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NASA's Method of Evaluating Adhesive Bond Strength is an accurate, robust, quantitative, and nondestructive bond strength measurement method that meets an immediate need in composite manufacturing. Even with careful control of the bonding procedure, destructive testing has shown that bonded joint strength shows substantial variation. Prior art in the field is insensitive to weak interfacial bonding, which leads to poor service life and potential catastrophic failure. Using NASA's method, phase measurements are acquired at a single frequency and then swept to obtain measurements at other frequencies. Narrowband filtering removes extraneous frequencies, which allows for much lower phase measurement uncertainty than other methods. Digital sine wave generation allows for better phase measurement resolution. The resultant system is a phase-based ultrasonic measurement tool for interrogating bonded joints and detecting weak adhesion with superior sensitivity than the state of the art. This new method models adhesive interfaces as a distributed spring system, where the interfacial stiffness constants of the joint can be determined from the zero- crossing frequency of the phase response and the "sharpness" or slope of the phase response. Previous theoretical research has shown that a linear correlation exists between interfacial stiffness constants and mechanically-measured interfacial bond strength. As such, the ultrasonic phase measurement method identifies intermediate bond strengths, rather than simply detecting good or bad bonds. This technique verifies bond quality in metal and composite joint systems, including those commonly found in aerospace, automotive, and many other transportation and infrastructure designs. The demonstrated ultrasonic phase method is applicable to a variety of bonding material systems.

When waves move a floating wind turbine, they drive fluid motion inside the MTLCD. This forces air in the vertical tanks through an orifice, increasing pressure much like a spring. As the air discharges, the fluid’s motion is damped and energy is dissipated. The MTLCD also incorporates added damping elements, such as an orifice or variable-aperture reciprocating reed valve, that create resistance to air flow, further controlling fluid motion and dissipating energy. By integrating these modifications, the MTLCD is easily tuned to the platform’s motions, reducing dependency on platform geometry. Eliminating damping elements from the fluid removes the need for marine-grade hardware, reducing system costs. The MTLCD can also be integrated into existing ballast tanks, maximizing space efficiency with minimal added parts. While initially developed for NASA’s Floating Wind Turbine Development project, this invention can support vibration mitigation applications across multiple industries, such as infrastructure, maritime systems, and aerospace. By enabling precise tuning of dynamic response characteristics, the MTLCD offers a compact solution for platforms requiring vibration suppression. The technology has completed preliminary design and simulation, is at a TRL 3 (proof-of-concept), and is available for patent licensing.