Method and system for analysing a test piece

1. A method for acoustically measuring material properties of a test piece at high temperatures, comprising the steps of:

(a) heating the test piece to within a testing temperature range;

(b) performing a background measurement within said testing temperature range by capturing a vibrational signal from the test piece within a calibration period, thereby obtaining a noise signal;

(c) performing an acoustic measurement on said test piece within said testing temperature range and within a testing period by:

(c1) imparting a vibrational excitation onto the test piece;

(c2) capturing a vibrational signal of the test piece within the testing period, thereby obtaining a vibrational response signal to said vibrational excitation, and

(d) obtaining the material properties of the test piece by analyzing the vibrational response signal, thereby taking into account the noise signal,

wherein the vibrational excitation of step c1 is mechanically induced onto the test piece,

wherein an impact system comprising a ballistic impactor and an impactor actuator is used,

wherein the impact actuator is configured to give an impulse to said ballistic impactor, and using said ballistic impactor for imparting a vibrational excitation onto the test piece,

wherein in the acoustic measurement step c, a measurement impulse is provided to the ballistic impactor which imparts a vibrational excitation onto the test piece in step c1,

wherein in the background measurement step b, a background impulse is provided to the ballistic impactor which does not impart a vibrational excitation onto the test piece, and

wherein the noise signal comprises noise arising from the impactor actuator and the ballistic impactor.

2. The method according to claim 1 , wherein the ballistic impactor is configured to approach the test piece from below along a vertical direction.

3. The method according to claim 2 , wherein the measurement impulse provided to the ballistic impactor is configured to mechanically contact the test piece and the background impulse provided to the ballistic impactor is configured to fall short of reaching the test piece.

4. The method according to claim 1 , wherein the steps a to d are performed more than once at the same temperature, at different temperatures or within different temperature ranges.

5. The method according to claim 4 , wherein the test piece is heated up continuously,

wherein the steps a-d are performed within subsequent temperature ranges.

6. The method according to claim 1 , wherein in step d, the temperature-dependence of the material properties are determined.

7. The method according to claim 1 , wherein in step d, a Young's modulus, a shear modulus and/or a Poisson modulus are determined.

8. The method according to claim 1 , wherein in step d, decay constants of the material properties are determined, said decay constants being decay constants of sinusoids making up the time-varying vibrational response signal.

9. A system for acoustically measuring material properties of a test piece at high temperatures, comprising:

a heating chamber comprising a heating element for bringing the test piece within a testing temperature range;

a sensor configured to capture a vibrational signal from the test piece during a period;

an impact system comprising an impactor and an impactor actuator, for imparting a vibrational excitation onto a test piece located in the heating chamber;

a control system in connection with the heating chamber, the sensor and the impactor, the control system configured to:

instruct the heating chamber to bring the test piece within a testing temperature range;

during a testing period, instruct the impact system to actuate the impactor with the impactor actuator such that a vibrational excitation is mechanically imparted by the impactor onto a test piece located in the heating chamber, and obtain from the sensor a vibrational response signal to said vibrational excitation,

during a calibration period, instruct the impact system to actuate the impactor with the impactor actuator such that the impactor does not mechanically impart a vibrational excitation onto the test piece located in the heating chamber, and obtain from the sensor a noise signal, and

obtain the material properties of the test piece by analyzing the vibrational response signal, thereby taking into account the noise signal,

wherein the noise signal comprises noise arising from the impactor actuator and the impactor,

wherein the impact system comprises a ballistic impactor and the impact actuator is configured to give an impulse to said ballistic impactor,

wherein the impact actuator is configured to give a measurement impulse to the ballistic impactor for imparting a vibrational excitation onto the test piece in an acoustic measurement step, and

wherein the impact actuator is configured to give a background impulse to the ballistic impactor for avoiding an impact onto the test piece in a background measurement step.

10. The system according to claim 9 , wherein the control system comprises processing means configured to analyze the vibrational response signal by subtracting the noise signal from the vibrational response signal in the time domain or in the frequency domain, or in a combination of the time domain and the frequency domain.