Life Extending Control - A Concept Paper

The concept of Life Extending Control is defined. Life is defined In terms of mechanical fatigue life. A brief description is given of the current approach to life prediction using a local, cyclic, stress-strain approach for a critical system component. An alternative approach to life prediction based on a continuous functional relationship to component performance is proposed. Based on cyclic life prediction an approach to Life Extending Control, called the Life Management Approach is proposed. A second approach, also based on cyclic life prediction, called the Implicit Approach, is presented. Assuming the existence of the alternative functional life prediction approach, two additional concepts for Life Extending Control are presented. These are called the Measured Damage Approach, and the Estimated Damage Approach. A simple, hydraulic actuator driven, position control system example is used to illustrate the main ideas behind the Life Extending Control concept and is based on a cyclic fatigue damage model. Some results are given which demonstrate that system durability can be maximized by more effectively managing the resource of critical component life. Some additional research is proposed to develop a functional life prediction method and to demonstrate the concept of Life Extending Control.