Experimental study of thermodynamic and fatigue properties of submicrocrystalline titanium under high cyclic and gigacyclic fatigue regimes

2014 ◽  
Vol 229 (7) ◽  
pp. 1271-1279 ◽  
Author(s):  
Oleg Plekhov ◽  
Oleg Naimark ◽  
Irina Semenova ◽  
Alexander Polyakov ◽  
Ruslan Valiev
Keyword(s):  
Experimental Study ◽  
Energy Dissipation ◽  
Stress Amplitude ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Amplitude Analysis ◽  
Self Heating ◽  
Grain Sizes ◽  
Continuous Energy ◽  
Heating Test

This paper presents an experimental study of the mechanical and thermal behavior of titanium samples (Grade 2 and Grade 4) with different grain sizes under cyclic loading. The self-heating test demonstrates that the structure of the material has a strong effect on the dissipation ability of titanium. The threshold of energy dissipation corresponding to the transition through the fatigue limit is shown for coarse-grained titanium. On contrary, submicrocrystalline samples exhibit the dependence of continuous energy dissipation on the applied stress amplitude. Analysis of the fatigue properties of titanium in a gigacyclic regime provides evidence that grain grinding improves substantially the fatigue properties of the material.

scholarly journals Study of load history effects on the high cycle fatigue properties of high-strength low-alloy steel from self-heating measurements

2018 ◽  
Vol 165 ◽  
pp. 14016 ◽  
Author(s):  
Julien Louge ◽  
Cédric Doudard ◽  
Sylvain Calloch ◽  
Bastien Weber
Keyword(s):  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Influential Factor ◽  
Scale Model ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Load History ◽  
Preliminary Loading ◽  
Self Heating ◽  
History Effects

In the context of high cycle fatigue (HCF), the experimental characterization of the fatigue properties is often performed by using specimens in a virgin state (i.e., without preliminary loading), and with a constant stress amplitude for each specimen. However, the load history applied to a real structure is more complex and the fatigue life prediction remains a difficult task because of the time dedicated to the classical fatigue tests (i.e., the specimen is loaded until failure) and the dispersion of fatigue lives. The load history effects on the HCF properties is characterized using an alternative method: self-heating measurements under cyclic loadings. This method is based on the observation of the mean steady state temperature evolution of a specimen under a successive series of cyclic loadings with increasing stress amplitude for each loading series. A probabilistic two-scale model was developed from the self-heating method able to predict HCF properties. Some self-heating tests are performed to study the influence of a load history effects. It seems that the plasticity is the most influential factor. So, the evolution of the plasticity is observed at the surface of the material under cyclic loading. There is a significant evolution in function of the plastic pre-strain.

scholarly journals Low Cycle Fatigue Characteristics of Oxygen-Free Copper for Electric Power Equipment

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4237
Author(s):  
Takuma Tanaka ◽  
Togo Sugioka ◽  
Tatsuya Kobayashi ◽  
Ikuo Shohji ◽  
Yuya Shimada ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electric Power ◽  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Ebsd Analysis ◽  
Fatigue Properties ◽  
Power Equipment ◽  
Cycle Fatigue ◽  
Fracture Surfaces ◽  
Heat Treated

The effect of heat treatment on tensile and low cycle fatigue properties of the oxygen-free copper for electric power equipment was investigated. The heat treatment at 850 °C for 20 min, which corresponds to the vacuum brazing process, caused the grain growth and relaxation of strain by recrystallization, and thus, the residual stress in the oxygen-free copper was reduced. The tensile strength and 0.2% proof stress were decreased, and elongation was increased by the heat treatment accompanying recrystallization. The plastic strain in the heat-treated specimen was increased compared with that in the untreated specimen under the same stress amplitude condition, and thus, the low cycle fatigue life of the oxygen-free copper was degraded by the heat treatment. Striation was observed in the crack initiation area of the fractured surface in the case of the stress amplitude less than 100 MPa regardless of the presence of the heat treatment. With an increase in the stress amplitude, the river pattern and the quasicleavage fracture were mainly observed in the fracture surfaces of the untreated specimens, and they were observed with striations in the fracture surfaces of the heat-treated ones. The result of the electron backscattered diffraction (EBSD) analysis showed that the grain reference orientation deviation (GROD) map was confirmed to be effective to investigate the fatigue damage degree in the grain by low cycle fatigue. In addition, the EBSD analysis revealed that the grains were deformed, and the GROD value reached approximately 28° in the fractured areas of heat-treated specimens after the low cycle fatigue test.

Experimental study on seismic performance of suspended ceiling components

2021 ◽  
Author(s):  
Yong Wang ◽  
Huanjun Jiang ◽  
Chen Wu ◽  
Zihui Xu ◽  
Zhiyuan Qin
Keyword(s):  
Experimental Study ◽  
Energy Dissipation ◽  
Seismic Performance ◽  
Seismic Vulnerability ◽  
Axial Loading ◽  
Deformation Capacity ◽  
Severe Damage ◽  
Strong Earthquakes ◽  
Static Tests ◽  
Load Carrying

<p>Suspended ceiling systems (SCSs) experienced severe damage during strong earthquakes that occurred in recent years. The capacity of the ceiling component is a crucial factor affecting the seismic performance of SCS. Therefore, a series of static tests on suspended ceiling components under monotonic and cyclic loadings were carried out to investigate the seismic performance of the ceiling components. The ceiling components include main tee splices, cross tee latches and peripheral attachments. All specimens were tested under axial loading. Additionally, the static tests of cross tee latches subjected to shear and bending loadings were performed due to their seismic vulnerability. The failure pattern, load-carrying ability, deformation capacity and energy dissipation of the ceiling components are presented in detail in this study.</p>

Self-Heating Test to Evaluate Temperature Stabilization in the Rolling Bearing

2013 ◽  
Author(s):  
Rafael V. Carvalho ◽  
Ludmila C. A. Silva ◽  
Milton Amaro ◽  
Alessandro A. Ferreira ◽  
Aparecido M. da Rosa
Keyword(s):  
Rolling Bearing ◽  
Temperature Stabilization ◽  
Self Heating ◽  
Heating Test

Tensile Pre-Strain Effects on Torsional Fatigue Properties of Medium Carbon Steels

2005 ◽  
Vol 297-300 ◽  
pp. 1126-1132 ◽  
Author(s):  
Cong Ling Zhou ◽  
Shinichi Nishida ◽  
Nobusuke Hattori ◽  
Wen Xian Sun
Keyword(s):  
Stress Amplitude ◽  
Surface Hardness ◽  
Strain Ratio ◽  
Carbon Steels ◽  
Fatigue Properties ◽  
Crack Initiation And Propagation ◽  
Medium Carbon ◽  
Torsional Fatigue ◽  
Initiation And Propagation ◽  
Medium Carbon Steels

This study was focused on the effects of pre-strain on the torsional fatigue properties of three kinds of medium carbon steels, including the fatigue strength, surface hardness, microstructure, and the crack initiation and propagation behaviors. The effect of pre-strain on the non-propagating cracks was also discussed. The main results obtained in this test are as follows: 1) the fatigue limits increase with the increasing of tensile pre-strain ratio for all kinds of the test materials; 2) under certain stress amplitude, with the increasing of tensile pre-strain ratio, the fatigue crack initiates a little earlier and propagates faster; 3) the length of non-propagating crack decreases with the increasing of tensile pre-strain ratio.

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