scholarly journals Fatigue Characteristics of Fe-Based Shape-Memory Alloys

2020 ◽  
Vol 10 (17) ◽  
pp. 5812
Author(s):  
Ki-Nam Hong ◽  
Yeong-Mo Yeon ◽  
Won-Bo Shim ◽  
Sang-Won Ji
Keyword(s):  
Yield Strength ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Test Results ◽  
Stress Range ◽  
Type Alloy ◽  
Constant Frequency

This study reports the details of an experimental study of fatigue behavior of two types of Fe-based shape-memory alloys (Fe–SMAs). The two types of Fe–SMAs developed for this study were used to prepare specimens according to ISO 12106 standards. All fatigue tests were conducted under a constant frequency of five hertz using a universal testing machine with a capacity of 100 kN. The stress ratio applied to the test was zero, and the fatigue tests were conducted until the number of loading cycles exceeded two million, by reducing the stress range from 700 MPa by 100 MPa for each test. At stress range of 700 MPa, the number of loading cycles that has a large ultimate elongation, was greater for the B-type alloy than the A-type alloy. On the other hand, the number of loading cycles at the low stress range below the yield strength was found to be higher in the A-type alloy, which had a higher yield strength than in the B-type alloy. Additionally, by analyzing the S–N relationship and performing a first order regression analysis for the test results, it was confirmed that the fatigue limits of the A-type and B-type alloys are 473 MPa and 330 MPa, respectively.

Gigacycle Fatigue of Welded Joints of Structural Materials (A Review)

2016 ◽  
Vol 17 ◽  
pp. 14-30 ◽  
Author(s):  
Okechukwu P. Nwachukwu ◽  
Alexander V. Gridasov ◽  
Ekaterina A. Gridasova
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Structural Materials ◽  
Fatigue Tests ◽  
Material Defects ◽  
Graphite Cast Iron ◽  
Ultrasonic Fatigue ◽  
Materials Used ◽  
Fatigue Failures

This review looks into the state of gigacycle fatigue behavior of some structural materials used in engineering works. Particular attention is given to the use of ultrasonic fatigue testing machine (USF-2000) due to its important role in conducting gigacycle fatigue tests. Gigacycle fatigue behavior of most materials used for very long life engineering applications is reviewed.Gigacycle fatigue behavior of magnesium alloys, aluminum alloys, titanium alloys, spheroid graphite cast iron, steels and nickel alloys are reviewed together with the examination of the most common material defects that initiate gigacycle fatigue failures in these materials. In addition, the stage-by-stage fatigue crack developments in the gigacycle regime are reviewed. This review is concluded by suggesting the directions for future works in gigacycle fatigue.

High-cycle fatigue tests of pretensioned concrete beams

PCI Journal ◽  
2022 ◽  
Vol 67 (1) ◽  
Author(s):  
Jörn Remitz ◽  
Martin Empelmann
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Concrete Beams ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Design Methods ◽  
Test Results ◽  
Cycle Fatigue ◽  
Pretensioned Concrete ◽  
Current Design

Pretensioned concrete beams are widely used as bridge girders for simply supported bridges. Understanding the fatigue behavior of such beams is very important for design and construction to prevent fatigue failure. The fatigue behavior of pretensioned concrete beams is mainly influenced by the fatigue of the prestressing strands. The evaluation of previous test results from the literature indicated a reduced fatigue life in the long-life region compared with current design methods and specifications. Therefore, nine additional high-cycle fatigue tests were conducted on pretensioned concrete beams with strand stress ranges of about 100 MPa (14.5 ksi). The test results confirmed that current design methods and specifications overestimate the fatigue life of embedded strands in pretensioned concrete beams.

Fatigue Behavior of Cement Asphalt Emulsion Mortar

2016 ◽  
Vol 847 ◽  
pp. 25-30 ◽  
Author(s):  
Dong Mei Tian ◽  
Jian Yin
Keyword(s):  
Elastic Modulus ◽  
Yield Strength ◽  
High Speed ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Permanent Deformation ◽  
Negative Temperature ◽  
Fatigue Tests ◽  
Asphalt Emulsion ◽  
Slab Track

As one of the key components of non-ballast slab track in high speed railway, cement asphalt emulsion mortar (CAM) has low compressive strength and low elastic modulus. This makes CAM possible to be served as supporting, height-adjusting, vibration-dissipating and deformation-fitting sandwich-layer between pre-stress slab and concrete roadbed. To study the fatigue behavior of the CAM, fatigue tests were conducted at room temperature and negative temperature, respectively. The permanent strain, elastic modulus and yield strength of fatigue-tested specimens were compared to the reference one. The results showed that the small permanent deformation lead to very little displacement differences among the slab track system. Secondly, the elastic modulus and yield strength of fatigue test specimens were both higher than that of reference one. Because the fatigue process might strengthen the CAM by compacting micro-cracks. Additionally, arising from the temperature sensitivity of asphalt, viscosity behavior of asphalt mortar at room temperature is changed to brittleness behavior at negative temperature.

