DETERMINATION OF PREDOMINANTLY MODE II STRESS INTENSITY FACTORS FROM ISOCHROMATIC DATA

Since the pioneering discussion by Irwin, a significant effort has been devoted to determining stress intensity factors (K) using experimental methods. Techniques have been developed to determine stress intensity factors from photoelastic, strain gage, caustics, and moire´ data. All of these methods apply to a relatively long single-ended-edge crack. To date, the determination of K for internal cracks that are double-ended by experimental methods has not been addressed. This paper describes a photoelastic study of tension panels with both central and eccentric internal cracks. The data recorded in the experiments was analyzed using a new series solution for the opening-mode stress intensity factor for an internal crack. The data was also analyzed using the edge-crack series solution, which is currently employed in experimental studies. Results indicated that the experimental methods usually provided results accurate to within three to five percent if the series solution for the internal crack was employed in an overdeterministic numerical analysis of the data. Comparison of experimental results using the new series for the internal crack and the series for an edge crack showed the superiority of the new series.

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Experimental Determination of Side Boundary Effects on Stress Intensity Factors in Surface Flaws

Journal of Engineering Materials and Technology ◽

10.1115/1.3443259 ◽

1975 ◽

Vol 97 (1) ◽

pp. 45-51 ◽

Cited By ~ 11

Author(s):

M. Jolles ◽

J. J. McGowan ◽

C. W. Smith

Keyword(s):

Stress Intensity ◽

Crack Length ◽

Taylor Series ◽

Stress Intensity Factors ◽

Taylor Series Expansion ◽

Correction Method ◽

Intensity Factors ◽

Surface Flaws ◽

Plate Width

A technique consisting of stress-freezing photoelasticity coupled with a Taylor Series Expansion of the maximum local in-plane shearing stress known as the Taylor Series Correction Method (TSCM) is applied to the determination of stress intensity factors (SIF’s) in flat bottomed surface flaws of flaw depth/length ratios of approximately 0.033. Flaw depth/thickness ratios of approximately 0.20 and 0.40 were studied as were plate width/crack length ratios of approximately 2.33 and 1.25, the former of which corresponded to a nearly infinite width. Agreement to well within 10 percent was found with the Rice-Levy and Newman theories using a depth-modified secant correction and equivalent flaw depth/length ratios. The Shah-Kobayashi Theory, when compared on the same basis, was lower than the experimental results. Using a modified net section stress correction suggested by Shah, agreement with the Shah-Kobayashi Theory was greatly improved but agreement with the other theories was poorer. On the basis of the experiments alone, it was found that the SIF was intensified by about 10 percent by decreasing the plate width/crack length from 2.33 to 1.25.

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Crack Propagation in Rolling Line Contacts

Journal of Tribology ◽

10.1115/1.2920937 ◽

1992 ◽

Vol 114 (4) ◽

pp. 690-697 ◽

Cited By ~ 38

Author(s):

H. Salehizadeh ◽

N. Saka

Keyword(s):

Stress Intensity ◽

Crack Propagation ◽

Stress Intensity Factors ◽

Mode Ii ◽

Pure Mode ◽

Intensity Factors ◽

Crack Face ◽

Normal Loading ◽

Line Contacts ◽

Crack Growth Model

The stress intensity factors for short straight and branched subsurface cracks subjected to a Hertzian loading are calculated by the finite element method. The effect of crack face friction on stress intensity factors is considered for both straight and branched cracks. The calculations show that the straight crack is subjected to pure mode II loading, whereas the branched crack is subjected to both mode I and mode II, with ΔKI/ΔKII < 0.25. Although KI is small, it strongly influences KII by keeping the branched crack faces apart. Based on the ΔKII values and Paris’s crack growth model, the number of stress reversals required to grow a crack in a rolling component from an initial threshold length to the final spalling length was estimated. It was found that the crack propagation period is small compared with the expected bearing fatigue life. Therefore, crack propagation is not the rate controlling factor in the fatigue failure of bearings operating under normal loading levels.

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