Extremely Low-Cycle Fatigue Tests of Thick-Walled Steel Bridge Piers

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

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Cumulative acoustic emission energy for damage detection in composites reinforced by carbon fibers within low-cycle fatigue regime at various displacement amplitudes and rates

Polymers and Polymer Composites ◽

10.1177/0967391120985709 ◽

2021 ◽

pp. 096739112098570

Author(s):

Mohammad Azadi ◽

Mohsen Alizadeh ◽

Seyed Mohammad Jafari ◽

Amin Farrokhabadi

Keyword(s):

Acoustic Emission ◽

Carbon Fibers ◽

Polymer Matrix Composites ◽

Low Cycle Fatigue ◽

Energy Parameter ◽

Fatigue Tests ◽

Matrix Cracking ◽

Matrix Composites ◽

Cycle Fatigue ◽

Cumulative Energy

In the present article, acoustic emission signals were utilized to predict the damage in polymer matrix composites, reinforced by carbon fibers, in the low-cycle fatigue regime. Displacement-controlled fatigue tests were performed on open-hole samples, under different conditions, at various displacement amplitudes of 5.5, 6.0, 6.5 and 7.0 mm and also under various displacement rates of 25, 50, 100 and 200 mm/min. After acquiring acoustic emission signals during cycles, two characteristic parameters were used, including the energy and the cumulative energy. Obtained results implied that the energy parameter of acoustic emission signals could be used only for the macroscopic damage, occurring at more than 65% of normalized fatigue cycles under different test conditions. However, the cumulative energy could properly predict both microscopic and macroscopic defects, at least two failure types, including matrix cracking at first cycles and the fiber breakage at last cycles. Besides, scanning electron microscopy images proved initially such claims under all loading conditions.

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Evaluation of the Heat Treatment Role for Light Aluminum Alloys Subjected to Creep and Low Cycle Fatigue

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.455 ◽

2010 ◽

Vol 638-642 ◽

pp. 455-460 ◽

Cited By ~ 1

Author(s):

A. Rutecka ◽

L. Dietrich ◽

Zbigniew L. Kowalewski

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Low Cycle Fatigue ◽

Numerical Models ◽

Cyclic Hardening ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Lower Stress ◽

Creep Tests ◽

Different Temperatures

The AlSi8Cu3 and AlSi7MgCu0.5 cast aluminium alloys of different composition and heat treatment were investigated to verify their applicability as cylinder heads in the car engines [1]. Creep tests under the step-increased stresses at different temperatures, and low cycle fatigue (LCF) tests for a range of strain amplitudes and temperatures were carried out. The results exhibit a significant influence of the heat treatment on the mechanical properties of the AlSi8Cu3 and AlSi7MgCu0.5. An interesting fact is that the properties strongly depend on the type of quenching. Lower creep resistance (higher strain rates) and lower stress response during fatigue tests were observed for the air quenched materials in comparison to those in the water quenched. Cyclic hardening/softening were also observed during the LCF tests due to the heat treatment applied. The mechanical properties determined during the tests can be used to identify new constitutive equations and to verify existing numerical models.

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Effect of Different Welded Structures on Mechanical Properties of TA2 Tube-to-Tubesheet Joints

Journal of Pressure Vessel Technology ◽

10.1115/1.4026566 ◽

2014 ◽

Vol 136 (4) ◽

Cited By ~ 1

Author(s):

Xinlong Wei ◽

Yang Qian ◽

Junhui Wang ◽

Jianxin Zhou ◽

Xiang Ling

Keyword(s):

Applied Load ◽

Low Cycle Fatigue ◽

Weld Zone ◽

Steel Tube ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Welded Structures ◽

Pull Out ◽

Weld Toe ◽

Welded Tube

Four types of TA2 welded tube-to-tubesheet joints prepared by manual tungsten arc argon-shielded welding technique are studied in this paper. The pull-out tests and low cycle fatigue tests were performed to optimize welded structures of tube and tubesheet. The results show that fractures of welded TA2 tube and tubesheet samples occur at weld zone of TA2 steel tube for the pull-out tests and low cycle fatigue tests. The extension-tubesheet welded joints have the maximum pull-out forces and the best fatigue resistance, and the internal-bore welded joint with 45 deg bevel occupies second place. Fractures are both initiated from weld toe of the outside of tube for the pull-out tests and low cycle fatigue tests. Crack propagates along the direction of 45 deg for the pull-out test. However, crack propagates perpendicularly to the direction of the applied load for low cycle fatigue test, and then fractures immediately parallel to the direction of the applied load. Fatigue striations with a spacing of about 10 μm can be observed on the fatigue crack propagation zone. However, hemispheroidal dimples exist on instant rupture zone.

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Damage in Adhesive Joints During Low Cycle Fatigue

Volume 9: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2010-40676 ◽

2010 ◽

Author(s):

Iva´n C. Ca´bulo-Pe´rez ◽

Juan P. Casas-Rodri´guez

Keyword(s):

