Abstract
Coreless Filament Winding (CFW) is a structural and time-efficient fabrication method for composite lattice structures. Since the fiber is wound around pins whose diameter cannot be infinitesimally small, each structural element may have four possible beam configurations, which depend on the in-plane local coordinates of the start and/or end of the beam. In this case, layer inconsistency, a condition that a structural element with multiple layers has different beam configurations, may inevitably occur in the fabricated structure. It will decrease the second moment of area of the structural element and may lead to reduced flexural stiffness of the structure. However, this effect was not considered in previous research. Therefore, a detailed Finite Element Model (FEM) which characterizes the practical beam configurations was developed to explore the influence of layer inconsistency on the flexural stiffness of the structure. To improve the structural-efficiency and the fabrication speed, a structural optimization was conducted to minimize the fiber-length and provide 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 detailed FEM provides a reliable prediction of the structural stiffness (average error ⩽ 5.4%). Moreover, the developed sequence optimization decreases the stiffness reduction 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.
