Investigation of Longitudinal and Transverse Reinforcing Single Lap Joints of the Polymer Composites/Al under Hygrothermal Condition

In this study, the effect of longitudinal and transversal reinforcing of epoxy based carbon fiber reinforced composite/Al (CFRP/Al) and glass fiber reinforced composite/Al (GFRP/Al) single lap joints (SLJs) by using of pins and wires has been investigated under hygrothermal conditions. Overall three sets of specimens for each composite/Al joint were manufactured which consist of single lap joint (SLJ), single lap joint reinforced with 6 steel pins of 1 mm diameter in transverse direction (SLJP) and single lap joint reinforced with wires of diameter 0.2 mm, in longitudinal direction (SLJW) for CFRP/Al and GFRP/Al adherends. The tensile properties of the samples were measured after 500 and 1000 hrs. in hygrothermal conditions of 70 °C, relative humidity of 85 % and compared corresponding to unheated samples. The results show that using of pins, increases the tensile strength by 14 % in GFRP/Al and 13.7 % in CFRP/Al SLJs. Also wire increased the tensile strength of the SLJs by 26 % in GFRP/Al and 19 % in CFRP/Al SLJs. Hygrothermal conditions decreased the tensile strength of both GFRP/Al and CFRP/Al SLJs samples, where the highest degradation was observed in simple GFRP/Al SLJs (34.45 %) and the lowest was in wire reinforced CFRP/Al SLJs (21 %). Overall it could be concluded that wires and pins increases the lifespan of both CFRP/Al and GFRP/Al SLJs under hygrothermal conditions.