Method for quantified monitoring bolt pre-tightening torque through active ultrasonic guided wave

Abstract

The invention discloses a method for quantified monitoring bolt pre-tightening torque through active ultrasonic guided wave. MFC (Macro-Fiber Composite) material elements serve as an exciter and a sensor to conduct directional excitation, acquire fluctuation response and establish a bolt pre-tightening torque reference and comparison database. In this way, on-line monitoring bolt pre-tightening torque based on the reference database is carried out. The tightness of a bolt can be rapidly monitored without disassembling a structure, the assembling cost is reduced, and the efficiency is improved. The method is simple in operation, and quantified monitoring precision for single-bolt torque value is relatively high. The MFC material elements are thin (about 0.2mm), and may not affect structure performance after being pasted.

Description

technical field [0001] The invention relates to the technical field of structural health monitoring, in particular to a method for quantitatively monitoring bolt pretightening torque by using active ultrasonic guided waves. Background technique [0002] Bolted connections are widespread in the fields of mechanical, civil, energy and aerospace engineering. Controlling and maintaining the bolt preload is an important prerequisite to ensure the safe service of engineering structures. However, the stress relaxation of bolts during long-term service, as well as mechanical environments such as external vibration and impact may lead to a decrease in bolt preload and loose connections, which seriously endanger the safety of the structure. [0003] At present, the monitoring methods of bolt pretension in engineering are conventional non-destructive monitoring methods, such as the use of ultrasonic imaging, X-ray flaw detection and other methods; the other method is to fix strain gau...

AI Technical Summary

Problems solved by technology

The former requires large-scale equipment support, and may need to disassemble the structure, which is not suitable for real-time online monitoring; the latter needs to lead the bolt holes or change the structure of the joint, which is difficult to apply in practice

[0004] In recent years, the damage monitoring method using the ultrasonic guided wave method has been applied to the damage monitoring of structures such as single-material pipes and flat plates, but there are few researches on bolt loosening monitoring in the open literature and the following limitations: using energy-directed Active ultrasonic excitation elements with poor performance cause the excitation energy to diverge, resulting in insufficient wave energy in the desired direction; a systematic method for monitoring the reference database cannot be established; the sensitivity and resolution of the characteristic parameters are low, so that it is impossible to quantitatively evaluate the bolt pretension state

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