Connecting nonlinearities: Damage precursors detection and control methodology

Fatigue damage precursors identification and control procedure is developed for nonlinear aero-structures and dynamic systems exposed to realistic vibratory conditions. The identification is achieved by connecting nonlinearities between macro-and micro-states, and including those connection in the equations of motion; i.e. the interplay between the local nonlinearities (or materials micro-plasticity) and the global nonlineari-ties (nonlinear dynamic parameters). Exploiting the nonlinear connections is key in linking the health of a system to its control algorithms, which can manipulate the structural dynamic responses in order to slow the progression of fatigue. This approach allows for continual re-estimation of the dynamics of the macro-states due to degradations in the properties of the micro-states at unhealthy locations by identifying precursors to damage prior to crack formation. Capturing and controlling the interplay between the local and global nonlinearities appear to hold promise in extending the service-life of high-value systems.