EFFECT OF INSERTION ANGLE AND DISTANCE OF BAMBOO Z-PIN ON SHEAR AND COMPRESSIVE STRENGTHS OF SANDWICH COMPOSITE

Polyurethane rigid foam as a core of sandwich composite has low strength so that the sandwich composite undergoes failure at the core when the sandwich composite receives the compressive stress perpendicular to the skin surface or shear stress parallel to the skin surface. Some forms of the reinforcement on z-direction (z-pin) that is inserted into the core and developed by researchers are made of synthetic materials. Bamboo stick that is grouped as the biodegradable material can be formed as a cylinder pin with a diameter of 2 mm is called bamboo z-pin. Bamboo z-pin inserted to the polyurethane rigid foam joins the two skins flanking it forms a sandwich composite. This paper presents the effect of bamboo z-pin as the core reinforcement of the sandwich composite on the compressive and shear strengths. The insertion angle of the z-pin on horizontal direction and the distance of the pin were varied, i.e. 60°, 75°, 90°, and 10 mm, 15 mm, 20 mm respectively. The sandwich composite skin was made of lamina fiberglass-polyester using hand layup method. The sandwich composite was then examined using compressive and shear tests. The compressive and shear strengths of the sandwich composite increases due to the bamboo z-pin inserted into the core. The compressive strengths of the sandwich composite increase with the decrease in the pin distance and with the increase in pin insertion angle. The shear strengths of the sandwich composite increase with the decrease in the pin distance and insertion angle