scholarly journals Fatigue Property of Additively Manufactured Ti-6Al-4V under Non-proportional Multiaxial Loading

2021 ◽  
Author(s):  
Yuya Kimura ◽  
Fumio Ogawa ◽  
Takamoto Itoh
Keyword(s):  
Fatigue Strength ◽  
Crack Propagation ◽  
Strain Path ◽  
Low Cycle Fatigue ◽  
Fatigue Property ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Multiaxial Loading ◽  
Proportional Loading ◽  
Strain Paths

Abstract Low cycle fatigue strength properties of additively manufactured Ti-6Al-4V alloy were experimentally investigated under proportional and non-proportional multiaxial loading. Fatigue tests have been conducted by means of hollow cylinder specimens with and without heat treatments, at room temperature in air. Fatigue tests with proportional loading represented by a push-pull strain path and non-proportional loading represented by a circle strain path were conducted, respectively. The fatigue lives of additively manufactured specimens were drastically reduced obviously by internal voids and defects in comparison with the specimens used in the previous study [1]. In addition, the defect size is measured, and the defect does not cause fatigue strength reduction above some size. The fracture surface was observed using SEM to investigate fracture mechanism of additively manufactured specimens under two types of strain path. Different fracture patterns are recognized for the two strain paths; however, both showed the retention of the crack propagation in spite of the presence of numerous defects. The crack propagation properties of the materials with numerous defects under non-proportional multiaxial loading were elucidated to increase the reliability of additive manufactured components.

Low Cycle Fatigue Life of Type 316 Stainless Steel Notched Specimen Under Proportional and Non-Proportional Multiaxial Loadings

2010 ◽  
Author(s):  
Takamoto Itoh
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Strain Path ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Notched Specimen ◽  
Life Estimation ◽  
316 Stainless Steel ◽  
Strain Parameter ◽  
Strain Paths

This study discusses multiaxial low cycle fatigue life of notched specimen under proportional and non-proportional loadings at room temperature. Strain controlled multiaxial low cycle fatigue tests were carried out using smooth and circumferentially notched round-bar specimens of type 316 stainless steel. Four kinds of notched specimens were employed of which elastic stress concentration factors, Kt, are 1.5, 2.5, 4.2 and 6.0. The strain paths include proportional and non-proportional loadings. The former employed a push-pull straining or a reversed torsion straining. The latter was achieved by strain path where axial and shear strains has 90 degree phase difference but their amplitudes is the same based on von Mises’ criterion. The notch dependency of multiaxial low cycle fatigue life and the life estimation are discussed. The lives depend on both Kt and strain path. The strain parameter for the life estimation is also discussed with the non-proportional strain parameter proposed by the author with introducing Kt. The proposed parameter gives a satisfactory correlation with multiaxial low cycle fatigue life of notched specimen of type 316 stainless steel under proportional and non-proportional loadings.

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.

THREE FACE ATTACHMENT RETROFIT AGAINST FATIGUE CRACKING AT STEEL GIRDER WEB PENETRATION

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Chihiro Sakamoto ◽  
Masahiro Sakano ◽  
Hideyuki Konishi ◽  
Takashi Fujii
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Stress Reduction ◽  
Fatigue Cracking ◽  
Highway Bridges ◽  
Lower Surface ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Lower Side ◽  
Steel Girder

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties. In this study, we investigate stress reduction effects of three face attachment retrofit through fatigue tests using a large girder specimen with web penetration details where cross beam lower flanges are connected to the lower surface of a slot by welding. As a result, there is very little difference between two and three face attachments about stress reduction effects, while they are more effective than one face attachment. The upper side attachment is more effective than the lower side attachment, while both side attachment is best. Two and three face both side attachments can reduce about 40% of stress concentration, while two and three face upper side attachments can reduce 50– 60%.

