scholarly journals Study on Energy States during Fatigue Process in Mild Steel : 3rd Report, Fatigue Damage Caused by Energy State in Surface Layer

1970 ◽  
Vol 36 (290) ◽  
pp. 1589-1598
Author(s):  
Shigemi SASAKI
Keyword(s):  
Surface Layer ◽  
Mild Steel ◽  
Fatigue Damage ◽  
Energy State ◽  
Fatigue Process ◽  
Energy States

scholarly journals Analysis of Damage Evolution in Concrete under Fatigue Loading by Acoustic Emission and Ultrasonic Testing

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 341
Author(s):  
Marc Thiele ◽  
Stephan Pirskawetz
Keyword(s):  
Acoustic Emission ◽  
Elastic Modulus ◽  
Cyclic Loading ◽  
Fatigue Damage ◽  
Fatigue Loading ◽  
Measurement Methods ◽  
Material Structure ◽  
Fatigue Process ◽  
Acoustic Methods ◽  
Normal Strength

The fatigue process of concrete under compressive cyclic loading is still not completely explored. The corresponding damage processes within the material structure are especially not entirely investigated. The application of acoustic measurement methods enables a better insight into the processes of the fatigue in concrete. Normal strength concrete was investigated under compressive cyclic loading with regard to the fatigue process by using acoustic methods in combination with other nondestructive measurement methods. Acoustic emission and ultrasonic signal measurements were applied together with measurements of strains, elastic modulus, and static strength. It was possible to determine the anisotropic character of the fatigue damage caused by uniaxial loading based on the ultrasonic measurements. Furthermore, it was observed that the fatigue damage seems to consist not exclusively of load parallel oriented crack structures. Rather, crack structures perpendicular to the load as well as local compacting are likely components of the fatigue damage. Additionally, the ultrasonic velocity appears to be a good indicator for fatigue damage beside the elastic modulus. It can be concluded that acoustic methods allow an observation of the fatigue process in concrete and a better understanding, especially in combination with further measurement methods.

Arcuate Na+,K+-ATPase senses systemic energy states and regulates feeding behavior through glucose-inhibited neurons

2015 ◽  
Vol 309 (4) ◽  
pp. E320-E333 ◽  
Author(s):  
Hideharu Kurita ◽  
Kai Y. Xu ◽  
Yuko Maejima ◽  
Masanori Nakata ◽  
Katsuya Dezaki ◽  
...  
Keyword(s):  
Feeding Behavior ◽  
Energy State ◽  
Glucose Lowering ◽  
First Order ◽  
Obesity And Diabetes ◽  
Metabolic States ◽  
Pump Activity ◽  
Single Arc ◽  
Energy States ◽  
Agouti Related Protein

Feeding is regulated by perception in the hypothalamus, particularly the first-order arcuate nucleus (ARC) neurons, of the body's energy state. However, the cellular device for converting energy states to the activity of critical neurons in ARC is less defined. We here show that Na+,K+-ATPase (NKA) in ARC senses energy states to regulate feeding. Fasting-induced systemic ghrelin rise and glucose lowering reduced ATP-hydrolyzing activity of NKA and its substrate ATP level, respectively, preferentially in ARC. Lowering glucose concentration (LG), which mimics fasting, decreased intracellular NAD(P)H and increased Na+ concentration in single ARC neurons that subsequently exhibited [Ca2+]i responses to LG, showing that they were glucose-inhibited (GI) neurons. Third ventricular injection of the NKA inhibitor ouabain induced c-Fos expression in agouti-related protein (AgRP) neurons in ARC and evoked neuropeptide Y (NPY)-dependent feeding. When injected focally into ARC, ouabain stimulated feeding and mRNA expressions for NPY and AgRP. Ouabain increased [Ca2+]i in single NPY/AgRP neurons with greater amplitude than in proopiomelanocortin neurons in ARC. Conversely, the specific NKA activator SSA412 suppressed fasting-induced feeding and LG-induced [Ca2+]i increases in ARC GI neurons. NPY/AgRP neurons highly expressed NKAα3, whose knockdown impaired feeding behavior. These results demonstrate that fasting, via ghrelin rise and LG, suppresses NKA enzyme/pump activity in ARC and thereby promotes the activation of GI neurons and NPY/AgRP-dependent feeding. This study identifies ARC NKA as a hypothalamic sensor and converter of metabolic states to key neuronal activity and feeding behaviour, providing a new target to treat hyperphagic obesity and diabetes.

