Parametric Damage of Concrete under High-Cycle Fatigue Loading in Compression

2016 ◽  
Author(s):  
Benard Isojeh ◽  
Frank Vecchio
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Cycle Fatigue

PSBs and Non-Propagation of Small Surface and Interior Cracks in Polycrystalline Copper

2013 ◽  
Vol 592-593 ◽  
pp. 777-780 ◽  
Author(s):  
Stefanie E. Stanzl-Tschegg ◽  
Bernd M. Schönbauer
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Lower Stress ◽  
Small Surface ◽  
Loading Method ◽  
Very High Cycle Fatigue ◽  
Small Cracks ◽  
Number Of Cycles ◽  
Very High

PSB formation and its relevance for an eventual fatigue limit of polycrystalline electrolytic copper was studied in the very-high cycle fatigue regime with the ultrasound fatigue loading method. PSBs are formed at much lower stress/strain amplitudes than reported in earlier literature, if a high enough number of cycles is applied. Fatigue fracture takes place at approximately 50% higher amplitudes than needed for PSB formation, which is likewise in contrast to former literature results. Non-propagation of small cracks, originating from intrusions or PSB-induced non-propagating grain-boundary cracks are made responsible for this different material response.

scholarly journals Process Induced Residual Stress Effect on Fatigue Lifetime of Automotive Steel Components

2014 ◽  
Vol 996 ◽  
pp. 808-813
Author(s):  
Elias Merhy ◽  
Ngadia Taha Niane ◽  
Bastien Weber ◽  
Philippe Bristiel
Keyword(s):  
Residual Stress ◽  
Heat Affected Zone ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Welding Process ◽  
Fatigue Loading ◽  
Stress Effect ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Fatigue Lifetime

Metal Active Gas (MAG) welding process of steel sheets generates, in the vicinity of the welding joint, the well-known Heat Affected Zone (HAZ) in which the material presents more microstructural defects compared to the original metal. Since high cycle fatigue is largely dependent on the material microstructure features, the HAZ is considered as the weakest zone under high cycle fatigue loading. In addition, the welding causes, in the Heat Affected Zone, irreversible plastic strains that induce important residual stress fields in this critical zone of the structure. Therefore, in order to properly predict the high cycle fatigue life time of the welded automotive components, it is of primordial importance to first identify and then consider, if necessary, the welding induced residual stress field in the structure modeling. In this work, it is found that residual stresses have non-negligible impact on high cycle fatigue lifetime, while its effect is minor in the low cycle fatigue domain.

Vibration of High-Speed Spur Gear Webs

1998 ◽  
Vol 120 (3) ◽  
pp. 791-800 ◽  
Author(s):  
N. K. Arakere ◽  
C. Nataraj
Keyword(s):  
Weight Reduction ◽  
High Speed ◽  
High Cycle Fatigue ◽  
Equations Of Motion ◽  
Fatigue Loading ◽  
Periodic Variation ◽  
Cycle Fatigue ◽  
Periodic Excitation ◽  
Mesh Stiffness ◽  
Plane Vibration

High cycle fatigue loading of gear webs due to in-plane stresses, caused by forced excitation resulting from centrifugal loading and dynamic tooth loads, has been known to cause radial fatigue cracks. This is especially prevalent in high-speed gears used in aerospace applications, with small web thickness, for weight reduction. Radial cracks have also been observed to originate at the outer edge of lightening holes machined in gear webs for weight reduction. This paper presents an analytical treatment of the in-plane vibration of high-speed gear webs resulting from rotational effects and periodic excitation from dynamic tooth loading. Dynamic tooth loads result from the combined effect of inertia forces of gear wheels which are significant at high speeds, the periodic variation of gear mesh stiffness, and involute tooth profile errors. The gear web is modeled as a thin rotating disc and the governing differential equations of motion and the associated boundary conditions are derived from first principles. The equations are then nondimensionalized which leads to some essential nondimensional parameters. A comprehensive tooth stiffness model for spur gears is used that accounts for periodic variation of mesh stiffness. The dynamic tooth loads are obtained by solving the pertinent equations of motion, using a collocation method, that yields a closed-form expression for the periodic excitation, that is used as an input for the in-plane vibration problem. The in-plane vibration equations are solved by an approximate method of weighted residuals. It is found that the displacement fields and the resulting stresses can be significant under certain speeds and loading conditions. The interaction between the forcing frequencies due to gear teeth dynamics and the in-plane vibration natural frequencies can result in resonances that induce high fatigue stresses in the gear web. The in-plane stresses leading to high cycle fatigue loading, and frequency components of the resulting response are discussed in detail.

