scholarly journals Proposal of Fatigue Limit Design Curves for Additively Manufactured Ti-6Al-4V in a VHCF Regime Using Specimens with Artificial Defects

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 964
Author(s):  
Yoshihiko Uematsu ◽  
Toshifumi Kakiuchi ◽  
Yaodong Han ◽  
Masaki Nakajima
Keyword(s):  
Fatigue Limit ◽  
High Cycle Fatigue ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Design Curve ◽  
Very High Cycle Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
The Relationship ◽  
Very High

Cantilever-type rotating bending fatigue tests were conducted under a very high cycle fatigue regime using conventionally manufactured Ti-6Al-4V specimens having drilled artificial defects with different sizes. The relationship between fatigue limit and defect size was defined as a fatigue limit design curve considering the transition from the fracture-mechanics dominating area to the fatigue-limit dominating area. A conventional Murakami’s equation was applicable as a design curve of additively manufactured Ti-6Al-4V with defects at 107 cycles. However, conventional equation gave un-conservative predictions for the fatigue limit at 108 cycles. Therefore, two kinds of modified Murakami’s equation were proposed as fatigue limit design curves for the very high cycle fatigue regime. Simple parallel shift of Murakami’s equation gave a conservative fatigue limit, whilst better result was obtained by changing the slope of Murakami’s equation. The proposed design curve was valid for the defect sizes ranging from 10 to 500 μm.

Effect of shot peening on very high cycle fatigue of 2024-T351 aluminium alloy

2020 ◽  
Vol 10 (7) ◽  
pp. 1032-1039
Author(s):  
Renhui Tian ◽  
Jiangfeng Dong ◽  
Yongjie Liu ◽  
Qingyuan Wang ◽  
Yunrong Luo
Keyword(s):  
Fracture Surface ◽  
Crack Initiation ◽  
Shot Peening ◽  
High Cycle Fatigue ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Fatigue Strength Improvement ◽  
Ultrasonic Fatigue ◽  
Very High

To investigate the influence of shot peening (SP) on very high cycle fatigue (VHCF) performance of 2024-T351, the specimens with three surface conditions were performed under ultrasonic fatigue tests: mechanicallypolished without peening (NP), ceramic shot peening (SP1), steel and glass mixed shot peening (SP2). The roughness, microhardness, residual stress, fractography measurement and scanning electron microscopy (SEM) were applied before fatigue test to characterize the effective layer induced by the peening treatment. For the failed specimens, the fracture surface were analysed using SEM to study the mechanisms of fatigue crack propagation. In addition, the fatigue life curve in ultra-high cycle region continuously decreased in the three series of specimens. However, the experimental results revealed that fatigue strength improvement resulting from shot peening treatment was negligible in very high cycle regime. Furthermore, the stress intensity factor for the surface crack initiation (SCI) and interior crack initiation (ICI) was discussed based on quantitative analysis on the fracture surface. The average values of ΔKfish-eye for NP, SP1 and SP2 specimens are about 2.22, 1.48 and 1.61 MPa · m1/2, respectively.

S0305-5-4 A Study on Very High Cycle Fatigue Property of Magnesium Alloy in Rotating Bending and Axial Loading

2010 ◽  
Vol 2010.1 (0) ◽  
pp. 165-166
Author(s):  
Noriyuki NINOMIYA ◽  
Yosuke NAKAMORI ◽  
Tatsuo SAKAI ◽  
Shoichi KIKUCHI ◽  
Yuki NAKAMURA ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
High Cycle Fatigue ◽  
Axial Loading ◽  
Fatigue Property ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Rotating Bending ◽  
Very High

OS1605 A Study on Very High Cycle Fatigue Properties of Zr-base Bulk Amorphous Alloy in Rotating Bending

2012 ◽  
Vol 2012 (0) ◽  
pp. _OS1605-1_-_OS1605-2_
Author(s):  
Shoichi KIKUCHI ◽  
Yanbin ZHANG ◽  
Tatsuo SAKAI ◽  
Akira UENO ◽  
Yoshihiko YOKOYAMA ◽  
...  
Keyword(s):  
Amorphous Alloy ◽  
High Cycle Fatigue ◽  
Fatigue Properties ◽  
Bulk Amorphous Alloy ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Rotating Bending ◽  
Very High

Period of Fine Granular Area Formation of Bearing Steel in Very High Cycle Fatigue Regime

2014 ◽  
Vol 891-892 ◽  
pp. 434-439 ◽  
Author(s):  
Noriyasu Oguma ◽  
Naoya Sekisugi ◽  
Katsuyuki Kida ◽  
Yasuhiro Odake ◽  
Tatsuo Sakai
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
High Cycle Fatigue ◽  
Bearing Steel ◽  
Cumulative Damage ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Rotating Bending ◽  
Very High

