Modal Acoustic Emission

Testing and qualifying composite cylinders using high-bandwidth stress waves

Hexagon Digital Wave was the first company to offer Modal Acoustic Emission (MAE) testing, and we continue to pioneer new improvements for this revolutionary test methodology. While there are many potential applications for MAE, we currently offer it in two very important areas:

  1. Extending the life of SCBAs (self-contained breathing apparatuses) used in firefighting from 15 to 30 years – doubling their lifespan for minimal cost.

  2. Requalifying natural gas, hydrogen and other industrial gas cylinders in situ – saving the weeks or months required by traditional hydrostatic testing to physically remove the cylinders, test the cylinders and then reassemble the system correctly.

Experience a faster, more accurate way to test

Hexagon Digital Wave’s accurate and efficient MAE technology makes the process of requalification incredibly simple for our customers. MAE is far superior to traditional AE methods for inspecting the structural integrity of composite over-wrapped pressure vessels because of its:

  • Broader-bandwidth
  • High-fidelity transducers (sensors)
  • Digital recording of high-speed wave forms
  • Advanced software

Each of these differentiating aspects has led to inspection advances. For example, the broader bandwidth of MAE makes it possible to use frequency analysis and machine learning to detect damage mechanisms in the highly heterogeneous microstructure of fiber-reinforced composite materials. It also makes it easier to analyze frequency and mode-content in metallic structures to identify fatigue-crack extensions.


  • By far the most advanced testing platform for composite cylinders
  • Detects and quantifies critical defects
  • Reduces total cost of cylinder ownership
  • Doubles the life of fire department SCBAs
  • Meets all ASME, NBIC, ISO, PHMSA/DOT and Transport Canada standards
  • Cost-effective modular testing design
  • Technology can be extended for testing other composite structures

How it works

MAE testing works by placing transducers on the surface of a composite vessel, applying stress to the structure and recording any ultrasonic stress waves that propagate from the epicenter of a flaw.

The waveforms that are detected during a MAE testing are analyzed with Hexagon Digital Wave’s proprietary software for measuring:

  • Frequency features

  • Mode content

  • Quantitative energy associated with the damage mechanism

  • Severity of a given damage mechanism

By examining wave forms generated from common damage mechanisms over a long period of time, we have produced predictive models that inform the machine learning tools our skilled analysts use to evaluate every inspection. Common damage mechanisms include:

  • Fiber fracture, matrix cracking, delamination and fiber pull-out in reinforced composite structures

  • Crack extension and corrosion popping in metallic structures

Reduce your total cost of ownership

It’s not every day that you can improve operational efficiencies while driving superior results, but this is precisely what MAE makes possible for our customers. From life extension of SCBAs to dramatically simplifying the way gas trailers and storage modules can be tested, MAE allows many different types of organizations to reduce their TCO.

A smarter way to fulfill your testing requirements

Our MAE testing helps composite pressure vessel manufacturers, their customers and fleet operators to meet ASME, NBIC, ISO, DOT/PHMSA and Transport Canada codes and standards.

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