Comparisons of processing and strength properties of two adhesive systems for composite joints

In the present study rheological, static and impact tests are carried out on two adhesive resins usually employed in marine applications; then single lap joint tests are conducted on composites joints evidencing the effect of the curing time of both resins on the mechanical properties of the joint. The applicability and workability conditions of the adhesive resins are determined evaluating the curing evolution by a preliminary rheological analysis; then the relation of curing properties with the mechanical performances of the resins themselves and with ones of the composite joints is estimated. Static flexural and Izod impact tests are performed on the resins at increasing time after the specimen production (curing time); also the resistance properties of adhesives joints are studied as well the stabilisation of the mechanical properties after long times. Moreover a relationship between the different failure mechanisms, observed for both resins joints, and the curing reaction is observed. A numerical model of the single lap joint test is developed: a simple and versatile numerical analysis (FEA with software ANSYS) is carried out in elastic regime. Such model should be suitable for designing and/or verifying the mechanical performances of composites joints, evaluating the shear, axial and peel stress trends on the joint overlap length.