Which non-destructive testing method is commonly used to locate delaminations in composites?

Which non-destructive testing method is commonly used to locate delaminations in composites?

• A. Radiography
• B. Infrared Thermography
• C. Acoustic Emission
• D. Ultrasonic C-scan (phased-array)

Answer: (D)

Delaminations create an interfacial boundary with a contrast in acoustic impedance, so ultrasound can reveal them by how the waves reflect and scatter. A C-scan using phased-array ultrasound lets the probe be steered and focused across the surface while sweeping through different depths. This produces a two-dimensional, plan-view image that shows the size, shape, and location of delaminations across a wide area, with good depth discrimination. That combination—high sensitivity to interlaminar boundaries and the ability to map defects over a region—makes it the most effective choice for locating delaminations in composites. Radiography can detect some delaminations, but it depends on geometry and orientation and may miss subtle or non-through-thickness separations. Infrared thermography can indicate delaminations through thermal contrasts, yet it relies on heating conditions and is less precise for mapping exact boundaries and depths. Acoustic emission monitors active damage as it occurs, but it doesn’t provide a static defect map of existing delaminations.

Delaminations create an interfacial boundary with a contrast in acoustic impedance, so ultrasound can reveal them by how the waves reflect and scatter. A C-scan using phased-array ultrasound lets the probe be steered and focused across the surface while sweeping through different depths. This produces a two-dimensional, plan-view image that shows the size, shape, and location of delaminations across a wide area, with good depth discrimination. That combination—high sensitivity to interlaminar boundaries and the ability to map defects over a region—makes it the most effective choice for locating delaminations in composites.

Radiography can detect some delaminations, but it depends on geometry and orientation and may miss subtle or non-through-thickness separations. Infrared thermography can indicate delaminations through thermal contrasts, yet it relies on heating conditions and is less precise for mapping exact boundaries and depths. Acoustic emission monitors active damage as it occurs, but it doesn’t provide a static defect map of existing delaminations.