scholarly journals Long-Life Fatigue Test Results for Two Nickel-Base Structural Alloys

1981 ◽  
Vol 103 (2) ◽  
pp. 126-132 ◽  
Author(s):  
D. F. Mowbray ◽  
E. V. Giaquinto ◽  
F. J. Mehringer
Keyword(s):  
Fatigue Test ◽  
Closed Loop ◽  
Iron Alloy ◽  
Fatigue Tests ◽  
Alloy 600 ◽  
Test Results ◽  
Loading Mode ◽  
Long Life ◽  
Cold Worked ◽  
Nickel Base

This paper reports the results of fatigue tests on two nickel-base alloys, hot-cold-worked and stress-relieved nickel-chrome-iron Alloy 600 and mill-annealed nickel-chrome-moly-iron Alloy 625 in which S-N data were obtained in the life range of 106 to 1010 cycles. The tests were conducted in air at 600°F, in the reversed membrane loading mode, at a frequency of ~ 1850 Hz. An electromagnetic, closed loop servo-controlled machine was built to perform the tests. A description of the machine is given.

scholarly journals Analysis of the Correlation between the Static and Fatigue Test Results of the Interlayer Bondings of Asphalt Layers

2016 ◽  
Vol 62 (1) ◽  
pp. 83-98 ◽  
Author(s):  
A. Szydło ◽  
K. Malicki
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Test Results ◽  
Static Tests ◽  
Bonding State ◽  
Road Pavement ◽  
The Future ◽  
Pavement Structure

Abstract The bonding state of the asphalt layers in a road pavement structure significantly affects its fatigue life. These bondings, therefore, require detailed tests and optimization. In this paper, the analyses of the correlation between the results of laboratory static tests and the results of fatigue tests of asphalt mixture interlayer bondings were performed. The existence of the relationships between selected parameters was confirmed. In the future, the results of these analyses may allow for assessment of interlayer bondings’ fatigue life based on the results of quick and relatively easy static tests.

Three Ways of Sampling and Fatigue Test Results of Steel P92

2014 ◽  
Vol 891-892 ◽  
pp. 273-277
Author(s):  
Josef Volák ◽  
Zbynek Bunda
Keyword(s):  
Mechanical Properties ◽  
Power Plant ◽  
Fatigue Test ◽  
Fatigue Tests ◽  
Energy Industry ◽  
Fatigue Properties ◽  
Test Results ◽  
Steam Turbines ◽  
Standard Samples ◽  
Energy Component

This paper describes the fatigue properties of the steel P92. This material is widely used in the energy industry, especially for pipes and pipe bends of supercritical steam turbines. Steel P92 is alloyed with 2 % of tungsten compared to steel P91. This increases a creep strenght of the material. It is possible to reduce wall thickness of the P92 pipe up to about 20%. Fatigue tests were carried out on standard samples and compared with SFT samples (Small Fatigue Test). Using the device SSam 2 made by company Rolce Royce, it is possible to gently remove a samples from energy component without power plant shutdowns. Consider these correlations, i tis possible to determine mechanical properties of the material from small amount of removed experimental material.

Comparison Between ASME Code-Case N-761, NUREG/CR-6909 and Stainless Steel Component Fatigue Test Results

2014 ◽  
Author(s):  
H. T. Harrison ◽  
Robert Gurdal
Keyword(s):  
Stainless Steel ◽  
Fatigue Test ◽  
Fatigue Tests ◽  
Test Series ◽  
Test Results ◽  
Actual Number ◽  
Steel Component ◽  
Class 1 ◽  
Asme Code ◽  
Number Of Cycles

For Class 1 components, the consideration of the environmental effects on fatigue has been suggested to be evaluated through two different methodologies: either NUREG/CR-6909 from March 2007 or ASME-Code Case N-761 from August 2010. The purpose of this technical paper is to compare these two methods. In addition, the equations from Revision 1 of the NUREG/CR-6909 will be evaluated. For these comparisons, two stainless steel component fatigue test series with documented results are considered. These two fatigue test series are completely different from each other (applied cyclic displacements vs. insurge/outsurge types of transients). Therefore, they are producing an appropriate foundation for these comparisons. In general, the severities of the two methods are compared, where the severity is defined as the actual number of cycles from the fatigue tests, including an evaluation of the scatter, divided by the number of design cycles from the two methods. Also, how stable the methods are is being evaluated through the calculation of the coefficient of variation for each method.

