Fatigue Evaluation of Trough Splice Joints in Orthotropic Steel Decks

2014 ◽  
Vol 1025-1026 ◽  
pp. 17-23
Author(s):  
Huang Yun ◽  
Qing Hua Zhang ◽  
Yi Zhi Bu ◽  
He Liang Liu ◽  
Shao Lin Yang
Keyword(s):  
Tensile Stress ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Fatigue Properties ◽  
Systematic Analysis ◽  
Longitudinal Ribs ◽  
Principal Tensile Stress ◽  
Orthotropic Steel Decks ◽  
Fatigue Evaluation

Fatigue tests for full-scale orthotropic steel decks were conducted to evaluate and validate the fatigue performance of welded and bolted splice joints of longitudinal ribs. The test results indicated that the fatigue properties of two splice joints met the design requirements. The bolted splice joints whose principal tensile stress was largely lower than welded splice joints under the same loading conditions appeared to have superior fatigue resistance to the welded one. No fatigue cracks were detected among all the specimens and the principal tensile stress of measuring points had few changes during the whole fatigue tests. Systematic analysis of test data showed that bolted splice joints appeared to be more reasonable for improving the fatigue performance of longitudinal ribs.

scholarly journals The Influence of Laser Shock Peening on Fatigue Properties of AA2024-T3 Alloy with a Fastener Hole

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 495
Author(s):  
Ruslan Sikhamov ◽  
Fedor Fomin ◽  
Benjamin Klusemann ◽  
Nikolai Kashaev
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracks ◽  
Initial Crack ◽  
Fatigue Tests ◽  
Laser Shock Peening ◽  
Fatigue Properties ◽  
Hole Drilling ◽  
Laser Shock ◽  
Fastener Hole ◽  
Shock Peening

The objective of the present study was to estimate the influence of laser shock peening on the fatigue properties of AA2024-T3 specimens with a fastener hole and to investigate the possibility to heal the initial cracks in such specimens. Fatigue cracks of different lengths were introduced in the specimens with a fastener hole before applying laser shock peening. Deep compressive residual stresses, characterized by the hole drilling method, were generated into the specimens by applying laser shock peening on both sides. Subsequently, the specimens were subjected to fatigue tests. The results show that laser shock peening has a positive effect regarding the fatigue life improvement in the specimens with a fastener hole. In addition, laser shock peening leads to a healing effect on fatigue cracks. The efficiency of this effect depends on the initial crack length. The effect of laser shock peening on the fatigue life periods was determined by using resonant frequency graphs.

scholarly journals On the Microstructures and Fatigue Behaviors of 316L Stainless Steel Metal Injection Molded with Gas- and Water-Atomized Powders

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 893 ◽  
Author(s):  
Yongyun Zhang ◽  
Ensheng Feng ◽  
Wei Mo ◽  
Yonghu Lv ◽  
Rui Ma ◽  
...  
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Fatigue Cracks ◽  
Selective Laser Sintering ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Metal Injection Molding ◽  
Strengthening Effect ◽  
Lower Oxygen ◽  
Order Of Magnitude

316L stainless steel samples are fabricated by metal injection molding using water-atomized and gas-atomized powder with different oxygen contents. The influences of oxygen on the microstructural evolution and fatigue properties of the samples are investigated. The oxygen tends to react with Mn and Si to form oxide particles during sintering. The oxides hamper the densification process and result in decreased sintered density. Moreover, their existence reduces the Mn and Si dissolving into the base metal and compromises the solution strengthening effect. The oxides lead to stress concentration in the tensile and fatigue tests and become the initiation sites of fatigue cracks. After sintering, the samples made from the gas-atomized powder have a much lower oxygen content compared to those made from the water-atomized powder, therefore, exhibiting much better mechanical properties. The tensile strength, yield strength and the elongation of the samples made from the gas-atomized powder are 560 MPa, 205 MPa, and 58%, respectively. Their fatigue lives are about one order of magnitude longer than the samples made from water-atomized powder, and also longer than those fabricated by powder metallurgy and selective laser sintering which were reported in other studies.

Effect of Pre-Strain on Fatigue Properties of NHH Rail

2004 ◽  
Vol 261-263 ◽  
pp. 1239-1244
Author(s):  
Wen Xian Sun ◽  
S. Nishida ◽  
Nobusuke Hattori ◽  
X.L. Yue
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Slip Lines ◽  
Propagation Behavior ◽  
Strain Process ◽  
Initiation And Propagation

In the present study, fatigue tests have been performed to study the effect of pre-strain on fatigue properties of NHH (New Head-Hardened) rail. The objectives of this study were: (1) to observe the microscopic behavior of specimens during pre-strain process, (2) to research the influence of pre-strain on fatigue strength of NHH rail and (3) to investigate initiation and propagation behavior of the fatigue crack. The results showed that plastic pre-strain decreased the fatigue strength of NHH rail; fatigue limits had no obvious variation among the different pre-strain ratios. Fatigue cracks initiated in the microscopic cracking or slip lines that were originated in the pre-strain process and propagated from these sites in the later fatigue test.

