scholarly journals Study on Fatigue Performance of Non-Uniform Thickness Markless Laser Lap Welding

2021 ◽  
Vol 2101 (1) ◽  
pp. 012009
Author(s):  
Huijuan Song ◽  
Longhua Zhang ◽  
Ke Niu ◽  
Gnativ Marina Petrovna
Keyword(s):  
Fatigue Limit ◽  
Fatigue Fracture ◽  
Plate Thickness ◽  
Fatigue Property ◽  
Fatigue Properties ◽  
Outer Plate ◽  
Welded Structures ◽  
Welded Structure ◽  
Laser Lap Welding ◽  
The Impact

Abstract In this paper fatigue properties of three groups of unequal thickness unmarked overlap laser welding of the external wallboard connected of type A and B vehicle were studied. In addition, a group of overlap penetration welded structures of 1.5mm-301L-HT+0.8mm-301L-DLT is designed to study the impact of penetration rate to the mechanical properties. The influence of the weld geometry and plate combination on fatigue fracture behavior and fatigue property is studied based on the combination of fatigue test and simulation stress analysis. Fatigue studies have shown that in spite of the thickness of the two lap unequal thickness welded plate is disparities -- unmarked non-penetration welding outer plate is thicker but it appears fatigue fracture on the outer plate. The safety fatigue limit of three different non-penetration welded structures of plate combinations and weld structures is close which further proofs that the stress state and microstructure of non-penetration outer plate is not conducive to fatigue fracture. It is consistent with the results of the finite element simulation. The fatigue limit of lap welded structure increase with the increase of plate thickness.

The Effect of Morphology and Distribution of Sulfides on Mechanical Properties and Fatigue Life of Non-Quenched and Tempered Steel

2008 ◽  
Vol 51 ◽  
pp. 11-20
Author(s):  
Ming Tu Ma ◽  
Guo Zhong Li ◽  
Zhi Gang Li ◽  
Hong Zhou Lu
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Fatigue Fracture ◽  
Rolling Direction ◽  
Impact Fracture ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Quenched And Tempered Steel ◽  
The Impact ◽  
Tempered Steel

The effect of morphology and distribution of sulfides on tensile, impact and bending fatigue properties of non-quenched and tempered steel 49MnVS3 has been investigated in this paper. Microscopic structure and morphology of sulfides are observed, and impact fracture and fatigue fracture have been analyzed by SEM. The results show that the morphology of sulfides is mostly strip and distributes in ferrite, which affects mechanical properties and fatigue life. The length direction of sulfide strip is parallel to the rolling direction of steel. When the length of sulfide is short relatively and is approximate to the shape of particles. The impact properties and bending fatigue performance of 49MnVS3 are higher. Under those conditions, there are more ductile characteristics in their impact fracture and the fatigue fracture. The reasons for the effect of sulfide morphology on the mechanical and fatigue properties are explained.

Effect of Scratch Depths on Fatigue Properties of PMMA for Aircraft Canopies

2014 ◽  
Vol 687-691 ◽  
pp. 81-84 ◽  
Author(s):  
Xin Hong Shi ◽  
Mei Juan Shan
Keyword(s):  
Fatigue Limit ◽  
Polymethyl Methacrylate ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Fatigue Properties ◽  
Scratch Depth

A series of fatigue tests is performed for polymethyl methacrylate (PMMA) specimens without scratches and with scratches. The scratch depth is set to be 0.2mm, 0.3mm and 0.4mm, respectively. Based on the experimental results, it can be deduced that contained fatigue limit of specimens with scratches significantly decreases compared to specimens without scratches. Besides, contained fatigue limit decreases gradually with scratch depth increasing from 0.0mm to 0.4mm. Consequently, it can be concluded that fatigue properties of PMMA will decrease when there exists scratch and for scratch depth from 0.0mm to 0.4mm, fatigue property decreases remarkably with deeper scratch.

