Mechanical model of needle-punched (NP) carbon/carbon (C/C) composites with isogeometric beams-extended springs at mesoscale

The NP C/C composites have strong load-bearing capacity in ultra-high temperature environments, become an indispensable material for aircraft production, which is widely used in aerospace sector. The NP preform transfers the fibers in the XY plane to the Z direction through the NP process, which overcomes the disadvantage of easy delamination of the C/C composites. However, the stiffness and strength in the layers of C/C composites are reduced by introducing defects. In this paper, a mesoscale mechanical model is proposed. Isogeometric circular arc beam element (CABE) is established to characterize the fiber bundles of NP C/C composites, and extended spring element(ESE) is established to characterize the matrix within layers, matrix and chopped fiber felt between layers, and chopped fiber felt at pinhole defects of NP C/C composites. By comparing the tensile, compression and bending tests with the simulation, the correctness of the mechanical model is fully confirmed.