Overview
ISO 8203-4:2025 - "Fibre-reinforced plastic composites - Non-destructive testing - Part 4: Laser shearography" defines the principal method for out-of-plane laser shearography NDT of fibre-reinforced polymer (FRP) composites. The standard covers inspection of both monolithic and sandwich FRP laminates (thermoset and thermoplastic matrices), including uni‑ and multi‑directional reinforcements, woven/stitched fabrics, short fibres or particulate fills, and honeycomb or foam cores. Laser shearography detects subsurface anomalies by measuring changes in surface displacement gradients under a controlled loading regime using coaxial illumination and perpendicular observation.
Key topics and technical requirements
- Principle of operation: self-referencing, common-path interferometry to monitor out-of-plane displacement gradients and generate shearograms/interferograms that reveal indications of defects.
- Measurements and sensitivity: methods for determining displacement derivatives, fringe contrast and resolution, and controlling decorrelation.
- Stress excitation methods: prescribed approaches for applying low-level mechanical, thermal, or vacuum loading to reveal defects via surface deformation.
- Equipment: specification and qualification of the shearing camera, imaging and shearing optics, coherent illumination (laser source), supports, data capture/analysis systems, and calibration/reference artefacts (calibration target, natural defect artefacts).
- Specimen preparation: cleaning, visual inspection, surface coating and reference markers to optimize speckle and fringe quality.
- Inspection procedure: camera settings, image projection and shear calibration, illumination/exposure control, shear selection, system verification, stress application, shearogram acquisition, image processing and interpretation.
- Image and defect analysis: procedures for defect sizing, depth estimation and locating, and guidance for reporting results.
- Safety and normative references: includes laser product safety per IEC 60825-1 and requirements for equipment qualification and operator competency.
Practical applications and users
Laser shearography (ISO 8203-4:2025) is ideal for fast, non‑contact, large‑area, portable and real‑time inspections of FRP components. Typical users and sectors:
- Aerospace, wind energy, marine and automotive manufacturers for production quality control and in-service inspection of composite parts.
- NDT technicians and inspection engineers implementing shearography as part of a composite inspection program.
- R&D and certification bodies evaluating composite manufacturing processes, damage mechanisms, and repair quality.
Benefits include rapid detection of disbonds, delaminations, core crush, impact damage and manufacturing defects; limitations and applicability are defined in the standard.
Related standards
- ISO 8203 series (other parts) - see ISO website for the full series.
- IEC 60825-1 - Safety of laser products (normative reference).
Keywords: ISO 8203-4:2025, laser shearography, FRP composites, non-destructive testing, NDT inspection, shearogram, displacement gradient, shearing camera, coherent illumination, defect sizing.