Fabrication of Polyurethane Based Fabric Composite Shaft and its Experimental Study Under Triple Point Bending

Semi-rigid urethane based fiber composite shafts are fabricated by high pressure injection molding process. The samples are made in Georgia Southern University’s laboratory where compressed air pressure is effectively used for this purpose. A special manufacturing process is suggested which can be used for mass production of these composites. This unique manufacturing technique creates a composite shaft with a core made of matrix material which is completely wrapped around by a woven fiber cloth with a very strong bonding between core and fibers. Three different types of woven fibers: fiber glass, Kevlar 49, and carbon fibers, are used. Triple point bending tests are carried out to test these three different types of composite samples and also samples made of only base or core material. During the test as the applied load is increased, a linear trend is observed between the load and mid-point deflection of the specimens up to a certain level. Higher load causes separation of fibers and core matrix and followed by local buckling of the separated fibers that are under compression region. This phenomenon brings down the bending stiffness of the composite significantly and it is quite pronounced in the load deflection curve diagram. Failure modes are observed to differ for each of these three types of composite and are discussed in details here. Composites with fiber glass wrapping are found to be the strongest among the three. Future work will involve determining the torsional and fatigue properties, and also the effect of fiber orientations on the mechanical properties of these composites.