scholarly journals Effect of micro-notches on fatigue strength of electrodeposited nanocrystalline nickel thin films

2018 ◽  
Vol 165 ◽  
pp. 04011
Author(s):  
Keisuke Tanaka ◽  
Yuta Murase ◽  
Hirohisa Kimachi
Keyword(s):  
Thin Films ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
Stress Ratio ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Fine Grained ◽  
Nickel Thin Films ◽  
Nano Crystalline ◽  
Fictitious Crack

The effect of micro-notches on the fatigue strength of nickel thin films was studied. Two types of thin films with 10 μm thickness were produced by electrodeposition using sulfamate solution without and with brightener: ultra-fine grained film (UFG) with the grain size of 384 nm and nano-crystalline grained film (NCG) with that of 17 nm. Micro-sized notches introduced by FIB had the width of 2 μm and various depths from 8 to 150μm. Fatigue tests were conducted under the stress ratio of 0.1. The fatigue strength decreased with increasing depth of notches. NCG had much higher strength than UFG compared at the same notch depth. Notches as small as 8μm did reduce the fatigue strength of both UFG and NCG. The fatigue limit was controlled by the initiation of cracks and no non-propagating crack was observed in specimens fatigued below the fatigue limit. A model of fictitious crack successfully predicted the reduction of the fatigue limit due to micro-notches. The characteristic crack length of NCG was much smaller than the UFG, while the fatigue strength of defect-free NCG was larger than that of UFG. SEM observation of fracture surfaces was conducted to reveal micromechanisms of fatigue crack initiation.

Effect of Grain Size on Mechanical Properties and Fatigue Strength of Nano-Crystalline Nickel Thin Films

2016 ◽  
Vol 2016 (0) ◽  
pp. OS02-01
Author(s):  
Yuta NAKATSUKA ◽  
Hiroyuki ENOMOTO ◽  
Ryota TAKESHIGE ◽  
Yoshikazu NAKAI ◽  
Shoichi KIKUCHI
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Grain Size ◽  
Fatigue Strength ◽  
Nickel Thin Films ◽  
Nano Crystalline

Influence of Inner Surface Defects on the Fatigue Strength of Pipe Subjected to Cyclic Internal Pressure

1978 ◽  
Vol 100 (4) ◽  
pp. 360-368
Author(s):  
Y. Yazaki ◽  
S. Hashirizaki ◽  
S. Nishida ◽  
C. Urashima
Keyword(s):  
Fatigue Strength ◽  
Internal Pressure ◽  
Test Specimen ◽  
Surface Defects ◽  
Fatigue Crack Initiation ◽  
Internal Surface ◽  
Fatigue Tests ◽  
Inner Surface ◽  
Surface Notch ◽  
Medium Diameter

Cyclic internal oil pressure fatigue tests were carried out on medium-diameter ERW pipes of API 5LX - X60 in an attempt to determine the influence of surface defects on the fatigue strength. Experimental factors investigated were the depth and location of internal surface notch in relation to the axis of pipe. The specimen was subjected to cyclic internal pressure, the cyclic rate being 0.3–0.5 Hz. During the test, Acoustic Emission (AE) techniques were applied to detect the fatigue crack initiation. Along with the aforementioned fatigue tests, pulsating tension fatigue tests were carried out on specimens with the same surface notches as the cyclic internal pressure fatigue test specimen.

Effect of Processing Layer on Fatigue Strength of Extruded AZ61 Magnesium Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 429-432 ◽  
Author(s):  
Yukio Miyashita ◽  
Kyohei Kushihata ◽  
Toshifumi Kakiuchi ◽  
Mitsuhiro Kiyohara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloy ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Crack Growth Resistance ◽  
Az61 Magnesium Alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

FATIGUE TEST OF STEEL GIRDER WEB PENETRATION DETAILS WITH A SLIT

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Naoto Yoshida ◽  
Masahiro Sakano ◽  
Hideyuki Konishi ◽  
Takashi Fujii
Keyword(s):  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Fatigue Cracking ◽  
Highway Bridges ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Bottom Surface ◽  
Steel Girder ◽  
Propagation Behavior