In order to examine the period of fine granular area (FGA) formation of bearing steel in very high cycle fatigue regime, rotating bending fatigue tests were carried out at the stress amplitude 1100 MPa below the fatigue limit. The tests were interrupted at the cumulative damage values ranging from 0.1 to 0.5 with an increment of 0.1 to charge hydrogen to the specimens. After the charge, the rotating bending tests were continuously carried out. The crack origin areas on all fracture surfaces were checked by a scanning electron microscope (SEM), and it was discovered that FGA was not formed in some of them. From a view point of fracture mechanics, the stress intensity factor ranges of FGA areas, ΔKFGA, were calculated by using Murakamis area model. The ΔKFGA values increase with the increase of the cumulative damage values. Furthermore, ΔKFGA values in this study were smaller than 5 MPam which was obtained from usual fatigue testing. Therefore, we conclude that the stable crack growth stage starts when the threshold stress intensity factor range decreases due to hydrogen embrittlement in the middle of formation of FGA.

scholarly journals Energy Dissipation in Very High Cycle Fatigue for Polycrystalline Pure Copper and Armco Iron

2015 ◽  
Vol 664 ◽  
pp. 33-46
Author(s):  
Antoine Blanche ◽  
Chong Wang ◽  
Ngoc Lam Phung ◽  
Nicolas Ranc ◽  
Véronique Favier ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Armco Iron ◽  
Pure Copper ◽  
Fatigue Tests ◽  
Crystallographic Structure ◽  
Loading Frequency ◽  
Face Centered Cubic ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

This paper aims at a deeper understanding of microplastic mechanisms leading to crack initiation in ductile metals in Very High Cycle Fatigue (VHCF). Fatigue tests were conducted using an ultrasonic technique at loading frequency of 20 kHz. The microplastic mechanisms are revealed via observations of slip markings at the specimen surface and self-heating measurements due to intrinsic dissipation. Pure copper and Armco iron (which contains a very low amount of carbon) were investigated. Both are single-phase ductile materials but the crystallographic structure of copper is face-centered cubic while it is body centered cubic for Armco iron. A good correlation was found between slip markings initiation and dissipation for both materials. The dissipation for both materials is of the same order of magnitude but the location, the morphology and the evolution over cycles of slip markings were found different.

scholarly journals Effect of Carburizing and Nitriding on Fatigue Properties of 18Cr2Ni4WA Steel in Very High Cycle Fatigue Regime

2021 ◽  
Vol 45 (3) ◽  
pp. 207-215
Author(s):  
Zhenduo Sun ◽  
Dongbo Hou ◽  
Wei Li
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Internal Defect ◽  
Surface Fatigue ◽  
Very High Cycle Fatigue ◽  
The Relationship ◽  
Very High

The work aims to study the influence of carburizing and nitriding on fatigue properties of 18Cr2Ni4WA high strength steel in very high cycle fatigue regime. Very high cycle fatigue tests were carried out on 18Cr2Ni4WA Steel after carburizing and nitriding respectively. The micro morphology of fatigue fracture was observed by scanning electron microscope, the failure mode and failure mechanism were discussed. The relationship between fatigue life and defect size, FGA size, fish eye size of fracture was analyzed. The characteristic size of defects is evaluated by Gumbel, Weibull and GEV distribution functions, and a modified Akiniwa fatigue life prediction model considering the relationship between FGA size and inclusion size was established. The results showed that, nitriding and carburizing treatment improve the surface fatigue limit of the steel. The fatigue life decreases with the increase of internal defect size and FGA size. After carburizing and nitriding treatment, the internal fatigue strength of the specimen decreases slightly. When the failure probability is 99%, the internal defect sizes of nitrided specimens calculated by Weibull, Gumbel and GEV distributions are 141.5 μm, 148.4 μm and 211.7 μm respectively. The calculated internal defect sizes of carburized specimens are 47 μm, 67.8 μm and 40 μm respectively. Compared with the experimental data, the fatigue strength predicted by GEV is the most appropriate. carburizing and nitriding treatment can improve the surface fatigue strength of 18Cr2Ni4WA steel, but slightly reduce the internal fatigue strength. The prediction result of the new model is conservative when the failure probability is 99%, which is suitable for engineering application.

OS1510 Statistical Analysis of Very High Cycle Fatigue Property of High Carbon Chromium Bearing Steel in Rotating Bending

2008 ◽  
Vol 2008 (0) ◽  
pp. _OS1510-1_-_OS1510-2_ ◽  
Author(s):  
Benning Lian ◽  
Tatsuo Sakai ◽  
Mitsuhiro Takeda ◽  
Kazuaki Shiozawa ◽  
Noriyasu Oguma ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
High Cycle Fatigue ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Cycle Fatigue ◽  
High Carbon ◽  
Very High Cycle Fatigue ◽  
Rotating Bending ◽  
Very High
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