부산대학교 도서관

The thermal effect on the shear load and fracture of MP55420 adhesively bonded joints of plates of 590/600 dual phase steel and AA6061-T6 aluminum alloy was investigated by means of single lap shear (SLS) testing, visual and SEM fractographic analysis applying radical temperatures (−20, 25, 60 and 100 °C). Results indicated that as the SLS load decreases the displacement increases in function of temperature increments for the steel-aluminum (St-Al), aluminum-aluminum (Al-Al) and steel-steel (St-St) unions. Three different fracture mechanism were detected in the fracture surface of each condition. The ST-St joint exhibited the better results at higher temperature than zero degrees with the largest values of SLS load and displacement. In this case, the failure mechanism consisted of cohesive and adhesive on both sides of the fracture joints containing morphology of micro-voids with different sizes depending on temperature. The St-Al joint exhibited mechanical degradation with the lowest load (0.45 kN) and middle displacement at 100 °C resulting in unacceptable adhesive fracture with the most of resin on one adherend, generating superficial shallow micro-voids with different size as a function of temperature. At −20 °C condition, the Al-Al joint reached the maximum load (11.55 kN), large displacement and cohesive failure assuring adequate mechanical behavior associated with the adhesive contraction, while inappropriate adhesive-cohesive failure was generated in the St-St joint leading to a reduction in the load and the lowest displacement (0.29 mm) linked to the degradation of the adhesive resistance.