Relationship of the spacing of the fatigue striations to the range in the stress intensity factor

1985 ◽  
Vol 21 (2) ◽  
pp. 144-152 ◽  
Author(s):  
L. R. Botvina ◽  
L. V. Limar'
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fatigue Striations ◽  
Relationship Of

The Numerical Analysis and Experimental Study of the Stress Intensity Factor and Outer Surface Strain of the Pressure Pipe with Internal Longitudinal-Cracks

2016 ◽  
Vol 853 ◽  
pp. 221-225
Author(s):  
Jia Sheng He ◽  
Meng Qi Yan ◽  
Xiao Ming Zhu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Outer Surface ◽  
Crack Size ◽  
Surface Strain ◽  
Strain Variation ◽  
Pressure Pipe ◽  
Longitudinal Cracks ◽  
Relationship Of

The strain characteristics in the outer surface of the pipe and the stress intensity factor in crack front with internal longitudinal-cracks were analyzed by the finite element method. According to the results of analysis, the outer surface strain variation to crack size was got and the relationship of stress intensity factor and crack size was known. Based on resistance strain gauges and fiber optic sensing technology, pressure pipe crack extension monitoring device was designed and the outer surface circumferential strain were tested .The results of finite element analysis and experiment are in good agreement. The outer surface strain variation in this paper can be used to analyze the situation of internal longitudinal-cracks extension.That relationship of stress intensity factor and crack size has an important reference to the safety assessment of pipe with internal longitudinal-crack.

Research on Fractal Crack Propagation Mechanism of Hydraulic Tunnel Concrete Lining

2013 ◽  
Vol 353-356 ◽  
pp. 1704-1708
Author(s):  
Xiao Sun ◽  
Yue Qiang ◽  
Ming Jie Zhao ◽  
Kui Wang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Concrete Lining ◽  
Propagation Mechanism ◽  
Crack Propagation Mechanism ◽  
Relationship Of ◽  
The Relationship ◽  
Fractal Fracture ◽  
Fractal Crack

Based on the fractal geometry theory, the bending form of crack expansion on concrete lining of hydraulic tunnel is described, according to the model of fractal fracture, stress intensity factor of concrete lining crack of hydraulic tunnel is established. Combined with the fracture mechanics theory, the relationship of stress intensity factor on l concrete lining crack is obtained under the hypothesis of crack linear expansion and crack irregular expansion, while the stress intensity factor of latter is less than the former, which is more close to the actual circumstance and more reasonable, whose fractal dimension is obviously larger than the former. The conclusion can provide reference for the engineering design.

Damage accumulation near a hole under low cycle fatigue proceeding from measurements of local deformation response

2020 ◽  
Vol 86 (10) ◽  
pp. 46-55
Author(s):  
S. I. Eleonsky ◽  
Yu. G. Matvienko ◽  
V. S. Pisarev ◽  
A. V. Chernov
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Damage Accumulation ◽  
Stress Ratio ◽  
Low Cycle Fatigue ◽  
Accumulation Process ◽  
Stress Range ◽  
Cycle Fatigue ◽  
Deformation Response

A new destructive method for quantitative determination of the damage accumulation in the vicinity of a stress concentrator has been proposed and verified. Increase of damage degree in local area with a high level of the strain gradient was achieved through preliminary low-cycle pull-push loading of plane specimens with central open holes. The above procedure is performed for three programs at the same stress range (333.3 MPa) and different stress ratio values 0.33, – 0.66 and – 1.0, and vice versa for two programs at the same stress ratio – 0.33 and different stress range 333.3 and 233.3 MPa. This process offers a set of the objects to be considered with different degree of accumulated fatigue damages. The key point of the developed approach consists in the fact that plane specimens with open holes are tested under real operation conditions without a preliminary notching of the specimen initiating the fatigue crack growth. The measured parameters necessary for a quantitative description of the damage accumulation process were obtained by removing the local volume of the material in the form of a sequence of narrow notches at a constant level of external tensile stress. External load can be considered an amplifier enhancing a useful signal responsible for revealing the material damage. The notch is intended for assessing the level of fatigue damage, just as probe holes are used to release residual stress energy in the hole drilling method. Measurements of the deformation response caused by local removing of the material are carried out by electronic speckle-pattern interferometry at different stages of low-cycle fatigue. The transition from measured in-plane displacements to the values of the stress intensity factor (SIF) and the T-stress was carried out on the basis of the relations of linear fracture mechanics. It was shown that the normalized dependences of the stress intensity factor on the durability percentage for the first notch (constructed for four programs of cyclic loading with different parameters), reflect the effect of the stress ratio and stress range of the loading cycle on the rate of damage accumulation. The data were used to obtain the explicit form of the damage accumulation function that quantitatively describes damage accumulation process. The functions were constructed for different stress ratios and stress ranges.

A new type of cracks adding to Griffith–Irwin cracks

2019 ◽  
Vol 485 (2) ◽  
pp. 162-165
Author(s):  
V. A. Babeshko ◽  
O. M. Babeshko ◽  
O. V. Evdokimova
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Tip ◽  
Stress Concentrations ◽  
New Type

The distinctions in the description of the conditions of cracking of materials are revealed. For Griffith–Irwin cracks, fracture is determined by the magnitude of the stress-intensity factor at the crack tip; in the case of the new type of cracks, fracture occurs due to an increase in the stress concentrations up to singular concentrations.

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