Fractal scaling and specimen-size effects on creep resistance

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: [email protected]

Abstract: Scaling effects governing the creep behaviour of unnotched and uncracked metallic specimens are investigated by applying similarity considerations and fractal modelling to experimental results provided in the literature. The focus is on stress rupture tests conducted at elevated temperatures on Cr-Mo-V steel cylindrical bars of different sizes. The observed specimen-size effects on the 𝜎 versus tR creep resistance diagrams are interpreted in terms of incomplete self-similarity and fractal weakening (lacunarity) of the specimen reacting cross-section. That leads to a scale-invariant (fractal) formulation of the creep rupture law in terms of renormalized stress.

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

DOI: 10.3233/SFC-200259

Journal: Strength, Fracture and Complexity, vol. 13, no. 2, pp. 105-114, 2020