Numerical predictions of fiber orientation and mechanical properties for injection‐molded long‐carbon‐fiber thermoplastic composites

The use of long carbon fiber‐reinforced thermoplastic composites as lightweight automotive materials offers superior mechanical performance compared to glass fibers. However, the anisotropic fiber orientation distribution with shell–core structure is critical to determine mechanical properties. Recently, both theoretical models of fiber orientation—Anisotropic Rotary Diffusion and Reduced Strain Closure and Improved Anisotropic Rotary Diffusion and Retarding Principal Rate—have been significantly developed in the field of fiber suspension rheology. From injection molding simulations, numerical predictions of fiber orientation are derived with related experimental validations, while dramatic changes in orientation distribution are discussed at various fiber concentrations and different polymer matrices. More importantly, the reinforcing ability is discussed in regard to the tensile modulus and the stress–strain response for a variety of long carbon fiber composites. POLYM. COMPOS., 39:3726–3739, 2018. © 2017 Society of Plastics Engineers