?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Noncontact+monitoring+of+fatigue+crack+growth+using+high+frequency+guided+waves&rft.creator=Masserey%2C+B&rft.creator=Fromme%2C+P&rft.description=The+development+of+fatigue+cracks+at+fastener+holes+due+to+stress+concentration+is+a+common+problem+in+aircraft+maintenance.+This+contribution+investigates+the+use+of+high+frequency+guided+waves+for+the+non-contact+monitoring+of+fatigue+crack+growth+in+tensile%2C+aluminium+specimens.+High+frequency+guided+ultrasonic+waves+have+a+good+sensitivity+for+defect+detection+and+can+propagate+along+the+structure%2C+thus+having+the+potential+for+the+inspection+of+difficult+to+access+parts+by+means+of+non-contact+measurements.+Experimentally+the+required+guided+wave+modes+are+excited+using+standard+wedge+transducers+and+measured+using+a+laser+interferometer.+The+growth+of+fatigue+cracks+during+cyclic+loading+was+monitored+optically+and+the+resulting+changes+in+the+signal+caused+by+crack+growth+are+quantified.+Full+three-dimensional+simulation+of+the+scattering+of+the+high+frequency+guided+ultrasonic+waves+at+the+fastener+hole+and+crack+has+been+implemented+using+the+Finite+Difference+(FD)+method.+The+comparison+of+the+results+shows+a+good+agreement+of+the+measured+and+predicted+scattered+field+of+the+guided+wave+at+quarter-elliptical+and+through-thickness+fatigue+cracks.+The+measurements+show+a+good+sensitivity+for+the+early+detection+of+fatigue+damage+and+for+the+monitoring+of+fatigue+crack+growth+at+a+fastener+hole.+The+sensitivity+and+repeatability+are+ascertained%2C+and+the+robustness+of+the+methodology+for+practical+in-situ+ultrasonic+monitoring+of+fatigue+crack+growth+is+discussed.+%C2%A9+2014+SPIE.&rft.publisher=Society+of+Photo-optical+Instrumentation+Engineers&rft.date=2014-03-08&rft.type=Proceedings+paper&rft.language=eng&rft.source=+++++In%3A++Proceedings+of+SPIE.++++Society+of+Photo-optical+Instrumentation+Engineers%3A+Bellingham%2C+US.+(2014)+++++&rft.format=application%2Fpdf&rft.identifier=https%3A%2F%2Fdiscovery.ucl.ac.uk%2Fid%2Feprint%2F1433720%2F1%2F90611D.pdf&rft.identifier=https%3A%2F%2Fdiscovery.ucl.ac.uk%2Fid%2Feprint%2F1433720%2F&rft.rights=open