3D Characterization of Mixed-Mode Fracture Toughness of Materials Using a New Loading Device

Abstract

In this paper, a new loading device was employed to conduct a mixed-mode fracture test. Therefore, disadvantages detected in the previous mixed-mode fracture toughness test methods can be avoided. The new fixture has perfect symmetry which provides a uniform stress state, creates the pure plane strain conditions and eliminates the unwanted mode-III loading conditions. The values of non-dimensional stress intensity factors for pure mode-I, pure mode-II, and pure mode-III were obtained using 3D models of new loading device and modified Arcan method in order to compare the results and investigate the variation of fracture parameters. Furthermore, the values of correction factors for pure mode-III in various loading angles were studied for both fixtures and it was resulted that in modified Arcan device there was a larger contribution of unwanted third mode loading conditions and therefore the values of mode-I and mode-II non-dimensional stress intensity factors were affected. In the present study, in order to compare the results, the fracture toughness values of ABS (Acrylonitrile butadiene styrene) polymeric material were determined experimentally for both fixtures and a full range of mixed-mode loading conditions including pure mode-I and pure mode-II loading were created and tested. The differences in critical stress intensity factors of the fixtures were found about 7.00% and 42.65% in mode-I and mode-II loading conditions, respectively. ness for three modes of loading (I, II and III) and also under mixed-mode loading conditions. Some of these methods include: the double cantilever beam (DCB) and the end notched flexure (ENF) specimens have been employed for mode-I and mode II tests, respectively (Davidson et al. 2012, Shokrieh and Heidari 2011, Zacharopoulos 2004. A crack rail shear (CRS) specimen has been proposed to determine the mode-III (tearing) critical strain energy release rate by Becht and Jr (1988). The mixed-mode bending (MMB) test has been proposed by combining the schemes used for DCB and ENF tests, which can produce a wide range of the ratios of mode-I and mode-II components by varying the lever arm of the specimen. A modified MMB test method was used for evaluation of the interlaminar fracture toughness of AS4/PEEK composite material by Reeder (1990), Reeder and Crews (1990). Furthermore, MMB test method was recently used for investigation of crack propagation in adhesively bonded joints by Ben Salem et al. (2014). Researchers like Verma et al. (1995) and Dharmawan et al. (2006) evaluated the fracture toughness of composite materials by using DCB, ENF and MMB specimens. However, for all these test methods there are problems in that a wide range of mixed-mode ratios cannot be tested which limits their usefulness (Reeder and Crews 1990). But in order to obtain reliable results for interlaminar fracture toughness for pure mode-I, pure mode-II, and mixed-mode loading conditions, different beam type specimens would be required. It is therefore necessary to develop other test methods to eval...

Experimental and numerical investigation of the effect of temperature on mixed‐mode fracture behaviour of AM60 Mg alloy

“…The modified Arcan fixture could create all in‐plane loading modes, ie, from mode I to mode II. In an attempt to resolve defects of previous versions, the authors have presented this modified version in 2014 . The device can be used to test butterfly specimens of different sizes.…”

“…In an attempt to resolve defects of previous versions, the authors have presented this modified version in 2014. 31,32 The device can be used to test butterfly specimens of different sizes. The geometry used in this research was in accordance with the geometry proposed by Arcan.…”

An investigation on the effects of equal channel angular pressing on the mixed‐mode fracture toughness and mechanical properties of 6063 aluminium alloy

“…38 A typical load curve and compliance lines for mixed-mode loading at α = 60 ∘ are presented in Figure 13. The average values of the critical fracture loads were used to determine critical mixedmode SIF.…”

“…The values of unwanted mode III SIF are negligible due to the perfect symmetry of modified Arcan fixture. 38 A typical load curve and compliance lines for mixed-mode loading at α = 60 ∘ are presented in Figure 13.…”

Investigation on the Effect of Different Pre-Cracking Methods on Fracture Toughness of RT-PMMA

“…et al 2010, Peres F.M. et al 2014, Oskui, A.E. et al 2016, Yan J. et al 2008, Wei Y. et al 1990, Hashemi S. & Williams J.…”