A Finite Element Based Ultrasonic Detection of Bolt Tightening Force and Determination of Key Detection Parameters
An ultrasonic testing and fastening force technology, applied in force/torque/work measuring instruments, measuring torque/torsion force during tightening, measuring devices, etc., can solve the problem of high cost, discrete torque coefficient, and unfavorable ultrasonic testing of bolt fastening force Method engineering application and other issues
Active Publication Date: 2020-02-18
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology
Among them, the resistance strain gauge method and the photomechanical method are rarely used in engineering due to the limitation of the detection principle and measurement conditions; the torque wrench method is currently the most commonly used bolt pretightening force control and measurement method in engineering, but due to the bolt and The discretization of the friction coefficient between the threaded surface of the nut and the contact surface between the nut and the connected part leads to the discretization of the torque coefficient. In practical applications, there will also be a large error, up to about 30%.
The key and premise of the ultrasonic measurement method is to obtain the accurate mathematical relationship between the ultrasonic propagation time and the fastening force, that is, the measurement coefficient. The general method is to obtain the measurement coefficient under different specifications of bolts and connection states through a large number of experiments. This method is expensive. , poor adaptability, which is not conducive to the engineering application of the bolt tightening force ultrasonic testing method
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[0020] Specific embodiments of the present invention are described in detail below:
[0021] 1. The principle of ultrasonic longitudinal wave detection of bolt tightening force based on finite element
[0022] According to the theory of sonoelasticity, when an isotropic solid material is subjected to a stress in one direction, the sound velocity of ultrasonic longitudinal waves propagating along the stress direction can be deduced as:
[0023] V L (σ)=V L0 (1-K L σ) (1)
[0024] In formula (1):
[0025] V L - the speed of sound of longitudinal waves;
[0026] V L0 ——the longitudinal wave sound velocity in zero stress state;
[0027] K L - longitudinal wave acoustic elasticity coefficient;
[0028] σ——stress, it is specified that the tensile stress is positive and the compressive stress is negative.
[0029] Since the stress distribution inside the bolt is not uniform, and the propagation path of the ultrasonic wave is along the axis of the bolt, under the action of ...
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The invention provides a bolt fastening force ultrasonic detection and key detection parameter determination method based on finite elements. The method is suitable for bolting force ultrasonic soundtime nondestructive measurement. The finite element theory and the acoustic elasticity principle are combined, and a bolt fastening force ultrasonic detection principle model is established. A bolt finite element model and a static simulation are established, the bolt axial stress distribution rule on the ultrasonic propagation path is obtained, so that the shape factor of the bolt is determined.The ultrasonic detection coefficient of the bolt fastening force is calculated by combining the acoustic elasticity coefficient of the bolt material measured by the critical refraction longitudinal wave. The method is low in cost and good in adaptability, and the detection coefficient can be accurately and quickly determined.
Description
[0001] 1. Technical field [0002] The invention relates to the technical field of bolt fastener testing, and provides a finite element-based ultrasonic testing method for bolt tightening force and a method for determining key testing parameters. [0003] 2. Background technology [0004] Bolted connections are widely used in armored vehicles, aerospace, special machinery and other industrial fields due to their advantages of simple assembly, convenient disassembly, high efficiency, low cost, and good adaptability. For different types of bolts, in order to ensure the working quality and reliability of the mechanical equipment, a certain pre-tightening force must be given to the bolts. The bolts with excessive pre-tightening force are prone to fracture under the action of axial load, and the pre-tightening force is too small. The required clamping effect cannot be achieved, so accurately controlling the size of the pre-tightening force and monitoring the size of the axial force ...
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IPC IPC(8): G01L5/24
CPCG01L5/246
Inventor 潘勤学邵唱潘瑞鹏刘晓豪宋炜
Owner BEIJING INSTITUTE OF TECHNOLOGYGY