Assessment of Bend Fatigue Tests Using RSE-M Stress Analysis Techniques and the ASME Section III Fatigue Design Rules

2015 ◽  
Author(s):  
Steven E. Booth ◽  
Willem J. J. Vorster
Keyword(s):  
Stress Analysis ◽  
Fatigue Damage ◽  
High Stress ◽  
Fatigue Tests ◽  
Careful Consideration ◽  
Division I ◽  
Industrial Plant ◽  
Design Rules ◽  
Fatigue Design ◽  
Combined Use

Preparing the scope and extent of components requiring inspections in industrial plant demands careful consideration given the commercial implications. Stress analysis can usefully be employed to ascertain whether pipework components should be inspected. This can be achieved by interpreting pipework loads whilst giving consideration to all relevant failure mechanisms. Moreover, due to the size of the components the use of stress analysis can provide a means of targeted inspections by identifying areas of high stress where material damage is most likely to be observed. This paper compares the findings of fatigue tests reported by MPA Stuttgart in the mid 1990s of pipework bends subjected to combined pressure and moment loading with calculated fatigue damage using an analytical approach which combines the RSE-M stress analysis methods with the ASME Division I Section III NB fatigue design rules. The comparison is of interest as it has been found that the combined use of RSE-M and the ASME Division I Section III NB fatigue damage rules provides good agreement of calculated stresses with the locations and orientation of crack initiation observed in the fatigue tests. The calculated ASME Division I Section III NB fatigue endurance was found to bound that determined for the tests by a reasonable margin. Therefore, this approach provides a powerful means of assessing the fatigue life of in-service bends and confirms that the use of these tools is appropriate.

Fatigue Performance of Grade R4 and R5 Mooring Chains in Seawater

2014 ◽  
Author(s):  
Jonathan Fernández ◽  
Walther Storesund ◽  
Jesús Navas
Keyword(s):  
Fatigue Test ◽  
Fatigue Damage ◽  
Fatigue Tests ◽  
Design Methods ◽  
Full Scale ◽  
Fatigue Performance ◽  
Test Program ◽  
Gas Industry ◽  
Fatigue Design ◽  
Cumulative Fatigue Damage

With more than 50.000 tons in service to date, the Oil&Gas Industry has the need to understand the tension fatigue performance of grade R5 chains in straight tension, and corroborate the validity of the existing design methods. The chain fatigue design curves in API and DNV are based on fatigue tests obtained in the nineties and early two thousands. However the tests were performed on lower grades such as ORQ, R3 and R4, and small chains, 76 mm diameter being the largest studless chain tested. The industry has moved towards the use of large studless chains, especially in permanent units, where chain diameters above 150 mm are not unusual. This paper gathers information from a full scale fatigue test program on grade R4 and R5 studless chains, performed in seawater and with diameters between 70 mm and 171 mm. The chains being tested are actual production chains supplied for different drilling units and large permanently moored production floating units. The paper analyses the data and determines tension-tension fatigue curves based on API and DNV methods for computation of cumulative fatigue damage, regardless of other damaging mechanisms. Improved fatigue capacity is obtained with respect to the above recommended design methods.

Nuclear Fatigue Codified Design Rules: Development Status, Margins and Screening Criteria

2018 ◽  
Author(s):  
Claude Faidy
Keyword(s):  
Fatigue Life ◽  
Environmental Effects ◽  
Fatigue Tests ◽  
Historical Background ◽  
Design Rules ◽  
Screening Criteria ◽  
Fatigue Design ◽  
Laboratory Test Results ◽  
Fatigue Life Evaluation ◽  
Open Question

In the past 10 years, different laboratory test results lead the International Standard Development Organizations (SDO) to review their fatigue design rules in different directions, in particular to consider consequences of environmental effects on existing design rules. The key document that ask different questions to Code developers is the USNRC NUREG 6909 report: “Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials” that confirms some environmental effects on S-N fatigue tests on small specimen. The open question is: how to transfer these results to Fatigue Design Rules of plant components? This paper will review existing codified rules in major nuclear Codes; in particular USA ASME Boiler and Pressure Vessel Code Section III and French AFCEN RCC-M Code. The paper will make a first historical background of these Codes and analyze background of these rules by consideration of field experience and existing tests results. To conclude, the paper will summarize to-day “fatigue road maps” to evaluate margins and screening criteria to assure reliable and safe codified design fatigue life evaluation.

scholarly journals Fatigue durability of asphalt-cement mixtures

2015 ◽  
Vol 63 (1) ◽  
pp. 107-111 ◽  
Author(s):  
J. Kuźniewski ◽  
Ł. Skotnicki ◽  
A. Szydło
Keyword(s):  
Fatigue Damage ◽  
Load Cycle ◽  
Fatigue Tests ◽  
Design Criterion ◽  
Asphalt Cement ◽  
Road Pavement ◽  
Fatigue Design ◽  
Fatigue Durability ◽  
Fatigue Design Criterion ◽  
Cement Mixtures

Abstract This paper focuses on examinations of asphalt-cement mixtures (ACM). This is a recycled material which can be used in road pavement layers. In the article stiffness modulus tests and fatigue tests of asphalt-cement mixtures were shown. The authors decided to lead research on fatigue durability of asphalt-cement mixtures to set fatigue characteristics of these materials. So far in research or other works any adequate fatigue criterion for ACM mixtures has not been developed. As a result of the examinations a level of fatigue damage was suggested. For new fatigue damage a strain level in one million load cycle was estimated. Based on that a fatigue design criterion for asphalt-cement mixtures was estimated.

