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Under certain conditions asymmetric composite laminates can have a bistable response to mechanical loading. A transition between the two stable states provides opportunities to produce large deflections or shape changes from relatively low energy inputs that do not need to be maintained to sustain a specific shape. Such laminates are attracting interest in aerospace applications, deployable structures and energy harvesting. Accurate modelling predictions of bistable laminate shapes has proven challenging, in part due to uncertainties in geometry, material properties and the operating environment of the laminates. In this paper a detailed sensitivity analysis of the influence of each of these properties on laminate curvature is undertaken and demonstrates that bistable laminates are most sensitive to uncertainties in the Young's moduli, thermal expansion coefficients, ply thickness and the temperature change from the elevated cure temperature. Accurate characterisation of these properties and quality control during manufacture can reduce the discrepancies between analytical models and experimental results and allow the models to be used as viable tools for the design of bistable laminates. It is also shown that laminates are highly sensitive to moisture absorption and temperature changes, especially when changes in material properties due to temperature were included in the modelling.

This paper considers a novel electro-thermal system combining aligned carbon nanotubes (A-CNT) as a resistive heater and bistable laminates. The use of A-CNT heaters to actuate bistable laminates is characterized in terms of steady-state shape as a function of applied voltage to the heating element and the transient response of the laminate to heating. Snap-through from one stable state to another was successfully achieved with a linear relationshiop between laminate curvature and applied voltage up to the snap-through event. Thermal actuation of a bistable wing skin has the potential for an efficient multifunctional thermo-mechanical ice protection system (IPS); using heat to address anti-and de-icing, and secondly using thermal actuation of the bistable laminate to deform or mechanically disturb the skin to initiate debond of the ice-skin interface. Nomenclature V= applied voltage I = current P = power T = temperature

The present paper introduces a new technique for simultaneously optimising the topology and continuous material distribution of a structure. Topology optimisation offers great potential for novel, improved structural designs and is an ideal design tool for additive manufacturing (AM) techniques. Level set based topology optimisation produces solutions with clear, smooth boundaries that can be directly fabricated using AM. Further benefits of AM may be realised by also optimising the material distribution within the structure. The sequential linear programming level set method is used to include material distribution design variables in the topology optimisation problem. This allows the topology and continuous material distribution to be optimised simultaneously. Several compliance minimisation problems are used to demonstrate the proposed approach.