PSBs and Non-Propagation of Small Surface and Interior Cracks in Polycrystalline Copper

2013 ◽  
Vol 592-593 ◽  
pp. 777-780 ◽  
Author(s):  
Stefanie E. Stanzl-Tschegg ◽  
Bernd M. Schönbauer
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Lower Stress ◽  
Small Surface ◽  
Loading Method ◽  
Very High Cycle Fatigue ◽  
Small Cracks ◽  
Number Of Cycles ◽  
Very High

PSB formation and its relevance for an eventual fatigue limit of polycrystalline electrolytic copper was studied in the very-high cycle fatigue regime with the ultrasound fatigue loading method. PSBs are formed at much lower stress/strain amplitudes than reported in earlier literature, if a high enough number of cycles is applied. Fatigue fracture takes place at approximately 50% higher amplitudes than needed for PSB formation, which is likewise in contrast to former literature results. Non-propagation of small cracks, originating from intrusions or PSB-induced non-propagating grain-boundary cracks are made responsible for this different material response.

scholarly journals Nonlinear dynamics and stages of damage of Ti6Al4V and Ti45Nb titanium alloys in very high cycle fatigue

2020 ◽  
pp. 145-153
Author(s):  
M. V Bannikov ◽  
V. A Oborin ◽  
D. A Bilalov ◽  
O. B Naimark
Keyword(s):  
Titanium Alloys ◽  
High Cycle Fatigue ◽  
Three Dimensional ◽  
Fatigue Properties ◽  
Experimental Program ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Number Of Cycles ◽  
Radial Shear Rolling ◽  
Very High

The paper presents an experimental methodology aimed at evaluating a very-high cycle resource for aviation titanium alloys Vt-6 (Ti6Al4V) and Ti45Nb for medical applications with different microstructures (large-crystal and submicrocrystalline ones). The submicrocrystalline (SMC) state was obtained by an intensive plastic deformation realized in two ways: the three-dimensional forging for Ti45Nb and radial-shear rolling for Ti6Al4V. The experimental program tests high-cycle and very-high-cycle loading (number of cycles 107-109) realized using the in situ determination method of the accumulation of the irreversible fatigue damage by analyzing nonlinear forms of feedback in a closed system ultrasonic fatigue setup. This makes it possible to establish the connection of the microscopic fatigue mechanisms with the model views and consider the stages of the damage development based on the nonlinear kinetics of the defect accumulation under cyclic loading in high- and gigacycle fatigue modes. We established various relations between changes in the amplitude of the second harmonic of vibrations of the free end of the samples with different internal structures, which are associated with the mechanisms of stress relaxation and damage accumulation. The grain size reduction in Ti45Nb alloy by the three-dimensional forging improved the fatigue properties by 1.3-1.5 times, whereas for VT-6 alloy, the radial-shear rolling method could not increase the fatigue properties in the very high cycle fatigue range, which may be caused by the presence of large residual internal stresses. Based on the scale parameters obtained earlier from the fracture surface morphology and the relations established in this work, the kinetic equations for the origin and growth of fatigue cracks in the gigacycle loading range will be constructed. This equation, based on the empirical power parameters related to the structure of the material, will allow us to determine the number of cycles for the origin of an internal crack and its growth to the surface.

Microcrack initiation mechanism of a duplex stainless steel under very high cycle fatigue loading condition: The significance of load partitioning and micro residual stresses

2020 ◽  
Vol 199 ◽  
pp. 278-287
Author(s):  
Hongwang Fu ◽  
Benjamin Dönges ◽  
Ulrich Krupp ◽  
Ullrich Pietsch ◽  
Claus-Peter Fritzen ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Residual Stresses ◽  
Loading Condition ◽  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Initiation Mechanism ◽  
Very High Cycle Fatigue ◽  
Microcrack Initiation ◽  
Very High

Inclusion initiated fracture in spring steel under axial and torsion very high cycle fatigue loading at different load ratios

2020 ◽  
Vol 134 ◽  
pp. 105525 ◽  
Author(s):  
Ulrike Karr ◽  
Yusuke Sandaiji ◽  
Ryota Tanegashima ◽  
Shogo Murakami ◽  
Bernd Schönbauer ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Spring Steel ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

Fatigue Behavior of Titanium Alloys under Very High Cycle Fatigue Loading

2018 ◽  
Vol 9 (1) ◽  
pp. 75-81 ◽  
Author(s):  
A. D. Nikitin ◽  
A. A. Shanyavskiy ◽  
N. N. Beklemishev
Keyword(s):  
Titanium Alloys ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

Evaluation of transverse crack initiation of cross-ply CFRP laminates subjected to very high cycle fatigue loading

2020 ◽  
Vol 2020 (0) ◽  
pp. 16A03
Author(s):  
Tsuyoshi MIYAKOSHI ◽  
Takeru ATSUMI ◽  
Kensuke KOSUGI ◽  
Atsushi HOSOI ◽  
Terumasa TSUDA ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Transverse Crack ◽  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Cfrp Laminates ◽  
Very High Cycle Fatigue ◽  
Very High
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