Experimental Investigation And Numerical Simulaton For The Anti-Symmetric Bistable Composite Structure

Bistable composite structure, such as the anti-symmetric cylindrical shell, which has two different stable configurations, is able to be stable in both shapes without the need for a going actuation force. It can be changed from one stable state to another with external actuators such as mechanical loads, piezoelectric patches and shape memory alloys or temperature field. As a novel composite structure with bistable characteristics, having advantages of light, superior mechanical properties and higher utilization ratio in space, bistable composite structures have been receiving sufficient attentions of researchers from around the world.Currently, the application of anti-symmetric bistable composite shells is restricted due to lack of experimental studies. Besides, the presented theories concerning anti-symmetric bistable composite shell still need to be improved. Furthermore, the coiled-up radius is very sensitive to the change of ply angle, which is not conducive to the design of the anti-symmetric bistable composite structure. Considering these, research works on anti-symmetric bistable composite shell are presented as follows:1.The theoretical model for the anti-symmetric bistable cylindrical shell taking the shear strain into account in the bending and stretching strain energy is presented in this paper as an extension of Iqbal’s theory. Bistable solutions of the specimens manufactured from carbon-fibre/epoxy prepreg with anti-symmetric layup are given using numerical computation.2. A novel experimental method named two points loading method is presented to capture the bistable behavior of the manufactured specimens. The coiled-up radius, load-displacement curves and the snap loads, including snap-through and snap-back load used to induce the bistable composite shell to snap between two stable shapes, are measured using the corresponding test apparatus. The factors affecting the bistable performance of the anti-symmetric composite shell, including structure sizes and layup conditions are discussed by comparing experimental test results and analytical solutions. Good agreement is found between analytical predictions and measured results.3、The finite element model associated with the experiment is created in ABAQUS. The influences of structure sizes, number of layups and ply angle on the bistable behaviors of the shell are discussed through numerical simulation and theoretical analysis. Meanwhile, the finite element predicted coiled-up radii are approximately in accord with experimental results, and possible reasons of the differences are also given.4、The irregular anti-symmetric lay-up is presented by introducing two or more ply angles in one bistable composite shell. Both analytical and finite element results show that irregular anti-symmetric cylindrical shells with different bistable behaviors can be obtained by changing the ply angles or sequence of the layups, which is very useful for the design and application of the anti-symmetric bistable structure.