performed. Second, verification of the real blade fatigue limit prediction was conducted. These tests were carried out using special test stand under the typical combined blades loading. Appropriate uniaxial and multiaxial fatigue criteria were applied. Achieved results were finally used in the process of the fatigue strength prediction of rotor blades.

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Performance Evaluation of Surface Modified Nano Al2o3 (P) Reinforced AZ91E Composites Under Impact and Fatigue Loading Conditions

Strojnícky casopis – Journal of Mechanical Engineering ◽

10.2478/scjme-2020-0003 ◽

2020 ◽

Vol 70 (1) ◽

pp. 29-38

Author(s):

Kumar D Sameer ◽

K N S Suman ◽

Palash Poddar ◽

Sasanka C Tara

Keyword(s):

Performance Evaluation ◽

Fatigue Strength ◽

Fatigue Loading ◽

Fatigue Tests ◽

Reinforced Composites ◽

Loading Conditions ◽

Modified Alumina ◽

Standard Procedures ◽

The Matrix ◽

Surface Modified

AbstractThis paper confers to compare the behavior of AZ91E, AZ91E with 2 wt. % plain and surface modified alumina reinforced composites under different loading conditions. The composites were prepared and specimens were cut in accordance with standard procedures to conduct impact and fatigue tests. Surface modified alumina reinforced AZ91E magnesium based composites resulted in improved impact and fatigue strength because of good interactions between the matrix and reinforcement. The results are discussed.

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Fatigue Qualification of Heavy Wall Line Pipe and Girth Weld for High Pressure Applications

Volume 3: Materials Technology; Ocean Space Utilization ◽

10.1115/omae2013-10853 ◽

2013 ◽

Cited By ~ 2

Author(s):

Philippe P. Darcis ◽

Noe Mota ◽

Enrique Garcia ◽

Israel Marines-Garcia ◽

Hector M. Quintanilla ◽

...

Keyword(s):

High Pressures ◽

Fatigue Loading ◽

Fatigue Tests ◽

Performance Comparison ◽

Full Scale ◽

Fatigue Performance ◽

Thick Wall ◽

Test Machine ◽

Line Pipe ◽

Pipe Materials

As the offshore oil & gas industry moves into deeper waters, more and more offshore projects, specifically the subsea, riser and flowline designs, rely on heavy wall line pipe materials. These pipe materials must be capable of operating in stringent working conditions such as high pressures, high temperatures, large deformations, fatigue loading, sour environments, etc. Within this context, ExxonMobil Development Company and Tenaris have jointly conducted a detailed technical assessment of the mechanical and fatigue performance of the newly developed heavy wall X65 line pipe (LP) developed by Tenaris. The main goal of such project is to evaluate and demonstrate via full-scale testing the fatigue performance of this new generation of heavy wall line pipe materials and the associated girth weld also recently developed by Tenaris. Although conclusive fatigue performance results at ID are not included in the present paper, the comprehensive test/qualification plan also includes a fatigue performance comparison at ID and OD. The present work clearly demonstrates weldability of this Heavy Wall X65 (273 mm OD × 46 mm WT) line pipe. A narrow-groove bevel welding procedure utilizing the STT® process for the root pass and single torch GMAW process for hot-pass, fill, and cap has been successfully developed. Four full scale fatigue tests were also successfully conducted using a resonant fatigue test machine. The presented fatigue results help demonstrate a realistic level of fatigue performance achievable with this thick wall LP/girth weld technology which will help facilitate assessment of riser/flowline design feasibility in ultra-deep water applications and/or high pressures fields.

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Full Scale Experimental Database of Dent and Gouge Defects to Improve Burst and Fatigue Strength Models of Pipelines

Volume 2: Pipeline Integrity Management ◽

10.1115/ipc2012-90620 ◽

2012 ◽

Cited By ~ 2

Author(s):

Mures Zarea ◽

Remi Batisse ◽

Brian Leis ◽

Philippe Cardin ◽

Geoff Vignal

Keyword(s):

Fatigue Strength ◽

Complex Function ◽

Mechanical Damage ◽

Fatigue Tests ◽

Full Scale ◽

Material Behavior ◽

Experimental Program ◽

Pipe Material ◽

External Interference ◽

Experimental Database

External interference on gas and oil transmission pipelines is consistently reported as leading cause of leaks in Europe and USA as identified in the EGIG and PHMSA incident databases. External interference due to ground working machinery strikes, rock strikes during backfilling, etc. on buried pipelines result mainly in dent and gouge defects. The long-term integrity of a pipeline segment damaged by a dent and gouge defect is a complex function of a variety of parameters, including pipe material properties, pipe geometry, defect geometry linked to indenter shape, aggression conditions. The complexity and extreme variability of these dent and gouge defect shapes and pipe materials lead simple assessment models to scattered predictions, hinting towards an insufficient description of real structural and material behavior. To improve knowledge beyond the numerous studies led in the past, and to provide a sound foundation for developing and validating mechanistic models for predicting burst and fatigue strength of such defects, a large experimental program was funded by PRCI and US DoT and further coordinated with a complementary EPRG program. The experimental program part dealing with combined “Dent and Gouge” defects is covered for modern pipes (24″ OD, X52 and X70) by PRCI project MD-4-1: realistically created (with a Pipe Aggression Rig) defects submitted to full scale burst and fatigue tests, in addition to extensive characterization. This work interfaces with modeling to predict the immediate burst strength and fatigue resistance of such damage in two PRCI projects denoted MD-4-3 and MD-4-4 respectively. This paper gives an overview of some of these activities: PRCI project MD-4-1 results: material characterization, full scale burst and fatigue tests on Dents with Gouges, as well as detailed explanations concerning the initial approach to model burst and fatigue life of these defects, as developed byr PRCI project MD-4-4. The final outcome of the expected knowledge improvements about the mechanical strength of dent and gouge combinations will be applicable by pipeline operators, in order to enhance integrity management systems designed to manage the threat associated with mechanical damage.

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