High-strain low-endurance fatigue behaviour of AISI 1018 steel in reversed torsion

1969 ◽  
Vol 4 (1) ◽  
pp. 45-47 ◽  
Author(s):  
L J Nypan
Keyword(s):  
Fatigue Life ◽  
Shear Strain ◽  
Strain Hardening ◽  
Cross Section ◽  
High Strain ◽  
Circular Cross Section ◽  
Cyclic Strain ◽  
Fatigue Behaviour ◽  
Cyclic Shear ◽  
Hardening And Softening

Experiments in repersed torsion of AISI 1018 solid-steel specimens of circular cross-section are reported. Cyclic strain hardening and softening were observed. The relations between shear strain and fatigue life and between cyclic shear strees and strain are presented.

Influence of Temperature on the Strain Controlled Fatigue Behaviour of Alloy 690 Tube Material

2004 ◽  
Author(s):  
Guocai Chai ◽  
Ping Liu ◽  
Johan Frodigh
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Strain Hardening ◽  
Fatigue Crack Initiation ◽  
Cyclic Strain ◽  
Fatigue Behaviour ◽  
Tube Material ◽  
Influence Of Temperature ◽  
Alloy 690 ◽  
Influence Of Temperature On

Strain controlled fatigue tests for hot-extruded tube material of Alloy 690 (Sandvik Sanicro 69) have been performed at room temperature (RT) and at elevated temperature (204°C). The influences of temperature on the cyclic deformation behaviour and the fatigue life have been investigated. The influence of temperature on the fatigue life is relatively small in the temperature range investigated. However, the fatigue behaviour at elevated temperature is quite different from that at RT. A second cyclic strain hardening was observed at 204°C. The possible mechanisms have been investigated using transmission electron microscopy. Besides dislocation mechanism, the interactions between moving dislocations and stacking faults and between interstitial atoms and moving dislocations could also contribute to this secondary cyclic strain hardening. The formation of micro-twins during cyclic loading at 204°C and its influence on the cyclic stress-strain response were also discussed. Temperature affects both fatigue crack initiation and propagation behaviour. Increase in temperature promotes duplex slipping process, which causes the formation of striation.

scholarly journals Effect of Rise and Fall Time on Dwell Fatigue Behavior of a High Strength Titanium Alloy

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 914 ◽  
Author(s):  
Qingyuan Song ◽  
Yanqing Li ◽  
Lei Wang ◽  
Ruxu Huang ◽  
Chengqi Sun
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Cross Section ◽  
Fatigue Behavior ◽  
Circular Cross Section ◽  
High Strength ◽  
Initiation Mechanism ◽  
Fall Time ◽  
Dwell Fatigue

Frequency is an important factor influencing the fatigue behavior. Regarding to the dwell fatigue, it corresponds to the effect of rise and fall time, which is also an important issue especially for the safety evaluation of structure parts under dwell fatigue loading, such as the engines of aircrafts and the pressure hulls of deep-sea submersibles. In this paper, the effect of rise and fall time (2 s, 20 s, 110 s, and 200 s) on the dwell fatigue behavior is investigated for a high strength titanium alloy Ti-6Al-2Sn-2Zr-3Mo-X with basket-weave microstructure. It is shown that the dwell fatigue life decreases with increasing the rise and fall time, which could be correlated by a linear relation in log–log scale for both the specimen with circular cross section and the specimen with square cross section. The rise and fall time has no influence on the crack initiation mechanism by the scanning electron microscope observation. The cracks initiate from the specimen surface and all the fracture surfaces present multiple crack initiation sites. Moreover, the facet characteristic is observed at some crack initiation sites for both the conventional fatigue and dwell fatigue tests. The paper also indicates that the dwell period of the peak stress reduces the fatigue life and the dwell fatigue life seems to be longer for the specimen with circular cross section than that of the specimen with square cross section.

