Adhesive bonding is prepared essentially with lap shear and tensile configuration. In general, materials of high rigidity, peel configuration is practically not possible. The detail of lap shear and tensile configurations is described in sections “Lap Shear Joint Preparation” and “Butt Joint Preparation,” respectively.

Lap Shear Joint Preparation

Rectangular configurations, having dimensions length x width x thickness: 150 x 25 x 3 mm3, are preferred for tensile lap shear testing. Prior to the preparation of an adhesive bonded joint, degassing of adhesive is an essential factor and generally carried out under a pressure of 1 Pa for 10 min. However, pressure and time of degassing varies subject to viscosity of adhesive. If there is any, excess adhesive present at the interface is expelled by mechanical pressing of the joint, which resulted in a joint having an adhesive of uniform thickness. Pressure is applied to the lap joint during the curing cycle by two binder clips.

Butt Joint Preparation

Rectangular specimens, having dimensions length x width x thickness: 150 x 25 x 6 mm3, are preferred for tensile testing with butt configuration.

Tensile Lap Shear Testing and Tensile Testing

Lap shear determines the shear strength of adhesives for bonding materials when tested on a single-lap-joint specimen. The single lap shear configuration is shown in Fig. 3a and is a common joint design for lap shear tensile test, and tensile configuration is shown in Fig. 3b.

Both the lap shear testing and tensile testing of butt joints can be carried out using computer-controlled testing machine, ZWICK 2010 or INSTRON as shown in Fig. 4, under a load cell of 50 kN. The specimens are loaded in tension at a test speed of 5 mm/min. Seven specimens of each joint should be tested and the mean value with standard deviation should be reported in the results. All tests should be performed at room temperature of 25o C and at 50 % humidity.