Thermo-Mechanical Geometry Generation for a Mesoscopic Simulation of a Triaxial Braid Carbon Fiber Reinforced Polymer

Abstract

In this study, an artificial thermal-mechanical method for generating an accurate and penetration free geometry of a triaxial braid fabric is developed. The quasiisotropic properties of triaxial braided fabric allow for more balanced and homogenized behavior compared with bi-axial woven fabrics. Moreover, the unidirectional and off-axial reinforcements in one layer increase mechanical stiffness properties and stability in the laminate. Simulation methods for predicting braided properties are vital for designing the use of triaxial braided fabric in industry. Based on the dimensions of a measured 0o/+60o/-60o braid architecture, an artificially thinned yarn geometry is defined using python scripting in the TexGen open source user interface for an initial penetration free model. Orthotropic material properties are assigned for the coefficient of thermal expansion and conductivity, and a finite element (FE) simulation is performed in Abaqus to artificially expand the yarn geometry using thermal fields. A post-expansion mechanical simulation compresses the braid to the desired ply thickness, with cross-section rendering confirming good compliance of the generated geometry to measured values. The geometry is merged with a matrix and meshed with reduced order voxel elements to create a representative volume element (RVE) of the braided carbon fiber reinforced polymer (CFRP). A linear elastic mesoscopic FE simulation using the developed RVE is performed for extraction of the orthotropic elastic constants, and excellent agreements with experimental data were obtained. 12