Three　Dimensional　AE　tomography　for　Image　Processing of　the　Deteriorated　Materia1

Abstract

The　occurrence　of　various　kinds　of　phellomena　in　materials　gives　rise　to　the　emission　of　elastic waves、These　waves　are cailed　acoustic　emission（AE）or　stress　wave　emission（SWE）．Wave　forms　and the velocity　of　AE　will　change　whlle　it propagates　in　a　non 1inear　medium、So，wave　forms　and　changes　of　arrival　times　are　conskiered　to　contain　informations　on the　source　phenomena　and　informations　on　the　path　where　AE　travels、 In　this　paper，therefore，in　order　to　get　the　informations　on　the　path　between　AE　source　and　AE　detector　and aound　the AE　source　caused　by　the　uni－axial　compression　test，deterlorated　concrete　is　used　as　a　specimen、 AE wave forms are measured by 12 AE detectors with three transient recorders with 1 M words memory which were designed　for　AE　measurement（see　Fig．3）．The　rise　times　of　AE　waves　are　decided　automatlcally，and　then　AE　source　is calculated　by　the　method　of　successive　approximation　of　which　variables　are（x，y，z），t，V（see　Fig、2）． Three　dimensional AE　tomography　of　which　generator　is　AE　is　simulated　by　SIRT（Simultaneous　Interactive　Reconstruc－ tion　Technique）method．The　deteriorated　part　of　the　concrete　specimen　is　visualized　by　means　of　computer　graphics（see Fig、7and　Fig．8）．