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. A one-meter-long crack was detected in Yamazoe Bridge in 2006. Since a number of highway bridges with such web penetration details may exist in Japan, it is of urgent importance to understand these fatigue-strength properties. However, few fatigue tests have been reported on steel girder web penetration details. The purpose of this study is to clarify fatigue behavior of steel girder web penetration details with a slit through fatigue tests of specimens with these details. We designed and fabricated girder specimens that have steel girder web penetration details, in which cross-beam bottom flanges are connected to each top or bottom surface of a slit by welding. First, we conducted static loading tests to understand the stress distributions around web penetration details. Second, we conducted fatigue tests to examine fatigue crack initiation and propagation behavior and fatigue strength.

Effects of Residual Stresses on the High Cycle Fatigue Behavior of Ti-6Al-4V

2010 ◽  
Author(s):  
Yu-Jia Li ◽  
Fu-Zhen Xuan ◽  
Zheng-Dong Wang ◽  
Shan-Tung Tu
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Stress Ratio ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Manufacturing Techniques ◽  
Stress Ratios ◽  
Effect Of Surface

Axial force-controlled fatigue tests are conducted at various stress ratios (R) on Ti-6Al-4V specimens prepared by two different manufacturing techniques (hard turning plus polishing with and without vacuum stress relieve anneal carried out after polishing). Residual stress is measured by using X-ray diffraction. Results indicate that the surface compressive residual stress lead to an increase of fatigue limit at a given life and stress ratio. This effect decreases with increasing stress ratio R. At R = 0.6, the effect of surface residual stress on fatigue limit fades away. In addition, the location of crack initiation shifts from surface to interior when the stress ratio changes from −1 to 0.6.

scholarly journals OS0727 Fatigue Properties of Electrodeposited Nano-crystalline Nickel Thin Films

2009 ◽  
Vol 2009 (0) ◽  
pp. 523-525
Author(s):  
Hiroaki ASANO ◽  
Yuki ISOGAWA ◽  
Keisuke TANAKA ◽  
Hirohisa KIMACHI
Keyword(s):  
Thin Films ◽  
Fatigue Properties ◽  
Nickel Thin Films ◽  
Nano Crystalline

High Cycle Fatigue of Ti-6Al-4V Alloy in Simulated Steam Environment

2015 ◽  
Author(s):  
Yu-Jia Li ◽  
Lin-Bo Mei ◽  
Fu-Zhen Xuan
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Stress Ratio ◽  
Fatigue Crack Initiation ◽  
Saturated Steam ◽  
Fracture Mechanisms ◽  
Low Oxygen ◽  
Critical Problems ◽  
Stress Ratios ◽  
Corrosion Pits

Fatigue life and reliability are the critical problems for long blades design due to complicated stress state, wet steam and aggressive environment. In this report, the effects of stress ratio, surface properties, steam, and sodium-chloride (NaCl) aqueous environments on the fatigue strength and fracture mechanisms of Ti-6Al-4V alloy have been investigated. Results indicate that residual compressive stress decreases and vanishes finally with increasing stress ratio. Compared to fatigue crack originating from surface for annealed specimens, the fatigue crack initiation sites are located in the interior of the specimen due to the effect of residual stress when low stress ratios are present. Fatigue experiments have been performed in saturated steam with low oxygen content at 100°C and NaCl aqueous at 80 °C. Results indicate that, for 0.1 stress ratio loading conditions, steam environment demonstrates the most serious effect on the endurance limit with 12.3% reduction of fatigue strength. NaCl aqueous leads to the 9.6% drop in fatigue strength corresponding to 107 cycles of design life. For all corrosion environments, cracks originated from the surface and no corrosion pits were observed.

