Influence of Carbon Nanotubes and Processing on Cyclic Fatigue and Final Fracture Behavior of a Magnesium Alloy

2011 ◽  
Vol 410 ◽  
pp. 3-16
Author(s):  
Tirumalai S. Srivatsan ◽  
C. Godbole ◽  
Muralidharan Paramsothy ◽  
Manoj Gupta
Keyword(s):  
Carbon Nanotubes ◽  
Fatigue Life ◽  
Magnesium Alloy ◽  
Fracture Behavior ◽  
High Cycle Fatigue ◽  
Load Ratio ◽  
Cyclic Fatigue ◽  
Unreinforced Alloy ◽  
Cycle Fatigue ◽  
Percent Improvement

Carbon nanotubes (CNT)-reinforced magnesium alloy (AZ31) was fabricated using the technique of solidification processing followed by hot extrusion. Test specimens of both the composite and the unreinforced alloy were cyclically deformed at two different load ratios spanning tension-tension loading (R = 0.1) and fully-reversed tension-compression (R= -1) loading under total stress amplitude-control. A comparison of the CNT reinforced magnesium alloy with the unreinforced counterpart revealed well over two hundred percent improvement in cyclic fatigue life at load ratio of 0.1 and about two-hundred and fifty percent improvement in the high cycle fatigue life under conditions of fully-reversed loading [R= -1.0]. At all values of maximum stress, the high cycle fatigue response of both the reinforced and unreinforced magnesium alloy was found to degrade at the lower load ratio (-1.0). The synergistic and interactive influences of reinforcement and processing on microstructural development, cyclic fatigue life and kinetics governing fracture behavior are presented and briefly discussed.

An Investigation of the High Cycle Fatigue and Final Fracture Behavior of Aluminum Alloy 2219

2008 ◽  
Vol 378-379 ◽  
pp. 207-230 ◽  
Author(s):  
T.S. Srivatsan ◽  
Satish Vasudevan ◽  
Lisa Park ◽  
R.J. Lederich
Keyword(s):  
Fatigue Life ◽  
Fracture Behavior ◽  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Load Ratio ◽  
Cyclic Stress ◽  
Cycle Fatigue ◽  
Final Fracture ◽  
Stress Load ◽  
Microstructural Effects

In this research paper, the cyclic stress amplitude controlled fatigue response and fracture behavior of an Al-Cu (Aluminum Association designation 2219) is presented and discussed. The alloy was provided as a thin sheet in the T62 temper in the fully anodized condition. A small quantity of the as-provided sheet was taken and the surface carefully prepared to remove the thin layer of anodized coating. Test specimens of the alloy, prepared from the two sheets (anodized and non-anodized), were cyclically deformed under stress amplitude control at two different load ratios with the primary objective of establishing the conjoint influence of magnitude of cyclic stress, load ratio and intrinsic microstructural effects on cyclic fatigue life and final fracture characteristics. The high cycle fatigue resistance of the alloy is described in terms of maximum stress, load ratio, and microstructural influences on strength. The final fracture behavior of the alloy sheet is discussed in light of the concurrent and mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the alloy microstructure, magnitude of cyclic stress, and resultant fatigue life.

scholarly journals Fatigue life time modelling of Cu and Au fine wires

2018 ◽  
Vol 165 ◽  
pp. 06002
Author(s):  
Golta Khatibi ◽  
Ali Mazloum-Nejadari ◽  
Martin Lederer ◽  
Mitra Delshadmanesh ◽  
Bernhard Czerny
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Load Ratio ◽  
Life Time ◽  
Material Model ◽  
Cycle Fatigue ◽  
Rate Dependency

In this study, the influence of microstructure on the cyclic behaviour and lifetime of Cu and Au wires with diameters of 25μm in the low and high cycle fatigue regimes was investigated. Low cycle fatigue (LCF) tests were conducted with a load ratio of 0.1 and a strain rate of ~2e-4. An ultrasonic resonance fatigue testing system working at 20 kHz was used to obtain lifetime curves under symmetrical loading conditions up to very high cycle regime (VHCF). In order to obtain a total fatigue life model covering the low to high cycle regime of the thin wires by considering the effects of mean stress, a four parameter lifetime model is proposed. The effect of testing frequency on high cycle fatigue data of Cu is discussed based on analysis of strain rate dependency of the tensile properties with the help of the material model proposed by Johnson and Cook.

