Processing and Probability Analysis of Pulsed Terahertz NDE of Corrosion under Shuttle Tile Data
This paper examines data processing and probability analysis of pulsed terahertz NDE scans of corrosion defects under a Shuttle tile. Pulsed terahertz data collected from an aluminum plate with fabricated corrosion defects and covered with a Shuttle tile is presented. The corrosion defects imaged were fabricated by electrochemically etching areas of various diameter and depth in the plate. In this work, the aluminum plate echo signal is located in the terahertz time-of-flight data and a threshold is applied to produce a binary image of sample features. Feature location and area are examined and identified as corrosion through comparison with the known defect layout. The results are tabulated with hit, miss, or false call information for a probability of detection analysis that is used to identify an optimal processing threshold.
Directed Design of Experiments for Validating Probability of Detection Capability of NDE Systems (DOEPOD)
The capability of an inspection system is established by applications of various methodologies to determine the probability of detection (POD). One accepted metric of an adequate inspection system is that there is 95% confidence that the POD is greater than 90% (90/95 POD). Directed design of experiments for probability of detection (DOEPOD) has been developed to provide an efficient and accurate methodology that yields observed POD and confidence bounds for both Hit‐Miss or signal amplitude testing. Specifically, DOEPOD demands utilization of observance of occurrences. Directed DOEPOD does not assume prescribed POD logarithmic or similar functions with assumed adequacy over a wide range of flaw sizes and inspection system technologies, so that multi‐parameter curve fitting or model optimization approaches to generate a POD curve are not required.
Nondestructive Evaluation (NDE) Capabilities Data Book (3rd Edition)
Abstract : This Data Book consolidates and organizes available reference data for demonstrated NDE performance capabilities into a single source. Guidelines are presented for selecting options for use of NDE and for assessing the potential to meet design requirements (critical flaw detection requirements). Guidelines for demonstration of specific NDE process capabilities are also presented. Following a 65 page text (7 chapters) describing various aspects of NDE capabilities quantification, probability of detection (POD), and damage tolerance concepts, 423 POD curves are organized and presented in a series of Appendices organized by NDE method. A documentation page precedes each dataset and provides a condensed description of the test object, test artifact and data collection conditions follow the documentation page. POD data are generally presented as a function of crack length. For selected datasets, POD data are also presented as a function of crack depth and crack depth-to-thickness ratio. POD curves are based on hit/miss data using the log-logistic model. Original reference source information is provided for each dataset.