Finite element analysis of a repaired thin-walled aluminum tube containing a longitudinal crack with composite patches under internal dynamic loading

One of the main issues with the cylindrical tubes is the propagation of cracks during their operational life wherein most of the cracks happen along the axial direction of the tube. This paper reports a 3D finite element simulation of the mechanical responses of an aluminum tube containing a longitudinal crack repaired with composite patches. After several loading-unloading cycles of the dynamic load, mechanical stresses at the crack tips may result in unstable crack propagation. Therefore, it is necessary to use a repair process to prevent the structure from final rupture. Glass/epoxy and boron/epoxy composite patches, with different number of patch layers, are considered in the analysis of the composite material repair effect on the crack tips stress distribution, evaluating the possibilities of crack propagation and patch delamination onset. Numerical simulations were partially compared with literature results to verify the modeling procedure, while a parametric study on the patch thickness was performed to verify the repair effectiveness. In general, boron and longer (140 mm) repair patches presented better performance than glass and shorter (70 mm) patches. Although thinner patches (2 layers) do not present the required resistance, thicker patches (16 layers) may precipitate delamination onset and thus should be avoided.