Application Cases

Experiment Name: Application of Power Amplifier in Selective Excitation of Pure Vibration Modes in Structures Based on Distributed Shear Piezoelectric Patches

Research Direction: Vibration Modal Analysis

Experimental Content:
Shear-type (d15) piezoelectric strips are used to simulate distributed line shear forces. Based on modal symmetry characteristics, by appropriately designing the distribution positions, polarization directions, and electric field directions of multiple d15 piezoelectric strips, arbitrary vibration modes of a structure can be selectively excited. Taking a stainless steel bar with a rectangular cross-section as an example, using different excitation methods with only one pair of d15 piezoelectric strips, selective excitation of the bar's bending, torsional, and longitudinal vibration modes was achieved.

Test Objective: To verify the feasibility of the method and ensure that the target modes can be selectively excited.

Testing Equipment: A pair of shear-type (d15) piezoelectric strips, stainless steel bar with rectangular cross-section, signal generator, ATA-2021H power amplifier, oscilloscope, etc.

Experimental Procedure:
As shown in the figure, a continuous sinusoidal electrical signal generated by a function generator is amplified by a power amplifier and then used to drive a pair of shear-type (d15) piezoelectric strips bonded to the rectangular stainless steel bar. This induces continuous shear deformation, thereby achieving a distributed line-shear-force-like excitation. By designing parameters such as the polarization direction, electric field direction, and placement position of the piezoelectric strips, the bending modes, torsional modes, and longitudinal vibration modes of the rectangular bar can be selectively excited. The vibration frequency response spectrum of the bar is measured using a Doppler laser vibrometer and acquired via an oscilloscope. The frequency sweeping, laser scanning, and data acquisition processes during the experiment are automatically controlled by a LabVIEW program written on a laptop computer.

Experimental Results:
The three curves in different colors represent the velocity response spectra of the rectangular bar measured by the laser vibrometer under three excitation methods. It can be observed that under the designed excitation methods, the bending (B), torsional (T), and longitudinal (L) vibration modes are selectively excited with high purity, facilitating the identification of modes with closely spaced resonant frequencies.

Figure: ATA-2021B High-Voltage Amplifier Specifications and Parameters