Fracture toughness characterization of several aluminum alloys in semi-brittle fracture

✍ Scribed by D.L Jones; H Liebowitz; J Eftis

• Publisher: Elsevier Science
• Year: 1974
• Tongue: English
• Weight: 930 KB
• Volume: 6
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(74)90063-0

✦ Synopsis

method has recently been developed for determining a nonlinear fracture toughness parameter defined by the relation where G, is the critical elastic strain energy rate as defined by Irwin. The C term is a function of the nonlinearity of the load-displacement test record and has been evaluated using the three parameter Ramberg-Osgood approach, although other curve fitting techniques could be applied as well. The method is quite straightforward and is applicable to plane stress, plane strain and mixed mode testing although only plane stress conditions are considered in this paper. For the case of a linear load-displacement record C + 1 and G, reduces to the linear elastic result. The toughness parameter G= has been evaluated for a number of high strength ahnninum alloys and compared with published G. values for these materials. The tests were conducted on center-cracked sheets of 2014-T6, 2024-T81, 7075T6 and 7475T61 aluminum alloys under conditions of varying specimen geometry and displacement gage length. It was found that the values of 6, obtained from_displacement readings with a gage length of 2 in. generally agreed with published values of G, = &'/E. The G, values were found to vary inversely with gage length and a/w ratios. The v_uiation in values for G, is of the same order of magnitude as the scatter in published values for G,. However, G, appears to be less sensitive than G, to changes in a/w.