Catching a Hidden Flaw in Aerospace Brake Discs

The Challenge

In safety-critical aerospace braking, a component that looks sound and measures dimensionally correct can still hide a subsurface integrity problem. A microcrack or a region of poor consolidation may not shift a part’s dimensions or its resonant frequency enough to trip a conventional check, yet it is exactly the kind of flaw that matters most. The manufacturer needed a fast, non-destructive way to tell a genuinely sound disc from one that only appears sound.

The Approach

GrindoSonic evaluated impulse excitation on a batch of brake discs, reading two independent signals from a single tap following ASTM E1876: the resonant frequencies, set by stiffness, and the damping, set by internal friction. Damping is the sensitive one. Internal friction rises with microstructural change and incipient cracking, often before any frequency shift is visible, so the way a part’s ring fades carries information a frequency-only or visual check does not.

The Results

Across the batch, one disc stood apart: markedly elevated damping identified it as having compromised structural integrity, even though it had passed conventional inspection. The measurement turned an invisible difference into a recorded number, demonstrating that impulse excitation can surface integrity problems a dimensional or frequency-only screen would let through. The study characterised the discs; it did not replace the manufacturer’s qualification programme, but it showed where an IET screen adds a layer other methods miss.