Detection of Micron-Scale Flaws through Nonlinear Wave Mixing

Storage of hydrogen is challenging due to high storage pressures and potential for hydrogen embrittlement.Pressure vessels are currently retired from service under conservative guidelines due to the inability to identify damage until damage is imminent.There exists a need for a system that can resolve micrometer-scale features and relate these to the damage state of pressure vessels for accurate life estimates resulting in reduced operating costs.Luna proposes develop an inspection system that leverages nonlinear interactions between two mixed acoustic waves to identify the presence of micrometer flaws in steel.The development effort will focus on EMAT technology to allow non-contact inspections and rapid surface scanning.The sensing system will produce maps of damage features that enable remaining useful life estimates to be formulated.Following a successful Phase I feasibility study, the Phase II program will focus on expanding upon the wave mixing techniques established in Phase I in order to tailor them for use on hydrogen tank inspections.Sets of test articles having relevant geometries, damage features, and compositions to the hydrogen industry will be developed and used to optimize the test protocols.Partnerships with hydrogen-material interaction experts at Sandia National Lab will be leveraged to develop a better understanding of the unique damage progression of pressure vessel walls exposed to hydrogen gas for development of remaining useful life models.A prototype system will be designed, manufactured, and demonstrated on full-scale test articles obtained from commercial hydrogen pressure vessel vendors (e.g., Fiba Technologies).The market for this inspection technology includes the energy, automotive, and aerospace sectors.In all of these markets, the ability to reliably identify damage early in a component’s life enables improved maintenance planning and reduced the numbers of inspections required.In an effort to move toward a condition-based rather than time-based maintenance protocol, there is increased adoption of non-destructive evaluation technology which will aid in the commercial success of the wave-mixing system.