scholarly journals Fatigue Performance of an Additively Manufactured Zr-Based Bulk Metallic Glass and the Effect of Post-Processing

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1064
Author(s):  
Navid Sohrabi ◽  
Milad Hamidi-Nasab ◽  
Baptiste Rouxel ◽  
Jamasp Jhabvala ◽  
Annapaola Parrilli ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Behavior ◽  
Near Surface ◽  
Powder Bed ◽  
Three Point Bending ◽  
Bending Fatigue Test ◽  
Cause Of Failure ◽  
Life Improvement ◽  
Shock Peening ◽  
Induced Defects

Fatigue is the most common cause of failure of mechanical parts in engineering applications. In the current work, we investigate the fatigue life of a bulk metallic (BMG) glass fabricated via additive manufacturing. Specimens fabricated via laser powder-bed fusion (LPBF) are shown to have a fatigue ratio of 0.20 (fatigue limit of 175 MPa) in a three-point bending fatigue test. Three strategies for improving the fatigue behavior were tested, namely (1) relaxation heat treatment, giving a slight fatigue life improvement at high loading conditions (≥250 MPa), (2) laser shock peening, and (3) changing the build orientation, the latter two of which yielded no significant effects. It was found that the presence of lack of fusion (LoF) had the preponderant effect on fatigue resistance of the specimens manufactured. LoF was observed to be a source of stress localization and initiation of cracks. The fatigue life in BMGs fabricated by LPBF is thus primarily influenced by powder quality and process-induced defects, which cannot be removed by the post-treatments carried out in this study. It is believed that a slight increase in laser power, either in the near-surface regions or in the core of the specimens, could improve the fatigue behavior despite the associated (detrimental) increase of crystallized fraction.

scholarly journals Fatigue Life Improvement of Cracked Aluminum 6061-T6 Plates Repaired by Composite Patches

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1421
Author(s):  
Armin Yousefi ◽  
Saman Jolaiy ◽  
Reza Hedayati ◽  
Ahmad Serjouei ◽  
Mahdi Bodaghi
Keyword(s):  
Fatigue Life ◽  
Fatigue Behavior ◽  
Weight Ratio ◽  
High Strength ◽  
Plastic Strain Amplitude ◽  
Composite Patch ◽  
Life Improvement ◽  
Cracked Structures ◽  
Aluminum Plates ◽  
High Flexibility

Bonded patches are widely used in several industry sectors for repairing damaged plates, cracks in metallic structures, and reinforcement of damaged structures. Composite patches have optimal properties such as high strength-to-weight ratio, easiness in being applied, and high flexibility. Due to recent rapid growth in the aerospace industry, analyses of adhesively bonded patches applicable to repairing cracked structures have become of great significance. In the present study, the fatigue behavior of the aluminum alloy, repaired by a double-sided glass/epoxy composite patch, is studied numerically. More specifically, the effect of applying a double-sided composite patch on the fatigue life improvement of a damaged aluminum 6061-T6 is analyzed. 3D finite element numerical modeling is performed to analyze the fatigue performance of both repaired and unrepaired aluminum plates using the Abaqus package. To determine the fatigue life of the aluminum 6061-T6 plate, first, the hysteresis loop is determined, and afterward, the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted and validated against the available experimental data from the literature. Results reveal that composite patches increase the fatigue life of cracked structures significantly, ranging from 55% to 100% for different applied stresses.

Fatigue Characteristics of Composite Antenna Structure

2004 ◽  
Vol 261-263 ◽  
pp. 1109-1114
Author(s):  
Dong Hal Kim ◽  
W. Hwang ◽  
Hyun Chul Park ◽  
W.S. Park
Keyword(s):  
Fatigue Life ◽  
Satellite Communication ◽  
Fatigue Behavior ◽  
Load Level ◽  
Tangent Loss ◽  
Antenna Structure ◽  
Antenna Performance ◽  
Bending Fatigue Test ◽  
Structural Surface ◽  
Good Agreement

The objective of this work was to design Surface Antenna Structure (SAS) and investigate fatigue behavior of SAS that was asymmetric sandwich structure. This term, SAS, indicates that structural surface becomes antenna. Constituent materials were selected considering electrical properties, dielectric constant and tangent loss as well as mechanical properties. For the antenna performance, SSFIP elements inserted into structural layers were designed for satellite communication at a resonant frequency of 12.5 GHz and final demonstration article was 16 x 8 array antenna. In cyclic loading, flexure behavior was investigated by 4-point bending and 4-point bending fatigue test. Fatigue life curve of SAS was obtained. Experimental results were compared with single load level fatigue life prediction equations (SFLPEs) and in good agreement with SFLPEs. SAS concept is the first serious attempt at integration for both antenna and composite engineers.

