scholarly journals INFLUENCE OF TEMPERATURE AND LOADING PROGRAM ON THE FATIGUE LIFE OF STEEL P91

2013 ◽  
Vol 7 (2) ◽  
pp. 93-98
Author(s):  
Stanisław Mroziński ◽  
Michał Piotrowski
Keyword(s):  
Fatigue Life ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Test Results ◽  
Influence Of Temperature ◽  
Program Type ◽  
Influence Of Temperature On ◽  
Two Temperatures ◽  
A Minor ◽  
The Impact

Abstract In this paper there are shown the results of low-cycle fatigue testing of steel P91 samples. During the testing there was conducted a fixed amplitude loading testing as well as programmed loading with various sequence degrees of the program. The testing was done in two temperatures: T=20°C and T=600°C. During the testing a cyclic steel weakening was observed without a clear period of stabilization. Greater changes of the cyclic properties were observed in temperature T=600°C. The influence of temperature on the fatigue life was determined in this paper. This influence is dependent on the degree of strain. It’s a minor one in the range of big strain and increases in the process of decreasing the degree of strain. Furthermore, the impact of the loading program type was determined on the test results and fatigue life calculations

Influence of temperature on low cycle properties of martensitic cast steel

2012 ◽  
Vol 59 (3) ◽  
pp. 329-342 ◽  
Author(s):  
Grzegorz Golanski ◽  
Stanisław Mrozinski ◽  
Krzysztof Werner
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Room Temperature ◽  
Cast Steel ◽  
Cyclic Softening ◽  
Influence Of Temperature ◽  
Influence Of Temperature On ◽  
Two Temperatures ◽  
Stabilization Period

The paper presents the results of research on low cycle properties of highchromium martensitic GX12CrMoVNbN9-1 (GP91) cast steel. The tests of fatigue strength were carried out at two temperatures: room temperature and at 600°C. At both temperatures the occurrence of cyclic softening of the cast steel was observed, revealing no clear stabilization period. Moreover, it has been proved that the fatigue life is influenced by the temperature which depends on the level of strain. The greatest influence was observed for the smallest strain levels applied in the research.

Strain Waveform Effects for Low Cycle Fatigue in Simulated PWR Water

2017 ◽  
Author(s):  
Tommi Seppänen ◽  
Jouni Alhainen ◽  
Esko Arilahti ◽  
Jussi Solin
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Reference Value ◽  
Steel Specimen ◽  
Feedback Signal ◽  
Test Results ◽  
Testing Facility ◽  
Reference Curves

In order to perform design code (ASME III, RCC-M, JSME) compatible direct strain-controlled tests in simulated PWR water, a unique environmental fatigue testing facility was previously developed. Pneumatic bellows are used to generate strain in the stainless steel specimen mid-section, while eddy current based measurement is used as a feedback signal. The NUREG/CR-6909 report gathered a large database of test results and proposed environmental reduction factors (Fen) to account for a reduction in fatigue life in simulated LWR environment when comparing to a reference value in air. The database was composed of non-stabilized stainless steels tested using methods which are not directly comparable to those used in air to define the reference curves. Applicability of the stainless steel Fen factors has already been challenged in previous PVP papers (PVP2013-97500, PVP2014-28465, PVP2016-63294). Results in this paper continue to show this trend of lower experimental Fen factors compared to predictions made by the NUREG report. Dual strain rate tests were performed, specifically focusing on the effect of strain waveform shape on fatigue life. Similarly to last year’s results (PVP2016-63294) a distinct effect of strain waveform, presently inadequately accounted for in Fen predictions, was observed.

