Mixed mode loading fracture toughness of Arcan adhesive joint: Effect of surface roughness

Abstract

The paper investigates the effect of surface roughness on mixed mode loading fracture toughness of Arcan adhesive joint. The problem of crack within the adhesive joint is a great importance to various industrial applications and fracture toughness is an important parameter to determine the strength of adhesive joints by using various adherend roughness. The study of fracture toughness was performed by using two varieties of modified Arcan specimens such as coated and normal. The modified Arcan jig and it specimen was made for Mixed Mode fracture test of adhesive bonded joint and are capable to determine the perfect range of fracture toughness under pure Mode I, Mode II and Mixed Mode loading condition. Furthermore, it is also used to analyse the crack propagation and effects of adherend with crack length of 5mm with adhesive thickness of 6mm. The Araldite (Huntsman) adhesive ratio 1:1 (Part by weight) was used to bonded specimen in special fixture, in which by varying the loading angle of 0°, 45° and 90. The modified Arcan jig is used to determine the maximum load can withstand by adhesive bonded joint and stress intensity factor for various loadings. With the trial outcomes, it can be noted that normal modified Arcan specimen has higher Stress Intensity Factor with adhesive joint at Shearing Mode (90°) and fracture toughness larger than the opening Mode (0°) of fracture toughness if compare to coated modified Arcan specimen. From the field, the cracked specimen is weaker in tensile loading condition and tougher in shear loading condition. With a high surface roughness of adherend, good bonding strength of adhesive joint was obtained.