Investigations on Fatigue Properties of Die Cast Magnesium Alloy AZ91HP at Very High Cycles

2007 ◽  
Vol 353-358 ◽  
pp. 235-238
Author(s):  
Tang Li ◽  
Qing Yuan Wang ◽  
Q.F. Dou ◽  
Chong Wang ◽  
M.R. Sriraman
Keyword(s):  
Magnesium Alloy ◽  
Fatigue Cracks ◽  
Ambient Air ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Loading Frequency ◽  
Die Cast ◽  
Cast Magnesium Alloy ◽  
Cast Magnesium ◽  
Very High

Very high cycle fatigue (VHCF) properties of high-pressure die cast Magnesium alloy AZ91HP have been investigated. Ultrasonic fatigue tests up to 109 cycles were conducted at the loading frequency of 20 kHz, under R=-1 condition and in ambient air. The experimental results show that specimens fail even after 107 cycles although the scatter seems to be large probably due to the presence of materials defects. However, there seems to be a fatigue limit at about 109 cycles. The fractures contain typical brittle features, with the fatigue cracks seen to initiate from the porosity in the material, either from the surface or beneath.

Effect of Fiber Volume Fraction on Low Cycle Fatigue Behavior of Al2O3f/Al-Si Composites

2012 ◽  
Vol 268-270 ◽  
pp. 87-91
Author(s):  
Jian Jun Cui ◽  
Bing Chao Li ◽  
Guo Hua Zhang ◽  
Jian Xin Zhang ◽  
Zuo Shan Wei ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Short Fibers ◽  
Fiber Volume ◽  
Large Size

The tensile and low cycle fatigue tests were carried out on alumina short fibers reinforced Al-Si piston alloy composites (Al-Si MMCs). Three Al-Si MMCs reinforced with 10, 17 and 25 vol.% of alumina short fibers were prepared to investigate the effects of volume fraction on tensile and low cycle fatigue properties at room temperature (RT) and 350°C. The results showed that the tensile strength decreased with the increasing of volume fraction of fibers at RT and was slight different at 350°C. Among the three MMCs, the 17%-MMCs showed highest stress level under the low cycle fatigue tests. The fatigue cracks were usually initiated from the clustered and large size fibers near the surface of specimen, propagated along the fiber/matrix interface at RT and grew rapidly by means of broken the fibers at 350°C.

Fatigue Properties of a Ck45 Steel Coated with a Post-Heat Treated Ni-Cu-P Electroless Deposit

2006 ◽  
Vol 514-516 ◽  
pp. 574-578
Author(s):  
Sasan Yazdani ◽  
N. Parvini-Ahmadi ◽  
Tohid Saeid
Keyword(s):  
Fatigue Life ◽  
Fatigue Testing ◽  
Crack Nucleation ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Interfacial Cracks ◽  
Heat Treated ◽  
Base Steel ◽  
Surface Notch

The Fatigue tests under rotating bending conditions have been conducted on samples of a quenched and tempered Ck45 steel in two different conditions: (a) uncoated, (b) coated with an electroless Ni-Cu-P deposit, followed by a post-heat treatment (PHT) at 673 K for 1 h. Such a deposit had a thickness of approximately 10µm, with Cu and P contents of 6wt.% and 13.7wt.% respectively. The results indicate that plating the base steel with this kind of deposit leads to a reduction of the fatigue life of the material. The reduction in fatigue life has been quantified in terms of the Basquin parameters of the materials tested under different conditions. The microscopic observation of the fracture surfaces of the samples indicates that the reduction in fatigue life is associated with the nucleation of fatigue cracks on the coating-substrate interface and the deposit remains well adhered to substrate during fatigue testing since interfacial cracks have been very rarely observed. It is therefore concluded that, in the present case, the interface acts as a surface crack source or surface notch, which decreases the fatigue life of the coated material by reducing the crack nucleation stage.

