Akpinar, Salih; Doru, Muhammet Onur; Özel, Adnan; Aydin, Murat Demir; Jahanpasand, Hamed Ghaffarzadeh

The mechanical behaviors of an adhesively bonded single lap joint with a spew fillet under bending moment, where the widths of the upper-adherend and lower-adherend are not the same, were studied experimentally and numerically. Using AA2024-T3 aluminum alloy as adherend and DP460 as paste adhesive, four different types of single-lap joint samples (without spew fillet, with spew fillet at joint edges, with spew fillet at joint ends and with spew fillet at all edges) were produced for experimental studies. Stress analyses in the single-lap joint were performed with a three dimensional non-linear finite element method by considering the geometrical non-linearity and non-linear material behaviors of both adhesives (DP460) and adherend (AA2024-T3). The single lap joint with the spew fillet with different widths had a significant effect on the stress distribution. Additionally, the spew fillet increased the load carrying capacity of the joint and decreased the stress concentration of the joint.

Akpinar, Salih; Aydin, Murat Demir; Özel, Adnan

In this study, the normal (σx,. σy,. σz) and shear stress (τxy,. τyz,. τzx) distributions occurring in a bi-adhesively bonded T-joint with was investigated via a non-linear three dimensional finite element analysis. For this purpose, first of all, using 2024-T3 aluminum alloy as the adherend and the support, a two-part paste (DP 460) and a film type (SBT 9244) as adhesive, two different types of T-joint samples (single-adhesively bonded T-joint and bi-adhesively bonded T-joint) were produced for experimental studies. After experimental studies on the three different T-joint types were conducted, stress analyses in the T-joints were performed with a three-dimensional finite element analysis by considering the geometrical non-linearity and the material non-linearities of the adhesive (DP460 and SBT9244) and adherend (AA2024-T3). Finally, for a given adherend, the lower the stiffness of the adhesive used in the overlap, the lower the stress concentration, leading to potentially higher joint strength. The use of relatively low stiffness adhesives at the ends of the overlap in a bi-adhesive can decrease the stress concentration and, therefore, potentially lead to higher joint strength.

Akpinar, Salih; Aydin, Murat Demir; Temiz, Şemsettin; Özel, Adnan

In the present study, it is aimed to compare mechanical behaviors of T-joint types with embedded and non-embedded supports subjected to bending moment. For this purpose, after experimental studies on the two different T-joint types were conducted, stress analyses in the T-joints were performed with a three-dimensional finite element method by considering the geometrical non-linearity and the material non-linearities of the adhesive (DP460) and adherend (AA2024-T3). Finally, stress analyses and experimental results show that the variation of the geometry of the bonding zone, e.g., embedding the supports, would change the stress distributions and strength of the joint. Additionally, it is seen that T-joints with embedded supports carry 30% more load than T-joints with non-embedded supports although their bending stiffnesses decrease.

Akpinar, Salih; Temiz, Semsettin; Aydin, Murat Demir; Özel, Adnan

In this work, elasto-plastic stress analysis of single lap joints with and without protrusion in adhesive bondline subjected to tension and bending was carried out using 2D non-linear finite element analysis and confirmed experimentally. AA 2024-T3 aluminum adherends were bonded with SBT 9244 film adhesive. The protrusion was obtained by extending the adhesive film by 2 mm from the overlap length at both overlap ends. Three different adherend thicknesses and overlap lengths for each loading and bondline type were used. The joints with and without protrusion, for comparison, were loaded with the same load for each adherend thickness and overlap length. Finally, it was observed that the protrusion reduces the strength in the joint under tension, while the protrusion increases the strength in the joint under bending.