scholarly journals Differences in the response to in-phase and out-of-phase multiaxial high-cycle fatigue loading

2019 ◽  
Vol 13 (50) ◽  
pp. 163-183 ◽  
Author(s):  
Jan Papuga ◽  
Martin Nesládek ◽  
Josef Jurenka
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Cycle Fatigue

scholarly journals Mean stress effect under Multi-Axial High Cycle Fatigue loading for cast A356-T6 alloy

2014 ◽  
Vol 12 ◽  
pp. 04025
Author(s):  
M. Iben Houria ◽  
Y. Nadot ◽  
R. Fathallah ◽  
M.J. Roy ◽  
D.M. Maijer
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Stress Effect ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Mean Stress Effect

Study on Continuum Damage Mechanics Model for High Cycle Fatigue

2016 ◽  
Vol 835 ◽  
pp. 564-567
Author(s):  
Xin Tong Shi ◽  
Ying Chun Xiao ◽  
Hong Chen ◽  
Bo Huang
Keyword(s):  
Experimental Data ◽  
Damage Mechanics ◽  
High Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Continuum Damage ◽  
Cycle Fatigue ◽  
Stress Effects ◽  
Mechanics Model ◽  
Proposed Model

A continuum damage mechanics model was proposed to predict the high cycle fatigue life. In order to consider mean stress effects, the Walker correction was introduced in proposed model. The model was verified by experimental data on LC4 and LY12CZ aluminum alloy under high cycle fatigue loading. The results showed that the predicted life of proposed model well correlated with experimental data.

FE Modeling of FRP-Concrete Interface for very High Cycle Fatigue Behavior

2013 ◽  
Vol 577-578 ◽  
pp. 165-168 ◽  
Author(s):  
M. Mahal ◽  
T. Blanksvärd ◽  
B. Täljsten
Keyword(s):  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Three Dimensional ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Finite Element Program ◽  
Element Program ◽  
Three Dimensional Finite Element ◽  
Concrete Interface

The fatigue damage of FRP-concrete interface is a major problem in strengthened structures subjected to fatigue loading. The available FRP-concrete interface models published in the literature usually deal with fracture mechanism approach, which is unsuitable for high cycle fatigue damage. In this study, a constitutive micro model is developed for FRP-concrete interface for high cycle fatigue and incorporated into a three dimensional finite-element program. Numerical analysis of a double lap joint is carried out, and the results show that the proposed model is reasonably accurate.

Elucidation of the High Cycle Fatigue Damage Mechanism of Modified 9Cr-1Mo Steel at Elevated Temperature

2015 ◽  
Author(s):  
Takuya Murakoshi ◽  
Motoyuki Ochi ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Elevated Temperatures ◽  
Surface Hardness ◽  
Diffraction Method ◽  
Fatigue Loading ◽  
Damage Mechanism ◽  
Fatigue Tests ◽  
Electron Back Scatter Diffraction ◽  
Cycle Fatigue

Modified 9Cr-1Mo steel is one of the heat-resistant steels developed for steam generator in a FBR (Fast Breeder Reactor). When it is used in a FBR, the lifetime of the steel under HCF (High Cycle Fatigue) and V-HCF (Very-High Cycle Fatigue) caused by flow-induced vibration has to be considered for assuring its long-term reliability up to 1011 cycles. Since previous studies showed that the fatigue limit did not appear up to 108 cycles, it is necessary to investigate the fatigue strength of this alloy in cycles higher than 108 cycles. In this study, in order to clarify high cycle fatigue strength and fracture mechanism of the modified 9Cr-1Mo steel, the change of the lath martensitic strengthening structure was observed in detail on the surface of specimens fractured by rotary bending fatigue tests by using EBSD (Electron Back-Scatter Diffraction) method. The Kernel Average Misorientation (KAM) value obtained from the EBSD analysis was used for the quantitative evaluation of the change of the lath martensitic texture. It was found that the average KAM values clearly decreased on the surface areas of the fractured specimens after the application of 107-108 cycles of fatigue loading at temperatures higher than 550°C. This result indicates that degradation of the lath martensitic texture occurred around the surface of specimens tested at the temperature higher than 550°C. In order to quantitatively evaluate the decrease of its strength, a hardness test was performed at room temperature by using a nanoindentation method. It was confirmed that the surface hardness of specimens decreased drastically in the specimens fractured at temperatures higher than 550°C. From these results, it was concluded that the effective 0.2%-proof stress decreased during the fatigue tests by the degradation of the lath martensitic texture caused by the fatigue loading at elevated temperatures. Further analyses are indispensable for explicating the damage mechanism more in detail.

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