Stress Intensity Factor Approximations for Cracks Located at the Thread Root Region of Fasteners

2009 ◽  
pp. 108-108-18 ◽  
Author(s):  
RC Cipolla
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Root Region ◽  
Thread Root

Comparison of Methods for Calculating Stress Intensity Factors for a Closure Thread

2002 ◽  
Author(s):  
David P. Kendall
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Continuous Distribution ◽  
Intensity Factors ◽  
Plane Normal ◽  
Proposed Modification ◽  
Thread Root ◽  
Distribution Of Stress

Non-mandatory Appendix D of Section VIII, Division 3 of the ASME Boiler and Pressure Vessel Code [2] provides a method for calculating the stress intensity factors for the region of a thread root of a threaded closure. This method involves calculation of the distribution of stress acting on a plane normal to the axis of the thread. This distribution is fitted with several different cubic equations for different regions and the coefficients of these cubic equations are entered into an equation to calculate the distribution of stress intensity factor for each region. The values of stress intensity factor for each region after the first one are shifted to obtain a continuous distribution. Neubrand and Burns, 1999 [1] determined the distribution of stress intensity factor for a specific closure thread using weight function methods. In the present paper the stress intensity factors for this same closure design were calculated using the method from Appendix D of Division 3 as described above. Distributions are also calculated using a proposed modification of this method, and also by the method given in Appendix D for cracks in areas of the vessel at which the gradient of the stress distribution is less steep.

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.

scholarly journals New Approaches on the Stress Intensity Factor Characterization - Review

2020 ◽  
Vol 28 ◽  
pp. 226-233
Author(s):  
Behzad V. Farahani ◽  
Francisco Q. de Melo ◽  
Paulo J. Tavares ◽  
Pedro M.G.P. Moreira
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
New Approaches
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