Braided textile composites under compressive loads: Modeling the response, strength and degradation

This paper discusses the results of a finite element (FE) based micromechanics study of the compressive damage development mechanisms of 2D triaxial braided carbon fiber composites (2DTBC). The micromechanics based study was carried out on a Representative Unit Cell (RUC) size 3D FE model. The uniaxial compressive response was established using an arc-length method in conjunction with the ABAQUS commercial FE code. In this work, explicit account of the braid microstructure (geometry and packing) and the measured inelastic properties of the matrix (the in situ properties) are accounted for via the use of the FE method. This enables accounting for the different length scales that are present in a 2DTBC. This detail is necessary for developing a mechanism based damage prediction capability. The computational model provides a means to assess the compressive strength of 2DTBC and its dependence on various microstructural parameters. In particular, the dependence of compressive strength on the axial fiber tow properties and axial tow geometrical imperfections is discussed and shown to be significant in capturing the mechanism of damage development.