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 Shear-Torque Fatigue Performance of Geogrid-Reinforced Asphalt Interlayers

2020 ◽  
Vol 12 (11) ◽  
pp. 4381
Author(s):  
Davide Ragni ◽  
Francesco Canestrari ◽  
Fatima Allou ◽  
Christophe Petit ◽  
Anne Millien
Keyword(s):  
Glass Fiber ◽  
Fatigue Tests ◽  
Shear Loading ◽  
Fatigue Performance ◽  
Asphalt Pavements ◽  
Test Results ◽  
Cyclic Shear ◽  
Shear Fatigue ◽  
Interesting Correlation ◽  
Valid Solution

Interlayer reinforcement systems represent a valid solution to improve performance and extend the service life of asphalt pavements, reducing maintenance costs. The main issue is that the presence of reinforcement may hinder the full transmission of stresses between asphalt layers, reducing the overall pavement bearing capacity. This study aimed at evaluating the mechanical behavior of geogrid-reinforced asphalt interlayers under cyclic shear loading. To this purpose, a trial section, characterized by three types of interface (reinforced with carbon fiber grid, reinforced with glass fiber grid and unreinforced), was built. Cores were taken from the trial section to carry out shear-torque fatigue tests. Static Leutner shear tests were also performed on cored specimens having the same interface configuration. From data gathered in the present study, shear-torque fatigue tests have proved to be a powerful tool for investigating reinforced specimens. Results clearly ranked the investigated materials, showing that the glass fiber grid has the lowest shear fatigue performance in comparison with the other two interfaces at 20 °C. However, the shear fatigue resistance of glass fiber grid increases significantly at 10 °C. Finally, an interesting correlation was found between cyclic and static shear test results that should be better investigated in future studies.

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.

Fatigue study on rib-to-deck welded joint considering weld penetration rate

2019 ◽  
Author(s):  
Xiaochen Ju ◽  
Xiaogang Liu ◽  
Zhibin Zeng ◽  
Xinxin Zhao
Keyword(s):  
Welded Joints ◽  
Welded Joint ◽  
Penetration Rate ◽  
Fatigue Cracks ◽  
Element Model ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Weld Penetration ◽  
Weld Fatigue ◽  
Weld Root

<p>The U-shaped rib-to-deck welded joint in orthotropic steel deck is a part with multiple fatigue cracks. The penetration rate which is the ratio of penetration depth to U-shaped rib thickness has an important influence on fatigue performance of partial joint penetration (PJP) welds. In this study, the influence of penetration rate on the fatigue performance of U-shaped rib-to-deck welded joints was studied. Firstly, the finite element model of U-shaped rib-to-deck welded joints with penetration rate of 65%, 75%, 85% and complete joint penetration (CJP) welds were established. The mechanical characteristics of different welding forms under typical loading conditions were analyzed. It was found that with the increase of penetration rate of PJP welds, the stress concentration at the weld root weakened. Then fatigue tests on specimens with different weld penetration rate were carried out. The fatigue cracks of CJP welds all started at the inner welding toe of the U-shaped rib. However, the fatigue cracks of PJP welds mainly started at the welding root of the unfused weld. Fatigue S-N curves for PJP and CJP were regressed, respectively, it could be found that the fatigue performance of CJP welds was superior to that of PJP welds.</p>

scholarly journals Experimental study on fatigue performance of Q420qD high-performance steel cross joint in complex environment

2021 ◽  
Author(s):  
Haigen Cheng ◽  
Cong Hu ◽  
Yong Jiang
Keyword(s):  
Fatigue Life ◽  
High Performance ◽  
Steel Structure ◽  
Steel Structures ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Corrosive Media ◽  
Joint Connection ◽  
High Performance Steel ◽  
The Cross

AbstractThe steel structure under the action of alternating load for a long time is prone to fatigue failure and affects the safety of the engineering structure. For steel structures in complex environments such as corrosive media and fires, the remaining fatigue life is more difficult to predict theoretically. To this end, the article carried out fatigue tests on Q420qD high-performance steel cross joints under three different working conditions, established a 95% survival rate $$S{ - }N$$ S - N curves, and analyzed the effects of corrosive media and high fire temperatures on its fatigue performance. And refer to the current specifications to evaluate its fatigue performance. The results show that the fatigue performance of the cross joint connection is reduced under the influence of corrosive medium, and the fatigue performance of the cross joint connection is improved under the high temperature of fire. When the number of cycles is more than 200,000 times, the design curves of EN code, GBJ code, and GB code can better predict the fatigue life of cross joints without treatment, only corrosion treatment, and corrosion and fire treatment, and all have sufficient safety reserve.