Novel Test Facility for Investigation of the Impact of Thermally Induced Stress Gradients on Fatigue Life of Cooled Gas Turbine Components

2018 ◽  
Author(s):  
Marcus Thiele ◽  
Uwe Gampe ◽  
Kathrin A. Fischer
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Heat Fluxes ◽  
Test Facility ◽  
Test Results ◽  
Cycle Fatigue ◽  
Thermally Induced ◽  
Stress Gradients ◽  
Induced Stress ◽  
The Impact

A novel test facility has been designed and set up for the investigation of the influence of stationary temperature, and thus thermally induced stress gradients with respect to the damage evolution of cooled gas turbine components. Thermally induced stress gradients differ from geometrically induced stress gradients. From the point of view of stress mechanics, they are independent from external loads. From the perspective of material mechanics, their impact on service life is influenced by locally different material properties and strength. However, the impact of thermally induced stress gradients on the cyclic life of high loaded, cooled components is not precisely known. In order to increase knowledge surrounding these mechanisms, a research project was launched. To achieve high temperature gradients and extended mechanical stress gradients, large heat fluxes are required. The authors developed a test bench with a unique radiant heating to achieve very high heat fluxes of q̇ ≥ 1.6MW/m2 on cylindrical specimen. Special emphasis has been placed on homogenous temperature and loading conditions in order to achieve valid test results comparable to standard low cycle or thermo-mechanical fatigue tests. Different test concepts of the literature were reviewed and the superior performance of the new test rig concept was demonstrated. The austenitic stainless steel 316L was chosen as the model material for commissioning and validation of the test facility. The investigation of thermally induced stress gradients and, based on this analysis, low-cycle fatigue tests with superimposed temperature gradients were conducted. Linear elastic finite element studies were performed to calculate the local stress-strain field and the service life of the test specimens. The test results show a considerable influence of the temperature gradient on the low-cycle fatigue life of the investigated material. Both the temperature variation over the specimen wall and thermally induced stresses are stated to be the main drivers for the change in low-cycle fatigue life. The test results increase the understanding of fatigue damage mechanisms under local unsteady conditions and can serve as a basis for improved lifetime calculation methods.

Influence of Temperature on the Fatigue of CC/PWB Joints

1990 ◽  
Vol 33 (1) ◽  
pp. 17-25
Author(s):  
Harvey Solomon
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Hysteresis Loops ◽  
Cycle Fatigue ◽  
Printed Wiring Board ◽  
Influence Of Temperature ◽  
Joint Resistance ◽  
Influence Of Temperature On ◽  
Chip Carrier ◽  
Wiring Board

This is a study of the low cycle fatigue of chip carrier/ printed wiring board joints tested at -55° C (-67° F) and 125° C (257° F). It is contrasted to a previous study where the joints were tested at 35° C (95° F). The behavior at 35° C and 125° C was the same. Differences were noted, however, at -55° C. The hysteresis loops were distorted. The slopes of the displacement vs. fatigue life curves were slightly lower and the fatigue lives were longer. These differences were especially significant when the change in joint resistance was used to define failure.

scholarly journals Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4070
Author(s):  
Andrea Karen Persons ◽  
John E. Ball ◽  
Charles Freeman ◽  
David M. Macias ◽  
Chartrisa LaShan Simpson ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Models ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Wearable Sensors ◽  
Fatigue Tests ◽  
Proof Of Concept ◽  
Cycle Fatigue ◽  
Wearable Sensing ◽  
Failure Data

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

scholarly journals Low-cycle fatigue behaviour of laser welded high-strength steel DOMEX 700 MC

2018 ◽  
Vol 157 ◽  
pp. 05013 ◽  
Author(s):  
Peter Kopas ◽  
Milan Sága ◽  
František Nový ◽  
Bohuš Leitner
Keyword(s):  
Fatigue Life ◽  
Welded Joints ◽  
High Strength Steel ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Fatigue Life Analysis

The article presents the results of research on low cycle fatigue strength of laser welded joints vs. non-welded material of high-strength steel DOMEX 700 MC. The tests were performed under load controlled using the total strain amplitude ɛac. The operating principle of the special electro-mechanic fatigue testing equipment with a suitable clamping system was working on 35 Hz frequency. Fatigue life analysis was conducted based on the Manson-Coffin-Basquin equation, which made it possible to determine fatigue parameters. Studies have shown differences in the fatigue life of original specimens and laser welded joints analysed, where laser welded joints showed lower fatigue resistance. In this article a numerical analysis of stresses generated in bending fatigue specimens has been performed employing the commercially available FEM-program ADINA.

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