# US 8,739,629 B2 · Ultrasonic non-destructive testing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,629 B2 - Document ID: US8739629B2 - Status: Granted - Kind: B2 - Application number: 13/712,257 - Filed: 2012-12-12 - Published: 2013-04-25 - Granted: 2014-06-03 - Earliest claimed: 2005-11-04 - Assignees: Imperial Innovations Limited - Applicants: Imperial Innovations Limited - Inventors: Peter Cawley; Frederick Bert Cegla - Web page: https://patentgrep.com/patent/US8739629B2 ## CPC - G01N 29/28: providing acoustic coupling {, e.g. water (impedance matching G10K11/02)} - G01N 2291/0234: Metals, e.g. steel - G01N 2291/0422: Shear waves, transverse waves, horizontally polarised waves - G01N 2291/044: Internal reflections (echoes), e.g. on walls or defects - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract An apparatus and method for ultrasonic non-destructive testing provides an elongate strip of ultrasound transmissive material coupled at a proximal end to an object under test. The elongate strip has a transverse cross-section with a width and thickness giving an aspect ratio greater than unity and matched to the ultrasonic transducer such that excitation induces a substantially non-dispersive ultrasonic signal to propagate along the elongate strip to the proximal end and to enter the object under test. These non-dispersive pulses are particularly suited for time-of-flight measurements, thickness measurements, crack measurements and the like. The elongate strip helps to separate the transducer from a potentially hostile environment associated with the object under test. The elongate strip also has a large area of contact with the object under test allowing efficient transmission of energy into the object under test. ## Claims ### Claim 1 Apparatus for ultrasonic non-destructive testing of a solid object, the apparatus comprising: an elongate strip of ultrasound transmissive material, said elongate strip having a transverse cross-section with a width and a thickness giving an aspect ratio greater than unity, a proximal end and a distal end; an ultrasonic transducer coupled to said elongate strip and matched thereto such that excitation of said ultrasonic transducer induces non-dispersive ultrasonic shear wave signals to propagate in a propagation direction along said elongate strip to said proximal end, said signals being formed of components of different frequencies having wavelengths extending from λshort to λlong and being polarized in a direction perpendicular to said propagation direction; coupling means for coupling said proximal end to a surface of a solid object, wherein said non-dispersive signals are coupled into the solid object; and an ultrasound receiver configured to receive reflected signals from the solid object that are non-dispersive ultrasonic shear wave signals and are polarized in a direction perpendicular to a propagation direction of the reflected signals; wherein said thickness is less than 2.5 λshort and said width is greater than 5 λlong. ### Claim 2 (depends on 1) Apparatus as claimed in claim 1, wherein said elongate strip is formed of a material having a shear velocity Cs and a shear wavelength λ, where λ=Cs/F and F is the frequency corresponding to λ. ### Claim 3 (depends on 1) Apparatus as claimed in claim 1, wherein said thickness is less than kshort. ### Claim 4 (depends on 1) Apparatus as claimed in claim 1, wherein said elongate strip is formed of a material having a transmission velocity Cbar and a transmission wavelength λbar where λbar=Cbar/F and F is the frequency corresponding to λbar. ### Claim 5 (depends on 1) Apparatus as claimed in claim 1, wherein said ultrasonic transducer excites substantially only a single mode of propagating guided wave. ### Claim 6 (depends on 1) Apparatus as claimed in claim 1, wherein said non-dispersive ultrasonic signals spread substantially cylindrically from said proximal end to an object under test. ### Claim 7 (depends on 1) Apparatus as claimed in claim 1, wherein said ultrasonic transducer is coupled to said distal end. ### Claim 8 (depends on 1) Apparatus as claimed in claim 1, wherein said elongate strip is bent around an axis that is substantially parallel to said width of said elongate strip and substantially perpendicular to the propagation direction. ### Claim 9 (depends on 1) Apparatus as claimed in claim 1, wherein said ultrasound receiver comprises one or more further elongate strips each coupled to said object under test at a respective position to receive said reflected ultrasound and having an ultrasonic transducer to detect said reflected ultrasound. ### Claim 10 (depends on 9) Apparatus as claimed in claim 9, wherein said one or more elongate strips and said ultrasonic transducer also form said ultrasound receiver. ### Claim 11 (depends on 1) Apparatus as claimed in claim 1, including a solid object under test, said proximal end being fixed to said solid object by one of: (i) welding; (ii) brazing; (iii) soldering; or (iv) bonding. ### Claim 12 (depends on 1) Apparatus as claimed in claim 1, including a solid object under test, said proximal end being clamped to said solid object. ### Claim 13 (depends on 12) Apparatus as claimed in claim 12, wherein ultrasound transmissive couplant is disposed between said proximal end and said solid object. ### Claim 14 (depends on 12) Apparatus as claimed in claim 12, wherein a clamp clamps said elongate strip to said solid object with an adjustable force. ### Claim 15 (depends on 14) Apparatus as claimed in claim 14, wherein said clamp is coupled to said solid object by studs welded to said object under test. ### Claim 16 (depends on 1) Apparatus as claimed in claim 1, wherein said solid object is: (i) at a temperature greater than 200° C.; and (ii) subject to above background levels of ionizing radiation.