PSI - Issue 28

M.Z. Sadeghi et al. / Procedia Structural Integrity 28 (2020) 1601–1620 M.Z. Sadeghi et al./ Structural Integrity Procedia 00 (2019) 000–000

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However, Mode-I dominates the fracture up to MMB ratio of 50% which is in line with the finding of an epoxy adhesive where the Mode-I ratio dominates up to 75% mode mix ratio. This was based on the assessment of fracture surfaces of the specimen (Khoo and Kim, 2011).

Fig. 13. Fracture envelopes based on the B-K Law for adhesive thickness t a = 0.35 mm and 1.0 mm.

Apart from Power law and B-K law, Abaqus provides another option – Tabular data to enter the values for Gc vs MMB ratio in a tabular. This avoids the need for curve fitting to determine the exponents. However, the working of the algorithm behind this is unclear, hence no attempt was made to validate the damage envelope sing tabular option. 4.3. Validation of the determined fracture properties in single lap joints: Experimental load-displacement (P-  ) curves for SLJs with different bond line thickness (t a ) is as shown in Fig. 14. The increase in the adhesive bondline thickness (t a ) in the SLJ decrease the failure load of the joint. It can be attributed to the increase in the bending moment on the bonded are induced by an increase in the eccentricity on the joint.

Fig. 14. Representative experimental load-displacement curves of SLJ for bondline thickness of 0.20 mm and 0.90 mm.