Carbon Fibre Reinforced Polymer composite (CFRP) is widely used in the aerospace industry, but is prone to delamination, which is a major causes of failure. Structural Health Monitoring (SHM) systems need to be developed to determine the damage occurring within it. Our motivation is to design cost-effective new sensors and a data acquisition system for magnetostrictive structural health monitoring of aerospace composites using a simple RLC circuit. The developed system is tested on magnetostrictive FeSiB and CoSiB actuator ribbons using a bending rig. Our results show detectable sensitivity of inductors as low as 0.6 μH for a bending rig radii between 600 to 300 mm (equivalent to 0.8 to 1.7 mStrain), which show a strain sensitivity resolution of 0.01 μStrain (surface area: ~36 mm2). This value is at the detectability limit of our fabricated system. The best resolution (1.86 μStrain) was obtained from a 70-turn copper (~64 μH) wire inductor (surface area: ~400 mm2) that was paired with a FeSiB actuator.
Structural health monitoring (SHM) represents the next generation of carbon fiber‐reinforced composite nondestructive testing. One challenge facing the application of magnetostrictive SHM is the lightweighting and ease of installation of actuators and sensors. Inkjet printing (IJP) technology is well suited to produce miniaturized electronic induction sensors that can be paired with magnetostrictive actuators to detect strain. These sensors have several advantages: their thicknesses can be minimized, the surface area can be maximized to increase sensitivity, and complex multifilar coil configurations can be fabricated. A parametric study of the efficacy of IJP induction coils with different parameters (number of coils, monofilar/bifilar, size) tested on a number of actuator‐functionalized composite coupons (FeSiB ribbon and impregnated epoxy sensors) is conducted. The samples are characterized by measuring their inductance response through induced strains. Increased sensitivity and accuracy of the 10‐turn monofilar IJP sensor are shown with respect to 1) 70‐turn hand‐wound coils, 2) a three‐axis AMR sensor, and 3) other IJP actuators with <10 turns. This is attributed to increased contact area to the composite surface and the requirement of minimum sensitivity (i.e., the number of turns and surface area) for strain detection.
The 45T hybrid magnet being constructed by the National High Magnetic Field Laboratory will generate the world's highest steady magnetic field. The coil is composed of four sections: A Nb-Ti outsert, two Nb,Sn outserts and a water cooled resistive insert. Teledyne W a h Chang produced the wire for the Nb,Sn coils (A and B) and oversaw the cabling. The wire design for the 45T hybrid magnet is a modified version of TWC's Nb diffusion barrier wire. This wire design provides excellent control of the IC and hysteresis toss. Coil A is composed of 525, 0.43mm diameter wires 939m in length. Coil B is a two piece cable composed of 315, 0.51mm diameter wires. The lengths of the Coif B pieces a r e 844m and 623111. The I,, %"-value and hysteresis loss of the wire a r e shown to be uniform. The variability in RRR for each coil is discussed. The results of triplet test cables are also reported.
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