Impact of joint boundary geometry on the mechanical behavior of variable‐diameter bistable composite structures

Abstract Variable‐diameter bistable composite structures with joint boundaries have significant potential for application in engineering, particularly in aerospace systems. This study focuses on analyzing the effects of joint boundary geometry, specifically the parameters of wavy boundaries, on the bending stiffness of these structures. To simplify the analysis, a beam model was established, with the joint boundary approximated as a rotational spring characterized by rotational stiffness. Using this model, the influences of wavy boundary geometric parameters, specifically the amplitude and wavelength, on the bending stiffness were systematically analyzed and compared against those of structures with straight joint boundaries. The findings indicate that larger amplitudes and suitable wavelengths can significantly enhance the bending stiffness, thereby improving the overall mechanical performance of the structure. The accuracy of the theoretical model was further verified through finite element numerical simulations. The experimental results demonstrated the practical influence of the wavy joint boundary parameters on the bending stiffness, underscoring the importance of the wavy boundary design in optimizing the performance of bistable structures, particularly in aerospace applications where an increased bending stiffness can contribute to lightweight and flexible structural designs. This work provides a theoretical foundation and practical guidance for the optimal design of variable‐diameter bistable composite structures. Highlights Investigated the impact of wavy spliced boundaries on the bending stiffness of bistable structures. A beam model for predicting the effect of the joint shape on the bending performance was developed. Compared with straight‐edge joints, irregularly spliced joints increased the peak bending load by 22%. The irregular joints had an MFS of 0.45, three times greater than that of the straight‐edge joints.