A potential repair alternative to restoring the mechanical properties of lightweight fiber-reinforced polymer (FRP) structures is to locally patch these areas with scarf joints. The effects of such repair methods on the structural integrity, however, are still largely unknown. In this paper, the mechanical property restoration, failure mechanism, and influence of fiber orientation mismatch between parent and repair materials of 1:50 scarf joints are studied on monolithic glass fiber-reinforced polymer (GFRP) specimens under tensile load. Two different parent orientations of [−45/+45]_2S and [0/90]_2S are exemplarily examined, and control specimens are taken as a baseline for the tensile strength and stiffness property recovery assessment. Using a layer-wise stress analysis with finite element simulations conducted with ANSYS Composite PrepPost to support the experimental investigation, the fiber orientation with respect to load direction is shown to affect the critical regions and thereby failure mechanism of the scarf joint specimens.

Composite tubes were filament-wound and cured using a vitrimer epoxy resin and carbon fiber (CF). The matrix was dissolved under mild conditions, and recovered continuous fiber tows were used to rewind a second-generation tube. Property retention and microstructural quality were evaluated by mechanical tests and examination of polished sections. The vitrimer–matrix composite exhibited a higher short-beam shear strength compared to specimens wound with a traditional epoxy, typical of hydrogen tanks. Single-fiber testing revealed that CFs were not degraded by the recycling process. The remanufactured composite exhibited mechanical properties comparable to those of the first-generation material when normalized to the fiber volume fraction. This work demonstrates a circular manufacturing process that includes full fiber recovery and re-use for producing a second-generation filament-wound article.