Notched graphite under multiaxial loading

S.M.J Razavi,F Berto,J Torgersen,M Peron

doi:10.3221/igf-esis.41.53

Abstract

Cylindrical specimens made of polycrystalline graphite and weakened by circumferential V-notches under mixed mode I/III loading were studied in this research. Different geometries of V-notches varying the notch opening angle and the notch tip radius were tested. Appling various ratios of tensile and torsion loads, the multiaxial static tests have been conducted. Averaged Strain Energy Density (ASED) criterion previously presented by the same authors is employed here for the case of tension and torsion loadings applied in combination. The fracture behavior of the tested joints under multiaxial loading has been successfully predicted using the ASED criterion.

Highlights

Due to its good compromise between thermal and mechanical properties, isostatic graphite is widely used in various industrial applications
Reviewing the published papers in the field of fracture behavior of graphite components reveals that only a limited number of researches are focused on the notch sensitivity of graphite components including the researches conducted by Bazaj and Cox [8] and Kawakami [9]
Due to the lack of information about the multiaxial behavior of graphite components in the literature, the authors aimed to investigate the static behavior of isostatic graphite subjected to multiaxial loadings which can be applied as a combination of tension and torsion with different values of the mode mixity ratios: 0.4, 0.5 and 1.0

Summary

INTRODUCTION

Due to its good compromise between thermal and mechanical properties, isostatic graphite is widely used in various industrial applications. A bulk number of the components made of graphite is subjected to loads transferred by the other parts of the structure According to this fact, numerous researches have been devoted to the fracture assessment of graphite. Considering a large variety of geometrical configurations obtained by varying the notch opening angle, notch radius and notch depth, a complete set of experimental data on cylindrical specimens subjected to combined tension and torsion loads was provided by the authors in previous paper [23]. The ASED criterion allows a sound fracture assessment of the critical load for the specific material under investigation and it can be potentially extended to other types of graphite and brittle materials subjected to different combinations of mode I and mode III loading conditions. The formulation and application of the ASED criterion is presented on the experimental data

FRACTURE EXPERIMENTS

Plain specimens

Tensile Torque σnom

SED APPROACH IN FRACTURE ANALYSIS OF THE TESTED GRAPHITE SPECIMENS

Findings

CONCLUSIONS