The Evaluation of the Effects of the Maximum Stress Intensity Factor for Fatigue Crack Opening Behavior by Finite Element Analysis

2007 ◽  
Vol 353-358 ◽  
pp. 1106-1109
Author(s):  
Hyeon Chang Choi ◽  
Hyeon Ki Choi ◽  
Jun Hyub Park
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Maximum Stress ◽  
Crack Opening ◽  
Crack Tip ◽  
Crack Tip Opening Displacement ◽  
Maximum Stress Intensity ◽  
Maximum Stress Intensity Factor

The cyclic crack tip opening displacement is well related to fatigue crack opening behavior. In this paper, we investigate the effect of the maximum stress intensity factor, Kmax, when predicting fatigue crack opening behavior using the cyclic crack tip opening displacement obtained from FEA. The commercial finite element code, ANSYS, for fatigue crack closure analysis in this study is used. We derive the prediction formula of crack opening behavior when using the cyclic crack tip displacement obtained from the FEA. The numerical prediction shows the good results regardless of stress ratios. It is confirmed that the crack opening behavior depends upon the maximum stress intensity factor Kmax.

Consideration on Fatigue Crack Growth Thresholds Under Negative Stress Ratio

2019 ◽  
Author(s):  
Kunio Hasegawa ◽  
Saburo Usami ◽  
Valery Lacroix
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Stress Ratio ◽  
Maximum Stress ◽  
Maximum Stress Intensity ◽  
Maximum Stress Intensity Factor

Abstract Fatigue crack growth thresholds ΔKth are provided by several fitness-for-service (FFS) codes. When evaluating cracked components subjected to cyclic loading, maximum stress intensity factor Kmax and/or minimum stress intensity factor Kmin are required. However, the definitions of the thresholds ΔKth under negative stress ratio R are not clearly written, except for BS (British Standards) 7910. In addition, the ΔKth are given by constant values under negative R. Fatigue crack growth rates under negative stress ratio is recommended to use maximum stress intensity factor Kmax by ASTM (American Society of Testing and Materials) E 647, because of the Kmax being close to crack driving force. Therefore, it deems that the ΔKth under negative R seems to be Kmax. This paper shows that the Kmax converted by the ΔKth are not constant values under negative R based on the survey of experimental data. The Kmax decreases with decreasing the stress ratio R. Therefore, the ΔKth for the FFS codes are less conservative. As experimental data under negative stress ratio R were taken by Kmax – Kmin, the definition of the threshold ΔKth is benefit to use Kmax – Kmin, instead of Kmax.

Observation of Crack Growth Behavior of Various Cracks in 4.762mm Diameter Silicon Nitride Balls under Cyclic Compressive Load

2019 ◽  
Vol 971 ◽  
pp. 101-105
Author(s):  
Takumi Toriki ◽  
Tomoya Matsui ◽  
Katsuyuki Kida
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Silicon Nitride ◽  
Intensity Factor ◽  
Maximum Stress ◽  
Compressive Load ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Maximum Stress Intensity ◽  
Maximum Stress Intensity Factor

In order to investigate the effect of pre-crack lengths on strength of silicon nitride balls under cyclic pressure loads, growth behavior of 600~700μm pre-cracks were compared to those of 200μm~300μm and 400~500μm pre-cracks. Furthermore, the change in initial threshold limit of the maximum stress intensity factor was discussed. It was found that the increasing ratio of stress intensity factor during N=0 and N=1000 distinguished the failure and non-failure, and pre-crack length had strong effect on the threshold limits of the increasing ratio.

Influences of Crack Face Bridging Stress and Microstructure on Fracture Toughness of Toughened Alumina Ceramics

2011 ◽  
Vol 462-463 ◽  
pp. 972-978
Author(s):  
Yoshihisa Sakaida ◽  
Hajime Yoshida ◽  
Shotaro Mori
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Opening ◽  
Stress Shielding ◽  
Crack Tip ◽  
Shielding Effect ◽  
Hot Press ◽  
Crack Face

Three types of polycrystalline alumina, one pressureless and two hot press sintered Al2O3, were used to examine the effects of the characteristics of microstructure and crack face bridging on fracture toughness. The crack opening displacements and microstructures along the pop-in crack of single edge precracked beam (SEPB) specimens were observed in situ at a constant applied stress intensity factor by scanning electron microscopy (SEM). The bridging stress distribution could be determined from the measured crack opening displacement by three-dimensional finite element analysis, and then the stress intensity factor and stress shielding effect at the crack tip could also be determined. Intergranular microcracks of toughened Al2O3 were deflected by a complicated microstructure, and crack closure due to bridging grains was observed near the crack tip. Bridging stress of Al2O3 was compressive perpendicular to the crack face and was distributed behind the crack tip. The maximum bridging stress of two hot press sintered Al2O3 was about twice as large as that of pressureless sintered Al2O3. The fracture toughness of hot press sintered Al2O3 was, therefore, higher than that of pressureless sintered Al2O3, because the total amount of bridging stress and stress shielding effect increased with increasing magnitude of microcrack deflection and the number of interlocking grains.

EFG Virtual Crack Closure Technique for the Determination of Stress Intensity Factor

2011 ◽  
Vol 250-253 ◽  
pp. 3752-3758 ◽  
Author(s):  
Xue Ping Chang ◽  
Jun Liu ◽  
Shi Rong Li
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Closure ◽  
Crack Opening ◽  
Crack Tip ◽  
Strain Energy Release ◽  
Virtual Crack Closure Technique ◽  
Opening Displacement ◽  
Closure Technique

The aim of this paper is to introduce a virtual crack closure technique based on EFG method for thread-shape crack. The cracked component is discretized and the displacement field is determined using a coupled FE/EFG method, by which EFG nodes are arranged in the vicinity of crack tip and FE elements in the remain part in order to improve computational efficiency. Two typical parameters, nodal force and crack opening displacement attached to crack tip are calculated by means of setting up an auxiliary FE zone around crack tip. Strain energy release rate (SERR), further stress intensity factor (SIF) are determined by the two parameters. The method to calculate SIF is named as virtual crack closure technique based on EFG method. It is showed by several numerical examples that using the method presented in this paper, SIF on the crack tip can be obtained accurately.

Crack Opening/Sliding Morphology and Stress Intensity Factor of Slant Fatigue Crack

2003 ◽  
Vol 2003 (0) ◽  
pp. 851-852
Author(s):  
Tashiyuki TORII ◽  
Kenichi SHIMIZU ◽  
Yasuyuki KIHARA ◽  
YOULI Ma
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Opening

scholarly journals Effect of gradient of stress intensity factor at a crack tip on fatigue crack growth and correction method for the effect

2014 ◽  
Vol 80 (815) ◽  
pp. SMM0194-SMM0194 ◽  
Author(s):  
Sho KAWATSU ◽  
Tetsuo YASUOKA ◽  
Yoshihiro MIZUTANI ◽  
Akira TODOROKI ◽  
Yoshiro SUZUKI
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Crack Tip ◽  
Correction Method
Sign in / Sign up

Export Citation Format

Share Document