GB/T 34886-2017 in English

Background and Significance of the Standard

GB/T 34886-2017 "Non-destructive Testing of Composite Materials by Laser Dislocation Speckle Detection Method" is the first national standard for composite materials laser dislocation speckle detection technology in my country. This standard is proposed and coordinated by the National Technical Committee for Non-destructive Testing Standardization, and is applicable to defect detection of various composite materials.

With the increasing demand for high-performance composite materials in aerospace, automobile manufacturing and other fields, traditional non-destructive testing methods have gradually revealed their limitations in sensitivity and applicability. As an advanced non-contact detection method, laser dislocation speckle detection technology can effectively identify defects such as debonding and delamination in composite materials, and has broad application prospects.

Comparative analysis of standard frameworks

Detection system composition and key technologies

Laser misalignment speckle detection system is mainly composed of the following parts:

• Laser: Provides a light source with high stability and high coherence.
• Misalignment speckle camera: Used to capture the speckle image of the measured surface, with a pixel number of not less than 1024×1024 and an analog-to-digital conversion accuracy of not less than 12 bits.
• Adjustment and control device: Realizes functions such as lens alignment, aperture adjustment and focus adjustment.
• Image processing computer: responsible for real-time image acquisition, processing and storage, and supports image stitching.

Key technology:Internal defects are determined by measuring the out-of-plane displacement of the object surface. The core of this technology lies in the analysis of interference fringe patterns and phase patterns, which can effectively identify defects such as debonding and delamination.

Implementation suggestions and precautions

Personnel qualification requirements

Qualification and certification shall be carried out in accordance with GB/T 9445 or the system recognized by all parties to the contract. The inspection personnel shall receive job training and obtain operation authorization.

Environmental condition control

• Avoid open-air inspection, and give priority to conducting inspections in hangars or factory buildings.
• When conducting indoor inspections, strong light must be blocked.
• Prevent electromagnetic interference, vibration and airflow interference.

Safety Precautions

• Strictly implement the laser protection standard (GB 7247.1) and avoid looking directly at the laser source.
• When using sonic excitation, all personnel on site must wear protective headphones.
• The laboratory should set up obvious laser protection and noise protection warning signs.