The High Cycle Fatigue and Fracture Behavior of Friction Stir Welded Aluminum Alloy 2024

2008 ◽  
Vol 378-379 ◽  
pp. 175-206 ◽  
Author(s):  
T.S. Srivatsan ◽  
Satish Vasudevan ◽  
Lisa Park ◽  
R.J. Lederich
Keyword(s):  
Fatigue Life ◽  
Fracture Behavior ◽  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Tensile Ductility ◽  
Cyclic Stress ◽  
Cycle Fatigue ◽  
Friction Stir ◽  
Final Fracture ◽  
Microstructural Effects

In this research paper, the cyclic stress amplitude controlled fatigue response and fracture behavior of an Al-Cu-Mg alloy (Aluminum Association designation 2024) is presented and discussed. The alloy was friction stir welded in the T8 temper to provide two plates one having high tensile ductility and denoted as Plate A and the other having low tensile ductility and denoted as Plate B. Test specimens of the alloy, prepared from the two plates, were cyclically deformed under stress amplitude control at two different load ratios with the primary objective of documenting the conjoint influence of magnitude of cyclic stress, load ratio and intrinsic microstructural effects on cyclic fatigue life and final fracture characteristics. The high cycle fatigue resistance of the alloy is described in terms of maximum stress, R-ratio, and microstructural influences on strength. The final fracture behavior of the friction stir welded alloy is discussed in light of the concurrent and mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the alloy microstructure, magnitude of cyclic stress, and resultant fatigue life.

An Investigation of the Cyclic Fatigue and Final Fracture Behavior of a Titanium Alloy

2008 ◽  
Vol 378-379 ◽  
pp. 271-298 ◽  
Author(s):  
T.S. Srivatsan ◽  
Mithun Kuruvilla ◽  
Lisa Park
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Fracture Behavior ◽  
Stress Amplitude ◽  
Load Ratio ◽  
Cyclic Fatigue ◽  
Cyclic Stress ◽  
Fatigue Properties ◽  
Final Fracture ◽  
Stress Load

In this technical manuscript the cyclic stress amplitude controlled fatigue properties and fracture behavior of an emerging titanium alloy (referred to by its designation as ATI 425TM by the manufacturer) is presented and discussed. The alloy was provided as rod stock in the fully annealed condition. Test specimens of the as-received alloy were cyclically deformed under total stress amplitude control at two different stress ratios (R = 0.1 and R = 0.3) with the purpose of establishing the conjoint and mutually interactive influences of magnitude of cyclic stress, load ratio and intrinsic microstructural effects on cyclic fatigue life, final fracture behavior and viable mechanisms governing failure at the microscopic level. The high cycle fatigue resistance of this titanium alloy is described in terms of maximum stress, load ratio, and maximum elastic strain. The final fracture behavior of the alloy under cyclic loading conditions is discussed in light of the mutually interactive influences of intrinsic microstructural features, magnitude of cyclic stress, load ratio and resultant fatigue life.

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.

High Cycle Fatigue Damage Evaluation of Steel Pipelines Based on Microhardness Changes During Cyclic Loads: Part II

2018 ◽  
Author(s):  
Geovana Drumond ◽  
Bianca Pinheiro ◽  
Ilson Pasqualino ◽  
Francine Roudet ◽  
Didier Chicot
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Steel Structures ◽  
New Method ◽  
Microplastic Deformation ◽  
Surface Phenomenon ◽  
Cyclic Loads ◽  
Cycle Fatigue ◽  
Indentation Tests

The hardness of a material shows its ability to resist to microplastic deformation caused by indentation or penetration and is closely related to the plastic slip capacity of the material. Therefore, it could be significant to study the resistance to microplastic deformations based on microhardness changes on the surface, and the associated accumulation of fatigue damage. The present work is part of a research study being carried out with the aim of proposing a new method based on microstructural changes, represented by a fatigue damage indicator, to predict fatigue life of steel structures submitted to cyclic loads, before macroscopic cracking. Here, Berkovich indentation tests were carried out in the samples previously submitted to high cycle fatigue (HCF) tests. It was observed that the major changes in the microhardness values occurred at the surface of the material below 3 μm of indentation depth, and around 20% of the fatigue life of the material, proving that microcracking is a surface phenomenon. So, the results obtained for the surface of the specimen and at the beginning of the fatigue life of the material will be considered in the proposal of a new method to estimate the fatigue life of metal structures.

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