Fracture behaviour of PC/ABS resin under mixed‐mode loading

Abstract

Fracture behaviour of polycarbonate (PC)/acrylonitrile‐butadiene‐styrene (ABS) under mixed‐mode loading conditions was studied for several weight fractions of PC and ABS. Mode I and mixed‐mode fracture tests were carried out by using compact–tension–shear specimens. At a certain value of mixed‐mode loading ratio KII /KI a crack of the shear type will initiates at the initial crack tip. Fracture toughness increases under mixed‐mode loading with an increase in the mode II component, whereas it reduces with the appearance of a shear‐type fracture. Fracture toughness and the appearance of a shear‐type fracture depends on the blending ratio of PC and ABS. The transition to shear‐type fracture occurs at lower value of KII /KI for resins with higher fracture toughness.

Fracture toughness of polymers in shear mode

“…9. The first pair of cracks are 'shear-like cracks' that were also observed by Husaini et al [2]. Formation of the first pair of cracks can be explained by the competition of maximum principal stress and maximum shear stress [17].…”

“…Since shear strength for some polymers are lower than their tensile strength [3,17], shear type cracking can occur at the yielding and crack initiation stage [2] in cases that the ratio of the applied shear stress to tensile stress is high. However, the subsequent fracture mode may switch to mode I as the crack and the accompanied plastic deformation zone evolve.…”

“…(2). Experiments have been conducted to elucidate such dependence, and the results will be shown later in this paper.…”

“…The reason, as Williams [1] stated, is that most polymers have much lower toughness in tension mode (mode I) than that in shear mode (mode II). Therefore, global failure behaviour of polymers in most loadbearing structures is believed to be in mode I even though in the initiation stage the behaviour can be in a shear-like mode [2,3]. Since current testing methods are not suitable for the measurement of mode II fracture toughness, especially for ductile polymers, no experimental data are available to support the above statement.…”

Mixed Mode Fracture Behavior of an Aluminum Alloy A6061 Investigated by using Compact Tension Shear Specimens

“…In an Finite Element Method (FEM) analysis, Aoki et al (1987) concluded that shear fracture in an aluminum alloy becomes more pronounced as the mode II component increases. Studies of fracture behavior of polymer alloys under various mixed mode loadings showed that crack initiation occurs in the opening-type fracture followed by the transition fracture from the opening-type to the shear-type fracture (Husaini et al, 2001;Husaini et al, 2000;Husaini et al, 1997).…”