1、Reliability considerations of NDT by probability of detection(POD)determination using ultrasound phased arrayJochen H.Kurza,Anne Jngertb,Sandra Duganb,Gerd Dobmanna,Christian BolleraaFraunhofer Institute for Nondestructive Testing(IZFP),Campus E3 1,66123 Saarbrcken,GermanybMaterials Testing Institut
2、e University of Stuttgart,Pfaffenwaldring 32,70569 Stuttgart,Germanya r t i c l ei n f oArticle history:Available online 20 June 2013Keywords:Probability of detection(POD)Ultrasound phased arrayUltrasound sampling phased arrayCracksQuantitative NDTa b s t r a c tReliable assessment procedures are an
3、 important aspect of maintenance concepts.Non-destructive testing(NDT)methods are an essential part of a variety of maintenance plans.Reliability aspects of NDT methods are of importance if quantitative information isrequired.Different design concepts e.g.the damage tolerance approach in aerospaceal
4、ready include reliability criteria of NDT methods.NDT is also an essential part duringconstruction and maintenance of nuclear power plants.This paper will show the resultsof a research project designed for POD determination of ultrasound phased array inspec-tions of real cracks.The continuative obje
5、ctive of this project is to generate quantitativePOD results and to integrate these results in a probabilistic damage assessment concept.The distribution of the crack sizes of the specimens and the designed inspection instructionwill be discussed,and results of the ultrasound inspections will be pre
6、sented.Furthermore,additional considerations for POD determination of phased array inspections of real crackswill be discussed.In the context of the results,the remaining uncertainty of the inspectionshas to be taken into consideration for failure analysis.?2013 Elsevier Ltd.All rights reserved.1.In
7、troductionA reliable prognosis of the condition and behavior of a structure or component is an important basis for an effective ser-vice life management.Non-destructive testing(NDT)methods are able to retrieve information on the geometry of flaws 13,on states of material degradation 4,on material pa
8、rameters 5 and on stress related material states 6.This informa-tion is required for damage assessment concepts,especially those related to the applied design concepts.The strongest rela-tion to NDT exists in case of damage tolerant(DT)design where non-destructive testing methods are an essential pa
9、rt of thedesign concept.So far this is primarily applied in the field of transportation vehicles and here especially with regard to avi-ation and also naval applications 7.Furthermore,other life cycle assessment concepts exist(e.g.database lifing,retirementfor cause)which are in some points differen
10、t from the classical DT approach(iterative life extension beyond damage tolerantlife by shorter service intervals)8.In contrast to the damage tolerant approach,the safe life(SL)design approach is appliedin a variety of industry sections 9.NDT is also an essential part during construction and mainten
11、ance of nuclear powerplants.In Germany,type and extent of inspection are specified by the Nuclear Safety Standards Commission(KTA).Only cer-tified inspections are allowed in the nuclear industry.The qualification of NDT is carried out in form of performance dem-onstrations of the inspection teams an
12、d the equipment,witnessed by an authorized inspector.The results of these tests aremainly statements regarding the detection capabilities of certain artificial flaws.In other countries,e.g.the U.S.,additional1350-6307/$-see front matter?2013 Elsevier Ltd.All rights reserved.http:/dx.doi.org/10.1016/
13、j.engfailanal.2013.06.008Corresponding author.Tel.:+49 681 9302 3880;fax:+49 681 9302 11 3880.E-mail address:jochen.kurzizfp.fraunhofer.de(J.H.Kurz).Engineering Failure Analysis 35(2013)609617Contents lists available at SciVerse ScienceDirectEngineering Failure Analysisjournal homepage: tests on tes
14、t blocks with hidden and unknown flaws may be required,in which a certain percentage of these flaws hasto be detected.The knowledge of the probability of detection(POD)curves of specific flaws in specific testing conditions isoften not present.A quantitative consideration of NDT methods in assessmen
15、t procedures requires quantitative statements about the reli-ability of the applied NDT method.The determination of the probability of detection(POD)is one possibility to quantify theprobability to detect a specific flaw with an NDT method.Each NDT measurement is influenced by a variety of factors:t
16、hestage of development and the quality of NDT equipment,the quality of written procedures,the skills and attitude of theoperators,the geometry and material of the component,the environment in which the inspection takes place,the location,orientation and size of flaws,as well as the material state.Therefore,reliability information about an NDT method requiresdefining a probability of detection which can be described as:the proportion of cracks that will be detected in the total num-ber of existin
