Predicting crack initiation site in polycrystalline nickel through surface topography changes

2019 ◽  
Vol 124 ◽  
pp. 70-81 ◽  
Author(s):  
Jalal Fathi Sola ◽  
Randall Kelton ◽  
Efstathios I. Meletis ◽  
Haiying Huang
Keyword(s):  
Crack Initiation ◽  
Surface Topography ◽  
Initiation Site ◽  
Polycrystalline Nickel ◽  
Crack Initiation Site

scholarly journals Forecast of the fatigue crack initiation site of commercially pure Titanium miniature specimens with local surface topography data

2020 ◽  
Vol 321 ◽  
pp. 11008
Author(s):  
L. Böhme ◽  
F. Ströer ◽  
A. Keksel ◽  
J. Seewig ◽  
E. Kerscher
Keyword(s):  
Grain Size ◽  
Crack Initiation ◽  
Surface Topography ◽  
Fatigue Crack Initiation ◽  
Pure Titanium ◽  
Initiation Site ◽  
Commercially Pure Titanium ◽  
Crack Initiation Site ◽  
Average Grain Size ◽  
Cp Ti

Surfaces of technical components rarely appear in perfectly smooth condition. During fatigue loading, stress concentrations at surface asperities cause localized plastic deformation that can lead to crack initiation. Therefore, we have established a computer-aided method based on material ratio curves to investigate the possibility to predict the crack initiation site in fatigue tests by using detailed information on the local surface topography. The present study shows the results of investigations on the mutual influence of the average grain size and the surface condition on the fatigue behavior of commercially pure Titanium (cp-Ti) miniature specimens. Three cp-Ti states were investigated: two types of coarse-grained cp-Ti Grade 2 with 35 µm and with 100 µm average grain size and one ultrafine-grained cp-Ti Grade 4 state with less than 2.5 µm average grain size. Confocal microscopy provided the surface topography data of all specimens and data post-processing was applied to the topography in order to locate critical areas where crack initiation may preferentially occur. These areas were compared with the actual crack initiation areas in fatigue test. Finally, scanning electron microscopy (SEM) images of the fracture surfaces were studied to analyze fatigue crack initiation site and crack path of the three microstructural states.

Analysis of the Failure of the Engine Piston of the AlSi Alloy

2017 ◽  
Vol 270 ◽  
pp. 80-85 ◽  
Author(s):  
Adéla Podepřelová ◽  
Vratislav Mareš ◽  
Martin Kraus
Keyword(s):  
Crack Initiation ◽  
Combustion Engine ◽  
Initiation Site ◽  
Damage Evaluation ◽  
Secondary Phases ◽  
Crack Initiation Site ◽  
Engine Piston ◽  
Alsi Alloy ◽  
Wide Range ◽  
Microstructure Of The Material

The aim of the article is piston damage evaluation of a highly exposed combustion engine. The analysed piston was made of an AlSi-based alloy. Atypical damage, which occurred relatively early in the lifetime of the component, was evaluated by metallographic and fractographic analyses. The analysis took into account influences of mechanical and thermal fatigue processes in relation to the microstructure of the material. The metallographic observations of the microstructure revealed the occurrence of cracks extending over the secondary phases and precipitates. Cracks were initiated on the coarser Si phase particles. The crack initiation site is located at the root of the bridge between the sealing piston rings. The damage of the piston was metallographically documented in wide range.

scholarly journals Damage-Based Assessment of the Fatigue Crack Initiation Site in High-Strength Steel Welded Joints Treated by HFMI

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 145
Author(s):  
Yuki Ono ◽  
Halid Can Yıldırım ◽  
Koji Kinoshita ◽  
Alain Nussbaumer
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Stress Relaxation ◽  
Crack Initiation ◽  
High Strength Steel ◽  
Fatigue Crack Initiation ◽  
High Strength ◽  
Initiation Site ◽  
High Peak ◽  
Crack Initiation Site

This study aimed to identify the fatigue crack initiation site of high-frequency mechanical impact (HFMI)-treated high-strength steel welded joints subjected to high peak stresses; the impact of HFMI treatment residual stress relaxation being of particular interest. First, the compressive residual stresses induced by HFMI treatment and their changes due to applied high peak stresses were quantified using advanced measurement techniques. Then, several features of crack initiation sites according to levels of applied peak stresses were identified through fracture surface observation of failed specimens. The relaxation behavior was simulated with finite element (FE) analyses incorporating the experimentally characterized residual stress field, load cycles including high peak load, improved weld geometry and non-linear material behavior. With local strain and local mean stress after relaxation, fatigue damage assessments along the surface of the HFMI groove were performed using the Smith–Watson–Topper (SWT) parameter to identify the critical location and compared with actual crack initiation sites. The obtained results demonstrate the shift of the crack initiation most prone position along the surface of the HFMI groove, resulting from a combination of stress concentration and residual stress relaxation effect.

216 Strength and Crack Initiation Site of Steel-Polyamide Adhesive Joint

2001 ◽  
Vol 2001 (0) ◽  
pp. 71-72
Author(s):  
Tetsuya AKIYAMA ◽  
Kohichi TANIMOTO ◽  
Toshio TERASAKI
Keyword(s):  
Crack Initiation ◽  
Adhesive Joint ◽  
Initiation Site ◽  
Crack Initiation Site

OS0527 Systematization of Analysis Method of Fatigue Crack Initiation Site in Pearlitic Steel Smooth Specimen

2011 ◽  
Vol 2011 (0) ◽  
pp. _OS0527-1_-_OS0527-3_
Author(s):  
Shigeru HAMADA ◽  
Daisuke SASAKI ◽  
Nobuo NAKADA ◽  
Toshihiro TSUCHIYMA ◽  
Masaharu UEDA ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Pearlitic Steel ◽  
Initiation Site ◽  
Smooth Specimen ◽  
Analysis Method ◽  
Crack Initiation Site
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