THE FILAMENT WINDING METHOD’S FINISHING PROCESS IMPACT ON HIGHFIDELITY SPECIMENS: HOMOGENITY OF DENSITY, FIBER VOLUME FRACTION, OUTER SURFACE ROUGHNESS AND TENSILE STRENGTH

Filament winding is a widely used method for producing tubes and pressure vessels from composite materials. However, overlapping of fibers during the winding process can lead to rough surface and increased voids in the finished product. To improve the quality of CFRP materials produced through filament winding, the structure is cured either at room temperature or in an oven with a controlled heat profile, depending on the type of resin used. Various finishing techniques, including shrink tape, compression molding, and vacuum compression molding, have been attempted to improve the quality of the specimen. Among these techniques, vacuum compression molding has been found to deliver the best results in terms of surface roughness, with average roughness (Ra) values of 0.35 μm in the fiber direction and 0.61 μm in the transverse direction. This level of roughness is comparable to that achieved through milling machine manufacturing. Moreover, this technique ensures uniformity in fiber composition and volume fraction, achieving a homogeneous density of 1364.49 kg/m³ and the highest fiber volume fraction of 63 %. As a result, remarkable mechanical attributes, such as a tensile strength of 926.07 MPa and a stiffness of 21.35 GPa, can be obtained. In addition, by utilizing various finishing techniques, the tensile strength of these properties can be increased by up to 80 %. CFRP is a versatile material with unique characteristics, and selecting appropriate finishing techniques such as vacuum compression molding can significantly enhance its overall quality and mechanical properties. However, one drawback of the filament winding method is the poor outer surface finish which can be improved by vacuum compression molding.