Fractal scaling and crack-size effects on creep crack growth

Article type: Research Article

Authors: Carpinteri, Alberto^a | Niccolini, Gianni^a | Rubino, Alessio^a;

Affiliations: [a] Department of Structural, Geotechnical and Building Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino, Italy

Correspondence: [*] Corresponding author: Alessio Rubino. E-mail: alessio.rubino@polito.it

Abstract: Scaling effects on the creep crack growth behaviour are investigated by analyzing the results of compact tension (CT) tests on different-sized notched steel specimens appearing in the literature. Creep crack growth rate data are correlated to the elastic stress-intensity factor in terms of a Paris-type law, da∕dt = C0Kq, where C0 turns out to be a crack-size dependent coefficient of proportionality. Considering specimens with the same loading configuration (CT) and the same thickness, the observed crack-size effect on the creep crack growth rate is discussed on the basis of self-similarity considerations, and geometrically interpreted in terms of fractal tortuosity of the crack profile. A size-independent formulation of the creep crack growth law correlating renormalized quantities is finally deduced and confirmed by the experimental results.

Keywords: Creep crack growth, scaling effects, incomplete self-similarity, fractal geometry, renormalization group theory

DOI: 10.3233/SFC-200260

Journal: Strength, Fracture and Complexity, vol. 13, no. 3, pp. 131-142, 2020