Brittle fracture in V-notches with end holes

Abstract

In the present research, two brittle fracture criteria were developed in terms of the notch stress intensity factors to predict mode I fracture in engineering components weakened by V-notches with end holes (VO-notches). The criteria were based on the point stress and the mean stress failure concepts. To evaluate the validity of the criteria, first, 36 new fracture tests were conducted on a new notched specimen, namely the Brazilian disk containing central V-notch with end hole (VO-BD specimen) made of polymethyl-metacrylate. Three notch angles and four notch radii were considered in the experiments. Then, the experimentally obtained fracture loads were converted to the corresponding mode I notch fracture toughness values by mean of the finite element method in order to compare the test results with the theories. It was found that very good agreement exists generally between the experimental and theoretical results. Also, found in this research was that by increasing the VO-notch angle, the accuracy of the mean stress criterion decreases, particularly for larger notch radii. Although the accuracy of the criteria depends significantly on the notch geometry, except for the angle 90°, the average discrepancies of the mean stress criterion were less than 8.5% as well as those of the point stress criterion for the entire angles showing acceptable accuracy of the predictions.

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].…”

Large plasticity induced crack initiation from U-notches in thin aluminum sheets under mixed mode loadin

“…The critical stress c  for brittle materials has been successfully shown in the literature to be equal to the tensile strength of material (Ayatollahi & Torabi, 2010a, 2010bTorabi, 2013d;Torabi et al, , 2014dTorabi & Amininejad, 2015aTorabi & Pirhadi 2015;Torabi & Abedinasab, 2015a. In order to eliminate c  from Eq.…”

“…Moreover, because EMC acts as a bridge between the linear elastic and elastic-plastic analyses, it is expected that it can basically be linked to various brittle fracture criteria, e.g. the maximum tangential stress (MTS) and mean stress (MS) (Ayatollahi & Torabi, 2010a, 2010bTorabi, 2013d;Ayatollahi et al, 2011aAyatollahi et al, , 2011bAliha & Ayatollahi 2013;Mirsayar et al 2014;Torabi et al, , 2014dTorabi & Amininejad, 2015aTorabi & Pirhadi 2015;Torabi & Abedinasab, 2015a criteria, the averaged strain energy density (ASED) criterion (Lazzarin & Zambardi, 2001;Berto & Lazzarin, 2014;Torabi et al, , 2015cBerto & Barati, 2011;Gomez et al, 2007Gomez et al, , 2009aGomez et al, , 2009bBerto et al, 2007Berto et al, , 2012Berto & Ayatollahi, 2011;Berto & Lazzarin, 2009;Aliha et al 2016), the cohesive zone model (CZM) (Gomez et al, 2000(Gomez et al, , 2006Gomez & Elices, 2003;Cendon 42 et al, 2015) and the finite fracture mechanics (FFM) (Sapora et al, 2013(Sapora et al, , 2015Cornetti et al, 2012Cornetti et al, , 2014Weißgraeber & Becker, 2013;Carpinteri et al, 2008) etc. under different in-plane loading conditions.…”

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

“…The most recent work on brittle fracture analysis of VO-notches is certainly that published in Ref. [59]. The authors, first, carried out extensive mode I fracture tests on the VO-notched Brazilian disk (VO-BD) specimens made of PMMA for different notch angles and various notch radii [59].…”