Understanding Fatigue Damage Under High-Cycle Random Fatigue on the Basis of the Actual Fatigue Process.

1998 ◽  
Vol 64 (624) ◽  
pp. 2152-2157
Author(s):  
Masahiro MIYAKE ◽  
Shoji HARADA ◽  
Yoshihito KUROSHIMA ◽  
Masao TAKAHARA
Keyword(s):  
Fatigue Damage ◽  
Fatigue Process ◽  
Random Fatigue

scholarly journals Multifeature Extraction of Three-Dimensional Topography of Carbon Steel Specimen during Fatigue Process

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Tao Liu ◽  
Jingxiong Wu ◽  
Jingfa Lei ◽  
Xue Wang ◽  
Bingqi Zhang ◽  
...  
Keyword(s):  
Surface Topography ◽  
Metal Surface ◽  
Fatigue Damage ◽  
Feature Fusion ◽  
Early Stage ◽  
Three Dimensional ◽  
Mean Deviation ◽  
Height Distribution ◽  
Fusion Method ◽  
Fatigue Process

In order to investigate the variation of three-dimensional metal surface topography during fatigue process, a three-dimensional (3D) topography acquisition platform was built with an in situ tensile tester and a three-dimensional profilometer. Q235 steel specimens were chosen as research objects, and the three-dimensional surface topography information at various stages of fatigue damage was obtained. Through the characterization of three-dimensional roughness, combined with surface height distribution and multifractal analysis, the variations of metal surface topography in the fatigue process were described. Results show that the arithmetic mean deviation of the surface (Sa), the width of the multifractal spectrum (Δα), and the mean value of surface height distribution (μ) and its standard deviation (δ) increase nonlinearly with the increase of fatigue cycles. The rate of fatigue damage is slow in the early stage and high in the middle and late stages. The surface height distribution amplitude (A) decreases with the increase of fatigue cycles, which indicates that the height data concentration decreases, and the metal surface becomes uneven. The Bayesian data fusion method was applied to establish a nonlinear mapping between the topography features and the damage, with the above five characteristic parameters (Sa, Δα, A, μ, and δ) as the data layer. Finally, a surface topography feature fusion method is proposed, and a case study is conducted to verify its applicability. The research results can provide reference for fatigue damage assessment.

3601 Fatigue Damage Evaluation of SUS304 by Magnetism Change in Fatigue Process

2006 ◽  
Vol 2006.1 (0) ◽  
pp. 739-740
Author(s):  
Daiki SHIOZAWA ◽  
Yoshikazu NAKAI ◽  
Masaki YOKOTA ◽  
Norihiro TERAMOTO
Keyword(s):  
Fatigue Damage ◽  
Damage Evaluation ◽  
Fatigue Process

Thermographic Determination of Fatigue Damage

1978 ◽  
Vol 100 (2) ◽  
pp. 200-203 ◽  
Author(s):  
J. A. Charles ◽  
F. J. Appl ◽  
J. E. Francis
Keyword(s):  
Fatigue Life ◽  
Mild Steel ◽  
Surface Temperature ◽  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Temperature Distributions ◽  
Fatigue Failures

The energy released due to hysteresis effects in cyclically loaded materials can be used to predict where fatigue cracks are likely to initiate and to determine the stage of fatigue life. In the present study, thermography is used to monitor the surface temperature distributions on a series of double-notched, mild steel fatigue specimens cyclically loaded in bending. The results indicate that the fatigue life of the material encompasses three thermal stages, each of which is indicative of the fatigue damage the material has sustained. This information can be used to avoid in-service fatigue failures.

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