| The bolt connection is a detachable connection,which has the advantages of convenient disassembly and assembly,simple structure,heavy load,low cost,etc.,and is widely used in many fields such as chemical industry,automobiles,large presses,ships,aerospace and aviation.The key to many mechanical equipment all parts are bolted.The axial force of the bolt has a direct impact on the quality of the bolt connection and the performance of the structure,and plays a very important role in the operation of mechanical equipment.In order to monitor the quality of the bolt connection and the contact state of the joint surface,so as to ensure the normal operation of the equipment,it is particularly important to accurately detect the axial force of the bolt.The detection of the axial force of the bolt has great engineer ing application value.The traditional methods for measuring the axial force of bolts are torque wrench method and strain gauge method.Although the torque wrench is simple to operate,there are errors caused by the friction of thread pair and the accuracy of torque wrench,and the influence of human operation is large,which results in large errors in the measured results;although the strain gauge method has high accuracy,it may need to dismantle the bolt when measuring,and it is not suitable for the condition with poor openness.At the same time,the axial force of the bolt will be attenuated in the service process,resulting in the looseness of the connected parts and affecting the performance of the equipment.At present,many scholars have not conducted in-depth analysis and research on the online detection of bolt axial force attenuation.To solve the above problems,based on the solid mechanics module of COMSOL Multiphysics software,this paper simulates the loading process of the actual bolt axial force and the propagation process of the ultrasonic wave on the bolt lap aluminum plate,and analyzes the relationship between the bolt axial force and the ultrasonic transmission signal sound pressure.In view of the bolt lap plate structure,the ultrasonic surface wave energy dissipation method is used to detect the axial force attenuation of the bolt.Based on the wave energy dissipation principle of the ultrasonic surface wave,the surface wave method test platform of the bolt axial force is built,and the correlation model between the bolt axial force and the surface wave transmission signal energy is established to realize the online detection of the axial force of the bolt,so as to detect the tightness of the bolt connection.At the same time,aiming at the attenuation of bolt axial force,the effect of the number of gaskets and lubrication conditions on bolt axial force attenuation was studied.The active control method of bolt axial force based on piezoelectric ceramic is proposed,and the active control system of axial force is built.The active control of axial force is realized by using the unique inverse piezoelect r ic effect of piezoelectric ceramic chip.The active control effect of axial force is detected by using the ultrasonic surface wave transmission signal,which verifies the effectiveness of the active control system of bolt axial force,and propose a new idea for bolt anti-loosening.The wave energy dissipation method of ultrasonic surface wave in this paper can detect the axial force of bolt accurately and quickly,and it can adjust the axial force of bolt accurately and actively by using piezoelectric ceramic plate,so as to prevent the bolt from loosening,which has very important scientific significance and research value. |