Modification of Plasma Spurt Spraying on Improving Fatigue Property of Welded Joint

2014 ◽  
Vol 556-562 ◽  
pp. 494-497
Author(s):  
Xiao Hui Zhao ◽  
Yu Liu
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Welded Joint ◽  
Base Alloy ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Test Results ◽  
Residual Stress Field ◽  
Modification Method ◽  
Nickel Base

The present paper introduces a modification method of welded joint, plasma spurt spraying (MPSS), for improving the fatigue life of welding structure. Nickel-base alloy powder was used to spray the welded joint of Q235B steel. The high cycle fatigue tests of specimens treated by MPSS were carried out to obtain the S-N curves. Meanwhile, numerical simulation was performed to obtain the residual stress field after spraying. Test results show that the fatigue strength of welded joint by MPSS is higher than that of as-welded joint. Based on the test results and simulation results, it can be concluded that MPSS improves fatigue strength mainly through the decrease of stress concentration and residual stress.

The Fatigue Behavior of Steel Structures under Random Loading

2008 ◽  
Vol 378-379 ◽  
pp. 3-16
Author(s):  
Henning Agerskov
Keyword(s):  
Fracture Mechanics ◽  
Fatigue Test ◽  
Steel Structures ◽  
Fatigue Tests ◽  
Test Series ◽  
Test Results ◽  
Random Loading ◽  
Mechanics Analysis ◽  
Miner’S Rule ◽  
Miner's Rule

Fatigue damage accumulation in steel structures under random loading has been studied in a number of investigations at the Technical University of Denmark. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series with a total of 540 fatigue tests have been carried through on various types of welded plate test specimens and full-scale offshore tubular joints. The materials that have been used are either conventional structural steel or high-strength steel. The fatigue tests and the fracture mechanics analyses have been carried out using load histories, which are realistic in relation to the types of structures studied, i.e. primarily bridges, offshore structures and chimneys. In general, the test series carried through show a significant difference between constant amplitude and variable amplitude fatigue test results. Both the fracture mechanics analysis and the fatigue test results indicate that Miner’s rule, which is normally used in the design against fatigue in steel structures, may give results, which are unconservative, and that the validity of the results obtained from Miner’s rule will depend on the distribution of the load history in tension and compression.

Concepts and Techniques for Helicopter Airframe Fatigue Tests

1966 ◽  
Vol 11 (3) ◽  
pp. 45-57 ◽  
Author(s):  
Walter A. Lane
Keyword(s):  
Experimental Design ◽  
Fatigue Test ◽  
Structural Integrity ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Test Facility ◽  
Test Results ◽  
Fail Safe ◽  
Inspection Techniques ◽  
Automatic Simulation

Between February 1961 and June 1963, Sikorsky Aircraft, under the sponsorship of the U. S. Navy Bureau of Naval Weapons, performed the first laboratory fatigue test of a full scale helicopter airframe. This paper presents the concepts and techniques developed by Sikorsky for such tests. Airframe fatigue test concepts are directed toward defining modes of fatigue cracking, measuring rates of crack propagation, and demonstrating the adequacy of recommended inspection techniques and intervals to provide “fail safe” structural integrity. The experimental design includes consideration of the test article configuration, acceleration of test loads, loading spectra, and evaluation of test fractures. The design of the SH‐3A airframe fatigue test facility to provide automatic simulation of flight and landing loads, and the development problems encountered in achieving this capability are described. The facility and techniques to be used for CH‐53A airframe fatigue tests reflect improvements resulting from SH‐3A test experience. Correlation of airframe fatigue test results and service experience demonstrates the validity of the test concepts and techniques as well as the “fail safe” characteristics of the SH‐3A airframe.

Statistical Analysis of Fatigue Test Data

2017 ◽  
Author(s):  
Carol Johnston
Keyword(s):  
Statistical Analysis ◽  
Fatigue Strength ◽  
Cyclic Loading ◽  
Fatigue Test ◽  
Test Data ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Test Results ◽  
Girth Welds ◽  
New Procedures