scholarly journals Fatigue Life Improvement of the High Strength Steel Welded Joints by Ultrasonic Impact Peening

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 619 ◽  
Author(s):  
Ján Lago ◽  
Libor Trško ◽  
Michal Jambor ◽  
František Nový ◽  
Otakar Bokůvka ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Welded Joints ◽  
Compressive Residual Stress ◽  
High Strength ◽  
Fatigue Properties ◽  
Low Alloy Steel ◽  
Residual Stress Field ◽  
Near Surface ◽  
Life Improvement

Ultrasonic impact peening was applied on welded joints manufactured from Strenx 700 MC high strength low alloy steel with the aim to improve the fatigue properties. Three different surface treatment parameters were tested, which resulted in transformation of the near-surface tensile residual stresses in the weld metal and heat affected zone to compressive residual stress field, while maximal values from −400 MPa up to −800 MPa were reached. The highest fatigue life improvement was reached by the double peening with the 85 N contact force, where the fatigue limit for N = 108 cycles increased from 370 MPa to 410 MPa.

Tensile and Fatigue Properties of Ti-6Al-4V Alloy Fabricated by Laser Powder-Bed Fusion Process

2020 ◽  
Author(s):  
M. Shafiqur Rahman ◽  
Uttam K. Chakravarty
Keyword(s):  
Fatigue Life ◽  
Fatigue Limit ◽  
Fatigue Behavior ◽  
Functional Materials ◽  
Fatigue Properties ◽  
Small Scale ◽  
Powder Bed Fusion ◽  
Cycle Fatigue ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

Abstract The tensile and fatigue properties of laser-powder-bed-fusion (L-PBF) processed Ti-6Al-4V specimens are investigated at different loading conditions. Two types of as-built and post-machined L-PBF processed dogbone specimens are considered for the study, one is an ASTME8M round specimen and the other one is a customized small-scale flat structure. The tensile and fatigue behavior of the specimens are investigated numerically using the finite element (FE) method. The FE modeling considers both low cycle fatigue (LCF) and high cycle fatigue (HCF) test conditions by applying cyclic loads in fully-reversed and stress ratio R = 0.1 conditions. The FE results for the von Mises stress, strain, total deformation, fatigue life, factor of safety, and fatigue limit of the Ti-6Al-4V specimens are obtained at room temperature (295 K). Results obtained from the model show that the fatigue life decreases as the load increases. It is also found that fatigue life does not vary with the change of the test frequency under a specific fatigue load. The comparison of mechanical properties of the L-PBF processed specimens with conventionally manufactured Ti-6Al-4V parts is also shown to understand the differences in the tensile and fatigue behavior. The validation of the FE model is performed by comparing the numerical results for the yield stress and fatigue limit with the experimental results found from the literature. The overall study contains a detailed analysis of the tensile and fatigue behavior of additively manufactured Ti-6Al-4V parts and provides a guide to investigating the similar properties for other functional materials used in the L-PBF process.

scholarly journals Three-Point Bending Fatigue Test of TiAl6V4 Titanium Alloy at Room Temperature

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Juraj Belan ◽  
Lenka Kuchariková ◽  
Eva Tillová ◽  
Mária Chalupová
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Room Temperature ◽  
Fatigue Tests ◽  
Dynamic Force ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Bending Fatigue Test ◽  
Number Of Cycles ◽  
Test Loading

A polycrystalline alpha-beta TiAl6V4 alloy in the annealed condition was used for the three-point bending fatigue test at frequency f∼100 Hz. The static preload Fstat. = −15 kN and variable dynamic force Fdyn. = −7 kN to −13.5 kN were set as fatigue test loading parameters. The fatigue life S-N curve presented the stress amplitude σa as a function of a number of cycles to fracture Nf. A limiting number of cycles to run out of 2.0 × 107 cycles were chosen for the 3-point fatigue tests of rectangular specimens. In addition, the Smith diagram was used to predict the fatigue life. The alpha lamellae width has a significant influence on fatigue life. It is assumed that the increasing width of alpha lamellae decreases fatigue life. A comparison of fatigue results with given alpha lamellae width in our material to the results of other researchers was performed. The SEM fractography was performed with an accent to reveal the initiation sites of crack at low and high load stresses and mechanism of crack propagation for the fatigue part of fracture.

scholarly journals Energy-Based Approach to Predict Fatigue Life of Asphalt Mixture Using Three-Point Bending Fatigue Test

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1696 ◽  
Author(s):  
Yazhen Sun ◽  
Chenze Fang ◽  
Jinchang Wang ◽  
Zuoxin Ma ◽  
Youlin Ye
Keyword(s):  
Fatigue Life ◽  
Mathematical Models ◽  
Strain Energy ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Average Value ◽  
Bending Fatigue Test ◽  
Fatigue Equation

