title: Tank measurements of scattering from a resin-filled fiberglass spherical shell with internal flaws.
abstract: This paper presents results of acoustic inversion and structural health monitoring achieved by means of low to midfrequency elastic scattering analysis of simple, curved objects, insonified in a water tank. Acoustic elastic scattering measurements were conducted between 15 and 100 kHz on a 60-mm-radius fiberglass spherical shell, filled with a low-shear-speed epoxy resin. Preliminary measurements were conducted also on the void shell before filling, and on a solid sphere of the same material as the filler. These data were used to estimate the constituent material parameters via acoustic inversion. The objects were measured in the backscatter direction, suspended at midwater, and insonified by a broadband directional transducer. From the inspection of the response of the solid-filled shell it was possible to detect and characterize significant inhomogeneities of the interior (air pockets), the presence of which were later confirmed by x-ray CT scan and ultrasound measurements. Elastic wave analysis and a model-data comparison study support the physical interpretation of the measurements.
authors.affiliation: NURC, Viale San Bartolomeo 400, 19126 La Spezia, Italy. tesei@nurc.nato.int
authors.forename: Alessandra
authors.initials: A
authors.lastname: Tesei
authors.forename: Piero
authors.initials: P
authors.lastname: Guerrini
authors.forename: Mario
authors.initials: M
authors.lastname: Zampolli
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D000388:Air; D004548:Elasticity; D004853:Epoxy Resins / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D008422:Materials Testing; D008962:Models, Theoretical; D009038:Motion; D010316:Particle Size; D015203:Reproducibility of Results; D013016:Sound; D013499:Surface Properties; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014159:Transducers; D014463:Ultrasonography; D014867:Water
chemical_list: D004853:Epoxy Resins; C009753:fiberglass; D014867:Water