Experimental Validation of a Time-Accurate Finite Element Model for Coupled Multibody Dynamics and Liquid Sloshing 2007-01-0139

A study for validating a time-accurate explicit finite element code for modeling fully-coupled flexible multibody systems carrying liquid-filled tanks is presented. The multibody system includes rigid bodies, flexible bodies, joints, and actuators. Rigid bodies rotational equations of motion are written in a body-fixed frame with the total rigid body rotation matrix updated each time step using incremental rotations. Flexible bodies are modeled using total-Lagrangian spring, truss, beam and hexahedral solid elements. A penalty model is used to impose the joint/contact constraints. An asperity-based friction model is used to model joint/contact friction. The fluid governing equations of motion are the incompressible Arbitrary Lagrangian-Eulerian Navier-Stokes equations along with a large-eddy simulation (LES) turbulence model. The fluid's free-surface is modeled using an acceptor-donor volume-of-fluid based algorithm. Coupling between the fluid and solid is achieved by solving Newton's equations of motions at the fluid-solid interface nodes.

The validation study is conducted using a multibody system consisting of a rigid baffled tank mounted on suspension springs. The springs are connected to a rigid frame mounted on two linear hydraulic-actuators. Experiments with various input ramp and harmonic excitation from the actuators are performed and the results of the experiments are compared to the results obtained using the model. The system response is measured using linear-displacement transducers at the springs and two cameras showing side and front views of the tank. The results show that the model can predict with reasonably good accuracy the test system's dynamic response.