Extreme mechanics in laminated shells: New insights

Fibre-reinforced composite laminates are increasingly popular for lightweight applications in the aerospace, wind turbine and automotive industries. Apart from their excellent specific strength and stiffness properties, their orthotropic and layered construction can be exploited to create bistable systems that are useful for shape-adaptive morphing or energy-harvesting applications. The nonlinear interaction between initial curvature and induced thermal stresses can lead to “extreme” mechanics with rich branching and multi-stable behaviour. Here, we explore the multi-stability of curved composite laminates in the two-dimensional parameter space of temperature and mechanical loading. Analyses conducted via finite element discretisation and numerical continuation algorithms reveal possible snapping behaviour between five different mode shapes for different combinations of applied load and temperature. Furthermore, we show that a composite laminate can exhibit four stable, self-equilibrated mode shapes for a narrow temperature range. Hence, the multi-stable and nonlinear mechanics of composite laminates is much more complex than previously assumed, and this may influence the design of more versatile morphing structures.