On the comparison of two mixed-mode I + III fracture test specimens

In this paper, extensive three-dimensional finite element analysis is conducted to study the asymmetric four-point shear (AFPS) specimen: a widely used mixed mode I/II fracture test specimen. Complete solutions of fracture mechanics parameters KI, KII, KIII, T11, and T33 have been obtained for a wide range of a/W and t/W geometry combinations. It is demonstrated that the thickness of the specimen has a significant effect on the variation of fracture parameter values. Their effects on crack tip plastic zone are also investigated. The results presented here will be very useful for the toughness testing of materials under mixed-mode loading conditions.

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A New Idea of Pure Mode-I Fracture Test of Bonded Bi-Materials

ASME 2010 Pressure Vessels and Piping Conference: Volume 3 ◽

10.1115/pvp2010-25759 ◽

2010 ◽

Author(s):

Zhenyu Ouyang ◽

Gefu Ji ◽

Guoqiang Li ◽

Su-Seng Pang ◽

Samuel Ibekwe

Keyword(s):

Mixed Mode ◽

Dissimilar Materials ◽

Test Method ◽

Interface Fracture ◽

Mode I ◽

Mixed Mode Fracture ◽

Pure Mode ◽

Fracture Test ◽

Engineering Structures ◽

Material Systems

Bi-material systems in which two dissimilar materials are adhesively joined by a thin adhesive interlayer have been widely used in a variety of modern industries and engineering structures. There are two fundamental issues that need to be adequately addressed: (1) Fracture of bonded bi-materials is mixed mode: Mode-I (pure peel) and Mode-II (pure shear). Fracture test implementation of bi-material systems with the traditional Mode-I methods will induce a noticeable mixed mode fracture due to the disrupted symmetry by the bi-material configuration; (2) The popular cohesive zone models (CZMs) for accurate fracture simulations require more than a single parameter (toughness) as is the case in the traditional linear elastic fracture mechanics (LEFM). Thus, J-integral is highly preferred. It can not only capture more accurate toughness value by considering the root rotation effect, but also facilitate the experimental characterizations of the interfacial cohesive laws, which naturally include all required parameters by CZMs. Motivated by these two important issues, a novel idea is proposed in the present work to realize and characterize the pure Mode-I nonlinear interface fracture between bonded dissimilar materials: Despite the approximation with the elementary beam theories, the accuracy is validated by numerical simulations. The proposed approach may be considered as a promising candidate for the future standard Mode-I test method of adhesively bonded dissimilar materials due to its obvious simplicity and accuracy.

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The Effect of Loading Mode on Fracture Toughness of Arcan Adhesive Joint

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.786.3 ◽

2015 ◽

Vol 786 ◽

pp. 3-7 ◽

Cited By ~ 1

Author(s):

Kevin Prakash ◽

Khairul Salleh Basaruddin ◽

Mohd Afendi Rojan ◽

Haftirman Idrus

Keyword(s):

Adhesive Joint ◽

Mixed Mode ◽

Initial Crack ◽

Mode I ◽

Mode Ii ◽

Mixed Mode Loading ◽

Fracture Test ◽

Crack Line ◽

Loading Mode ◽

Adhesive Thickness

This paper presents the experimental investigation on adhesive joint under three loading angles using a modified Arcan jig. Fracture test was performed using the fabricated Arcan specimens and Araldite adhesive with loading angle of 0°, 90° and 45° to represent Mode I, Mode II and mixed Mode loading, respectively. Eighteen specimens were prepared with adhesive thickness of 6 mm and nine of them with interface crack length of 5 mm. The result shows the stress intensity factor, K is influenced by the loading angle and the initial crack-line directions. KI was found greater than KII .

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