scholarly journals Development of an ultrasonic fatigue testing system for gigacycle fatigue

2019 ◽  
Vol 2 (6) ◽  
Author(s):  
Paul Ilie ◽  
Xavier Lesperance ◽  
Ayhan Ince
Keyword(s):  
Fatigue Testing ◽  
Testing System ◽  
Ultrasonic Fatigue

VHCF Behavior and Word Hardening of a Ferritic-Martensitic Steel at High Mean Stresses

2015 ◽  
Vol 664 ◽  
pp. 246-254 ◽  
Author(s):  
Tilmann Beck ◽  
Stephan A. Kovacs ◽  
Fabian Ritz
Keyword(s):  
Crack Initiation ◽  
Fatigue Testing ◽  
Turbine Blades ◽  
Cyclic Creep ◽  
Cyclic Hardening ◽  
Testing System ◽  
Fine Grained ◽  
Ultrasonic Fatigue ◽  
Stress Ratios ◽  
Mean Stresses

Low-pressure steam turbine blades undergo VHCF-loadings induced by inhomogenous flow behind the vanes resulting in excitation frequencies of ≈ 2 kHz for rotational speeds of 50 Hz and a typical number of stator vanes of ≈ 60. The VHCF loading is superimposed by considerable mean stresses caused by centrifugal forces. In the present study, the VHCF-behavior of the ferritic-martensitic turbine blade steel X10CrNiMoV12-2-2 is investigated using an ultrasonic fatigue testing system up to cycle numbers of 5∙109 at stress ratios from R = -1 up to 0.7, i.e. up to very high mean stresses. Generally, crack initiation changes from the surface to internal inclusions at fatigue lives around 4∙107. The transition between fatigue failure and run-outs is shifted to higher lifetime with increasing R, and fine grained areas (FGAs) at the crack initiation sites only occur at R < -0.1. However, the fracture mechanics approach proposed by Murakami consistently describes the lifetime behavior for all load ratios over 4 decades of lifetime. At R up from 0.5 considerable cyclic creep occurs, even for lifetimes above 108 cycles, resulting in cyclic hardening which was proved by microhardness measurements at longitudinal sections. This effect at least partially explains the high maximum stresses close to the tensile strength of the material occurring in the VHCF regime at load ratios ≥ 0.5.

scholarly journals Development of High-Temperature Ultrasonic Fatigue Testing System

2012 ◽  
Vol 78 (789) ◽  
pp. 718-727 ◽  
Author(s):  
Yoshiyuki FURUYA ◽  
Kazuo KOBAYASHI ◽  
Masao HAYAKAWA ◽  
Masao SAKAMOTO ◽  
Yutaka KOIZUMI ◽  
...  
Keyword(s):  
High Temperature ◽  
Fatigue Testing ◽  
Testing System ◽  
Ultrasonic Fatigue

Influence of Defects on High Cycle Fatigue Response of Ti45Nb Biocompatible Alloy

2016 ◽  
Vol 258 ◽  
pp. 337-340 ◽  
Author(s):  
Mitra Delshadmanesh ◽  
Golta Khatibi ◽  
Martin Lederer ◽  
Michael Zehetbauer ◽  
Herbert Danninger
Keyword(s):  
High Cycle Fatigue ◽  
Surface Defects ◽  
Fatigue Testing ◽  
Stress Amplitude ◽  
Testing System ◽  
Cycle Fatigue ◽  
Early Failure ◽  
Element Analysis ◽  
Notch Geometry ◽  
Ultrasonic Fatigue

The high cycle fatigue response of Ti-45Nb alloy was investigated by using an ultrasonic fatigue testing system. The effect of notch geometry on the fatigue response was studied on samples with different circumferential grooves. The experiments showed a decrease of fatigue notch sensitivity with decreasing the notch radius. Finite element analysis (FEA) was conducted for calculation of the stress distribution in the samples and interpretation of the experimental results. Further, the lifetime of the alloy showed a strong dependency on the location of the defects and microstructural inhomogeneities. It was observed that at the same stress amplitude, early failure was caused by surface defects, while those with a longer lifetime failed due to cracks originating from internal flaws.

High-Temperature Ultrasonic Fatigue Testing at 1000°C

2014 ◽  
Vol 891-892 ◽  
pp. 1413-1418
Author(s):  
Yoshiyuki Furuya ◽  
Kazuo Kobayashi ◽  
Masao Hayakawa ◽  
Masao Sakamoto ◽  
Yutaka Koizumi ◽  
...  
Keyword(s):  
High Temperature ◽  
Fatigue Testing ◽  
Turbine Blades ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Testing System ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Ultrasonic Fatigue

