Non-invasive inspection methods for the defect analysis of filament wound composite cylinders and the process optimization

Filament winding is a manufacturing process used to produce cylindrical shapes pieces like pipes or pressure vessels for pressurized fluids, where high strength and stiffness are required. However, the manufacturing process often make the products susceptible to many defects, such as delaminations, voids, cracks, or fibre misalignments. The identification of these defects by non-destructive inspection methods is essential, also in the preliminary process optimization phase. This paper assesses some metrological characteristics of an ultrasonic inspection technique applied to composite filament wound cylinders. In particular, the ultrasonic technology is used to measure the thickness and determine the presence and the depth of gaps between layers, before and after a compression test. Interesting aspects about the uniformity of the fabrication are also looked at, useful for the production process optimization.