Upper Bound Analysis of the ECAE Process by Considering Circular Cross-Section and Strain Hardening Materials

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
C. J. Luis Pérez ◽  
R. Luri
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Strain Hardening ◽  
Cross Section ◽  
Upper Bound ◽  
Equal Channel Angular Extrusion ◽  
Circular Cross Section ◽  
Experimental Tests ◽  
Extrusion Force ◽  
Deformation Processes

Severe plastic deformation processes have a great deal of importance because of the improvement in mechanical properties of the processed parts as a consequence of the grain size reduction in the material due to the accumulation of deformation. One of the main severe plastic deformation (SPD) processes is called the equal channel angular extrusion (ECAE). Although a large amount of studies, which deal with experimental analysis of processed parts exist, few studies dealing with the force required to perform the process have been developed. In this study, an analytical modeling of the force required to perform the ECAE process has been developed using the upper bound method (UBM). The analytical equations developed take into account the material strain hardening and the ECAE dies with circular cross-section. Moreover, the experimental tests have been performed and the extrusion force has been measured. The UBM and experimental results have been compared showing a great deal of agreement.

High-Temperature cumulative damage for stage I crack growth

1977 ◽  
Vol 12 (4) ◽  
pp. 253-261 ◽  
Author(s):  
K J Miller ◽  
T Gardiner
Keyword(s):  
Shear Strain ◽  
High Strain ◽  
Strain Range ◽  
Fatigue Tests ◽  
Cumulative Damage ◽  
Stage I ◽  
Shear Strain Rate ◽  
Cyclic Shear ◽  
Environmental Processes ◽  
Accumulation Of Damage

The effects of cyclic shear strain-range, shear strain-rate and temperature on the accumulation of damage during constant and variable shear strain range fatigue tests on a 1 per cent Cr-Mo-V steel are reported. The hypothesis of linear accumulation of damage and the summation of cyclic fractions to unity are shown to be incorrect for interactions of time, cyclic and environmental processes which are considered in detail. Stage I cracks may be accelerated, retarded or stopped and new cracks nucleated. Nevertheless only 8 per cent of the cumulative damage tests in the high strain fatigue regime gave unsafe linear summation factors less than 0.8. None fell below 0.7.

Normalized behavior of offshore clay under uniform cyclic loading

1988 ◽  
Vol 25 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Mladen Vucetic
Keyword(s):  
Cyclic Loading ◽  
Shear Strain ◽  
Cyclic Strain ◽  
Cyclic Behavior ◽  
Repeated Loading ◽  
Fundamental Parameter ◽  
Test Model ◽  
Backbone Curve ◽  
Cyclic Shear

A method for characterization of normally consolidated and overconsolidated clay subjected to undrained constant shear strain amplitude cyclic loading is presented and verified. The method is based on laboratory evidence that shows that clays exhibiting static normalized behavior with respect to the vertical consolidation stress, i.e., along the lines of the SHANSEP method, also exhibit a similar cyclic normalized behavior. The method is illustrated by cyclic results obtained on an offshore clay for the range of overconsolidation ratio (OCR) from 1 to 4, and is verified by predicting the initial backbone curve, cyclic stiffness degradation, and pore pressure variation for the same clay for OCR = 1.4. The predicted behavior for OCR = 1.4 successfully describes the corresponding laboratory results. Also, very consistent relationships between cyclic shear strain and other cyclic parameters obtained by means of cyclic strain-controlled testing in this and other similar studies confirm that the cyclic shear strain is probably the most fundamental parameter governing the undrained cyclic behavior of clay. Key words: clay, laboratory test, model, ocean soil, overconsolidation, soil dynamics, repeated loading, simple shear test.

SAF file: It's really three dimensional file

2018 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Prof. Dr. Jamal Aziz Mehdi
Keyword(s):  
Cross Section ◽  
Root Canal ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Circular Motion ◽  
Root Canal Treatment ◽  
Metal Core ◽  
Rotating Blade

The biological objectives of root canal treatment have not changed over the recentdecades, but the methods to attain these goals have been greatly modified. Theintroduction of NiTi rotary files represents a major leap in the development ofendodontic instruments, with a wide variety of sophisticated instruments presentlyavailable (1, 2).Whatever their modification or improvement, all of these instruments have onething in common: they consist of a metal core with some type of rotating blade thatmachines the canal with a circular motion using flutes to carry the dentin chips anddebris coronally. Consequently, all rotary NiTi files will machine the root canal to acylindrical bore with a circular cross-section if the clinician applies them in a strictboring manner

Sign in / Sign up

Export Citation Format

Share Document