Federal Aviation Administration Advisory Circular 33.70-2 Calibration Test Using DARWIN Part I

Abstract

<p>The Federal Aviation Administration (FAA) Advisory Circular (AC) 33.70-2 provides definitions and acceptable methods for determining the probability of failure (PDF) of hole features in high-energy turbine engine rotors. A calibration test case is used as a means for the FAA to assess a contractor's capability to perform analytical lifing procedures. The calibration test case specifies the necessary information needed to determine the PDF of a bolt hole feature of a rotating titanium ring. This test case information is discussed in detail as well as steps taken to verify the analytical models used. Two essential pieces of information were noted as missing from the circular, Le., a stressstrain mode" and a tabular data set for the probability of detection curve. The probabilistic risk analysis program Design Assessment of Reliability With INspection (DARWIN) has been approved by the FAA as a suitable tool to conduct risk analysis for certification of new titanium rotor designs in compliance with AC 33.70-2. DARWIN requires the maximum stress conditions in order to determine the PDF of the rotating ring. The maximum stress state was determined using ABAQUS. Both elastic and plastic material properties were used. Nominal stress and strain were converted to true stress and strain with strain decomposed into its elastic and plastic strain portions. The ABAQUS stress model was validated against a closed form solution for an elastic annular disk without a hole. A finite element mesh convergence study was also conducted. This ABAQUS stress analysis, in conjunction with the information in the AC calibration test case, was used to determine the PDF of the rotating ring by Ashley Whitney-Rawls. The PDF analysis is presented in part-two of the presentation.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 16, 2010</p>