A Macromechanical Constitutive Model of Shape Memory Alloys Under Uniaxial Cyclic Loading

2012 ◽  
Vol 28 (3) ◽  
pp. 469-477 ◽  
Author(s):  
H. Lei ◽  
B. Zhou ◽  
Z. Wang ◽  
Y. Wang
Keyword(s):  
Cyclic Loading ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Mechanical Behavior ◽  
Shape Memory ◽  
Hysteretic Behavior ◽  
Test Results ◽  
Model Match ◽  
Number Of Cycles ◽  
The Relationship

AbstractIn this paper, the thermomechanical behavior of shape memory alloys (SMAs) subjected to uniaxial cyclic loading is investigated. To obtain experimental data, the strain-controlled cyclic loading-unloading tests are conducted at various strain-rates and temperatures. Dislocations slip and deformation twins are considered to be the main reason that causes the unique cyclic mechanical behavior of SMAs. A new variable of shape memory residual factor was introduced, which will tend to zero with the increasing of the number of cycles. Exponential form equations are established to describe the evolution of shape memory residual factor, elastic modulus and critical stress, in which the influence of strain-rate, number of cycles and temperature are taken into account. The relationship between critical stresses and temperature is modified by considering the cycling effect. A macromechanical constitutive model was constructed to predict the cyclic mechanical behavior at constant temperature. Based on the material parameters obtained from test results, the hysteretic behavior of SMAs subjected to isothermal uniaxial cyclic loading is simulated. It is shown that the numerical results of the modified model match well with the test results.

On the Fatigue of Shape Memory Alloys

2013 ◽  
Vol 594-595 ◽  
pp. 133-139 ◽  
Author(s):  
Dragos Cristian Achitei ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Andrei Victor Sandhu ◽  
Petrică Vizureanu ◽  
Alida Abdullah
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Thermal Stresses ◽  
Fatigue Behavior ◽  
Memory Loss ◽  
Maximum Load ◽  
Computing System ◽  
Fatigue Properties ◽  
Recovered Memory ◽  
Electric Contacts

When we use effectively shape memory alloys require knowledge of operational behavior at the thermal stresses and mechanical variables. Measurements performed on a CuZnAl alloy, revealed fatigue properties by considering the size of the maximum load deformation corresponding recovered memory. It requires knowledge in design fatigue behavior of shape memory alloy components after education, fatigue strength by performing partial memory loss or physical destruction. The properties of memory shape alloys recommend their use for complex mechanical applications in domains as follows medicine, robotics, aeronautics, electric contacts, actuators. Shape memory metal alloys in the construction of such installations are subject to mechanical stress, and the thermal stresses, so their inclusion in a computing system fatigue involves consideration of the function performed.

A Study on Fatigue Behavior of SM490A Steel under Low Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 142-145 ◽  
Author(s):  
Ki Weon Kang ◽  
Byeong Choon Goo ◽  
J.H. Kim ◽  
Heung Seob Kim ◽  
Jung Kyu Kim
Keyword(s):  
Fatigue Life ◽  
Low Temperature ◽  
Test Temperature ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Static Strength ◽  
Experimental Results ◽  
Railway Vehicle

This paper deals with the fatigue behavior and its statistical properties of SM490A steel at various temperatures, which is utilized in the railway vehicle. For these goals, the tensile ad fatigue tests were performed by using a servo-hydraulic fatigue testing machine at three temperatures: +20°C, -10°C and -40°C. The static strength and fatigue limits of SM490A steel were increased with decreasing of test temperature. The probabilistic properties of fatigue behavior are investigated by means of probabilistic stress-life (P-S-N) curve and they are well in conformance with the experimental results regardless of temperature. Also, based on P-S-N curves, the variation of fatigue life is investigated and as the temperature decreases, the variation of fatigue life increases moderately.

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