Study On Configuration And Snapping-though Behavior Of Bistable Composite Laminates Actuated By MFC

Bistable structure refers to the structure with two stable configurations.As a kind of deformable structure,bistable structure does not require continuous energy input,and can complete snap-though under the action of external load over the energy barrier of two configurations,and stabilize the configuration state after the snap-though.The characteristics of bistable structure make it have good application prospect in future deforming aircrafts.In this paper,the application of Macro-Fibei Composite(Macro-Fiber Composite)to bistable laminates is discussed.In the structure discussed in this paper,MFC,as an actuator,only needs to be used for the deformation process of bistable structure from one equilibrium state to the other,so continuous input energy is not required.Firstly,the theoretical model of anti-symmetric bistable structure actuated by MFC is established in this paper.Based on the Rayleigh-ritz method and the principle of minimum potential energy theory,the corresponding out-of-plane displacement function and strain function are derived,and the configuration state under different circumstances is calculated by the minimum strain energy theory.In the finite element simulation process,the effective driving part in the MFC is equivalent to a simple piezoelectric material,and the structural model of the[90/0]anti-symmetric bistable laminated plate actuated by the MFC 150mm×150mm is constructed.The actual actuating experiment of geometric size model is carried out.Finally,the overall configuration of the structure is determined,the snap-though process and the configuration results obtained by model calculation and experiment are compared.The minimum actuating voltage was measured by the experiment is1370V,which is higher than the 1000V minimum actuating voltage obtained by finite element simulation.With reference to the research process of anti-symmetric bistable structure actuated by MFC,the snap-though study of three hybrid symmetrical bistable laminates actuated by MFC is carried out in this paper.Different from anti-symmetric bistable laminae,the main curvature directions of hybrid symmetric bistable laminae under the two configurations are parallel and completely symmetric,and there are two orthogonal curvature directions of x and y exist in each configuration.Aiming at the characteristics of double curvature,two actuating schemes of[90/glass fiber/90]union[90/0/90]symmetric bistable laminates laying MFC in the x and y directions of the 100mm×60mm laying mode are designed,and the corresponding finite element simulation and experiment are carried out respectively.Experimental results show that the actuating effect of laying three pieces of MFC in longitudinal array is not as good as laying one piece of MFC in transverse array.In the experiment of laying a piece of MFC horizontally,the minimum driving voltage is 1000V,which is still higher than the 600V minimum driving voltage simulated by finite element method.Bistable cylindrical shells with initial curvature are different from antisymmetric bistable laminates and symmetric bistable laminates.Therefore,the theoretical model with initial curvature no longer follows the theoretical derivation of symmetric bistable and antisymmetric laminates.The two configurations of bistable cylindrical shells with initial curvature have different curvature directions and are orthogonal to each other,just like anti-symmetric laminated plates.As the size of the MFC used in the experiment is 43mm×12mm,and the difference in the size of length and width is nearly three times,MFC bonding will always have a greater impact on the curvature of one configuration than the other.During the experiment,the bistable cylindrical shell with dimensions L=100mm,R=25mm,C=180~o and laying mode[-45,45,-45,45]can be made to snap-though when MFC is used at the lowest driving voltage of 700V.