The need for a better aircraft performance is increasingly prompting designers towards the concept of ‘morphing’ or ‘shapeadaptable’ structural systems. To improve the performance of the aircraft, multistable composites could provide an interesting alternative to traditional designs. One approach to morphing aircraft is to use bistable structures that have two stable equilibrium configurations to define a discrete set of shapes for the morphing structure. Moving between these stable states may be achieved using an actuation system or by aerodynamic loads. Studding the application of bistable composite plate in the morphing wing is aim of forthcoming investigation in this project. Figures 1 and 2 show two conceptual novel designs of morphing airplane.
Fig. 1 Advanced concepts NASA envisions for an aircraft of the future

Fig. 2 RoboSwifts : tiny micro planes with unique "morphing" wings have been developed by engineering students in the Netherlands

The interest in bistable composite structures comes from the fact that these structures can have two different shapes and they are completely stablein both shapes without need to a continuous power supply and mechanical hinges. It is well known that in the asymmetric composite laminates bistability occurs due to residual stresses resulting from differences in coefficients of thermal expansion and elastic properties in each lamina. Consequently these structures when subject by a thermal load can have large out of plane deflection.


(a) the first stable shape

(b) the second stable shape

Fig. 3 The first and the second stable shapes for graphiteepoxy asymmetric laminate with composition [0/90]

(a)

(c)

(b)

(d)

Fig 5 (a),(b) The first and second stable shapes respectively by considering the temperature dependency of mechanical and thermal expansion properties , (c),(d) The first and second stable shapes respectively without considering the temperature dependency of mechanical and thermal expansion properties
