Observations on comparable aluminium alloy crack growth curves: additively manufactured Scalmalloy® as an alternative to AA5754 and AA6061-T6 alloys?

A comparison of currently available codes for assessment of fatigue crack growth, including ASME (America Society of Mechanical Engineers) SEC. XI, FKM (Forchungskuratorium Maschinenbau) guideline, WES (Japan Welding Engineering Society) 2805, BS7910 and JSME (The Japan Society of Mechanical Engineers), was carried out by paying attention to the suitability of application and the easiness to obtain the parameters, based on fatigue crack growth data of Cr-Ni-Mo-V steel welded joints. Results showed that fatigue crack growth curves provided by the FKM or WES were good choice when few inputs were at hand while the curves in the BS7910, JSME and ASME were recommended for precise estimation. It was indicated that the assessment of welded joints solely by fatigue crack growth behavior at base metal part and the assessment of fatigue crack growth for the aged condition by as-received one both resulted in non-conservativeness, albeit dependent on the range of stress ratios, R. A new bilinear form of fatigue crack growth model independent of R was developed based on transition point occurred in the near-threshold regime. This constituted the bilinear approach to fatigue assessment, and thus contributed to the optimization of fatigue assessment in the near-threshold regime.

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Preparation of diffusion bonding and adhesive bonding of aluminium alloy specimens for fracture toughness and fatigue crack growth resistance measurements in different orientationsHariprasad, S., Sastry, S.M.L., and Jerina, K.L. Mater. Sci. Eng. A (Sept. 1993) A169(1–2), L13–L16

International Journal of Fatigue ◽

10.1016/0142-1123(94)90558-4 ◽

1994 ◽

Vol 16 (8) ◽

pp. 592-592

Keyword(s):

Fracture Toughness ◽

Fatigue Crack ◽

Fatigue Crack Growth ◽

Aluminium Alloy ◽

Crack Growth ◽

Diffusion Bonding ◽

Adhesive Bonding ◽

Crack Growth Resistance ◽

Fatigue Crack Growth Resistance

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Predicting the Effects of Overloads on Fatigue Crack Growth in an Al-SiC MMC Using a Computational Model

Journal of Engineering Materials and Technology ◽

10.1115/1.1647126 ◽

2004 ◽

Vol 126 (2) ◽

pp. 172-178

Author(s):

M. S. Bruzzi ◽

P. E. McHugh

Keyword(s):

Crack Growth ◽

Growth Curves ◽

Cyclic Stress ◽

Crack Growth Behavior ◽

Matrix Composites ◽

Modeling Approach ◽

Sic Particles ◽

The Impact ◽

Modelling Approach ◽

Fatigue Modeling

A defect tolerant approach to fatigue modeling for constant amplitude loading was developed by Bruzzi and McHugh (2002) and applied to two metal matrix composites: (1) a forged 2124 Al reinforced with 17 percent SiC particles and (2) a cast 359 Al reinforced with 20 percent SiC particles MMC in Bruzzi and McHugh (2003). In reality, however, engineering components are invariably subjected to varying cyclic stress amplitudes. In order to investigate the suitability of extending the fatigue modelling approach developed to variable amplitude loading, the effects of single and periodic peak tensile overloads are investigated in this work for the case of the Al 2124 MMC. The effects of overloads in causing significant changes to the level of closure in the wake of the crack tip, following the overload, in addition to changes in the nominally applied stress amplitude are firstly discussed in an overview. The quantification of the effects of overloads by use of experimental “resistance to crack growth curves” and the extension of the fatigue modeling approach to account for these effects are then described and investigated. Finally the predicted results of the impact of overloads on the short crack growth behavior of the Al 2124 MMC are presented and discussed. The extension of the fatigue modeling approach to account for the effects of overloads provides an additional means of validating the modelling approach developed by Bruzzi and McHugh (2002, 2003).

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