Effect of Fiber Volume Fraction on Low Cycle Fatigue Behavior of Al2O3f/Al-Si Composites

2012 ◽  
Vol 622-623 ◽  
pp. 1340-1344
Author(s):  
Jian Jun Cui ◽  
Bing Chao Li ◽  
Guo Hua Zhang ◽  
Jian Xin Zhang ◽  
Zuo Shan Wei ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Short Fibers ◽  
Fiber Volume ◽  
Large Size

The tensile and low cycle fatigue tests were carried out on alumina short fibers reinforced Al-Si piston alloy composites (Al-Si MMCs). Three Al-Si MMCs reinforced with 10, 17 and 25 vol.% of alumina short fibers were prepared to investigate the effects of volume fraction on tensile and low cycle fatigue properties at room temperature (RT) and 350°C. The results showed that the tensile strength decreased with the increasing of volume fraction of fibers at RT and was slight different at 350°C. Among the three MMCs, the 17%-MMCs showed highest stress level under the low cycle fatigue tests. The fatigue cracks were usually initiated from the clustered and large size fibers near the surface of specimen, propagated along the fiber/matrix interface at RT and grew rapidly by means of broken the fibers at 350°C.

scholarly journals Enhancing Fatigue Performance of Sandwich Composites with Nanophased Core

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
S. Zainuddin ◽  
H. Mahfuz ◽  
S. Jeelani
Keyword(s):  
Carbon Nanofiber ◽  
Fatigue Cracks ◽  
Interface Layer ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Sandwich Composites ◽  
Ultimate Shear Strength ◽  
Cell Structures ◽  
Shear Fatigue ◽  
Delayed Initiation

We report fatigue performance of sandwich composites with nanophased core under shear load. Nanophased core was made from polyurethane foam dispersed with carbon nanofiber (CNF). CNFs were dispersed into part-A of liquid polyurethane through a sonication process and the loading of nanoparticles was 1.0 wt%. After dispersion, part-A was mixed with part-B, cast into a mold, and allowed to cure. Nanophased foam was then used to fabricate sandwich composites. Static shear tests revealed that strength and modulus of nanophased foams were 33% and 19% higher than those of unreinforced (neat) foams. Next, shear fatigue tests were conducted at a frequency of 3 Hz and stress ratio (R) of 0.1. S-N curves were generated and fatigue performances were compared. Number of cycles to failure for nanophased sandwich was significantly higher than that of the neat ones. For example, at 57% of ultimate shear strength, nanophased sandwich would survive 400,000 cycles more than its neat counterpart. SEM micrographs indicated stronger cell structures with nanophased foams. These stronger cells strengthened the sub-interface zones underneath the actual core-skin interface. High toughness of the sub-interface layer delayed initiation of fatigue cracks and thereby increased the fatigue life of nanophased sandwich composites.

scholarly journals Fatigue Evaluation of Recycled Asphalt Mixture Based on Energy-Controlled Mode

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Tao Ma ◽  
Kai Cui ◽  
Yongli Zhao ◽  
Xiaoming Huang
Keyword(s):  
Fatigue Life ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Fatigue Performance ◽  
Fatigue Properties ◽  
Dissipated Energy ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt ◽  
Bending Fatigue Test ◽  
Fatigue Evaluation

The fatigue properties of asphalt mixtures are important inputs for mechanistic-empirical pavement design. To understand the fatigue properties of asphalt mixtures better and to predict the fatigue life of asphalt mixtures more precisely, the energy-controlled test mode was introduced. Based on the implementation theory, the laboratory practice for the energy-controlled mode was realized using a four-point-bending fatigue test with multiple-step loading. In this mode, the fatigue performance of typical AC-20 asphalt specimens with various reclaimed asphalt pavement (RAP) contents was tested and evaluated. Results show that the variation regulation of the dissipated energy and accumulative energy is compatible with the loading control principle, which proves the feasibility of the method. In addition, the fatigue life of the asphalt mixture in the energy-controlled mode was between that for the stress-controlled and strain-controlled modes. The specimen with a higher RAP content has a longer fatigue life and better fatigue performance.

scholarly journals Effect of Turning and Surface Polishing Treatments on Surface Integrity and Fatigue Performance of Nickel-Based Alloy GH4169

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 549 ◽  
Author(s):  
Daoxia Wu ◽  
Dinghua Zhang ◽  
Changfeng Yao
Keyword(s):  
Surface Integrity ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Fatigue Properties ◽  
Small Surface ◽  
Axial Texture ◽  
Surface Polishing ◽  
Microhardness And Microstructure ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

In this paper, the effects of turning and surface polishing treatments on surface integrity and fatigue properties of superalloy GH4169 were investigated. Finish turning (FT), surface circumferential polishing treatment (TCP), surface oblique texture (TCPO), and surface axial texture (TCPA) were applied to GH4169 superalloy. The surface roughness, surface topography, residual stress, microhardness, and microstructure after different processes were studied. Rotating bending fatigue tests were carried out to investigate the effects of surface integrity and surface texture direction on the fatigue performance of GH4169. The experiments reveal that the TCPA specimens present the longest fatigue life of 15.01 × 104 cycles. By comparison with the FT, TCP, and TCPO specimens, the fatigue lives of TCPA specimens are increased by 134.2%, 183.7%, and 96.2%, respectively. Single crack initiation source is observed for TCPA specimen. It is mainly attributed to the small surface stress concentration factor and surface axial texture.

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