Magnetostrictive composite inspection for structural health monitoring commended at Tech Briefs Design the Future design Contest

An idea developed by University staff was placed as one of the top five design ideas in the Aerospace and Defense category of the Create the Future Design Contest, receiving an Honourable Mention, and in the top 100 design ideas out of more than 1,000 entries. The contest is organised by Tech Briefs, publishers of NASA Tech Briefs (NASA is required by charter to report new commercially significant technologies) to help stimulate and reward engineering.

Fabricated Composite Samples with attached actuator layer

Composites are complicated materials, by nature. Different materials are combined in a pre-defined way, each with their own role in imparting properties to the overall product to give a materials superior properties to the individual component materials. Damaged composites are even more complicated - the damage may be superficial, catastrophic, or somewhere in-between. Detection of damage to composite materials is challenging, as it can often be hidden by the outer layers. While there are a number of techniques for non-destructively testing composites, these are not without their drawbacks:

  • They are time consuming and tedious
  • They are prone to mistakes and human error
  • There is a high cost for automated visual systems
  • It is inaccurate if damage is not visible on the surface, or subsurface, making visual inspection inappropriate
  • It is challenging for mid-flight or in-line inspection.

Comparison of magentostrictive ferrite-epoxy actuators for damage-impacted samples.

Researchers from the Department of Materials Science and Engineering at the University of Sheffield recently presented a design idea to addresses these drawbacks using magnetostrictive technology. The idea, developed by Dr Zhaoyuan Leong, Professor Nicola Morley, and Dr Pratik Desai (Perlemax Ltd.), utilised actuator/sensor pairs for damage detection by embedding dispersions of inexpensive magnetostrictive microparticles within a suitably thin flexible matrix. On to this a sparse-array sensor grid is attached, from which damage position can be determined. This approach can be used to monitor critical components in aircraft to obtain near instantaneous updates even for off-line detection.

Prototype determining damage positioning from a 3-sensor array.

More information about the technique can be found in the contest submission, available here.