The offshore environment contains many sources of cyclic loading. Standard design S-N curves, such as those in DNVGL-RP-C203, are usually assigned to ensure a particular design life can be achieved for a particular set of anticipated loading conditions. Girth welds are often the ‘weak link’ in terms of fatigue strength and so it is important to show that girth welds made using new procedures for new projects that are intended to be used in fatigue sensitive risers or flowlines do indeed have the required fatigue performance. Alternatively, designers of new subsea connectors, used for example in tendons for tension leg platforms, mooring applications or well-heads which will experience cyclic loading in service, also wish to verify the fatigue performance of their new designs. Often operators require contractors to carry out resonance fatigue tests on representative girth welds in order to show that girth welds made using new procedures qualify to the required design S-N curve. Operators and contractors must then interpret the results, which is not necessarily straightforward if the fatigue lives are lower than expected. Many factors influence a component’s fatigue strength so there is usually scatter in results obtained when a number of fatigue tests are carried out on real, production standard components. This scatter means that it is important first to carry out the right number of tests in order to obtain a reasonable understanding of the component’s fatigue strength, and then to interpret the fatigue test results properly. A working knowledge of statistics is necessary for both specifying the test programme and interpreting the test results and there is often confusion over various aspects of test specification and interpretation. This paper describes relevant statistical concepts in a way that is accessible to non-experts and that can be used, practically, by designers. The paper illustrates the statistical analysis of test data with examples of the ‘target life’ approach (that is now included in BS7608:2014 + A1) and the equivalent approach in DNVGL-RP-C203, which uses the stress modification factor. It gives practical examples to designers of a pragmatic method that can be used when specifying test programmes and interpreting the results obtained from tests carried out during qualification programmes, which for example, aim to determine whether girth welds made using a new procedure qualify to a particular design curve. It will help designers who are tasked with specifying test programmes to choose a reasonable number of test specimens and stress ranges, and to understand the outcome when results have been obtained.

A Method for Determining the “Safe” Life of an Aircraft Wing From Fatigue Test Results

1954 ◽  
Vol 58 (521) ◽  
pp. 361-366 ◽  
Author(s):  
A. P. Kennedy
Keyword(s):  
Great Britain ◽  
Fatigue Test ◽  
Tensile Load ◽  
Fatigue Tests ◽  
Test Results ◽  
Aircraft Wing ◽  
Usual Practice ◽  
Safe Life

It is now the usual practice in Great Britain to estimate the “ safe ” life of an aircraft wing from fatigue tests which are carried out on specimens representing the more highly stressed portions of the tension boom or booms. Such tests are designed to produce a tensile load in the boom equal to that produced in steady flight, and superimposed on this, a small fluctuating load corresponding to that which would be produced by an up gust immediately followed by a down gust of the same magnitude.

Mean Load Impact on Mooring Chain Fatigue Capacity: Lessons Learned From Full Scale Fatigue Testing of Used Chains

2019 ◽  
Author(s):  
Øystein Gabrielsen ◽  
Kjell Larsen ◽  
Oddgeir Dalane ◽  
Hans B. Lie ◽  
Svein-Arne Reinholdtsen
Keyword(s):  
Fatigue Test ◽  
Limit State ◽  
Fatigue Tests ◽  
Load Level ◽  
Full Scale ◽  
General Corrosion ◽  
Test Results ◽  
Original Design ◽  
The Mean ◽  
Mooring Chain

Abstract Fatigue of mooring chain is for many floating offshore installations a limiting factor in design. With aging installations and the need for field life extension beyond the original design life, questions on mooring chain endurance are raised. Current SN curves utilized in fatigue limit state (FLS) calculation are based on full scale testing of new chain, performed at a high mean load level (20% of the chains minimum breaking load (MBL)). The high mean load level in the tests do not correspond to the conditions for many chains in operation, as mean load in fatigue relevant seastates are often significantly less than mean load used in the new chain fatigue tests. Mooring chains in operation also experience different degree of corrosion, both general corrosion and pitting. Surface roughness and corrosion pits contribute to crack initiations, and thus reduce fatigue capacity. Fatigue tests with new chain condition cannot be assumed representative for corroded chains. As part of mooring integrity programs, Equinor has been replacing mooring chains since year 2000. To assess actual fatigue capacity, many chain segments have been full scale fatigue tested. First tests started in 2011, and the tests cover different degrees of corrosion. The tests have been performed at typical mean load levels relevant for operation of the installations, which for most cases are less than 20%MBL. From these tests it is observed that fatigue capacity in some cases are better than expected for new chain, even for chain segments with significant corrosion. Fatigue test results show a large effect of the mean load. For test cases with significant corrosion and high mean load (20%MBL), a significant reduction in fatigue capacity compared to new chains is found. This paper presents some of the fatigue test results on used chain, highlighting the effect of the mean load for the given chain conditions. Effect of corrosion at mean load of 20%MBL is also included. The paper discusses some of the underlaying causes for the mean load dependency.

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