Comprehensive Simulation Based Rotorcraft Loads/Fatigue Analysis and Alleviation Method

Rotorcraft experience vibratory loads due to the constantly varying airloads under all flight conditions. Maximizing the fatigue life of their structural components is a vital factor for sustained operations with low-maintenance. Most existing fatigue analysis methods are empirical and, hence, are limited for use in investigating the effects of maneuvering f light as well as for exploring modern control methods (e.g., on-blade controls (OBC)) for alleviating fatigue. This paper discusses comprehensive simulation-based rotorcraft loads/stress analysis and fatigue alleviation control methods toward the goal of minimum maintenance for future vertical lift. The paper covers several aspects, including comprehensive modeling for loads prediction, blade stress analysis with the applied loads, fatigue estimation, and loads/stress reduction control formulation. The paper also presents simulation results that demonstrate the successful reduction of vibratory loads/stress using modern on-blade active control methods.