On the Direction of Fatigue Cracks in Polycrystalline Ingot Iron

1952 ◽  
Vol 19 (1) ◽  
pp. 54-56
Author(s):  
F. A. McClintock
Keyword(s):  
Statistical Analysis ◽  
Shear Failure ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Tensile Failure ◽  
Bending Fatigue ◽  
Polycrystalline Iron

Abstract A statistical analysis is developed to show how a microscopic shear failure can result in the apparent tensile failure of polycrystalline iron in rotary bending fatigue tests.

scholarly journals Fatigue Resistance Characterization of Warm Asphalt Rubber by Multiple Approaches

2018 ◽  
Vol 8 (9) ◽  
pp. 1495 ◽  
Author(s):  
Jiangmiao Yu ◽  
Xianshu Yu ◽  
Zheming Gao ◽  
Feng Guo ◽  
Duanyi Wang ◽  
...  
Keyword(s):  
Fatigue Test ◽  
Fatigue Resistance ◽  
Crumb Rubber ◽  
Waste Recycling ◽  
Fatigue Performance ◽  
Four Point Bending ◽  
Asphalt Rubber ◽  
Shear Fatigue ◽  
Tensile Fatigue ◽  
Indirect Tensile

Warm asphalt rubber (WAR) mixture is a sustainable paving material with advantages including waste recycling and noise reducing. A comprehensive understanding of the fatigue performance of WAR specimens is helpful to its wide application. However, research on evaluating the fatigue performance of WAR binder and mixtures is very limited. This paper applies five fatigue analysis approaches to evaluate the fatigue life of WAR samples with three different warm mix asphalt (WMA) additives. The conventional G*sinδ, linear amplitude sweep (LAS), indirect tensile fatigue test (ITFT), and four-point bending beam (4PB) test were conducted based on available standards. In addition, a novel shear fatigue test was performed on WAR mortars. Test results indicated that the incorporation of crumb rubber has a significantly positive effect on fatigue resistance. WAR with chemical and foaming additives exhibited a poorer performance than asphalt rubber (AR), but their fatigue performance was still greatly superior to the non-rubberized samples. Finally, LAS as well as mortar shear fatigue and 4PB tests provided the same prediction of fatigue resistance, while the results of G*sinδ and the ITFT were inconsistent. It is recommended to use LAS, the mortar shear fatigue test, and the 4PB test for the fatigue resistance evaluation of rubberized specimens. The validation of the findings with more materials and field performances is recommended.

The effect on the fatigue strength of bone cement of adding sodium fluoride

2001 ◽  
Vol 215 (2) ◽  
pp. 251-253 ◽  
Author(s):  
C Minari ◽  
M Baleanil ◽  
L Cristofolini ◽  
F Baruffaldi
Keyword(s):  
Fatigue Strength ◽  
Bone Cement ◽  
Sodium Fluoride ◽  
Biomedical Applications ◽  
Cement Mantle ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Bone Cements ◽  
The Novel ◽  
Pmma Bone Cement

New bone cements that include several additives are currently being investigated and tested. One such additive is sodium fluoride (NaF), which promotes bone formation, facilitating implant integration and success. The influence of NaF on the fatigue performance of the cement as used in biomedical applications was tested in this paper. In fact fatigue failure of the cement mantle is a major factor limiting the longevity of a cemented implant. An experimental bone cement with added NaF (12wt%) was investigated. The fatigue strength of the novel bone cement was evaluated in comparison with the cement without additives; fatigue tests were conducted according to current standards. The load levels were arranged based on a validated, statistically based optimization algorithm. The curve of stress against number of load cycles and the endurance limit were obtained and compared for both formulations. The results showed that the addition of NaF (12 wt %) to polymethylmethacrylate (PMMA) bone cement does not affect the fatigue resistance of the material. Sodium fluoride can safely be added to the bone cement without altering the fatigue performance of the PMMA bone cement.

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.

Using the Three-Stage Weibull Equation and Tree-Based Model to Characterize the Mix Fatigue Damage Process

2005 ◽  
Vol 1929 (1) ◽  
pp. 227-237 ◽  
Author(s):  
Bor-Wen Tsai ◽  
John T. Harvey ◽  
Carl L. Monismith
Keyword(s):  
Crack Initiation ◽  
Fatigue Damage ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Data Set ◽  
Warm Up ◽  
Weibull Parameters ◽  
Damage Process ◽  
Initiation Stage ◽  
Weibull Equation

The primary purpose of this paper is to demonstrate the applicability of the three-stage Weibull equation to describe the fatigue damage process using flexural controlled deformation fatigue tests. A data set of 179 beam fatigue tests originally designed for exploring the fatigue performance of conventional dense graded asphalt concrete (DGAC) and asphalt–rubber hot-mix gap-graded (ARHM-GG) mixes was used to inspect the three-stage Weibull parameters that were estimated using a genetic algorithm. The tree-based regression–category models were then used to uncover the data structure of the estimated parameters as a function of material properties, conditioning methods, temperatures, compaction methods, and strain levels. In general, the three-stage Weibull equation provides satisfactory fitting results for the three-stage fatigue damage process occurring in a beam test. It was found that the tree-based models of three-stage Weibull parameters associated with the crack initiation stage were statistically adequate and reliable compared with the models of parameters related to the warm-up stage and the crack propagation stage. It might suggest that these crack initiation parameters are better indexes to assess the fatigue performance.

Sign in / Sign up

Export Citation Format

Share Document