Arena Information

Arena Name: Competitive Arena for In-situ Detection of Fatigue Cracks on Threads of Hexagon Head Bolts

Arena Type: Competitive Arena

Arena Host

Real Name: Zheng Kai

Organization: Special Equipment Safety Supervision Inspection Institute of Jiangsu Province

Specimen Parameters

Material: 42CrMo

Specification and Dimension: See Appendix. Thread size: M16-M56, bolt length: 45-500mm

Surface Condition: Forged bolt head end face with markings

Restrictions and Conditions

Testing Method: No restrictions

Testing Instrument: No restrictions

Testing Technology: No restrictions

Maximum Number of Participants: ≤ 2 persons

Testing Surface: End face of bolt hexagon head

Time Limit: ≤ 1h

Evaluation Rules

Challengers shall conduct testing only from the end face of the bolt hexagon head. All fatigue cracks and artificial grooves on the specimens shall be detected, and no false defects shall be reported. The positioning error shall not exceed ±10mm, and the azimuth error shall not exceed ±10°.

Participants shall submit test result records and testing images (test videos or photos). The images shall be clear with sufficient signal-to-noise ratio to identify the machined grooves and fatigue cracks on threads or bolts.

Technical Difficulty Description

At present, cylindrical guided waves or phased array linear array rotation technology are adopted for in-situ nondestructive testing of thread areas. There is an obvious cross-sectional variation between the hexagon head and bolt shank of hexagon head bolts. Meanwhile, the bolt shank and thread sections are slender columnar structures. The interaction between ultrasonic beams and bolt structures results in complex signals and severe signal attenuation, making it difficult to detect fatigue cracks buried in the threaded section.

This event was set as a difficult problem challenge arena at the 2025 Far East NDT New Technology Forum, and the defender successfully defended the challenge. Over the past year, many experts and testing personnel have carried out relevant research and achieved remarkable progress. This arena is now held as a competitive arena.

Defect Information

The defects are surface fatigue cracks easily generated on the load-bearing areas of bolts, including real fatigue cracks and artificial defects for sensitivity calibration.

Contact Information

Contact Person: Zheng Shanpu

Mobile: 13905382089

Email: zhengshanpu_zjtj@163.com

You may contact Zheng Shanpu to join the WeChat group: 2026 Far East NDT New Competition Arena for registration, technical consultation and relevant event information.