A high-temperature ultrasonic fatigue testing system was developed to evaluate the gigacycle fatigue properties of single-crystal superalloys used in aircraft engine turbine blades. In this development, a commercial ultrasonic fatigue testing machine was considerably modified to achieve high-temperature fatigue testing. The developed system took account of temperature dependency of Youngs modulus, and also had a function to evaluate the Youngs modulus. In order to protect the testing system from the heat of a specimen, straight and round rods were inserted between the testing system and the specimen. Other modifications achieved accurate control of temperature, edge displacement and resonance frequency, which were necessary for accurate control of stress amplitude. The testing system was first applied to a heat-resistant steel at 650 °C to check its accuracy, and next to SC superalloy samples at 1000 °C. In the conventional fatigue tests on the heat-resistant steel, the results were coincident in a frequency range from 1 Hz to 800 Hz, suggesting that comparable results would be obtained in ultrasonic fatigue testing at 20 kHz. In case of the SC superalloy samples, conventional fatigue tests were conducted at only 10 Hz, so the frequency effects were not clarified. In both cases, ultrasonic fatigue testing showed good agreement with conventional fatigue testing. The accuracy of the developed system is therefore high, even at 1000 °C. In these results, the SC superalloys showed no fatigue limit, indicating gigacycle fatigue tests to be necessary.

scholarly journals Giga-Cycle Fatigue Behavior of the Nuclear Structure of 316L Weldments

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhihong Xiong ◽  
Engao Peng ◽  
Lianghua Zeng ◽  
Qirong Xu
Keyword(s):  
Fatigue Strength ◽  
Arc Welding ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Laser Beam Welding ◽  
Fatigue Loading ◽  
Testing System ◽  
Cycle Fatigue ◽  
Gas Tungsten Arc ◽  
Ultrasonic Fatigue

Some components made of 316L stainless steel in nuclear reactors are connected by welding, and these are under giga-cycle fatigue loading. Therefore, the giga-cycle fatigue behavior of 316L weldments, which are fabricated by Laser Beam Welding (LBW) and Gas Tungsten Arc Welding (GTAW), were investigated using an ultrasonic fatigue testing system. The results indicate that the fatigue strength of LBW-made weldments is almost the same as that of GTAW-made weldments even though the microstructure and mechanical properties of the weldments are different. For the LBW-made specimens, the LBW-induced internal pores with a diameter range of about 89–270 μm were observed in the fracture surface. However, an obvious decrease in fatigue life was not observed in such cases. For the GTAW-made specimens, the quality requirement of the weld seam has to be more strict to prevent fatigue strength from decreasing. The fatigue failure mode of the GTAW-made specimens is the same as that of LBW-made specimens in the high-cycle fatigue regime but different in the giga-cycle fatigue regime.

scholarly journals Very High Cycle Fatigue Behavior of Carbon Manganese Steels

2010 ◽  
Vol 146-147 ◽  
pp. 1780-1783
Author(s):  
Hong Qian Xue ◽  
Danièle Wagner
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Effect Of Temperature ◽  
Testing System ◽  
Loading Frequency ◽  
Ultrasonic Fatigue ◽  
Carbon Manganese Steels ◽  
Temperature Scanning ◽  
Initial Results ◽  
Manganese Steels

An ultrasonic fatigue testing system capable of operating at temperatures at 250 has been introduce to study the fatigue behavior of carbon manganese steels (A42 and A48) and loading frequency of approximately 20 kHz. Endurance limit results were comparable to those generated at room temperature to determine the effect of temperature. Scanning electron microscopy was then used to determine the initiation sites and the failure mechanisms. Initial results indicate that fatigue strength decrease a little at 250 , interior inclusions were the major microstructural feature responsible for crack initiation in the alloy.

Fatigue of Unidirectional Cord-Rubber Composites

1999 ◽  
Vol 27 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Y. Liu ◽  
Z. Wan ◽  
Z. Tian ◽  
X. Du ◽  
J. Jiang ◽  
...  
Keyword(s):  
Damage Accumulation ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Constant Load ◽  
Testing System ◽  
Rubber Composites ◽  
Cycle Frequency ◽  
Periodic Loading ◽  
Fatigue Damage Accumulation ◽  
Rubber Composite

Abstract A fatigue testing system is established with which the real-time recording of stress, strain, temperature, and hysteresis loss of rubbers or cord-rubber composite specimens subjected to periodic loading or extension can be successfully carried out. Several problems are connected with the experimental study of the fatigue of rubber composites. In constant extension cycling, the specimen becomes relaxed because of the viscoelasticity of rubber composites, and the imposed tension-tension deformation becomes complex. In this method, the specimen is unlikely to fail unless the imposed extensions are very large. Constant load cycling can avoid the shortcomings of constant extension cycling. The specially designed clamps ensure that the specimen does not slip when the load retains a constant value. The Deformation and fatigue damage accumulation processes of rubber composites under periodic loading are also examined. Obviously, the effect of cycle frequency on the fatigue life of rubber composites can not be ignored because of the viscoelasticity of constituent materials. The increase of specimen surface temperature is relatively small in the case of 1 Hz, but the temperature can easily reach 100°C at the 8 Hz frequency. A method for evaluating the fatigue behavior of tires is proposed.

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