Modification of Plasma Spurt Spraying on Improving Fatigue Property of Welded Joint

2014 ◽  
Vol 556-562 ◽  
pp. 494-497
Author(s):  
Xiao Hui Zhao ◽  
Yu Liu
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Welded Joint ◽  
Base Alloy ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Test Results ◽  
Residual Stress Field ◽  
Modification Method ◽  
Nickel Base

The present paper introduces a modification method of welded joint, plasma spurt spraying (MPSS), for improving the fatigue life of welding structure. Nickel-base alloy powder was used to spray the welded joint of Q235B steel. The high cycle fatigue tests of specimens treated by MPSS were carried out to obtain the S-N curves. Meanwhile, numerical simulation was performed to obtain the residual stress field after spraying. Test results show that the fatigue strength of welded joint by MPSS is higher than that of as-welded joint. Based on the test results and simulation results, it can be concluded that MPSS improves fatigue strength mainly through the decrease of stress concentration and residual stress.

SEM Study of Fatigue Crack Propagation in Chromium Martensitic Steel after LCF

2017 ◽  
Vol 754 ◽  
pp. 15-18 ◽  
Author(s):  
Tamaz Eterashvili ◽  
G. Abuladze ◽  
L. Kotiashvili ◽  
T. Dzigrashvili ◽  
M. Vardosanidze
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Low Cycle Fatigue ◽  
Experimental Studies ◽  
Complex Problem ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Sem Study ◽  
Deformation Tests ◽  
Microstructure Of The Material

Crack propagation after low-cycle fatigue (LCF) deformation has been studied in the chromium martensitic structural steel. Although the study of a fundamental mechanism of fatigue crack growth has received much attention over the last decade, it still remains a sufficiently complex problem and needs full understanding. Moreover, the recent studies show that the cracks propagate discontinuously even on the millisecond timescale, and their growth rate significantly depends on a microstructure of the material. In the present work the boundaries of the former austenitic grains were revealed on the polished surfaces of the thermally treated samples, which subsequently were undergone low-cycle fatigue tests. The experimental studies show that fatigue macrocracks mainly grow along the boundaries of the former austenitic grains, and changetheir propagation direction when crossing the grain boundary, however, remain within 45 ̊ interval with regard the cycling axis. In particular cases, when the boundaries of a martensite packets and those of the former austenite grains lay along the length of a packet, the macrocrack is better formed and with regular borders. After a macrocrack reaches a definite length ~30-50μ, a microcrack is nucleated ahead of the macrocrack tip, and is oriented along the substructure element of the steel. Further deformation tests provide an increase in the length of the main crack via aggregation of microcracks initiated ahead of it during the LCF. In the cases when the macrocrack is deviated, slip bands are formed in martensitic structures along the boundaries of martensite packets (laths). A correlation is revealed between the microcrack components and the substructure elements of the steel as well. The same results were obtained by fractography of the tested and fractured samples. However, in the latter case correlation was established between the cleavage facets and the dimensions of packets.

S031021 A Study on Low Cycle Fatigue Strength Properties of Lead Free Solder Materials

2011 ◽  
Vol 2011 (0) ◽  
pp. _S031021-1-_S031021-3
Author(s):  
Syungo SATAKE ◽  
Takashi KAWAKAMI ◽  
Takahiro KINOSHITA ◽  
Hiroyuki KOBAYASHI ◽  
Tetsuya KUGIMIYA ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Low Cycle Fatigue ◽  
Strength Properties ◽  
Lead Free ◽  
Lead Free Solder ◽  
Cycle Fatigue ◽  
Free Solder

Effect of Non-Proportional Loading on Fatigue Crack Initiation and Growth Behavior of Maraging Steel

2012 ◽  
Author(s):  
Hiroshi Nakamura ◽  
Masahiro Takanashi ◽  
Tatsuya Masaki ◽  
Shengde Zhang ◽  
Masao Sakane
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Maraging Steel ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Shear Loading ◽  
Uniaxial Loading ◽  
Strain Intensity ◽  
Proportional Loading

