Dynamics and control of a spatial rigid-flexible multibody system with multiple cylindrical clearance joints

The dynamics and control of a rigid-flexible multibody system with multiple cylindrical clearance joints are studied via the Absolute Coordinate Based (ACB) method that combines the Natural Coordinate Formulation (NCF) describing rigid bodies and the Absolute Nodal Coordinate Formulation (ANCF) describing flexible bodies. The spatial cylindrical joints with clearances are modeled by two rigid bodies, that is, the journal and bearing, where the difference in radius and axial directions defines the radial clearance and axial clearance, respectively. A new four-point contact kinematic model of NCF is proposed for the rigid cylindrical clearance joint. A combined control scheme consisting of a feedforward torque and a PID feedback controller is adopted to track the joint trajectories. Based on the principle of virtual work, a new and simple method is proposed to evaluate the feedforward torque. To improve computational efficiency, an OpenMP based parallel computational strategy is used to solve the large scale equations of motion. Three examples are given to verify the effectiveness of the proposed formulations and demonstrate the complex dynamics of rigid-flexible multibody systems with multiple cylindrical clearance joints.