RANS-Based Stick-to-Stress Dynamic Flight Simulation for Aircraft Life Prediction

ABSTRACT: Both commercial and military aircraft are being flown/utilized for extended operational time. The aircraft cumulative flight hours often extends the original design limits. Each aircraft manufacturer calculates aircraft fatigue and damage using different techniques. A more accurate prediction of the remaining life and inspection intervals for an individual aircraft is required, as these aging aircraft are kept in operational status. ZONA Technology, Inc. has been working closely with The Boeing Company to develop a software process to more accurately predict the maneuver loads on an aircraft. This program is called Stick-to-Stress Dynamic Flight Simulation (StS-DFS); which can generate structural component loads and stresses due to a pilot stick input command. In the Phase I effort, we will further enhance StS-DFS using the Reynolds-averaged Navier-Stokes (RANS) solver to generate the steady aerodynamic forces and the ZONA Unstructured Linearized Unsteady Solver to generate the unsteady aerodynamic forces. This enhanced StS-DFS is referred to as RANS-based StS-DFS.F-15 Saudi aircraft, an on-going Boeing project for verifying a new "fly-by-wire" capability, was selected to validate the RANS-based StS-DFS system with the newly acquired flight test data from the F-15 Saudi flight test.; BENEFIT: Recently, the Air Force Research Laboratory has produced a long-term vision, called the Airframe Digital Twin that calls for the development of a physics-based process of determining initial or remaining aircraft structural life. The outcome of the proposed Phase I effort will be one of the crucial early steps towards the Airframe Digital Twin vision.Several U.S. military aircraft such as F-16, F-15, C-5 and A-10 and commercial aircraft are reaching or are already beyond their originally designed fatigue lives. To identify their residual fatigue life or extend their fatigue life by retrofit, accurate loads spectra to perform fatigue analysis or ground fatigue tests on these aircraft is required.Such an accurate loads spectra can be generated by RANS-based StS-DFS using the recorded flight test data of individual fleet members of these aircraft as input to keep track of the individual fatigue life as proposed in the USAF Digital Twin vision with the concept of improved fatigue calculation.In Phase II, the ZONA/Boeing team will develop a process that can extract the stresses generated by the RANS-based StS-DFS software around the identified fatigue critical regions in the structure and use these stresses as input to their respective structural component damage tolerance models; leading to an updated life prediction and inspection interval of an individual aircraft.