Pure shear fracture study in a brittle graphite material containing a U-notch

Abstract

A disc-type specimen containing a central bean-shaped slit, called the U-notched Brazilian disc specimen, was utilized to measure experimentally the mode II notch fracture toughness of a type of commercial polycrystalline graphite. First, 24 U-notched Brazilian disc graphite specimens were fabricated for four different notch tip radii, and the monotonic fracture tests were performed under pure mode I and pure mode II loading conditions; 12 for each loading mode. The recorded fracture loads were converted to the corresponding notch fracture toughness values, and the ratio mode II notch fracture toughness/mode I notch fracture toughness was experimentally determined. Then, assuming that the experimental values of mode I notch fracture toughness are known, the mode II notch fracture toughnesses were theoretically predicted by means of two brittle fracture criteria, namely the existing U-notched maximum tangential stress and the newly developed U-notched mean stress. A very good agreement was found to exist between the theoretical and the experimental results. Also, found in this research was that both the criteria could predict well the experimentally measured fracture initiation angles.

Ductile failure prediction of thin notched aluminum plates subjected to combined tension-shear loading

“…If the notched structural component is made of a brittle or quasi-brittle material, sudden fracture will be probable that may result in human and/or finance losses. Therefore, the lowest level of the design reliability is obtained when the structural component is weakened by a notch of great stress concentration and made of a brittle or quasibrittle material [3][4][5][6]. Due to such a weak point of brittle materials (i.e.…”

Theoretical and experimental investigation of brittle fracture in V-notched PMMA specimens under compressive loading

“…For example, the following publications can be quoted under (i) pure mode I loading [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]; (ii) mixed mode I/II loading ; (iii) pure mode II loading [39][40][41]; and (iv) mode III and mixed mode I/III loadings [42][43][44]. Most of the investigations carried out in the context of brittle fracture of notched components have been quoted in two valuable review papers [45,46].…”

Fracture assessment of VO-notches under mode II loading: Experiments and theories

“…The experimental results reported in Ref. [50] have been more recently predicted in Ref. [51] using the SED criterion.…”

“…[50], the authors tested the same specimens made of polycrystalline graphite and predicted well the notch fracture toughness ratio and the fracture initiation angle by using the UMTS and the U-notched mean stress (UMS) criteria. The experimental results reported in Ref.…”