Passive Morphing in Insect Wings: From Biological Mechanisms to Aerospace Structures

Passive morphing enables insect wings to adapt their shape under aerodynamic and inertial loads without direct actuation, contributing to efficient, stable, and agile flight. These natural mechanisms have attracted growing interest as a source of inspiration for adaptive aerospace structures. This review examines the structural and material features governing passive morphing, including wing geometry, venation architecture, membrane mechanics, and material heterogeneity, and discusses their influence on wing deformation and aerodynamic performance. Experimental approaches for characterizing wing kinematics and deformation, together with computational modelling techniques ranging from reduced-order models to fluid-structure interaction simulations, are comparatively evaluated, with emphasis on their capabilities, limitations, and validation requirements. The translation of biological morphing principles into engineering applications, including morphing wings, bio-inspired unmanned aerial vehicles, and lightweight adaptive structures, is also reviewed. Finally, the paper identifies current challenges and future research directions, emphasizing the need for integrated experimental and computational frameworks capable of bridging biological understanding with engineering design. By consolidating recent advances across biomechanics and aerospace engineering, this review provides a comprehensive perspective on passive morphing, emphasizing the transfer of biological mechanical principles rather than the direct scaling of insect-wing behaviour to aerospace applications.