Computational Modal Analysis of Microvascular Composite Panels

This paper investigates the modal characteristics of microvascular composite panels, which incorporate fluid-filled microchannels within their plies to enable functionality beyond bearing loads, such as thermal regulation or self-healing. The study focuses on undeformed, flat square panels composed of two fiber-reinforced plies and one microvascular ply featuring a periodic network of parallel, straight microchannels with circular cross sections. It examines how the microchannel network geometry (diameter, spacing, and orientation) affects the natural frequencies and mode shapes of the isolated microvascular ply and the three-ply laminate, considering different stacking sequences, boundary conditions, and filling fluids. A low-order model is developed by combining homogenization, classical laminate theory, and Rayleigh–Ritz approximation to facilitate computational modal analysis. The model’s accuracy in capturing natural frequencies and mode shapes is evaluated against results for a detailed finite element model that explicitly resolves the microchannel geometry. Parametric modal analyses reveal that increasing the microchannel diameter and decreasing the spacing can reduce natural frequencies by up to 35%. Microchannel orientation impacts the modal characteristics of the isolated microvascular ply and asymmetric laminate, but not the symmetric configuration. While the qualitative impact of the microchannels is similar under both pinned and clamped boundary conditions, tighter constraints mitigate changes in modal behavior. These findings can inform the design of multifunctional aerospace structures that incorporate microvascular composite materials. The proposed low-order model also enables parametric modal analyses of panels with plies made from other composite materials featuring similar microstructures.