  The advent of multi-material additive manufacturing and automated composite
manufacturing has enabled the design of structures featuring complex
curvilinear anisotropy. To take advantage of the new design space, efficient
computational approaches are quintessential. In this study, we explored a new
NURBS-based Isogeometric Analysis (IGA) framework for the simulation of
curvilinear fiber composites and we compared it to standard Finite Element
Analysis (FEA). A plate featuring a semi-circular notch under tensile loading
with different fiber configurations served as a case study. We showed that,
thanks to the exact geometric representation and the enriched continuity
between elements, NURBS-based IGA outperforms classical FEA in terms of
computational efficiency, time-consumption, and estimation quality of field
variables for same number of degrees-of-freedom. To further demonstrate the use
of the IGA framework, we performed optimization studies aimed at identifying
the fiber paths minimizing stress concentration and Tsai-Wu failure index. The
model showed that curvilinear anisotropy can be effectively harnessed to reduce
the stress concentration of up to 82 % compared to unidirectional composites
without affecting the overall plate stiffness significantly.
