Damage-Mitigating Control of Power Systems for Structural Durability and High Performance

A major goal in the control of complex power systems such as advanced aircraft, spacecraft, and electric power plants is to achieve high performance with increased reliability, availability, component durability, and maintainability. The state of the art in the synthesis of control systems for complex mechanical processes focuses on improving performance and diagnostic capabilities under constraints that do not often adequately represent the dynamic properties of the materials. The reason is that the traditional design is based upon the assumption of conventional materials with invariant characteristics. In view of high performance requirements and availability of improved materials, the lack of appropriate knowledge about the properties of these materials will lead to either less than achievable performance due to overly conservative design, or overstraining of the structure leading to unexpected failures and drastic reduction of the service life. The key idea of the research work reported in this paper is that a significant improvement in service life can be achieved by a small reduction in the system dynamic performance. The concept of damage mitigation is introduced and, to this effect, a continuous-time model of fatigue damage dynamics is formulated. Finally, the results of simulation experiments are presented for transient operations of a reusable rocket engine.