###### Abstract  
Until now, some test specimens with different shapes and loading mechanisms have been utilized for investigating the cracking behavior of adhesive bounded joints. In this research, using a novel test configuration called adhesive short bend beam specimen containing an inclined crack and loaded by three-point bending, mixed mode I/II fracture parameters of a crack initiated in the adhesive part is studied. Compared to other test methods, the specimen used in this research needs a lesser amount of material and the fracture test can be performed easily. A large number of finite element models of this specimen were analyzed using ABAQUS code to study the effect of adhesive and adherent type, and also the crack length and loading span distance on \(K_{\text{I}}\), \(K_{\text{II}}\), \(T\)-stress and fracture initiation direction under different mode mixities. The results showed that the fracture parameters (and in particular the shear mode component) are sensitive to the type and location of adherent in the bounded joint; however, the shape and size of fracture plastic zone is not affected noticeably by the type of adhesive-adherent materials. It was also shown that the complete mode mixities ranging from pure mode I to pure mode II can be introduced for adhesive bounded joints using the proposed test specimen and therefore the specimen is a good candidate test configuration for investigating the mixed mode I/II fracture behavior of adhesive bounded joints. adhesive bounded joints; bi-material inclined crack short beam; fracture parameters; numerical analyses; adhesive and adherent effects +
Footnote †: journal: Applied Sciences  
1  
Interfacial fracture can be investigated via employing the framework of fracture mechanics in which the intensity of stress/strain field is defined by some parameters such as stress intensity factor and the fracture energy. The critical values of such parameters are often considered as mechanical properties characterizing the fracture behavior of adhesive bounded joints. Some experimental methods and testing specimens have been used in several studies to evaluate the load bearing capacity or fracture energy of such components. For example, double cantilever beam (DCB) and tapered double cantilever beam (TDCB) [2; 3] are two well-known test configurations for tensile type or mode I fracture study of adhesive bounded joints. For mode II fracture study of such components there are some testing methods and specimens including edge notch flexural (ENF) [4] and end-loaded split (ELS) [5] that have been widely used by several researchers to measure the shear type fracture energy. However, in practice adhesive bounded joints can be subjected to complex state of loads and deformations. This loading situation may result in mixed mode tensile-shear (i.e., mixed mode I/II) fracture phenomenon in adhesive bounded joints. Thus, some other test samples have been proposed for evaluating and studying the mixed mode I/II fracture in these components. The asymmetric DCB and asymmetric TDCB specimens proposed by [PERSON] et al. [6] and [PERSON] [7], respectively are modified forms of DCB and TDCB samples which can produce mixed mode I/II (but limited range of mode mixities) in addition to the pure mode I case in adhesive bounded joints. Other test configurations such as mixed mode bending (MMB) [8], single leg bending (SLB) [9] and semi-circular bend (SCB) [10] specimens were also employed by some researchers for fracture study of adhesive bounded joints. However, the aforementioned testing methods have some shortcomings and difficulties such as lack of ability for introducing the full range of mode mixities, requirement of complex testing fixtures and rigs for conducting the experiments, large size of test specimen, etc. Therefore, designing and proposing new and suitable testing methods for investigation mixed mode I/II fracture behavior of adhesive bounded joints is still a necessary and interesting subject.