Crack-arrest in-hole expansion fixing sleeve set and adaptive adjustment method

By designing an expansion fixing sleeve inside the crack-stopping hole and utilizing a combination of bolts and bushings, uniform expansion and directional reinforcement of large steel components such as bridges can be achieved, solving the problem of frequent secondary cracking in traditional methods and improving the fatigue life and maintenance convenience of steel structures.

CN121932437APending Publication Date: 2026-04-28NORTH CHINA UNIVERSITY OF TECHNOLOGY
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
NORTH CHINA UNIVERSITY OF TECHNOLOGY
Filing Date
2026-01-28
Publication Date
2026-04-28

AI Technical Summary

Technical Problem

Existing technologies struggle to achieve uniform expansion in large, thick-walled steel components such as bridges, leading to frequent secondary cracking. Furthermore, traditional methods cannot provide directional reinforcement based on crack morphology and stress distribution.

Method used

Design a crack-resistant hole expansion fixing sleeve assembly, including bolts and bushings. The bolt thread end is tapered, the inner wall of the bushing is provided with an expansion groove, a limiting ring and an auxiliary end. Uniform expansion is achieved by tightening the bolt and the bushing, and directional expansion is achieved by cutting the local angle adjustment surface.

Benefits of technology

It effectively counteracts the tensile stress around the crack arrestor hole, delays crack propagation, reduces equipment and labor costs, is suitable for various crack morphologies and structural types, and significantly extends the fatigue life of steel structures.

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Abstract

The invention relates to the technical field of crack arrest hole expansion optimization, in particular to a crack arrest hole internal expansion fixing sleeve set and an adaptive adjustment method. The bushing is in threaded fit with the bolt; the threaded end of the bolt is conical, the large-diameter face of the threaded end is connected with the top clamping end of the bolt, and the small-diameter face of the threaded end is located at the end away from the top clamping end. The inner wall of the bush is conical to be matched with the threaded end of the bolt, and an expansion groove is fixedly formed in the end face of the bush. Local angle expansion or 360-degree full expansion of the bushing is selected according to actual requirements on site; measuring an adjusting surface required by local angle expansion and cutting; and after the bushing is mounted, the bolt is tightened. By introducing the uniform residual compressive stress, the tensile stress around the crack arrest hole can be effectively offset, secondary cracking is delayed, and the scheme is suitable for various crack forms and structure types due to the angle expansion design. The auxiliary end and the supporting piece of the bushing can ensure that the bushing is set to be at a standard installation height, a clamping instrument can conveniently carry out auxiliary operation, and a stress detection piece can be additionally arranged between the limiting ring and the steel plate to be detected for on-site debugging inspection.
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