Dissertation
Dissertation > Industrial Technology > Machinery and Instrument Industry > Instruments, meters > Mechanical quantity measuring instruments > Force measuring instruments

Research on the Ultrasonic Measurement Technology of Bolt Tension Based on the Sono-elasticity Principle

Author ZhangJun
Tutor GuLinZuo
School Zhejiang University
Course Mechanical and Electronic Engineering
Keywords Material factor Ultrasonic wave Tester Bolt head Transit time Acoustoelasticity Transmitting and receiving Acoustic coupling Force Measurement Measuring principle
CLC TH823
Type Master's thesis
Year 2005
Downloads 321
Quotes 4
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To ensure the structural steelwork reliability and security, must be strictly controlled connecting bolt tightening force, if necessary, work online monitoring bolt stress. Thesis, according to sound principles of flexibility, proposed the use of bolt tightening axial stress with ultrasonic transit-time difference before and after the relationship, combined with the bolt material factor, clamping thickness and other parameters, the bolt axial stress indirect detection method. Eliminating the bolt head and tighten the nut segment size of uncertainty and stress effects and non-uniform distribution of the measurement error caused by temperature changes, substantially increased the stress measurement accuracy. On this basis, the proposed material factor predicted correction method. Accuracy analysis showed that the bolt stress measurement accuracy better than 5%, which can meet the requirements of most industrial scene. Papers bolt stress measurement principle of ultrasonic, ultrasonic bolt tightening force tester design has been systematically studied. Focuses on the phenomenon of ultrasound-based Acoustoelasticity bolt stress measurement principle, and targeted research of ultrasonic transmitting and receiving principle, high-precision measurement principle when the sound, acoustic coupling principle and other key technologies. Currently developed ultrasonic bolt tightening strength testing prototypes for ultrasonic transit-time measurements and stress calculation precision. Paper is divided into six chapters. The first chapter reviews the current strength bolt fastening force measurement method, the expression of the phenomenon and propose sound elastic elastic phenomena based on acoustic ultrasonic bolt stress measurement techniques. An overview of the basic theory underlying ultrasound and ultrasound technology in the application of bolt stress testing. Chapter II of the sound bomb method bolt axial stress measurement techniques to conduct a comprehensive theoretical derivation, including sound mathematical formulation of the theory of elasticity, the material factor is defined, mechanical elongation method of calculating the length of the bolt and bolt force effective axial stress calculation. Theoretical formula fixed temperature, in addition to the bolt material coefficients proposed prediction method. Based on theoretical derivation conclusion, the development of ultrasonic bolt tightening force tester system. Tester introduces hardware structure of man-machine interface and on-site method of operation. With this tester ultrasonic bolt stress measurement and test curve fitting. Discusses in detail the coefficient of the material through the curve fitting method to predict. The third to fifth chapters on various key technologies for targeted research, including ultrasound coupling principle, ultrasonic transmitting and receiving principle, high-precision sound when the measuring principle, temperature compensation technology. Chapter Six Summary and Outlook. Gives the thesis research, pointed out the direction of further research.

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