The use of adhesive bonding to join metals, composites, plastics and other materials is increasing across many industries. The aircraft industry widely adopted metal to metal bonding after World War 2 and this has since spread to different material combinations and other industrial sectors including modern aerospace, automotive, marine and wind energy.
Bonded joints offer many advantages over conventional methods such as bolting, riveting and welding. Weight saving is key but other benefits include an improved distribution of stresses by eliminating the need for holes and welds, easier design and assembly of large area joints or curved external surfaces and an integrally sealed joint, often using dissimilar materials, that can avoid electrolytic corrosion and is less sensitive to crack propagation.
The integrity of these bonds is critical to the quality of the final product and so techniques to assess the quality of the bond have seen a resurgence. With new material combinations come new possible flaw types and the challenge is to develop inspection techniques to detect these. For example, a modern composite sandwich construction made with two skins and a core material may contain flaws like cracks, disbonds, delaminations, voids and crushed core but conventional inspection techniques can be of limited use because of the multiple glue lines and attenuative materials that are inherent in the lay-up.
With such a range of materials and configurations used in multi-layered bonded structures, different types of testing methods have been developed to attempt to cover all combinations. Bond testing is already established as a requirement in maintenance manuals and technical directives for multiple commercial and private aircraft types but is now seeing its use expanding.
The Bondascope 3100 bond tester has 3 modes of operation to cover a range of applications and can detect delaminations, disbonds, crushed or damaged core, porosity, foreign objects and much more in monolithic, sandwich constructions and bonded structures.
NDT Systems Inc., provides the most capable bond testers in the market for composite inspection, skin to core sandwich construction, adhesively bonded fittings, metal to metal bonded joints, highly attenuative materials and any material that need a high penetrating power.
The low frequency Pitch-Catch (P/C) and Mechanical Impedance (MIA) modes are able to penetrate through glue lines and across core and have the additional advantage of being dry coupled which is ideal for inspections where water or any kind of wet couplant cannot be used. Far side defects can also regularly be detected which is ideal when there is only access to only one side of a part.
Resonance mode is most suitable for monolithic structures, or bonded structures. This mode requires couplant but can penetrate through multiple glue lines and is much less affected by included air. Furthermore, with multi-layer bonded structures, the system can determine which layer the defect occurred in.
The BondHub Imaging Bond Tester utilizes the full capability of the well-established Bondascope 3100 and connects to any of our manual or automatic scanners to generate high-resolution bond testing C-scan images in Pitch-catch, MIA and Resonance modes. Inspection of composites and adhesively bonded materials has not seen such advancement for many years. The power of full-field inspection images using bond testing elevates non-destructive inspection capability onto a new level. Imaging offers many advantages including:
• Easy interpretation
• Increased probability of detection
• Digital Archiving of results
• More consistent and reliable results
• Reduced human error
• Increased speed of inspection
For even higher penetrating power, the fully non-contact Curlin Air uses through transmission to detect anomalies in the sound path. The Curlin Air requires no surface preparation and can penetrate up to 6 inches (150mm) of foam, wood, honeycomb and other attenuating materials and can detect skin to core or core defects. The Curlin air uses different sized yokes to maintain alignment of the transmitting and receiving probe.
NovaScope 6000View Details
- Class leading ultra thin spatial resolution
- High-Resolution (0.0001in, 0.0025mm)
- Multi-probe capability
- Touchscreen controls
Bondascope 3100View Details
- Handheld Bond Tester
- Pitch-catch, Mechanical Impedance (MIA) and Resonance modes
- Programmable user setups
- Automatic probe recognition
- Alarm modes, impedance plane
Curlin AirView Details
- Air coupled UT
- Non-contact, no surface preparation
- Remarkable penetrating power
- Alarm modes
- Programmable user setups