Application Cases

Experiment Name: Application of Power Amplifier in Bolt Connection Looseness Detection System for Timber Structures

Experimental Equipment:
Computer, piezoelectric sensor (PZT), D-type digital torque wrench, NI ELVIS II+ data acquisition card, ATA-2021B power amplifier, etc.

Experimental Procedure:
A bolt connection looseness detection system for timber structures based on the piezoelectric time reversal method was designed. Two piezoelectric ceramic (PZT) patches were respectively bonded onto two timber blocks connected by bolts. One PZT was used to generate ultrasonic signals, while the other PZT converted the transmitted ultrasonic signals into electrical signals. After time reversal, ultrasonic signals were generated again, and the transmitted signals were simultaneously acquired. The hardware of the bolt looseness detection system was built by connecting the computer, data acquisition card, piezoelectric ceramics, power amplifier, etc. On the LabVIEW platform, system software was developed featuring Lamb wave impact signal generation and secondary digital trigger acquisition. By applying different pre-tightening forces to the timber structure, the relationship between the amplitude of the focused signal and the axial pre-tightening force of the bolts was tested.

Experimental Results:
Looseness in bolted connections of timber structures is a key issue affecting their stability. Based on the principle of the piezoelectric time reversal method and through secondary trigger acquisition of ultrasonic signals, a bolt looseness detection system was implemented. The tightness state of the bolted connections was analyzed using the amplitude of the focused signal.

Specifications of ATA-2021B Power Amplifier: