A novel Non-Destructive Inspection (NDI) method for improved defect detection in composites and traditional materials


Cyclic stress localisation in steel steering bracket

Technology abstract

Theta Technologies, a UK SME, has developed a novel NDI technique that can detect early stage defects (kissing bonds, cracks, and delaminations) in traditional materials and composites. Such defects reduce the strength and fatigue life of components and – crucially – are not readily detectable by traditional NDI. This game-changing technology can reduce waste and provide greater reliability by ensuring that materials and products are safe, compliant, and fit-for-purpose.

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Technology Description

Non-destructive inspection (NDI) allows users to ‘see’ inside a material or component in order to check for defects. NDI is standard practice for many industrial sectors (such as aerospace manufacture) where verifying the integrity of safety-critical, complex, and high-value components is essential.  However, conventional NDI techniques suffer limitations that prevent their application in certain areas.
Theta Technologies, a UK SME that specialises in ultrasonic NDI, has developed novel NDI capability that can find early stage defects with unprecedented detection sensitivity. The non-linear acoustic NDI methods can detect defects such as micro-cracks (of the order of 100um x 1um), kissing bonds (where two surfaces are in intimate contact but have greatly reduced bond strength), and delamination, in a wide range of materials including metals, alloys, and composites.
As well as traditional ultrasonic NDI applications (e.g. aerospace manufacture, rail inspection, offshore oil & gas), the novel methods have been successfully applied to kissing bond detection in Friction Stir Weld (FSW) parts. This is a major area of application as FSW is used for many industries including shipbuilding, automotive manufacture, robotics, and space craft component manufacture.

Innovations & Advantages

  • Ability to detect early stage defects including micro-cracks, delaminations, and kissing bonds
  • Multi-mode use
  • Earlier warning of degradation than is achievable with conventional NDI
  • Applicable to wide range of materials including composites (PMCs and CMCs) and traditional materials (alloys and metals)
  • Applicable to welds, coatings, sandwich constructions, and granular materials
  • Bespoke Turnkey System including installation, commission, onsite training, and a maintenance and support programme

Current and Potential Domains of Application

The multi-mode NDI instrument was originally developed to detect early stage defects in a range of materials, including:

  • Alloys and metals
  • Welds
  • PMCs (polymer matrix composites)
  • CMCs (ceramic matrix composites)
  • Coatings
  • Granular materials
  • Sandwich constructions

Ultrasonic NDI is widely used for industrial sectors including:

  • Offshore oil (pipe quality checks)
  • Aerospace (component verification)
  • Defence
  • Marine
  • Transport (rail inspection)

For detection of kissing bonds in Friction Stir Weld (FSW) parts, which are widely used for:

  • Automotive manufacture
  • Rail car manufacture
  • Fabrication (pressure vessels, vacuum vessels, façade panels)
  • Heat exchanger production