Sofema Aviation Services (SAS) www.sassofia.com reviews the tapping hammer tool (TAP) test process with different composite materials
Introduction
The procedure involves tapping the surface of the composite structure with a specialized hammer and analyzing the resulting sounds or vibrations to detect any defects or abnormalities.
- The testing procedures and interpretation of results may vary depending on the specific composite material being evaluated.
- Ensure the composite structure is clean and free from debris or contaminants.
- Familiarize yourself with the specific composite material being tested and any applicable industry standards or guidelines.
Selection of Tapping Hammer
Choose a tapping hammer appropriate for the composite material. The hammer’s characteristics (size, weight, material) should suit the specific application and the desired sensitivity.
Tapping Technique
- Hold the tapping hammer lightly, allowing it to rebound freely after each tap.
- Tap the surface of the composite structure using consistent force and technique.
- Maintain a systematic and organized approach, tapping across the entire surface in a grid pattern or following a predetermined test plan.
Sound or Vibration Analysis
- Listen to the audible sounds produced by the tapping hammer. Pay attention to variations in pitch, tone, or resonance.
- Observe any visible vibrations or movements in the composite structure during tapping.
- Use your experience and knowledge of the material to assess the significance of any detected anomalies.
Interpretation of Results
Different composite materials may exhibit different responses to tapping, so it’s essential to understand the material being tested.
Carbon Fiber Reinforced Polymer (CFRP)
When tapped, CFRP materials typically produce a sharp, high-pitched sound with minimal dampening, indicating a stiff and intact structure.
If there are any defects or delaminations in CFRP, the tapping sound may change, becoming duller or muffled, suggesting a compromised structure.
Fiberglass Reinforced Polymer (FRP)
When tapped, FRP materials produce a sound that is typically less sharp compared to CFRP. The sound may have a moderate pitch with some dampening.
Delaminations or defects in FRP may cause the tapping sound to become even duller, indicating a loss of integrity in the structure.
Aramid Fiber Reinforced Polymer (AFRP) (Kevlar)
AFRP materials generally produce a lower-pitched sound when tapped compared to CFRP and FRP. The sound may be more muted but still have some resonance.
Delamination or damage in AFRP may result in a more pronounced dampening of the tapping sound, indicating potential structural issues.
Summary
An experienced technician or engineer can interpret the results based on their knowledge of the composite’s properties, expected behaviour, and applicable standards.
In general, a clear, crisp sound or vibration indicates a healthy, defect-free area, while a dull or muted sound may suggest a potential defect or delamination.
The location, intensity, and nature of anomalies can provide insights into the type and severity of potential issues, such as voids, disbands, impact damage, or delaminations.
It’s important to note that tapping hammer testing is a qualitative method and should be used in conjunction with other NDE techniques (such as ultrasonic testing, visual inspection, etc.) for a comprehensive evaluation of composite structures.
The interpretation of results should always be performed by trained professionals with expertise in composite materials and NDE techniques, considering the specific requirements and standards of the aviation industry.
Next Steps
Follow this link to our Library to find & Download related documents for Free.
Sofema Aviation Services (www.sassofia.com) offers the following 2-day course – Composite Material TAP Testing for Aviation Inspectors
For comments or questions please contact team@sassofia.com
Tags:
SAS blogs, TAP Testing, Composite Materials, Carbon Fibre-Reinforced Polymers (CFRP), Aviation Inspectors, TAP Hammer, Fiberglass Reinforced Polymer (FRP), Aramid Fiber Reinforced Polymer (AFRP) (Kevlar), Composite Material TAP Testing
