3D shape shearography technique for surface strain measurement of free-form objects

Area of Science:

• Optical Measurement Techniques
• Non-Destructive Testing (NDT)
• Surface Strain Analysis

Background:

• Shearography is a non-destructive testing (NDT) method for full-field surface strain characterization.
• Existing shearography techniques are limited to inspecting flat objects or simple geometric shapes.
• Real-world applications in aerospace, transport, and cultural heritage often involve complex, non-flat surfaces requiring advanced inspection methods.

Purpose of the Study:

• To develop a general solution for shearography on highly curved or free-form surfaces.
• To enable accurate strain measurement and defect detection on complex geometries.
• To integrate in-line object shape measurement with 3D shearography data processing.

Main Methods:

• Development of a novel 3D shape shearography system prototype.
• Integration of a structured light projector for in-line shape measurement.
• Processing of shearography data in three dimensions (3D) combined with measured object shape.
• Experimental validation using a cylinder specimen subjected to internal pressure.

Main Results:

• The developed 3D shape shearography system successfully characterized surface strain on a curved object.
• The system's performance was evaluated and compared against traditional strain gauges.
• Demonstrated the feasibility of applying shearography to complex geometries.

Conclusions:

• The proposed 3D shape shearography approach offers a viable solution for inspecting non-flat objects.
• This technique enhances defect detection and material characterization capabilities for complex structures.
• Paves the way for broader applications of shearography in industries with intricate components.