Method for measuring elastic properties using ultrasound
A method measuring elastic properties using ultrasound of a part made of a material having a curved surface, includes: emission of bundles of ultrasound waves in a direction of a point of impact on the part's surface to generate waves within the part; knowing a thickness d of the part at the point of impact in a first direction D 1 and a thickness d2 in a second direction forming an angle determined with respect to the first direction, taking a first measurement t1 of time taken by the longitudinal waves transmitted to travel d1 from the point of impact, and taking a second measurement t2 of the time taken by the transverse waves to travel d2 from the point of impact; and determining the Young's modulus and/or Poisson's ratio of the material based on the longitudinal velocity VL=d1/t1 and transverse velocity VT=d2/t.
1. A method for determining elastic properties of a spherical part, comprising;
positioning an emitting transducer in a first position, the emitting transducer operating also as a receiver in said first position;
emitting beams of ultrasound waves towards a point of impact on a surface of the spherical part so as to generate waves within the spherical part, the beams of ultrasound waves being emitted through a coupling fluid;
determining a diameter d 1 of the spherical part at a first point of impact forming an angle of incidence θ with a first direction D 1 and a length of a cord d 2 in a second direction D 2 forming an angle β with respect to the first direction D 1;
providing a measurement of the transmission time t R of ultrasound waves to travel from the emitting transducer in said first position to the first point of impact;
providing a first measurement t 1 of a time taken by longitudinal ultrasound waves transmitted to travel the distance d 1 the first point of impact based on the first position;
displacing the emitting transducer to a second position with a second point of impact, in such a way to bring the beam to a top of the spherical part and to maintain the angle of incidence θ with the first direction D 1 producing waves forming the angle β with the first direction D 1 ;
providing a second measurement t 2 of the time taken by transverse ultrasound waves transmitted to travel the length of a cord d 2 from the second point of impact, given that for the measurement of t 2 , the transmission time t R of the waves through the coupling fluid is corrected for displacement of the transducer to the second position, the transmission time t m in both the spherical part and the coupling fluid until a receiving transducer that is different from the said emitting transducer is measured, and the corrected time t R is then subtracted from the time t m ; and
determining a Young's modulus and/or a Poisson's ratio of a material of the part based on a longitudinal velocity V L =d 1 /t 1 and a transverse velocity V L =d 2 /t 2 .
2. The method according to claim 1 , wherein the material of the part is isotropic.
3. The method according to claim 2 , wherein the material is metal or ceramic.
4. The method according to claim 1 , wherein the angle β 45° .
5. The method according to claim 1 , wherein the coupling fluid is water.