Application Cases

Experiment Name: Application of Power Amplifier in the Characterization of Particle Shape Features and Their Influence on the Shear Modulus of Sand

Experimental Equipment: Function generator, power amplifier, transmitting bender element, charge amplifier, oscilloscope, etc.

Experiment Objective: To study the relationship between sand particle shape features and shear modulus by characterizing particle shape features using digital image processing techniques and investigating the shape features of actual sand particles.

Experimental Procedure:

(1) Construction of the experimental platform:
Shear wave signals were first generated by a function generator. The output signal voltage of the function generator was relatively low. To enhance the signal strength, the signal was amplified by an ATA-4011 high-voltage power amplifier before being input to the transmitting bender element. The amplified signal was then sent to the transmitting bender element. The piezoelectric ceramic patch on the bender element vibrated under the action of the pulse voltage, generating shear waves in the soil. The receiving bender element had the same structure as the transmitting bender element but operated in reverse. Upon receiving the shear wave signal, the piezoelectric ceramic patch vibrated, converting mechanical energy into electrical energy.

The signal received by the receiving bender element was typically weak and needed to be amplified by a charge amplifier before being finally displayed on an oscilloscope. While the power amplifier sent the signal to the transmitting bender element, it also sent the signal to the oscilloscope. By comparing the received signal with the excitation signal, the shear wave velocity was obtained, and the shear modulus of the soil was subsequently calculated.

(2) Sample preparation:
Specimens with two different initial void ratios were prepared for each of the four sand samples, resulting in a total of 8 test groups for measurement.

Experimental Results:

During the loading stage of the test, the normalized shear modulus of the specimens showed a good correlation with their shape factor. Under the same vertical load, the greater the particle shape roughness, the larger the corresponding normalized shear modulus.

Figure: Specifications of the ATA-4011C High-Voltage Power Amplifier