Strength prediction of axial fiber-reinforced 3D5D circular braiding composites

At the microscale, a unit cell model of axially-reinforced three-dimensional five-directional (3D5D) circular woven composite materials was established based on the spatial topology of the unit cell. This model considers the changes in cross-sectional shape of the yarns due to mutual compression and incorporates periodic boundary conditions for the circular unit cell. Combining this unit cell model with an progressive damage approach and failure models for the yarn bundles, a strength prediction model for the axially-reinforced 3D5D circular woven composite materials was developed. The model was used to simulate the damage evolution of the fibers and matrix under progressively increasing tensile loads. The tensile strength predicted by the strength prediction model is 420 MPa, with a deviation of 5.12% compared to the experimental value. The failure modes of the axially-reinforced 3D5D circular woven composites are predominantly fiber tensile failure and fiber-matrix interfacial cracking. The damage evolution sequence shows that matrix failure occurs first, followed by fiber-matrix interfacial cracking, and finally fiber tensile failure.