Viscoelastic bistable behaviour of antisymmetric laminated composite shells with time-temperature dependent properties

Due to the bistable characteristics, antisymmetric laminated ([+α/−α]n) composite bistable shells have been used as novel morphing structures in many engineering fields. Previous theoretical analyses were mainly based on the hypothesis that the composite shell is elastic, which leads to unexpected calculation and prediction errors. In this paper, the fiber reinforcements are assumed to be elastic while the matrix is treated as a viscoelastic material. The resulting viscoelastic material properties of the composite shell are obtained through the experimental test and numerical modeling. Based on the classical lamination theory, together with the principle of minimum potential energy and Maxwell viscoelasticity model, a theoretical model is developed to predict the bistable behaviour of those composite shells with viscoelastic material properties. Subsequently, the influences of applied temperature and relaxation time on the second stable configuration of bistable composite shells are analytically investigated. The results are then compared with those obtained from the experiments and numerical modeling. Comprehensive results show that the principal curvature of the shell's second stable state increases as the applied temperature and relaxation time increase. In contrast, the twisting curvature of the second stable shape generally decreases with the relaxation time increasing but increases with the applied temperature rising.