PSI - Issue 41

M.R.M. Aliha et al. / Procedia Structural Integrity 41 (2022) 87–93 Aliha et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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As a consequence, an improved design for Short Beam was presented in this work to cover the drawbacks of the BISBB specimen. In the improved specimen that is called "Bi-material asymmetric short beam (Bi-ASB)", both adherent parts are rectangular and a vertical crack is considered in the adhesive layer. For altering the contribution of opening-shearing deformations the specimen is loaded asymmetrically using three-point bend fixture. The manufacturing procedure for this new specimen is straightforward and there is no need to adjust the crack inclination angle throughout the manufacturing process for conducting mixed-mode I/II tests on adhesively bonded joint. As a result, the suggested Bi-ASB specimen keeps all of the benefits of the BISBB specimen while simultaneously covering its drawbacks. As a result, the cost of producing and fracture testing via the Bi-ASB specimens is significantly less than that of traditional and previous specimens such as DCB, ENF, MMB, BISBB and etc. In the following sections of this study, after introducing the proposed test sample, its fracture parameters including modes I and II stress intensity factors (K I and K II ) and T-stress, are determined and presented for different geometrical and loading conditions and also adherent types. 2. Suggested Test Specimen The Bi-ASB test specimen suggested for fracture analysis of the ABJs under mixed-mode I/II loading conditions is shown in Fig. 1. The Bi-ASB specimen's overall shape is a rectangle formed by two adherents (of the same size of width=W and length = L) bonded together by an epoxy adhesive. The width of adhesive is d and a straight edge crack with length a is assumed to be introduced in the middle of the adhesive layer. The specimen is loaded asymmetrically with a three-point bend fixture. The state of mode mixity in the Bi-ASB specimen can easily be changed by changing the locations of two bottom span supports (i.e. S and S ′ ). Pure mode I occurs when the bottom span supports are located symmetrically relative to the crack (i.e. when S ′ = S). Mode II, footprint appears when the Bi-ASB specimen is subjected to asymmetric loading (i.e. S ′ ≠ S ). Controlling the contribution of mode I and mode II in this specimen is done by selecting appropriate S ′ and S values. In this research Alumina ceramic and Aluminum metal alloy were investigated for joining using an epoxy adhesive to construct the suggested Bi-ASB specimen. Four distinct permutations of the Bi ASB specimen based on the adherent type are seen in Fig. 2. Table 1 shows also the mechanical properties of the chosen materials.

Fig. 1. Overall schematics of the suggested Bi-ASB specimen for fracture study of adhesively boned joints subjected to mixed mode I/II loading