Application Cases

Application of High-Voltage Amplifier in Bolt Loosening Detection

Experimental Content:
This study investigates a bolt loosening detection method based on vibro-acoustic modulation, where a single-frequency signal serves as the low-frequency pump wave and a frequency-swept signal acts as the high-frequency probe wave. The vibro-acoustic modulation response of the pump and probe waves at the contact interface is utilized to detect the degree of bolt loosening. Through bolt loosening experiments, the modulation response characteristics of signals under different loosening conditions were thoroughly compared and analyzed. The nonlinear modulation index was calculated based on signal modulation features, establishing a correlation between the nonlinear modulation index and the degree of bolt loosening.

Test Equipment:
Function signal generator, ATA-2022H high-voltage amplifier, Piezoelectric ceramic patches, Data acquisition card, Oscilloscope, PC, etc.

Experimental Process:

Figure 1: Schematic diagram of the experimental platform

A single-bolt structure was used, with receiving and excitation piezoelectric ceramic patches tightly attached to both sides of the structure. Two piezoelectric ceramic patches were attached to the excitation side: one for generating the low-frequency pump wave and the other for generating the high-frequency probe wave. The pump and probe wave signals were generated by a function signal generator. The probe wave was directly output to the piezoelectric ceramic, while the pump wave was amplified by a power amplifier before being output to the piezoelectric ceramic. The modulated signal at the bolt connection was received by the piezoelectric ceramic patch on the other side and transmitted to an oscilloscope and data acquisition card for signal observation and acquisition, respectively. Signal analysis was performed on a PC. During the experiment, a high-precision torque wrench was used to control the tightening torque of the bolt, thereby varying the degree of bolt loosening. Vibro-acoustic detection was conducted under different bolt loosening conditions.

Experimental Results:

Figure 2: Experimental results

The results show that the nonlinear modulation index, calculated based on the modulation characteristics of the vibro-acoustic modulation signal, exhibits a monotonically decreasing trend as the bolt torque increases. When the bolt torque is small, the nonlinear modulation index decreases rapidly. When the bolt torque approaches the standard preload torque, the nonlinear modulation index decreases very gradually. This demonstrates that the vibro-acoustic modulation method can effectively detect the degree of bolt loosening, and the nonlinear modulation index can be used to quantify the extent of bolt loosening.

Voltage Amplifier Recommendation: ATA-2022B

Figure: ATA-2022B High-Voltage Amplifier Specifications

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