A Sensor For Bolt Connection Status Monitoring Based On Piezoelectric Active Sensing Method

The changes of the bolt connection status will lead to the connecting equipment failure,what’s worse is caused economic loss or personal injury,therefore,it is great significance to real-time monitoring of bolt connection structure.This paper,a washer sensor for bolt connection status monitoring has been designed that based on piezoelectric active sensing method and the propagation characteristics of ultrasonic through the contact interface.The main work and conclusions of this dissertation are as follows:1)It was deduced that the relation among the bolt connection contact area,the wave energy propagated through the contact area and bolt preload force,according to the piezoelectric active sensing method,Hertz contact theory,ultrasonic propagation characteristics through the contact interface and the time reversal method.The conclusion is the peak of the focused signal(transmission wave energy)change monotonously with the bolt preload force.2)Based on piezoelectric active sensing method,a washer sensor that macroscopic contact area can be controlled for bolt connection status monitoring was designed.The design method of washer sensor was determined,and analyzed the related influencing factors of contact area,the result show the washer can be applied to monitor diverse bolts which prload force are different by choosing size parameters reasonably.3)By establishing finite element models,the propagation process of ultrasonic through the washer sensor contact interface was simulated,and the ultrasonic wave energy information is obtained,also,the relationship between the energy of the ultrasonic wave through the contact area and the bolt preload force is got.The effectiveness of the washer sensor was verified by numerical analysis,this laid the foundation for the analysis of the experiment.4)The experiments that bolt connection status monitoring by the washer sensor were carried out,the experimental results show that the amplitude of the focused signal can indicate the bolt preload obviously,the peak amplitude increases with the increase of the preload force force.It is to say that the washers can effectively monitor the bolt connection stasus.The proposed washer sensor based on the piezoelectric active sensing method has a a good application prospect in monitoring the bolt connection status.