Current FrictionHarmonics system 

The current version of the FrictionHarmonics system has been validated in TWI’s Friction Stir Welding facilities. The tests have been carried out on more than 50 Friction Stir Welded flat aero plates, a sample size big enough to validate FrictionHarmonics defect detection features. Specifically, FrictionHarmonics has been proved to detect kissing bonds of 0.3mm in length with 100% accuracy and only 98% false-positives. This is half of the critical size that has been shown to associate with crack generation (i.e. 0.67mm). These levels of accuracy were constant across multiple values of depth up to 6mm, the maximum used in the Aerospace, Automotive and Railway industries. Figure 1 shows the current system in operation during these tests.

Figure 1: FrictionHarmonics current version: (a) FrictionHarmonics in action, (b) Close-up on scanner and probes, (c) Graphical User Interface


Future FrictionHarmonics system 

The design of the previous scanner was focused purely on handling flat surfaces. During this project, we aim to capture the most robust and innovative design solution in order for our system to handle more complex geometries and also adapt to the requirements of the operational environment. More precisely, the final scanner configuration should be flexible enough to carry out inspections on curved surfaces which are common in e.g. aerospace components, one of our main target segments.

The final system, as shown in Figure 2, a) can be manually handled by a single operator, b) is designed in such a way so as to protect operators from accidents i.e. pinch,crush etc., c) provides the tools to perfectly and easily align the probes with the welding seam with the use of laser generators, d) can be rigidly attached on concave and convex samples due to its 8 degrees of freedom.


Figure 2: FrictionHarmonics scanner on a concave sample with 500mm radius

FrictionHarmonics software 

The final software was designed based on the following features:

  1. GUI overhaul including simple/advanced view, graph zoom in / out, detected peaks displayed in different colors
  2. Detection / Signal processing including multi peak detection and good / borderline / bad signal detection
  3. Integration of scanner controls such as scan start/stop button, move backwards/forwards jog button, motor speed slider control, motor position slider control
  4. Reporting including live report generation and report saving tab
  5. Save / Load / Playback feature inclduing file load/save, local cache access through "Data" tab, playback slider, raw data import


Figure 3: GUI Main Screen, Advanced View Figure 4: Scanner controls tabs