Tensegrity system dynamics in fluids

International audience; This paper provides compact vector and matrix forms of the nonlinear dynamics of class-1 and class-k tensegrity systems with fluid forces incorporated. Firstly, the equation of motion (both translation and rotation) of a single rod is modeled. Then, the fluid forces by fluid particles interacting with the rod are modeled and added to the derived dynamic equations of the rod. Then, by stacking all the governing equations of motion for each rod, compact vector and matrix forms of class-1 and class-k tensegrity dynamics are formulated. Finally, three examples based on a three-dimensional prism model with and without considering fluid forces, with and without fluid inlet velocity, and landing to the ground with and without fluid influence are simulated and compared. Results show that the simulations match well with physics. The fluid provides significant damping to the dynamics of the structure. This work enables the ability to do fluid-structure interaction studies of any tensegrity structures. The principles developed here can also be used for analyzing various kinds of tensegrity structures operating in the air or underwater.