Fracture Toughness Determination for Aluminium Alloy 2011-T6 using Tensile Notched Round Bar (NRB) Test Pieces

Fracture Toughness Determination for Aluminium Alloy 2011-T6 using Tensile Notched Round Bar (NRB) Test Pieces

While the use of notched round bar (NRB) test pieces to determine planestrain fracture toughness K Ic is not novel, relatively few authors have so far attempted this. This letter serves to report a series of such tests conducted on Al 2011-T6, a high mechanical strength, free-machining aluminium all...

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Bibliographic Details
Published in:International journal of fracture 2013-05, Vol.181 (1), p.147-154
Main Authors: Vanian, G. G., Hellier, A. K., Zarrabi, K., Prusty, B. G.
Format: Article
Language:eng
Subjects:
Aluminum
Aluminum base alloys
Automotive Engineering
Characterization and Evaluation of Materials
Chemistry and Materials Science
Civil Engineering
Classical Mechanics
Correlation
Crack propagation
Extrapolation
Fatigue (materials)
Fatigue failure
Fatigue tests
Fracture mechanics
Fracture toughness
Heat treating
Letters in Fracture and Micromechanics
Machining
Materials Science
Mechanical Engineering
Plane strain
Precracking
Round bars
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Summary:While the use of notched round bar (NRB) test pieces to determine planestrain fracture toughness K Ic is not novel, relatively few authors have so far attempted this. This letter serves to report a series of such tests conducted on Al 2011-T6, a high mechanical strength, free-machining aluminium alloy. A total of 9 specimens was used, comprising 3 specimens each of 3 different notch root radii, ρ . No fatigue precracking was carried out. A graph of apparent fracture toughness K ρ versus ρ / D was extrapolated to zero, corresponding to a fatigue pre-cracked configuration. The resulting K Ic for this alloy tested using the NRB specimens was thus found to be 27.9 MPa√m. This is a valid K Ic value, as there is only a 6.8% difference between it and the median value (26.0 MPa√m) determined previously from 67 tests using the existing ASTM E399 standard. A new geometric correlation based on ρ , D and d is proposed to linearly extrapolate K ρ values, measured on NRB specimens with arbitrary geometries (but assuming plane-strain conditions hold), back to a single value of K Ic .
ISSN:0376-9429
1573-2673