Acoustic resonator for measuring force
First Claim
Patent Images
1. An acoustic resonator for measuring force comprising:
- a cylindrical body having;
a central section with a first radius (a) comprising a material having a plane-wave shear velocity ν
a ; and
two distal sections with a second radius (b) comprising a material having a plane-wave shear velocity ν
b wherein the ratio a/ν
a differs from the ratio b/ν
b by an amount selected to trap some acoustic resonant modes in the central section.
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Abstract
A force sensor including a cylindrical body having a central section and two distal sections wherein selected acoustic resonant modes are trapped in the central section and decays exponentially in the distal sections. An electromechanical acoustic transducer (EMAT) can be used to excite and detect the selected resonant modes in the central section. Force applied to the distal sections, including axial stress and torque, alter the resonant frequencies of the selected modes.
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Citations
28 Claims
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1. An acoustic resonator for measuring force comprising:
a cylindrical body having; a central section with a first radius (a) comprising a material having a plane-wave shear velocity ν
a ; andtwo distal sections with a second radius (b) comprising a material having a plane-wave shear velocity ν
b wherein the ratio a/ν
a differs from the ratio b/ν
b by an amount selected to trap some acoustic resonant modes in the central section.- View Dependent Claims (2, 3, 4, 5)
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6. An acoustic resonator for measuring force comprising:
a cylindrical body having; a central section with a first radius (a) comprising a material having a plane-wave shear velocity ν
a ; andtwo distal sections with a second radius (b) comprising a material having a plane-wave shear velocity ν
b wherein the ratio a/ν
a differs from the ratio b/ν
b, ν
a =ν
b and a>
b.
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7. An acoustic resonator for measuring force comprising:
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a cylindrical body having; a central section with a first radius (a) comprising a material having a plane-wave shear velocity ν
a ;two distal sections with a second radius (b) comprising a material having a plane-wave shear velocity ν
b wherein the ratio a/ν
a differs from the ratio b/ν
b ; andmeans for applying force to the cylindrical body through at least one of the distal sections.
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8. An acoustic resonator for measuring force comprising:
a cylindrical body having; a central section with a first radius (a) comprising a material having a plane-wave shear velocity ν
a ;two distal sections with a second radius (b) comprising a material having a plane-wave shear velocity ν
b wherein the ratio a/ν
a differs from the ratio b/ν
b ; andtransition regions between the central section and each of the two distal sections wherein the diameter of the transition regions is graduated from the first radius (a) to the second radius (b).
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9. An acoustic resonator for measuring force comprising:
a cylindrical body, wherein the cylindrical body comprises a solid metal cylinder having; a central section with a first radius (a) comprising a material having a plane-wave shear velocity ν
a ; andtwo distal sections with a second radius (b) comprising a material having a plane-wave shear velocity ν
b.
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10. An acoustic resonator for measuring force comprising:
a cylindrical body having; a central section with a first radius (a) comprising a material having a plane-wave shear velocity ν
a ;two distal sections with a second radius (b) comprising a material having a plane-wave shear velocity ν
b wherein the ratio a/ν
a differs from the ratio b/ν
b ;a plurality of permanent magnets surrounding the central section so that alternating North-South poles of the permanent magnets face a surface of the central section; and an electromechanical acoustic transducer (EMAT) sensor comprising both a first coil for torsional modes and a second coil for flexural modes, the EMAT sensor being positioned around the central section between the surface of the central section and the plurality of permanent magnets.
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11. A force sensor comprising:
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a cylindrical body having a central section and two distal sections wherein a diameter of the central section is larger than a diameter of the distal sections; two permanent magnets positioned about the circumference of the central section such that alternating north-south poles of the permanent magnets face the surface of the central section; a coil positioned around the central section between the surface of the central section and the two permanent magnets, the coil having inputs for receiving a first excitation signal. - View Dependent Claims (12, 13, 14, 15, 16)
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17. An acoustic resonator comprising:
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a cylindrical body having a central section and two distal sections; and means for substantially trapping selected acoustic resonant modes in the central section. - View Dependent Claims (18, 19)
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20. An acoustic resonator comprising:
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a cylindrical body having a central section and two distal sections; means for substantially trapping selected acoustic resonant modes in the central section, wherein the means for substantially trapping comprises an abrupt change in diameter of the cylindrical body at an interface between the central section and each of the two distal sections.
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21. An acoustic resonator comprising:
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a cylindrical body having a central section and two distal sections; means for substantially trapping selected acoustic resonant modes in the central section, wherein the means for substantially trapping comprises a thin film formed in intimate contact with an exterior surface of the central section.
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22. An acoustic resonator comprising:
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a cylindrical body having a central section and two distal sections; means for substantially trapping selected acoustic resonant modes in the central section; and mounting means for coupling a load to each of the distal portions.
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23. A force sensor comprising:
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a cylindrical body having a central section and two distal sections wherein selected resonant modes are substantially trapped in the central section and exponentially decay in the distal sections; means for exciting the selected resonant modes in the central section; means for detecting a resonant frequency of the selected resonant modes in the central section. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification