Effect of Irregularity in Shape and Boundary of a Macro-Texture Region in Titanium (Postprint)
Abstract
Peak amplitudes of mode converted shear wave signals back scattered from macro-texture regions (MTRs) in an aerospace grade titanium alloy material are measured to be about the same level as corner trapped shear wave signals. In addition to the abnormally high shear wave responses, the time of flight data indicates that the MTR signals are back scattered from a location deep in the sample so that the round trip travel time is close to that of corner trapped signals. In this work, these two ultrasonic properties of an MTR in a test specimen cut from a titanium jet engine disk are closely studied to understand the root cause of abnormally high shear wave responses. Based on the amplitude and time of flight data collected in a laboratory condition, a decision has been made to investigate further experimentally and computationally how surface irregularity of an acoustically reflective surface affects incoming shear waves upon reflection. Attempts are made to correlate the localized back scattered signal response of the MTR in the test specimen to the beam focusing effect of a non-planar surface of an acoustically impedance mismatched boundary layer such as a fatigue crack face.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 15, 2015
- Accession Number
- AD1032029
Entities
People
- James L. Blackshire
- Jeong K. Na
- Shaun L. Freed
Organizations
- Air Force Research Laboratory Materials and Manufacturing Directorate