Topology and fiber path optimization of composite structures: A critical review

Fiber-reinforced composites have gained worldwide popularity due to their superb properties including high specific stiffness and strength. In addition to their favorable physical attributes, the mechanical characteristics of these materials can be tailored to maximize their performance for distinct applications. Recent advances in additive manufacturing have enabled the fabrication of curvilinear fibers, which can further improve internal load allocation. Composite structures become even more effective when stiffness tailoring is combined with topology optimization, which concerns determining the ideal material distribution for a specific structural design problem. However, collective optimization of material anisotropy and geometry poses inherent challenges that prompted the development of diverse methodologies. This review article summarizes the state-of-the-art composite design techniques developed to optimize fiber paths and structural topology sequentially or simultaneously. The available approaches are categorized according to their scope and intrinsic principles unlike many existing works employing classification based on optimization or material parametrization schemes. The paper also covers experimental results as another rare feature. The advantages and shortcomings of the investigated methods are discussed considering various aspects including effectiveness, ease of use, computational cost, versatility, robustness, and suitability for manufacturing. The review concludes with remarks on relevant open problems and potential future research directions.