ABSTRACT
The single lap joint (SLJ) along with adhesive bonding is being used widely in engineering industry due to its easy design process as well as continuously increasing demand for lightweight designing structure. However, yet the precise information about the correlation among the different factors of SLJ such as overlap length, surface pattern, shear strength is not available.
The purpose of this  study was  to  investigate  the influence of overlap length  and  surface  pattern  on  shear  strength  in-depth  as  well  as  analyze  the bonding failure mode.
The SLJ was designed following ASTM standard protocol where Carbon 3K and Aluminium-2024 were used as adherend and the epoxy resin with Aluminum powder was used as adhesive. The adherend and adhesive thickness were 3mm and 0.5 mm respectively as well as depth of surface pattern was 0.1 mm. A Compressive load pressure (0.9 MPa) was applied at the joint area using compression moulding machine at room temperature. Then the shear strength was measured and analyzed the feature at different overlap length and defined surface pattern. SEM images were obtained at both low and high magnifications. The low magnification images were used to determine the uniformity of specimen as well as bonding failure features present. SEM result of different overlap length and designed surface pattern showed that there was no massive crack  exist at interface bonding area.
The result showed that there is a non-linear relationship between overlap length and shear strength. The maximum shear strength was obtained at 20 mm overlap  length  and  900   cross  surface  pattern.  Additionally,  cohesive  type  of bonding failure mode was found to be the best after analysis SEM image.
Keywords : SLJ, Adhesive, Adherend, Shear Strength, SEM