Detection of Micron-Scale Flaws through Nonlinear Wave-Mixing

Safety codes that set the lifetime of hydrogen storage vessels are very conservative because of the high storage pressures and potential for hydrogenenhanced fatigue, resulting in increased fueling station operating costs. Vessels life extension would be possible if nondestructive evaluation of the damage state were possible after installation, but no technology exists for conducting these inspections. The development of a system that capable of detecting small flaws e.g., micrometerscale flaws in pressure vessels could enable savings upwards of $100k/year for hydrogen fueling stations. Luna proposes to 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 noncontact 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 and Phase II prototype development, the Phase IIB program will focus on fully maturing the tank inspection technology to enable successful transition to commercial sales. In the Phase IIB, Luna will work with partners to integrate the novel inspection techniques into fullysupported commercial hardware, and will characterize sources of variability that could confound measurement results to improve reliability and repeatability. The outcome of the Phase IIB program will be a commercialrepresentative tank inspection unit complete with calibration processes, analysis software, and integrated damage models for use in hydrogen tank inspections. Luna will finalize business arrangements with partners such that commercial sales can begin shortly after Phase IIB completion. 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 conditionbased rather than timebased maintenance protocol, there is increased adoption of nondestructive evaluation technology which will aid in the commercial success of the wavemixing system.