Structural and winding sequence optimization of coreless filament wound composite lattice structures

Coreless Filament Winding (CFW) is a structural and time-efficient fabrication method for composite lattice structures. Winding with continuous roving(s) is preferable to ensure the load-bearing capacity of composite and reduce the time consumption in the cutting and restarting process during fabrication. However, as the continuous roving(s) is wound around pins, layer inconsistency due to non-ideal beam configurations may inevitably occur which reduces the second moment of area of the structural elements and the flexural stiffness of the structure, and this was not considered in previous research. Therefore, a detailed Finite Element Model (FEM) was developed in this study to characterize the practical beam configurations and explore the influence of layer inconsistency on the structural stiffness. To improve the structural-efficiency and the fabrication speed, a structural optimization was conducted to provide the structural design with minimal fiber-length and the feasibility to wind with continuous roving(s). In addition, a winding sequence optimization was then implemented to minimize the stiffness reduction effect due to layer inconsistency. The results show that the detailed FEM provides a reliable prediction of the structural stiffness (average error≤5.4%). Moreover, the sequence optimization decreases the stiffness reduction percentage due to layer inconsistency from 51.3% to 13.7%. The proposed strategies of structural and sequence optimization provide instructions for the design and fabrication of CFW structures, which improve the fabrication time-efficiency and the structural-efficiency.