Effect of Water Jet and Electroerosion Cutting on Fatigue Strength of Thick Al-Alloy Sheet

2010 ◽  
Vol 636-637 ◽  
pp. 1525-1530 ◽  
Author(s):  
Ivo Černý ◽  
Dagmar Mikulová
Keyword(s):  
Fatigue Strength ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Alloy Sheet ◽  
Water Jet ◽  
Al Alloy ◽  
Water Jet Cutting ◽  
Deterioration Effect ◽  
Point Bend

Results of an experimental investigation of effects of two advanced technologies for materials cutting, namely water-jet and electroerosive cutting, respectively, are described. Water jet cutting, with abrasive particles and specific parameters, and electroerosive cutting were applied to an aircraft Al-alloy sheet Al 2124 T851 of a considerable thickness, namely 50.8 mm. Reference batch of specimens was manufactured using fine finishing milling. Surface quality of each of the cutting and machining technologies was evaluated and fatigue strength was investigated. Three point bend fatigue tests performed at constant stress amplitude showed a considerable deterioration effect of both technologies on fatigue strength. The damaging effect of both technologies was comparable. Fractographical analysis using scanning electron microscopy (SEM) showed fatigue crack initiation in numerous surface micro-notches occurring as a result of the cutting. In addition, the crack initiation was frequently accelerated by surface or subsurface fairly large particles of intermetallic phases. This mechanism also occurred with milling specimens.

Effect of Stress Ratio and Loading Mode on High Cycle Fatigue Properties of Extruded Magnesium Alloys

2014 ◽  
Vol 891-892 ◽  
pp. 557-562
Author(s):  
Kazuaki Shiozawa ◽  
Atsushi Ikeda ◽  
Tsuyoshi Fukumori
Keyword(s):  
Magnesium Alloys ◽  
Stress Ratio ◽  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Fatigue Crack Initiation ◽  
High Stress ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Loading Mode ◽  
Amplitude Level

The aim of this study is to discuss an effect of stress ratio and loading mode on high cycle fatigue performances of extruded magnesium alloys. Axial loading fatigue tests under three conditions of stress ratio, R, of 0, -1 and-1.5, and also rotating bending fatigue tests have been performed in laboratory air at room temperature using hourglass shaped specimens of AZ31, AZ61, AZ80 and T5-treated AZ80 alloy. From the experimental results, some materials showed a specific stepwise S-N curve on which two knees appear. The shape of S-N diagram depended on a kind of tested materials, applied stress ratio and loading mode. It was suggested from the detail observation of fracture surface that fatigue crack initiation mechanism changed from a twin-induced failure mode at high stress amplitude level to a slip-induced one at low stress amplitude level. This transition was determined with the relation between the minimum stress during a fatigue cycle and the compressive yield stress at which deformation twin occurs.

Research of Fatigue Limit and Stress Concentration on Structural Steel with Double-Notches

2009 ◽  
Vol 419-420 ◽  
pp. 849-852
Author(s):  
Sheng Wu Wang ◽  
Shu Juan Sun ◽  
Ai Ling Wen ◽  
Wei Da Wang ◽  
Shinichi Nishida
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Strength ◽  
Stress Concentration ◽  
Fatigue Limit ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Notched Specimen ◽  
Blind Hole ◽  
Element Method

The fatigue limit of parts and components that have the multi-notches is important data for the design and manufacture of machinery and traffic equipment which are operated under the high speed or pressure. In this paper the rotating bending fatigue tests have been carried out to investigate the fatigue limit of specimen with double-notch that is constructed of step and blind hole, and analyzed the effect of stress concentrations at the double-notched bottoms on the fatigue limits, using three-dimensional elastic finite element method. Firstly, the fatigue tests of 8 group specimens have been performed for examining the of fatigue limits of the single-notched specimen and double-notched specimen, respectively. Additionally, the stress field interactions between two stress fields by the blind hole notch and step are discussed using three-dimensional elastic finite element method. The main results obtained in this study are as follows: The fatigue limit of the double-notched specimen are down comparison with the fatigue limit of the single-notched specimen; the fatigue limit of the double-notch specimen is insensitive to distance between the blind hole and step for the low carbon structure steel with better ductility; for the high-strength steel, superposition and intensification of the stress concentration by the blind hole and step mutually may be avoided so that their adverse effects on the fatigue strength may be become to minimize, as take appropriate distance between the blind hole and step. The results are significant for the design of engineering design of the multi-notched parts, and the study of fatigue strength.

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