1A4 Evaluation of fracture strength for sharp notch specimen by using the stress intensity factor of small crack

2014 ◽  
Vol 2014 (0) ◽  
pp. _1A4-1_-_1A4-2_
Author(s):  
Yuki SHIMODA ◽  
Kazuhiro ODA ◽  
Noriko TSUTSUMI
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fracture Strength ◽  
Small Crack ◽  
Sharp Notch

Contact between a pin and a plate with a hole under interference-fit and clearance-fit conditions

2001 ◽  
Vol 215 (6) ◽  
pp. 629-639 ◽  
Author(s):  
J P Hou ◽  
D A Hills
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Brittle Fracture ◽  
Contact Problem ◽  
Fracture Strength ◽  
Radial Crack ◽  
Radial Force ◽  
Interference Fit ◽  
Yield Criteria

The contact problem of a circular pin journalled in an almost conforming hole in a plate, and subject to a radial force, is considered. Both interference-fit and clearance-fit cases are treated, uniformly, as is the problem when the elements are elastically dissimilar, but the interface frictionless. The strength of the contact is assessed by classical yield criteria, and a calibration is given for the crack tip stress intensity factor for a radial crack, so that the brittle fracture strength may also be assessed.

Fracture Toughness of 7075-T6 and -T651 Sheet, Plate, and Multilayered Adhesive-Bonded Panels

1967 ◽  
Vol 89 (3) ◽  
pp. 503-507 ◽  
Author(s):  
J. G. Kaufman
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fracture Strength ◽  
Critical Stress Intensity Factor ◽  
Critical Fracture ◽  
Strain Stress ◽  
Metallurgical Bond ◽  
The Individual

Fracture-toughness tests have been made of 7075-T6 sheet and -T651 plate and of multi-layered panels of the sheet and plate. The nominal net fracture strength and the critical fracture-toughness parameters (Kc and Gc) of multilayered adhesive-bonded panels are greater than those of sheet or plate of the same total thickness, because the individual layers may fracture independently, each developing shear surfaces. The fracture strength and critical stress intensity factor, Kc, for a 0.5-in. thick panel made up of eight layers of 0.063-in. sheet are approximately twice those of 0.5-in. plate. Multilayered metallurgically bonded panels do not exhibit any advantage over sheet or plate of the same thickness, if the metallurgical bond retards shear-surface formation on the individual layers. The plane-strain stress-intensity factor, determined at pop-in on multi-layered adhesive-bonded or metallurgically bonded panels, is independent of thickness or number of layers.

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.

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