Ultra‐Thin Tow‐Based Discontinuous Composites—Material Overview and Aspirations

ABSTRACT Ultra‐thin Tow‐Based Discontinuous Composites (µt‐TBDC) are emerging as a transformative alternative to conventional continuous‐fiber composites, offering the potential to overcome longstanding limitations in manufacturability, waste, and design flexibility. This paper presents a comprehensive overview of µt‐TBDCs, spanning manufacturing, forming, mechanical characterization, and multi‐scale modelling. Experimental results demonstrate that reducing tow thickness fundamentally alters the material response, enabling µt‐TBDCs to achieve stiffness, strength, and notched performance comparable to quasi‐isotropic laminates, while delivering enhanced compressive strength, fatigue resistance, and significantly improved energy absorption in tearing. These gains are attributed to a transition towards stable, interface and fibre dominated‐controlled failure mechanisms, combined with reduced mesostructural variability arising from the increased number of tows through the thickness and reduced tow wavinesss. Analytical and numerical modelling approaches are reviewed, highlighting the effectiveness of simplified methods for predicting average behavior and the necessity of stochastic frameworks to capture strength and variability. Crucially, µt‐TBDCs enable a broad and tunable design space, where fibre properties, tow thickness, and architecture act as independent design variables rather than fixed constraints. By linking material architecture, processing, and structural performance, this work positions µt‐TBDCs as a paradigm shift in composite design, with significant implications for the future of high‐performance lightweight structures.