The three-point bending fatigue tests were carried out in order to accurately predict the fatigue life of an asphalt mixture based on the plateau value (PV) of the dissipated strain energy ratio (DSER). The relations of the dissipated strain energy (DSE) to the stress-strength ratio, temperature and loading rate were studied, and the constructions of the mathematical models of DSE and DSER were completed based on the change laws of the DSE. The relation of the fatigue life to the PV was determined based on the analysis of damage evolution, based on which the fatigue equation was established and used to predict the fatigue life. The results show that the change laws of DSE and DSER can be well described by the proposed mathematical models. The PV is defined as the average value of the DSER in the second stage and the fatigue life decreases in power function with the increase of PV, based on which the fatigue equation of Nf = A(PV)B was established, and the established fatigue equation is very close to that is used in the MEPDG. The fatigue equation can well predict the fatigue life asphalt mixture.

Large versus Small Grain Sizes on Fatigue Life of Aluminum Aircraft Wheels

2019 ◽  
Vol 391 ◽  
pp. 174-194 ◽  
Author(s):  
Fahad Alzubi ◽  
Mark Timko ◽  
Yong Jun Li ◽  
Ray Toal ◽  
Kelly Tovalin ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Microstructural Analysis ◽  
Cycle Fatigue ◽  
Sem Images ◽  
Stress Levels ◽  
Bending Fatigue Test ◽  
Rotating Bending Fatigue

The high cycle fatigue behavior of an aluminum alloy of small and large grains was investigated. Samples of small and large grains were provided as rotating bending fatigue test specimens. The samples were tested at eight different stress levels from 103 MPa (15 ksi) to 345 MPa (50 ksi) with a 34 MPa (5 ksi) increase at each level. As-received samples were evaluated for optical microstructural analysis. Scanning electron microscopy (SEM) images were used to evaluate the fractured surface of several samples. High cycle fatigue S-N curves were generated. The fatigue test results showed that grain size has a strong influence on the fatigue life. The high cycle fatigue S-N curves of small grains showed better fatigue life as compared to large grains in the lower stress levels. At higher stresses, the situation was reversed.

Experimental and numerical investigation of the effect of gaps on fatigue behavior of unidirectional carbon/epoxy automated fiber placement laminates

2016 ◽  
Vol 51 (6) ◽  
pp. 759-772 ◽  
Author(s):  
Yasser Mahmoud Elsherbini ◽  
Suong V Hoa
Keyword(s):  
Fatigue Life ◽  
Applied Stress ◽  
Fatigue Behavior ◽  
Damage Model ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Fiber Placement ◽  
Automated Fiber Placement ◽  
Induced Defects

Automated fiber placement (AFP) process provides high potential to repeatability and flexibility required for manufacturing of complex parts in many industries. Performance of such parts can be influenced by AFP manufacturing induced defects such as gaps and overlaps. In this work, the effect of gaps on fatigue behavior of unidirectional carbon/epoxy laminates was investigated. Tension–tension fatigue tests were conducted on defected samples and compared to reference samples free from defects. Infrared thermography technique was used for monitoring of damage propagation during fatigue loading. Moreover, a fatigue progressive damage model (FPDM) was developed and applied to laminates containing gaps to predict fatigue damage progression and failure. The experimental results revealed that the effect of gaps depends on the maximum applied stress during fatigue. The higher is the applied stress, the higher is the reduction in fatigue life. Good agreement was found between the results of fatigue life prediction from the FPDM and the experimental results for defected specimens.

scholarly journals Laser Shock Peening of SiCp/2009Al Composites: Microstructural Evolution, Residual Stress and Fatigue Behavior

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1082
Author(s):  
Rujian Sun ◽  
Ziwen Cao ◽  
Yongxin Zhang ◽  
Hepeng Zhang ◽  
Yingwei Yu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Behavior ◽  
Base Material ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Modification Technique ◽  
Shock Peening ◽  
Sic Particle

SiC particle reinforced aluminum alloy has a wide application in the aerospace industries. In this study, laser shock peening (LSP), an advanced surface modification technique, was employed for SiCp/2009Al composite to reveal its microstructure, microhardness and residual stress evolution. After peening, high densities of dislocations were induced in the aluminum substrate, and stacking faults were introduced into the SiC particle. The microhardness was increased from 155–170 HV to 170–185 HV, with an affected depth of more than 1.5 mm. Compressive residual stresses of more than 200 MPa were introduced. The three-point bending fatigue of the base material, laser peened and milled after laser peened specimens with artificial crack notch fabricated by a femtosecond laser was investigated. The average fatigue lives of laser peened and milled after laser peened specimens were increased by up to 10.60 and 2.66 times, compared with the base material. This combined fundamental and application-based research seeks to comprehensively explore the applicability of LSP on metal matrix composite.

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