Quantification of the reliability of flaw detection (NDT) using probability of detection (POD) based on synthetic data - Validation of the ultrasonic phased array model Håkan Wirdelius Advanced NDT /SCeNDT Chalmers

Applications of NDE To monitor, improve or control manufacturing processes Structure and Microstructure Characterization Estimation of Mechanical and Physical Properties Dimensional Measurements To inspect for in-service damage Flaw Detection and Evaluation Leak Detection

Reliability of used NDE method NDE reliability is the degree that an NDE system is capable of achieving its purpose regarding detection, characterization, sizing and false calls. Performance demonstrations A systems reliability can be quantified by its: capability (POD or Qualification) reproducibility (calibration) repeatability (NDE process control in application) Unknown Defect Situation in Testsample or Real Component Non-Destructive Test Report Black Box True Data Test Result Comparison

NDE capability by POD Defect size Signal magnitude Probability of detection (POD) Response Experiments or simulation a â

Quantitative NDE What is the critical flaw size that will cause failure for a given component subject to service stress and temperature conditions? How long can a pre-cracked structure be safely operated in service? What inspections must be performed to prevent catastrophic failure? Redundant design, i.e. how can a structure be designed to prevent catastrophic failure from pre-existing cracks?

Definitions by signal response Nondestructive Testing (NDT). UT, ET, RT UT, ET, RT (technique, method) Nondestructive Evaluation (NDE). UT, ET, RT Hit/Miss (procedure, calibration) Quantitative Nondestructive Evaluation (QNDE). UT, ET, RT Characterization, (capability, reproducibility size, position & repeatability) Integrity and quality assessment by NDE (IqNDE). UT, ET, RT residual life, KIC, (math. models of NDE da/dN, nodularity & meta-modeling)

Mathematical modelling of UT simSUNDT The simSUNDT program (freeware) consists of a Windows®-based pre-processor and postprocessor UTDefect used as a mathematical kernel Model of ultrasonic backscattering due to grain growth in a welded region The result can be read by a number of commercial analysis software Reduce number of test pieces and synthetic defects

Quantification of the reliability of flaw detection for phased array techniques WP 1 Development of simulation model: WP 2 Experimental verification of the model:

WP 1 Development of simulation model Phased array UT E.A. Ginzel1 and D. Stewart2 , PHOTO-ELASTIC VISUALISATION OF PHASED ARRAY ULTRASONIC PULSES IN SOLIDS, Proc WCNDT 2004

WP 2 Experimental verification of the model Dimensions of used test specimen 20 40 60 10 80 300 5 Side-Drilled Holes 6 Flat- Bottom Holes all f = 2.4 mm 35 5 Depth 20, 40 and 60 Depth 10, 30 and 50

Initial experimental validation of the set-up

Initial experimental results

Validation of energy divergence (number of elements)

Validation of energy divergence (number of elements)

B & C-scan validation (amplitude)

Quantification of the reliability of flaw detection for non-destructive techniques using probability of detection (POD) based on synthetic data WP 3 Procedure for synthetic data based POD: Develop a technique that uses mathematical models in order to develop a data base that will be used as the basis for a POD curve. The procedure shall be for a specific NDT task based on experiences made in WP1 and 2. WP 4 Experimental validation of the synthetic POD: Experimentally validate the above evolved POD curve. This in order to optimize the inspection procedure and also to make it as a convention tool in the development of POD characteristics.

Academic SME Industry H T S PICASSO imProved reliabIlity inspeCtion of Aeronautic structure through Simulation Supported POD H T S Hoch Technologie Systeme World Centre for Materials Joining Technology Industry Academic SME