Calculation about Stress Concentration Coefficient of Welded Cruciform Joints of Magnesium Alloy Based on FEM

2014 ◽  
Vol 989-994 ◽  
pp. 931-934 ◽  
Author(s):  
Bo Lin He ◽  
Ying Xia Yu ◽  
Xiao Dong Zhang ◽  
Song Song Xia
Keyword(s):  
Magnesium Alloy ◽  
Stress Concentration ◽  
Fatigue Property ◽  
Tangent Line ◽  
Concentration Coefficient ◽  
Cruciform Joints ◽  
Welded Structures ◽  
Welded Structure ◽  
Line Angle ◽  
Stress Concentration Coefficient

Geometrical parameters of welded joint affect the stress concentration coefficient seriously. In order to increase the fatigue property of welded structure, it has great significance to reduce stress concentration coefficient of welded structures by researching and improving the geometry of welded joints. In this paper, the effects of weld tangent line angle θ on the stress concentration coefficient of welded cruciform joints of magnesium alloy were analyzed by using ABAQUS finite element program, and the change rule of stress concentration coefficient with the variation of the parameter was also researched. The calculation results indicate that reducing the weld tangent line angle θ can effectively decrease the stress concentration coefficient of welded cruciform joints, so as to improve the fatigue property of welded structures. In order to have high reliability and safety of welded structures of magnesium alloy, the true weld tangent line angle θ should be controlled less than 25°.

scholarly journals Effect of Loading Methods on the Fatigue Properties of Dissimilar Al/Steel Keyhole-Free FSSW Joints

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4247
Author(s):  
Zhongke Zhang ◽  
Yang Yu ◽  
Huaxia Zhao ◽  
Hui Tong
Keyword(s):  
Fatigue Limit ◽  
Fatigue Fracture ◽  
Fracture Mechanism ◽  
Fatigue Loading ◽  
Fatigue Properties ◽  
Loading Frequency ◽  
Fatigue Load ◽  
Friction Stir ◽  
Absorption Energy ◽  
Spot Welded

The energy evolution, fatigue life and failure behaviour of dissimilar Al/steel keyhole-free Friction stir spot welding (FSSW) joints were studied under different fatigue loads. The absorption energy of fatigue fracture, the fracture mechanism and the sensitivity of the fatigue limits to the fatigue load parameters were analysed. It was found that the stress ratio R determines the fatigue limit Ff, while the fatigue limit Ff is not sensitive to the loading frequency. The high-frequency fatigue load will increase the displacement deformation μ and fatigue fracture absorption energy Ea of the spot-welded joint, which are larger under asymmetric fatigue loading than those under symmetrical fatigue loading. At the same time, the symmetrical fatigue load can form the steady-state hysteresis loop, while asymmetric fatigue loading cannot, but asymmetric fatigue loading exhibits the displacement increment of fatigue softening. The fracture failure of spot-welded joints is a multiple crack source and the mixed-mode of ductile and brittle fracture mechanism, which exhibits typical fatigue striations in the fatigue fractures.

Study on High-Frequency Fatigue Properties of PVD AlTiN Coating of Cutting Tool

2018 ◽  
Vol 764 ◽  
pp. 370-375 ◽  
Author(s):  
N.C. Wang ◽  
Qing Feng Liu ◽  
Xin Cheng ◽  
Feng Jiang
Keyword(s):  
High Frequency ◽  
Impact Test ◽  
Cutting Tool ◽  
Fatigue Property ◽  
Maximum Tensile Stress ◽  
Fatigue Properties ◽  
Diamond Indenter ◽  
Tool Coating ◽  
Altin Coating ◽  
The Impact

Based on ultrasonic vibration-assisted mode, high-frequency impacting tests with diamond indenter at different amplitudes on AlTiN coating of cutting tool are carried out. The microstructure and morphology are obtained by scanning electron microscopy (SEM) and 3D profiler. The failure mechanism of coating under impact is analyzed. The high frequency fatigue property of the coating is analyzed. The results show that: lateral crack could be seen under impact test; the maximum tensile stress occurs close the edge of the contact zone of impact center; AlTiN coating is easy to emerge the fatigue damage under the high-frequency impact loading, and the adhesion strength of the coating and substrate interface affects the impact fatigue strength of cutting tool coating.

