An airfoil includes an airfoil structure defining a damping network that includes a first cavity, a second cavity, a flow passage connecting the first and second cavities. The airfoil further includes a damping material configured to flow through the damping network. A method of forming an airfoil includes forming an airfoil body having a damping network that includes a first cavity, a second cavity, and a flow passage connecting the first and second cavities. The method further includes adding a damping material configured to flow through the damping network.