More Like this

1. Active magnetic sensing for subterranean urban target discrimination

   https://doi.org/10.1117/12.2561554  

   Ezequelle, Wilson; Orfeo, Daniel; Burns, Dylan; Xia, Tian; Huston, Dryver R. (April 2020, SPIE Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, Civil Infrastructure, and Transportation IX)

   Shull, Peter J.; Yu, Tzu-Yang; Gyekenyesi, Andrew L.; Wu, H. Felix (Ed.)

   Location and identification of subterranean infrastructure is crucial for managing and maintaining urban infrastructure and utility, and locating subsurface hazards. Low-frequency oscillating magnetic fields suffer less attenuation due to propagating media than ground penetrating radar. Here, electronically-geared, rotating neodymium magnets project oscillating magnetic fields which are manipulated to provide object identification from rapid analysis of dynamic magnetometer data. Ferromagnetic materials interact directly with the rotating magnetic field. Eddy currents, which induce a counter-propagating magnetic field, are generated in conductive, non-ferromagnetic materials. Two applications are highlighted by preliminary experiments: discrimination between copper, aluminum and steel pipes, and improved detection of buried explosive devices. 

   more » « less
2. Nondestructive Evaluation of Additively Manufactured Metal Components with an Eddy Current Technique

   B. Schneider, B; Shoaib, M; Taheri, H; Koester, L; Bigelow, T; Bond, L (January 2018, ASNT 27th Research Symposium Proceedings)

   The ability of Additive Manufacturing (AM) processes to ensure delivery of high quality metal-based components is somewhat limited by insufficient inspection capabilities. The inspection of AM parts presents particular challenges due to the design flexibility that the fabrication method affords. The nondestructive evaluation (NDE) methods employed need to be selected based on the material properties, type of possible defects, and geometry of the parts. Electromagnetic method, in particular Eddy Current (EC), is proposed for the inspections. This evaluation of EC inspection considers surface and near-surface defects in a stainless steel (SS) 17 4 PH additively manufactured sample and a SS 17 4 PH annealed plates manufactured traditionally (reference sample). The surfaces of the samples were polished using 1 micron polishing Alumina grit to achieve a mirror like surface finish. 1.02 mm (0.04”), 0.508 mm (0.02”) and 0.203 mm (0.008”) deep Electronic Discharge Machining (EDM) notches were created on the polished surface of the samples. Lift off and defect responses for both additive and reference samples were obtained using a VMEC-1 commercial instrument and a 500 kHz absolute probe. The inspection results as well as conductivity assessments for the AM sample in terms of the impedance plane signature were compared to response of similar features in the reference sample. Direct measurement of electromagnetic properties of the AM samples is required for precise inspection of the parts. Results show that quantitative comparison of the AM and traditional materials help for the development of EC technology for inspection of additively manufactured metal parts. 

   more » « less
3. Computational modelling of a triaxial vibrating sample magnetometer

   https://doi.org/10.1063/9.0000787  

   Rodriguez, Leo; Sapkota, Arjun; Alvarado, Jonathan; Tate, Jitendra_S; Geerts, Wilhelmus_J (February 2024, AIP Advances)

   Magnetic Field Assisted Additive Manufacturing (MFAAM) enables 3D printing of magnetic materials of various shapes which exhibit a complex anisotropy energy surface containing contributions generated from different origins such as sample, particle, and agglomerate shape anisotropy, flow and field induced anisotropy, and particle crystal anisotropy. These novel magnet shapes require the need to measure the x, y, and z components of the magnetic dipole moment simultaneously to fully understand the magnetic reversal mechanism and unravel the complex magnetic anisotropy energy surface of 3D printed magnetic composites. This work aims to develop a triaxial vibrating sample magnetometer (VSM) by adding a z-coil set to a pre-existing biaxial VSM employing a modified Mallison coil set. The optimum size and location of the sensing coils were determined by modeling the sensitivity matrix of the z-coil set. The designed coil set was implemented using 3D printed spools, a manual coil winder, and gauge 38 copper wire. A 3D printed strontium ferrite nylon composite sample was used to estimate the sensitivity of the z-coils (50 mV/emu). The results herein are applicable for any VSM using a modified Mallison biaxial coil configuration allowing for a quick implementation on pre-existing systems. 

   more » « less
4. Energy Sensors and Absorbers Based on Nanoscale Magnetic Tunnel Junction Metamaterials

   https://doi.org/10.1115/IMECE2023-117058  

   Mengesha, Betelhiem N; Estevez_Hernandez, Juan; Feutmba, Arnold; Tyagi, Pawan (October 2023, American Society of Mechanical Engineers)

   Abstract This paper explores nanoscale energy sensors and absorber metamaterials that can be used in various applications, such as solar cells and infrared detectors. It is possible to gain highly efficient and adjustable energy absorption, creating absorber metamaterials at the nanoscale that enhance the performance of solar cells. These metamaterials are based on molecular spintronics devices (MSD) and magnetic tunnel junctions (MTJ). The pillar shaped MTJs are made of two ferromagnetic metals separated by an insulating barrier, such as aluminum oxide (AlOx). The manufacturing process includes photoresist spin coating on a silicon wafer, photolithography, thin film sputtering, and liftoff. Following fabrication, the top and bottom electrodes are covalently bonded by a single molecule magnet (SMM) on the exposed side edges for strong magnetic coupling that changes the magnetic properties of both ferromagnetic metals. This study has considered different thin film deposition materials, configurations, and thicknesses. Magnetic field resonance and light reflectance measurements have been performed before and after molecule attachment to understand the molecule effect on the metamaterials’ energy absorption behavior. The Electron Spin Resonance (ESR) test revealed that the devices shifted following molecule attachment in both acoustic and optical modes. Moreover, due to molecule attachment, there have been significant alterations in the MTJ’s electromagnetic wave absorption characteristics with about 49% less reflectance. This metamaterial has various potential applications in aerospace, renewable energy, sensing, imaging, and communication. It is also a cheaper alternative to traditional solar cells and can inspire the development of smart metamaterials with selective absorption and tunable response. 

   more » « less
5. Development of a Steel Bridge Climbing Robot

   https://doi.org/10.1109/IROS40897.2019.8967748  

   Nguyen, Son Thanh; La, Hung Manh (November 2019, 2019 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS))

   Motivated by a high demand for automated inspection of civil infrastructure, this work presents an efficient design and development of a tank-like robot for structural health monitoring. Unlike most existing magnetic wheeled mobile robot designs, which may be suitable for climbing on flat steel surface, our proposed tank-like robot design uses reciprocating mechanism and roller-chains to make it capable of climbing on different structural shapes (e.g., cylinder, cube) with coated or non-coated steel surfaces. The developed robot is able to pass through the joints and transition from one surface to the other (e.g., from flat to curving surfaces). Taking into account several strict considerations (including tight dimension, efficient adhesion and climbing flexibility) to adapt with various shapes of steel structures, a prototype tank-like robot integrating multiple sensors (hall-effects, sonars, inertial measurement unit, Eddy current and cameras), has been developed. Rigorous analysis of robot kinematics, adhesion force, sliding failure and turn-over failure has been conducted to demonstrate the stability of the proposed design. Mechanical and magnetic force analysis together with sliding/turn-over failure investigation can serve as an useful framework for designing various steel climbing robots in the future. The robot is integrated with cameras and Eddy current sensor for visual and in-depth fatigue crack inspection of steel structures. Experimental results and field deployments confirm the adhesion, climbing, inspection capability of the developed robot. 

   more » « less