Abstract
Dimensionless stress-intensity factors were determined for single-edge-crack solid and hollow round bars loaded in bending. These factors were calculated from experimental compliance (inverse slope of load-displacement curve) measurements made on round bars loaded in three-point bending. The compliance specimens had span to diameter ratios of 6.67 and 3.33, and measurements were made over a range of dimensionless crack lengths from 0.002 to 0.70. The tests were made using 3-in. (76-mm) and 6-in. (152-mm) solid and hollow round bars notched on one side; the hollow bars had an inner to outer diameter ratio of 0.33. A comparison was made with data in the literature for rectangular bars; for ana/D of 0.0001, the dimensionless stress-intensity factor for a solid round bar is 1.3 vs. 2.0 for a rectangular bar.
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Abbreviations
- a :
-
crack length or notch depth
- A :
-
area of cracked surface
- b :
-
coefficient-of-compliance curve-fitting equation
- B :
-
width of cracked front
- c :
-
compliance,v/P
- COD :
-
cracking-opening-displacement
- D :
-
diameter of round bar
- E :
-
Young's modulus, used 10.6×106 psi (73.1×103 MPa) for aluminum
- G :
-
energy-release rate
- I :
-
moment of inertia
- ID :
-
inner diameter of hollow round bar
- K I :
-
plane strain-stress intensity factor
- l :
-
one-half of the support span
- M :
-
bending moment
- μ:
-
Poisson's ratio, 0.32 for aluminum
- n :
-
exponent-of-compliance curve-fitting equation
- P :
-
load
- S :
-
support span of bend specimen
- σ:
-
stress
- SEC-RBB :
-
single-edge crack-round bend bar
- T :
-
thickness of rectangular bar
- U :
-
total strain energy of elastic deformation in specimen
- v :
-
displacement
- W :
-
width of rectangular bar
- Y′, Y :
-
dimensionless stress-intensity factors; the prime sign indicates a different form
References
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Bush, A. J. and Wilson, W. K., “Determination Of Energy Release Rate For Biaxial Brittle Fracture Specimen,” (Available from DDC as AD611659) (Aug. 1964).
Bluhm, J. I., “The Effects Of Non-Linear Hertzian Deformations And Of Gage Length On The Experimental Determination Of Elastic Energy Release Rate,” U.S. Army Materials Research Agency, Watertown, MA, ASTM E-24 Comm. Mtg. (June 1966).
Tada, H., Paris, P. C. and Irwin, G. R., “The Stress Analysis of Cracks Handbook,” Del Research Corporation, Appendix A (1973).
Standard Method Of Test For Plane Strain Fracture Of Metallic Materials,” E399-72, ASTM Standards, Part 31 (July 1972).
Federowicz, A. J. and Powell, B. A., “A Computer Program To Obtain Min-Max Regression Model By Linear Programming,” Westinghouse Research Report 68-1C3-COMP-R2 (July 1968).
Wilson, W. K., Private Communication, Westinghouse Research, Pgh., PA (April 1975).
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Bush, A.J. Experimentally determined stress-intensity factors for single-edge-crack round bars loaded in bending. Experimental Mechanics 16, 249–257 (1976). https://doi.org/10.1007/BF02321148
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DOI: https://doi.org/10.1007/BF02321148