Plastic Strain ◽

Low Cycle Fatigue ◽

Stress Test ◽

Damage Model ◽

Fatigue Tests ◽

Constant Stress ◽

Cycle Fatigue ◽

Damage Behavior ◽

Non Linear ◽

Compressive Loads

The objective of this research is to study the damage behavior of bulk adhesive and single lap joint (SLJ) specimens during low cycle fatigue (LCF). Fatigue tests under constant stress amplitude were done and strain response was measured through cycles to failure using the bulk adhesive and SLJ data. A non linear damage model was used to fit experimental results. Identification of the damage parameters for bulk adhesive was obtained from the damage against accumulated plastic strain plot. It is shown that the plastic strain can be obtained from the constant stress test if the instantaneous elastic modulus, i.e. modulus affected by damage, is evaluated for each cycle. On the other hand, damage in SLJ was seen mainly in the adhesive for itself — no substrate failure — this fact is used to propose that fatigue response in the joint is due to continuum damage accumulation in the adhesive as the number of cycles increases. Damage behavior under compressive loads was not taken into account but good correlation of numerical and experimental data was obtained. It was found that damage evolution behaves in a non linear manner as the plastic deformation grows for each cycle: on fatigue onset an accelerated damage grow is observed, then a proportional evolution, and finally a rapid failure occurs; this characteristics were seen in both the SLJ and bulk adhesive specimen. So far, this research takes the damage model found in a standard adhesive specimen and assumes it is accurate enough to represent the damage behavior of the SLJ configuration.

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Impact of Temperature on Low-Cycle Fatigue Characteristics of the HR6W Alloy

Materials ◽

10.3390/ma14226741 ◽

2021 ◽

Vol 14 (22) ◽

pp. 6741

Author(s):

Grzegorz Junak ◽

Anżelina Marek ◽

Michał Paduchowicz

Keyword(s):

Fatigue Life ◽

Room Temperature ◽

Low Cycle Fatigue ◽

Fatigue Tests ◽

Total Strain ◽

Cycle Fatigue ◽

Fatigue Characteristics

This paper presents the results of tests conducted on the HR6W (23Cr-45Ni-6W-Nb-Ti-B) alloy under low-cycle fatigue at room temperature and at 650 °C. Fatigue tests were carried out at constant values of the total strain ranges. The alloy under low-cycle fatigue showed cyclic strengthening both at room temperature and at 650 °C. The degree of HR6W strengthening described by coefficient n’ was higher at higher temperatures. At the same time, its fatigue life Nf at room temperature was, depending on the range of total strain adopted in the tests, several times higher than observed at 650 °C.

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Low Cycle Fatigue Properties of FGH720Li Superalloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1035.292 ◽

2021 ◽

Vol 1035 ◽

pp. 292-296

Author(s):

Zi Chao Peng ◽

Jun Ying Sheng ◽

Xu Qing Wang ◽

Yue Tang

Keyword(s):

Fatigue Life ◽

Powder Metallurgy ◽

Applied Stress ◽

Low Cycle Fatigue ◽

Influencing Factor ◽

Fatigue Tests ◽

Fatigue Properties ◽

Nickel Base Superalloy ◽

Loading Frequency ◽

Cycle Fatigue

Low cycle fatigue (LCF) properties of a powder metallurgy(PM) nickel base superalloy FGH720Li were systematically studied in this work, including smooth LCF and notched LCF tested at various temperatures and different stress. The relationship between the fatigue life and applied stress was analyzed both for smooth fatigue and notch fatigue tests. The effects of loading frequency and stress ratio on LCF behavior were also studied. As an important influencing factor of the fatigue life in powder metallurgy superalloy, the effect of inclusions on LCF life was also investigated. The results showed that the fatigue properties of FGH720Li alloy was excellent, when tested at the temperature of 450°C and applied stress of 1230MPa, the fatigue life could exceed 5×104 cycles. When tested at 650°C and 1150MPa, the average fatigue life was still beyond 2×105 cycles.

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Über den Zusammenhang zwischen Brucharbeit und Lastspielzahl im dehnungskontrollierten Dauerschwingversuch / Low-cycle fatigue tests with constant true-strain amplitude, correlation of fatigue life and total plastic-strain hysteresis energy to fracture / La corrélation entre l’énergie de rupture et la durée de vie dans l’essai de fatigue à amplitudes constantes de l’allongement vrai

Materials Testing ◽

10.1515/mt-1968-100502 ◽

1968 ◽

Vol 10 (5) ◽

pp. 151-154

Author(s):

Istvan Havas

Keyword(s):

Fatigue Life ◽

Plastic Strain ◽

Strain Amplitude ◽

Low Cycle Fatigue ◽

True Strain ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Amplitude Correlation

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Effect of Surface Finish and Loading Conditions on the Low Cycle Fatigue Life of Stainless Steel Welded Piping in PWR Environment

Volume 1A: Codes and Standards ◽

10.1115/pvp2013-97157 ◽

2013 ◽

Author(s):

Yuichi Fukuta ◽

Yuichiro Nomura ◽

Seiji Asada

Keyword(s):

Stainless Steel ◽

Fatigue Life ◽

Austenitic Stainless Steel ◽

Surface Finish ◽

Loading Condition ◽

Low Cycle Fatigue ◽

Complex Loading ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Effect Of Surface

NUREG/CR-6909 of USA and JSME of Japan proposed new rules for evaluating environmental effects in fatigue analyses of reactors components. These rules were established from a lot of fatigue data with polished specimens under simple loading condition. The effects of surface finish or complex loading condition were reported in some papers, but these data were obtained with the simple shaped specimens. In order to evaluate the effects of surface finish and loading condition and to confirm the applicability of the proposed rules to actual components, Low Cycle Fatigue tests are performed in PWR environment with the specimens cut from 316 austenitic stainless steel welded piping. The pipes are machined to have three levels of surface finish condition and the load pattern simulating the thermal stress is applied to specimens. In this study, the effect of surface finish on fatigue life is included to be small for 316 austenitic stainless steel welded piping. Considering the insensitive region in the current evaluation rule, predicted accuracy is increased and possibility of improving the current rule is indicated.

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