Abstract
Asymmetric laminates of fibrous composites have strong elastic and thermal anisotropic properties, resulting in the curved surfaces caused by residual thermal strain during curing process. Specific asymmetric laminates indicate bi-stable states in terms of surface shapes, and these bi-stable states enable large deformation with relatively small energy input. This becomes an advantage when the asymmetric laminate is applied to the aerospace structures such as a morphing airfoil. The present paper first reveals occurrence criteria of bi-stable states for asymmetric laminates. In-plane buckling strengths are employed as an index of occurrence and calculated for plates with different width-to-thickness ratio and lay-up configurations. Then, vibration properties of bi-stable composite shells are evaluated by using both numerical study with the Ritz method based on Donnel-Mushtari theory and the experimental modal analysis technique. The numerical and experimental results show that there are some relations between the buckling strength and the occurrence of bi-stable states within plates having specific lay-up configurations, and asymmetric laminates with bi-stable states indicate different vibration characteristics before and after snap-thorough deformation.