Strength and Fatigue Analysis of VIM Suppression Strakes for Large Diameter Spars

2007 ◽  
Author(s):  
Sudhakar Tallavajhula ◽  
Jim Wang ◽  
Inge Solberg
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Fatigue Damage ◽  
Global Analysis ◽  
Large Diameter ◽  
High Stress ◽  
Hydrodynamic Pressure ◽  
Frequency Domain Analysis ◽  
Unit Load ◽  
Principal Stresses

The efficiency of spar vortex induced motion (VIM) suppression strakes has been found to be dependent upon the height of the strakes, the number of strakes in the helix, the pitch of the helix and the extent of strake coverage. As spars have increased in diameter, the height of the VIM suppression strakes has grown to maintain strake efficiency. This has introduced new challenges to the structural design of the strakes as a result of the increased hydrodynamic pressure loads on the strakes and the effect of global bending of the spar hull. The connection of the strakes to the hard tank outer shell often has high stress concentration, which in combination with the cyclic hydrodynamic loading, tends to result in fatigue considerations governing the design of these connections. As a result, finite element models, both global and local, are required to perform detailed stress analysis for the structural strength and fatigue assessment of the strakes and surrounding hard tank structures. This paper will use a generic, large diameter truss spar as an example to outline the methodology and key elements used for strength and fatigue analyses of the strakes. In particular, an efficient unit load method will be presented, which has been used to de-couple the finite element stress analysis and the actual hydrodynamic pressure load analysis for fatigue damage calculation. This method incorporates a time domain global analysis of spar hull global bending loads, and a frequency domain analysis of wave induced hydrodynamic pressure loads on the strakes. Final fatigue damage is calculated based on combined principal stresses using the spectral method. Analysis results and findings are presented for both the in-place condition and the wet tow condition. By applying this procedure, Technip has been able to repeatedly design robust and reliable VIM suppression strakes in a cost efficient process, within the constraints of tight fabrication schedules.

scholarly journals Fatigue Damage of Al/SiC Composites - Macroscopic and Microscopic Analysis

2015 ◽  
Vol 60 (1) ◽  
pp. 101-105 ◽  
Author(s):  
A. Rutecka ◽  
Z.L. Kowalewski ◽  
K. Makowska ◽  
K. Pietrzak ◽  
L. Dietrich
Keyword(s):  
Fatigue Damage ◽  
Microscopic Analysis ◽  
Inelastic Strain ◽  
Damage Parameter ◽  
Fatigue Tests ◽  
Cyclic Plasticity ◽  
Damage Mechanisms ◽  
Before And After ◽  
Fatigue Damage Parameter ◽  
Sic Composites

Abstract The results of comparative examinations of mechanical behaviour during fatigue loads and microstructure assessment before and after fatigue tests were presented. Composites of aluminium matrix and SiC reinforcement manufactured using the KoBo method were investigated. The combinations of two kinds of fatigue damage mechanisms were observed. The first one governed by cyclic plasticity and related to inelastic strain amplitude changes and the second one expressed in a form of ratcheting based on changes in mean inelastic strain. The higher SiC content the less influence of the fatigue damage mechanisms on material behaviour was observed. Attempts have been made to evaluate an appropriate fatigue damage parameter. However, it still needs further improvements.

Analysis of Fatigue Mechanical Behaviors of Welding Conformations in Orthotropic Steel Bridge Deck

2015 ◽  
Vol 1096 ◽  
pp. 562-566 ◽  
Author(s):  
Bo Yu ◽  
Tao Hong ◽  
Jian Zhang ◽  
Qing Yu Liang
Keyword(s):  
Fatigue Damage ◽  
Bridge Deck ◽  
Fatigue Tests ◽  
Steel Bridge ◽  
Test Results ◽  
Practical Application ◽  
Mechanical Behaviors ◽  
Homogeneous Test ◽  
Orthotropic Steel Bridge Deck ◽  
Damage Theory

Due to the superior structure style, orthotropic steel bridge deck has been getting more and more widely practical application. The static and fatigue tests of the orthotropic steel bridge deck models were carried out in this research paper, which presented the fatigue damage developing laws, compared the test results with homogeneous test results in existing documents, and according to the relative fatigue accumulative damage theory, the fatigue accumulative damage equations of the sectional specimen and the whole specimen are respectively studied.

scholarly journals PWR Effect on Crack Initiation Under Equi-Biaxial Loading Development of the Experiment

2016 ◽  
Author(s):  
G. Perez ◽  
C. Gourdin ◽  
S. Courtin ◽  
J. C. Le Roux
Keyword(s):  
Biaxial Loading ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Structural Effect ◽  
Fatigue Tests ◽  
Fatigue Lifetime ◽  
New Device ◽  
Fatigue Design ◽  
Penalty Factor ◽  
Mean Strain

Fatigue lifetime assessment is essential in the design of structures. Under-estimated lifetime predictions may generate overly conservative usage factor values and hence result in unnecessary in-service inspections. In the framework of upgrading the fatigue design rules (RCC-M, RCC-MRx), the uniaxial reference fatigue curve was altered by taking into account effects like: Multiaxiality, Mean stress or strain, Surface roughness (polished or ground), Scale effect, Loading History... In addition to this effect, Environmentally Assisted Fatigue is also receiving nowadays an increased level of attention. To formally integrate these effects, some international codes have already proposed and suggested a modification of the austenitic stainless steels fatigue curve combined with a calculation of an environmental penalty factor, namely Fen, which has to be multiplied by the usual fatigue usage factor. The aim of this paper is to present a new device “FABIME2E” developed in the LISN in collaboration with EDF and AREVA. These new tests allow quantifying accurately the effect of PWR environment on semi-structure specimen. This new device combines the structural effect like equibiaxiality and mean strain and the environmental penalty effect with the use of PWR environment during the fatigue tests.

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