Navy supports U of M Mechanical Engineering thru STTR program on helicopter reliability

Rotorcraft structures are subject to damage accumulation due to the harsh environment and conditions in which they operate. Components are currently designed using a safe-life approach, in which analytical methods are used to calculate the predicted service life of components. The major disadvantage is that the components are retired from use after a specified number of service hours, regardless of the remaining useful life of the component, and consequently some parts are not utilized to their full potential of useful life. Efforts are currently underway to transition from a safe-life design approach to a more practical conditional maintenance approach, in order to achieve optimum service life out of structural components.

 
The Navy desires a model for structural health measurement that is capable of assessing the accumulated damage and remaining useful life of components in a timely manner post-flight. This will eliminate the need for load tracking during flight and prevent the additional weight and complexity (hence increased cost) of components utilized during flight. The desired model will relate the current level of accumulated damage in a component/s to the remaining useful life of the component/s. There are multiple technologies available for measuring the amount of accumulated damage in a component, such as acoustic emissions, surface temperature, ultrasound, and electromagnetic readings. Recent research efforts at University of Memphis have demonstrated that acoustic emission technology provides the clearest signal transmission when a damage event occurs, i.e. they have established a data-enabled approach to quantify random damage of materials and structures by constructing a measureable multi-variate, (D). This variate can then be analyzed by means of mathematical statistics, allowing for data-enabled decision-making concerning material failure.
Our STTR project partner is Safe Inc., Tempe, AZ.

Fig. Helicopter Rotorhead component reliability and associated Acoustic Emission approach developed by University of Memphis.