An investigation into the effects of fabric reinforcements in the bonding surface on failure response and transverse impact behavior of adhesively bonded dissimilar joints

The purpose of the current study is to evaluate the failure response and transverse impact behavior of adhesively bonded dissimilar single-lap composite joints fabricated by using fiber-reinforced polymer. The adherend materials utilized for the experimental tests were AA6082-T6 and glass fiber reinforced polymer (GFRP) in the form of thin sheets. The adhesive used was a warm to hot curing epoxy system (Araldite LY 1564 SP/Aradur 3487 BD) manufactured by Huntsman. In this study, some modifications were provided to enhance the failure response of single-lap composite joints. These modifications comprise the addition of different type and number of fabric reinforcements in the bonding surface. Based upon the test results, an increase of 33.6% in the failure load at room temperature is obtained for the joint fabricated by the addition of double-layer glass fabric reinforcement in the bonding surface. However, the failure load of all types of joint modifications decreases with the increasing tensile test temperature from room temperature to 75 °C. Similarly, tensile tests of the same specimen also resulted in double failure displacement by comparison with the adhesively bonded joint through only epoxy without any fabric reinforcement. The effect of low velocity impact on the failure response of the joints at the impact energy level of 2.5 J is also evaluated. From the tensile tests subsequent to impact treatment, it was found that the transverse impact significantly reduced the failure load of all types of joint modifications. However, the adopted modifications provided tensile failure loads over 1875 N and 1270 N for the joint fabricated by using double-layer carbon and glass fabric reinforcements, respectively.