Application of Average Stress Criterion to Fracture of Aluminium Alloys Used in Aerospace Applications
- 132 Downloads
- 3 Citations
Abstract
Aluminium has been the dominant material in the aircraft industry for a half century due to its attractive combination of light weight, strength, ductility, corrosion resistance, ease of assembly and low cost. This study covers modifications made in one of the stress fracture criteria known as the average stress criterion for accurate prediction of notched tensile strength of aluminium alloy specimen used in aerospace applications. To examine the adequacy of these modifications, fracture data for centre-cracked 2XXX, 6XXX and 7XXX aluminium alloy specimens are considered. The notched (fracture) strength estimates are found to be close to the test results. The modified average stress criterion proves to be a very simple method to predict the notched tensile strength.
Keywords
2XXX 6XXX and 7XXX aluminium alloys Centre-cracked tensile specimen Average stress criterion Failure assessment diagram Fracture strengthAbbreviations
- \({a_{\rm ca} }\)
Damage zone size
- c
Half crack length
- \({K_{\rm F} ,m,p}\)
Fracture parameters in Eq. (1)
- \({K_{\rm ASC}, \delta_{\rm aca} }\)
Fracture parameters in Eq. (8)
- \({K_Q ( {\equiv \sigma_{\rm NC}^{\infty} \sqrt{\pi \,c}})}\)
Parameter in failure assessment diagram
- \({K_{\rm max}}\)
Stress intensity factor at failure
- t
Specimen thickness
- W
Specimen width
- Y
Finite width correction factor
- \({{\sigma}}\)
Applied far-field stress
- \({\sigma_{\rm NC}^\infty}\)
Fracture strength of a wide specimen
- \({{\sigma}_{\rm NC}}\)
Fracture strength of finite width specimen
- \({{\sigma}_{\rm o}}\)
Ultimate tensile strength (unnotched strength)
- \({\sigma_{\rm f}}\)
Failure stress normal to crack
- \({\sigma_{\rm u}}\)
Nominal stress to produce plastic hinge on net section
Preview
Unable to display preview. Download preview PDF.
References
- 1.Starke Jr. E.A., Staleyt J.T.: Application of modern aluminum alloys to aircraft, Pro 9. Aerospace Sci. 32, 131–172 (1996)CrossRefGoogle Scholar
- 2.Christopher T., Sankaranarayanasamy K., Nageswara Rao B.: Fracture behavior of maraging steel tensile specimens and pressurized cylindrical vessels. Fatigue Fract. Eng. Mater. Struct. 27, 177–186 (2004)CrossRefGoogle Scholar
- 3.Christopher T., Sankaranarayanasamy K., Nageswara Rao B.: Correlating cryogenic fracture strength using a modified two-parameter method. Eng. Fract. Mech. 72, 475–490 (2005)CrossRefGoogle Scholar
- 4.Christopher T., Sankaranarayanasamy K., Nageswara Rao B.: Failure assessment of flawed steel cylinders tested under internal pressure. Steel Grips (J. Steel Relat. Mater.), 3(2), 130–137 (2005)Google Scholar
- 5.Damage Tolerant Design Handbook: A compilation of Fracture and Crack Growth Data for High Strength Alloys. Metals and Ceramics Information Center, Battelle, Columbus Laboratories, Ohio. Report No. MCIC-HB-01 (January 1975)Google Scholar
- 6.Paris, P.C.; Sih, G.C.:Stress analysis of cracks. In: Fracture Toughness Testing and Its Applications, ASTM-STP-381, pp. 30–83 (1965)Google Scholar
- 7.Lekhnitskii, S.G.: Anisotropic Plates. Translated from the second Russian Edition by S.W. Tsai and T. Cheron, Gordon and Breach, New York (1968)Google Scholar
- 8.Whitney J., Nuismer R.: Stress fracture criteria for laminated composites containing stress concentrations. J. Compos. Mater. 8, 253–265 (1974)CrossRefGoogle Scholar
- 9.Murakami Y.: Stress Intensity Factors Handbook. Pergamon Press, New York (1987)Google Scholar
- 10.Brighton H., Christopher T.: Tensile-fracture strength of heat-treated 2xxx series aluminium alloys. Mater. Sci. Res. J. 3(1/2), 23–40 (2009)Google Scholar