Stress intensity factors for surface cracks in round bar under single and combined loadings

Abstract

This paper numerically discusses stress intensity factor (SIE) calculations for surface cracks in round bars subjected to single and combined loadings. Different crack aspect ratios, a/b, ranging from 0.0 to 1.2 and the relative crack depth, a j D , in the range of 0.1 to 0.6 are considered. Since the torsion loading is non-symmetrical, the whole finite element model has been constructed, and the loadings have been remotely applied to the model. The equivalent SIE F& is then used to cnmbiue the individual SIF from the bending or tension with torsion loadings. Then, it is compared with the combined SIF, FgE obtained numerically using the finite element analysis under similar loadings. It is found that the equivalent SIF method successfully predicts the combined S E F i Q for Mode I when compared with F;E. However, some discrepancies between the results, determined from the two different a~c h e s ,~ it is also noted that the F$E is higher than the FgQ A.E. Ismail (€3)

Probabilistic analysis of surface crack in round bars under bending moments

“…where, F I,b is the geometrical correction factor are obtained from [5][6][7], M is the bending moment, D is the diameter of bar and a is the crack length or crack depth. Due to the uncertainties of mechanical, geometrical and loading properties, a Monte Carlo Simulation (MCS) is used in the probabilistic analysis to determine the probability of failure.…”

Mode I stress intensity factors of sickle-shaped surface cracks in round solid bars under bending moment

“…However, when a/b > 0.2, most of the SIFs located around the outer points start to decrease when compared with the SIFs closer to the central point. This behaviour is due to the fact that when the crack aspect ratio increases, the cracks appear circumferentially around the solid bar [7][8][9][10][11]. It is difficult for the circumferential cracks to experience mode I opening mechanism and therefore this reduces the SIFs.…”

“…There are several factors affecting the formation of cracks, for example material defects [1] and mechanical discontinuities [2][3][4][5][6][7][8][9][10][11][12]. There are tremendous numbers of work focused on such cracks [13][14][15][16].…”

“…The SIFs obtained from [28], were not well documented where it is hard to find the complete SIFs across the crack front. The SIFs for semi-ellipticalshaped surface cracks can be found in [8,29,30] under modes I, II and III. Therefore, the purpose of this paper is to present and analyze the stress intensity factors (SIFs) along the crack front for the sickle-shaped surface crack in round bars.…”

Stress intensity factor estimation for unbalanced rotating cracked shafts by artificial neural networks

“…So, it is common to recognize fatigue failures due to a surface crack formation and propagation, 1 which typically originate at an existing defect site in the material (such as notches, corrosion and metallurgical defects) and usually grow up following transversal planes to their longitudinal axis. 2 These kinds of breakdowns, [3][4][5] if not early detected, are often catastrophic and produce personal injuries or economic problems. For this reason, it is necessary to enable the proper maintenance at the initial damage phase, so that the structural safety and reliability are guaranteed with a minimum of costs.…”