Method for detecting distribution of steel member absolute stress along depth on basis of Lcr wave method

Abstract

At present, a steel member stress nondestructive detecting method mainly has the following defects that only variable quantity of stress can be detected, and absolute stress can not be detected; detected stress is located on the surface of a member and on the portion in the depth range of dozens of microns to the maximum below the surface, and the stress in the deeper depth range can not be detected; one-way absolute stress can be detected, the distribution of the absolute stress along the depth can not be detected. In order to overcome the defects in the prior art, the invention provides a method for detecting distribution of the steel member absolute stress along the depth on the basis of a critical refraction longitudinal wave method. Due to the fact that the propagation depth in the steel member and the sonoelastic coefficient B in a fixed sonic path distance of the Lcr waves with different frequencies are calibrated, a self-made caliper probe is adopted to detect propagation sound-timing t of the Lcr waves with the different frequencies in the steel member to solve the distribution of steel member absolute stress sigma along the depth. According to the method for detecting the distribution of the steel member absolute stress along the depth on the basis of the critical refraction longitudinal wave method, the accuracy of the detection result is high, error requirements in actual engineering can be met, and damage can not be caused to the structural member in the detection process.

Description

technical field [0001] The invention belongs to the field of non-destructive detection of absolute stress of steel components, and in particular relates to a method for detecting distribution of absolute stress of steel components along depth. Background technique [0002] With the rapid development of economy, more and more steel structure engineering projects are being built and planned in our country. At the same time, people are paying more and more attention to the safety of such projects. In order to ensure the safety of structures and people's lives, properties and safety, it is very necessary to carry out health monitoring of steel structures. There are many contents of structural health monitoring, such as load monitoring, temperature monitoring, acceleration monitoring, displacement monitoring, strain monitoring, stress detection and so on. The internal stress of steel components in service is an important indicator of the structural safety state, and plays an im...

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Problems solved by technology

However, there are still several deficiencies in the following aspects: first, the ultrasonic wave mode used in this method is surface wave, and the characteristics of this wave mode make it only possible to detect the surface stress of the component; second, the method proposed by the invention patent The detected stress object is the two-dimensional absolute stress on the surface of the component, which cannot detect the absolute stress inside the component, nor can it detect the distribution of the absolute stress along the depth direction of the component; Energy devices, which require strict requirements on the size of the component surface, are not suitable for the most commonly used long and thin steel components in building structures

It mainly includes the following aspects: First, the difference in component materials. The steel used for steel structures is mainly low-carbon steel and alloy steel, while the steel used for rails in the railway industry is all special steel, and the type of steel is relatively single, and the welding residual stress In the test, the texture of the base metal will change due to the influence of temperature, which is different from the steel types in the construction industry; secondly, the influence of component size, steel components, such as section steel, steel pipe, etc., have special surface morphology and component shape. Due to the influence of this factor, it is very different from the wave pattern and probe arrangement selected in the above method such as the axial stress detection of bolts; thirdly, the wave pattern selection, the wave pattern selected in the above method is longitudinal wave, The combination of longitudinal and transverse waves, etc., the absolute stress inside the steel member cannot be measured using these wave modes

Moreover, the current non-destructive stress testing methods for steel components mainly have the following disadvantages: first, they can only detect the change in stress, but not the stress in the current state; The depth range of a few millimeters cannot be detected; the third is that the detected absolute stress is unidirectional stress, and the distribution of absolute stress along the depth cannot be detected

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