Open Access

ARTICLE

Experimental Assessment of Stress Intensity Factors in Internal Cracks under Mixed-mode Loading

C. Colombo¹, M. Guagliano^1,2, L. Vergani¹

1 Dipartimento di Meccanica, Politecnico di Milano, Via La Masa 1, 20156 Milano, ITALY.
2 Corresponding author: Tel.: +39 022399.8206; Fax.: +39 022399.8202; E-mail: mario.guagliano@polimi.it

Structural Durability & Health Monitoring 2008, 4(2), 67-76. https://doi.org/10.3970/sdhm.2008.004.067

Abstract

With the aim of experimentally assessing the stress intensity factors under mixed-mode loading along a crack front, the case of an internal elliptical crack is analyzed. An experimental test is performed on a three-dimensional photoelastic model made in epoxy resin. This model contains an inner natural crack, created by thermal shock. The crack is inclined in the cylindrical model, loaded with a tensile stress field.
Exploiting the characteristics of the epoxy resin, and using the stress freezing technique, it is possible to keep memory of the stresses near to the crack tip, once the specimen is unloaded. The final specimen is cut in slices and K_I, K_II, and especially K_III are evaluated along the crack front with particular techniques. Comparisons are finally proposedwithrespect to theanalyticalsolutionand the numerical valuesfrom a FEM model.

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Keywords

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