This paper deals with multiaxial low cycle fatigue (LCF) crack behavior of maraging steel under non-proportional loading. Strain controlled LCF tests under proportional and non-proportional loading with 90° out-of-phase shift between the axial and shear strains were carried out on tube specimens at room temperature. In the correlation with Mises strain, LCF lives under non-proportional loading were underestimated by a factor of 10 from those under proportional loading. Observation of the specimen surface during fatigue tests showed that a large number of cracks were initiated in shear loading and non-proportional loading compared with uniaxial loading. Finite element analyses for estimating the stress concentration around inclusions revealed that the inclusion under shear loading and non-proportional loading had more locations to initiate cracks than the inclusion under uniaxial loading. The crack initiation life under proportional loading did not significantly differ from that under non-proportional loading. Fatigue cracks under non-proportional loading, however, propagated faster than those under proportional loading. The faster fatigue crack propagation under nonproportional loading presumably results from higher strain intensity at crack tips than that under proportional loading. The fatigue lives were predicted from the crack propagation analysis. Most calculated lives were within a factor of 2 scatter band so that the correlation of the test results appears satisfactory. Therefore, the main cause of shorter fatigue life under non-proportional loading resulted from the faster crack growth due to the higher strain intensity.

Fatigue resistance of Fe3Al-based alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Florian Gang ◽  
Manja Krüger ◽  
Alexandra Laskowsky ◽  
Heike Rühe ◽  
Joachim H. Schneibel ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Iron Aluminide ◽  
Cycle Fatigue ◽  
Grain Sizes ◽  
Cast Alloys

ABSTRACTThe low cycle fatigue (LCF) behaviour of two cast as well as two hot extruded Fe3Al-based iron aluminide alloys, either with or without Cr, is investigated. All four alloys contain microalloying additions of Zr, Nb, C and B. Fatigue tests were carried out under strain control for strain amplitudes in the range of εa = 0.1 – 0.4 % for the cast alloys and εa = 0.1 – 0.7 % for the extruded materials, at frequencies of 1 Hz (extruded Fe3Al) and 3 Hz (all other alloys) and at room temperature and 300 °C. Within the first cycles all alloys show strong cyclic hardening. Furthermore the fatigue strain – fatigue life curves are steeper at 300 °C than at room temperature, showing increased fatigue strength at low cycle numbers due to increasing ductility and decreased fatigue strength at increasing cycle numbers because of reduced yield strength. Cr is found to have only a negligible influence on the fatigue behaviour of Fe3Al-based alloys. Comparison between the differently processed materials shows superior LCF properties of the hot extruded iron aluminides due to significantly smaller grain sizes.

Influence Analysis of Multifactor on LCF Damage of Single Crystal Nickel-Based Superalloy under Multiaxial Non-Proportional Loading

2010 ◽  
Vol 139-141 ◽  
pp. 198-204
Author(s):  
Zhi Ping Ding ◽  
Ji Ping Chen ◽  
Teng Fei Wang ◽  
Ming Li
Keyword(s):  
Single Crystal ◽  
Fatigue Damage ◽  
Phase Angle ◽  
Strain Path ◽  
Biaxial Tension ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cycle Fatigue ◽  
Nickel Based Superalloy ◽  
Strain Paths

A formula of equivalent strain for FCC single crystal superalloy was derived based on Hill’s yield criterion and was used for design of biaxial tension-torsion strain paths and loading levels of specimens. biaxial tension-torsion non-proportional cyclic loading process for single crystal nickel-based superalloy at the temperature of 680°C and 850°C was simulated by FEM analyzes; and influence degree of factors, such as strain range, strain path angle, tension-torsion loading phase angle, cycle characteristics and temperature etc., to low cycle fatigue damage of single crystal nickel-based superalloy were analyzed by using analysis of variance based on orthogonal experiments. The results show that if Hill’s equivalent stress range is used as a fatigue damage parameter, the factors produce effects on low cycle fatigue damage of single crystal nickel-based superalloy. The factors are listed in the order of significance as followed: temperature, strain range, tension-torsion loading phase angle, strain path angle and axial loading strain ratio.

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