Changes of Fatigue Property with Heat Exposure in INVAR/AW Wire

2005 ◽  
Vol 475-479 ◽  
pp. 1873-1876
Author(s):  
Shang Shu Kim ◽  
Su Dong Park ◽  
Byung Geol Kim ◽  
Hee Woong Lee ◽  
Goo Yong Sin ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Yield Strength ◽  
Life Span ◽  
Fatigue Limit ◽  
Outer Surface ◽  
Heat Exposure ◽  
Fatigue Property ◽  
Fatigue Properties ◽  
Stable Operation

Fatigue properties of INVAR/AW wires have been investigated under the heat exposure in order to ensure stable operation and to estimate life span of their power line. In the case of heat exposure for 1000hr, fatigue life and limit increased. For further heat exposure, fatigue limit decreased due to the decrease in yield strength. The variation fatigue of strand wire was strongly dependent on its amplitude. Also, cracks in wires of 7 strands were caused by stress concentration at the outer surface and fretting between each wire during vibration.

scholarly journals Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Chao Gu ◽  
Min Wang ◽  
Yanping Bao ◽  
Fuming Wang ◽  
Junhe Lian
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Critical Size ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
Bearing Steels ◽  
Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

Mechanical Properties of Equal-Channel Angular Extrusion-Processed Al-20Zn Alloy

2012 ◽  
Vol 445 ◽  
pp. 195-200
Author(s):  
Murat Aydin ◽  
Yakup Heyal
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Equal Channel Angular Extrusion ◽  
Considerable Change ◽  
Fatigue Properties ◽  
Dendritic Microstructure ◽  
Two Phase ◽  
Angular Extrusion ◽  
Alloy Increase ◽  
The Impact

The mechanical properties mainly tensile properties, impact toughness and high-cycle fatigue properties, of two-phase Al-20Zn alloy subjected to severe plastic deformation (SPD) via equal-channel angular extrusion (ECAE) using route A up to 2 passes were studied. The ECAE almost completely eliminated as-cast dendritic microstructure including casting defects such as micro porosities. A refined microstructure consisting of elongated micro constituents, α and α+η eutectic phases, formed after ECAE via route A. As a result of this microstructural change, mechanical properties mainly the impact toughness and fatigue performance of the as-cast Al-20Zn alloy increased significantly through the ECAE. The rates of increase in fatigue endurance limit are approximately 74 % after one pass and 89 % after two passes while the increase in impact toughness is 122 %. Also the yield and tensile strengths of the alloy increase with ECAE. However, no considerable change occurred in hardness and percentage elongation of the alloy. It was also observed that the ECAE changed the nature of the fatigue fracture characteristics of the as-cast Al-20Zn alloy.

Effect of Pre-Strain and Roller Working on Torsional Fatigue Properties of a Structural Steel

2011 ◽  
Vol 295-297 ◽  
pp. 2227-2230
Author(s):  
Cong Ling Zhou
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Work Hardening ◽  
Compressive Residual Stress ◽  
Strain Ratio ◽  
Fatigue Tests ◽  
The Other ◽  
Fatigue Properties ◽  
Torsional Fatigue ◽  
Stress Work

In this study, fatigue tests have been performed using two kinds of specimens made of 25 steel. One is pre-strained specimen with pre-strain ratio changing from 2% to 8% by tension, the other is roller worked with deformation of 0.5 mm and 1.0 mm in diameter direction. In the case of pre-strained specimen, the fatigue limit increases according to increase of tensile pre-strain, the fatigue limit of 8% pre-strained specimen is 25% higher than that of non-pre-strained one; in the case of roller worked specimen, the fatigue limit of R05 and R10 is 126% and 143% to that of non-roller worked specimen, respectively. These remarkable improvements of fatigue limit would be caused by the existence of compressive residual stress, work-hardening and the elongated microscopic structures.

Influence of Phase Transformations on Residual Stresses in Welded Structures

2013 ◽  
Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Numerical Models ◽  
Material Model ◽  
Transformation Model ◽  
Austenitic Steels ◽  
Beam Specimen ◽  
Welded Structures ◽  
The Impact

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.

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