The major focus of our group is the dynamics of complex nonlinear systems such as wind turbines, rotational systems with noise, metamaterials and metastructures, and granular media. We are using computational and experimental tools to study nonlinear system response, including complex phenomena such as multi-stable behavior, parametric resonances, and stochastic jumps.
1. Dynamics of Offshore Wind Turbines
Predicting the structural behavior of wind turbines is of utmost importance since failure or malfunction of turbines/turbine parts is extremely costly. These systems show complicated behavior not only due to unsteady winds but also due to nonlinearities in the turbine structure. We are creating dynamical models to identify the conditions that would lead to large blade deformations and turbine failure. We also do parametric studies to relate these conditions to structural parameters of turbine parts and turbine speeds. These studies are essential for developing design guidelines for more reliable systems and avoiding critical operation conditions through control schemes.
2. Nonlinear Metastructures
Structures that are equipped with a periodic internal geometry to achieve a specific dynamical behavior, such as vibration isolation or nonreciprocal wave propagation are quite popular. Current designs include structures with periodic linear inserts, which are good at suppressing oscillations around a particular frequency. However, their bandwidth is rather low due to their linear behavior. We are exploring the use of geometric and parametric nonlinearities to create metastructures that can exhibit wider bandgaps and nonreciprocal behavior. These studies include systems under rotation and multi-frequency excitation, such as fluid-structure interactions.
3. Stochastic Dynamics of Systems with Noise
Noise is inherent in many mechanical systems. Small noise perturbations can lead to abrupt changes in the behavior of nonlinear systems that are sensitive to perturbations. Using statistical methods, we are exploring changes in system behavior in response to a noise input. We are focusing on rotational systems that have nonlinear characteristics such as turbines and fans. These studies are used to identify how system behavior is affected by the inherent noise, as well as to explore the potential use of noise input to avoid large deformations that could lead to mechanical failure.