Bending Behaviors of Thin Composite Pipes with Reinforcing Nodes

Abstract

This paper reports on the improvement of the bending strength of thin circular pipes by reinforcing nodes. Thin composite pipes are attractive to the design of structural parts owing to their high stiffness and strength with less weight, and are applied to various mechanical parts such as rotating shafts, robot arms, and other sports and leisure goods. However, the bending stiffness of composite pipes are often reduced under heavy bending loads owing to the change in sectional shape. Specimen pipes with and without reinforcing nodes were fabricated by filament winding of carbon fibers impregnated with epoxy resin in different fiber angles and reinforcement spacings. Geometry of tested pipes were of 21 (diameter)×0.5 (thickness)×1000 (length) (mm). Reinforced specimens were fabricated by winding angles of 20, 30 and 45° with reinforcement spacings of 60, 90, 180mm. Four-point bending tests were conducted to examine the bending behaviors of the pipes. Experimental results revealed a distinct effect of the reinforcing rings to delay the onset of the sectional ovalization.