Microstructural Influences on the Development and Growth of Small Fatigue Cracks in the Near Threshold Regime

2005 ◽  
Vol 2 (1) ◽  
pp. 12050 ◽  
Author(s):  
JA Schneider ◽  
E Kenik
Keyword(s):  
Fatigue Cracks ◽  
Threshold Regime ◽  
Near Threshold

Evaluation of Fatigue Crack Growth Curves in Existing Codes and a Proposed Modification Based on Experimental Data of Cr-Ni-Mo-V Steel Welded Joints

2016 ◽  
Author(s):  
Yan-Nan Du ◽  
Ming-Liang Zhu ◽  
Fu-Zhen Xuan ◽  
Shan-Tung Tu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Welded Joints ◽  
Growth Curves ◽  
Crack Growth Behavior ◽  
Fatigue Assessment ◽  
Crack Growth Model ◽  
Threshold Regime ◽  
Near Threshold

A comparison of currently available codes for assessment of fatigue crack growth, including ASME (America Society of Mechanical Engineers) SEC. XI, FKM (Forchungskuratorium Maschinenbau) guideline, WES (Japan Welding Engineering Society) 2805, BS7910 and JSME (The Japan Society of Mechanical Engineers), was carried out by paying attention to the suitability of application and the easiness to obtain the parameters, based on fatigue crack growth data of Cr-Ni-Mo-V steel welded joints. Results showed that fatigue crack growth curves provided by the FKM or WES were good choice when few inputs were at hand while the curves in the BS7910, JSME and ASME were recommended for precise estimation. It was indicated that the assessment of welded joints solely by fatigue crack growth behavior at base metal part and the assessment of fatigue crack growth for the aged condition by as-received one both resulted in non-conservativeness, albeit dependent on the range of stress ratios, R. A new bilinear form of fatigue crack growth model independent of R was developed based on transition point occurred in the near-threshold regime. This constituted the bilinear approach to fatigue assessment, and thus contributed to the optimization of fatigue assessment in the near-threshold regime.

scholarly journals Mixed-mode crack tip fields in a polycrystalline aluminum alloy

2019 ◽  
Vol 300 ◽  
pp. 11004 ◽  
Author(s):  
Marcel Wicke ◽  
Angelika Brueckner-Foit
Keyword(s):  
Mixed Mode ◽  
Crack Tip ◽  
Strain Partitioning ◽  
Crack Tip Field ◽  
Polycrystalline Aluminum ◽  
Digital Twin ◽  
Crack Tip Fields ◽  
Mixed Mode Crack ◽  
Threshold Regime ◽  
Near Threshold

Carefully performed experiments with long cracks in the near-threshold regime have shown that the crack tip field of these cracks significantly deviate from the expected mode-I butterfly-shaped ones and resemble strongly to mixed-mode crack tip fields. A simulation study using a crystal plasticity (CP) approach has been utilized in order to understand this phenomenon. To this end, a digital twin of an aluminum sample fatigued in the near-threshold regime was generated with the help of electron backscatter diffraction (EBSD) and X-ray tomography. Once set-up, the digital twin was loaded in uniaxial tension using the fast spectral solver implemented in the Düsseldorf Advanced Material Simulation Kit (DAMASK). The versatility of this experimental-computational approach for studying the strain partitioning at the crack tip is demonstrated in this work.

Design and Characterization of Bulk Driven MOS Varactor based VCO at Near Threshold Regime

2018 ◽  
Author(s):  
Lalit Mohan Dani ◽  
Neeraj Mishra ◽  
Shashank Kumar Banchhor ◽  
Sandeep Miryala ◽  
Aditya Doneria ◽  
...  
Keyword(s):  
Mos Varactor ◽  
Threshold Regime ◽  
Near Threshold

Fatigue Crack Growth in Ultrafine-Grained Copper Obtained by ECAP

2014 ◽  
Vol 891-892 ◽  
pp. 1099-1104 ◽  
Author(s):  
Mandana Arzaghi ◽  
Christine Sarrazin-Baudoux ◽  
Jean Petit
Keyword(s):  
Crack Growth ◽  
Growth Rates ◽  
Fatigue Cracks ◽  
Deformation Texture ◽  
Coarse Grained ◽  
Fine Grained ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Crack Growth Rates ◽  
Threshold Regime

The propagation of long fatigue cracks in ultra fine-grained (UFG) copper obtained by equal channel angular pressing (ECAP) is investigated in the mid ΔK range and in the near threshold regime. The crack growth rates in UFG copper are substantially faster than in coarse-grained (CG) copper. A huge influence of environment is observed, with growth rates faster of more than two orders of magnitude in air compared to vacuum. The crack growth mechanisms are discussed on the basis of microfractographic observations and the deformation texture.

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