Authors: You Tang Li, Zhi Yuan Rui, Chang Feng Yan
Abstract: A uniform model, in which the crack, V-notch, U-notch and arc are described as breach
uniformly, is put forward in this paper. The tip radius, depth and field angle of breach are regarded as
the parameter of annularly breached bar. The stress field and displacement field near the tip of the
annularly breached bar under bending, in which takes fα(a/b) as its descriptive parameter, was given.
All forms of breaches according to the change of tip radius, depth and field angle were discussed. The
effects of parameters on fα(a/b) in bending were analyzed. The criteria for the safety design and
fracture design both of which on fα(a/b) were obtained. The results not only can be applied widely to
anti-fracture design but also be used for reference in anti-fatigued design in product lifecycle
management.
751
Authors: Jien Jong Chen, Yan Shin Shih
Abstract: James performed a series of experimental study on austenitic stainless steels and
suggested an equation for assessing the influences of temperature, stress ratio and loading frequency
on the fatigue crack growth rate. Authors have studied the effect of either loading frequency alone
or of temperature alone on the fatigue crack growth rate by employing the mechanical behaviors of
material. In this study, the mechanical behaviors of material are employed for evaluating the
combined effect of loading frequency and temperature. Using the derived dimensionless functions
of yielding stresses and Young’s modulus, the equation represented the combined effect of loading
frequency and temperature on fatigue crack growth rate of 304SS was proposed.
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Authors: Al Emran Ismail, Ahmad Kamal Ariffin, Shahrum Abdullah, Mariyam Jameelah Ghazali, Ruslizam Daud
Abstract: This study presents a numerical investigation on the stress intensity factors (SIF), K of surface cracks in round bars that were obtained under pure torsion loadings or mode III. ANSYS finite element analysis (FEA) was used to determine the SIFs along the crack front of surface cracks embedded in the solid circular bars. 20-node isoparametric singular elements were used around the crack tip by shifting the mid-side node ¼-position close to a crack tip. Different crack aspect ratio, a/b were used ranging between 0.0 to 1.2 and relative crack depth, a/D were ranged between 0.1 to 0.6. Mode I SIF, KI obtained under bending moment was used to validate the proposed model and it was assumed this proposed model validated for analyzing mode III problems. It was found that, the mode II SIF, FII and mode III SIF, FIII were dependent on the crack geometries and the sites of crack growth were also dependent on a/b and a/D.
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Authors: Roberto Brighenti, Andrea Carpinteri, Sabrina Vantadori
Abstract: The aim of the present paper is to evaluate the effect of residual stresses, due to cold-drawing process, on the fatigue crack propagation in a pearlitic steel wire with a V-shaped circumferential notch. In order to analyse the effect of the notch severity on the residual stress distribution, three different values of the notch root radius are examined. The residual stress distributions in the reduced cross-section of such wires are numerically evaluated through FE analyses which simulate the material removing operation in the notched region. The stress-intensity factors (SIFs) related to tension loading and residual stresses are computed. Then, the crack propagation under cyclic tension combined with the residual stresses is analysed by taking into account the above SIF values and the actual stress ratio, which is different from that due to cyclic tension only.
229
Authors: Bo Chen, You Tang Li
Abstract: The tip radius ρ, depth t and field angle α of notch and the geometrical sizes a and b of shaft are looked as descriptive parameters in the annular notched shaft. Taken the crack, blunt crack and notch as breach, the stress field and displacement field near the tip of breach which serve dimensionless factor fα(a/b) as descriptive parameter are obtained. The effects of parameters ρ, t and α to fα(a/b) are analyzed. The connections between stress intensity factor of crack and stress concentrator factor of notch, between sharp V-notch and crack, between V-notch and U-notch have been founded.
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