Ames, IA, United States

Etrema Products, Inc.

www.etrema.com
Ames, IA, United States
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Oates W.S.,Florida State University | Zrostlik R.,Etrema Products, Inc. | Eichhorn S.,Etrema Products, Inc. | Smith R.,North Carolina State University
Journal of Intelligent Material Systems and Structures | Year: 2010

Non-linear optimal and narrowband feedback control designs are developed and experimentally implemented on a magnetostrictive Terfenol-D actuator. The non-linear optimal control design incorporates a non-linear and hysteretic ferromagnetic homogenized energy model within an optimal control formulation to reduce displacement tracking errors and increase bandwidth. Improvements in robustness in the steady-state regime are achieved by utilizing narrowband feedback. A narrowband filter is implemented by treating the nonlinear and hysteretic magnetostrictive constitutive behavior as higher-order harmonic disturbances which are mitigated by tuning the narrowband filter to penalize these harmonics for displacement tracking control problems. The control designs are then combined into a hybrid optimal controller with perturbation narrowband feedback. Both transient and steady-state tracking control is assessed to illustrate performance attributes in different operating regimes. Narrowband perturbation feedback is shown to mitigate errors in the steady-state operating regime, while non-linear optimal control provides enhanced tracking control in the transient regime. The hybrid control design is relevant to a broad number of smart material actuators that exhibit non-linear and hysteretic field-coupled constitutive behavior. © 2010 The Author(s).


Nolting A.E.,Defence R&D Canada Atlantic | Summers E.,Etrema Products, Inc.
Journal of Materials Science | Year: 2015

Iron–gallium alloys, known as Galfenol, have a unique combination of magneto-mechanical and structural properties that make them an attractive choice for use in robust sensing, actuating, and energy harvesting devices. The high strength and toughness of Galfenol, when compared to traditional active materials such as Terfenol-D and piezoelectric ceramics, are leading to multi-functional (structural and active) applications, such as active-damping engine mounts. Although the toughness of Galfenol is high compared to other functional materials, further improvements in toughness and ductility are beneficial for structural applications. Qualitative analysis of fracture surfaces from binary Galfenol tensile specimens suggests an inverse correlation between the degree of intergranular fracture and the amount of plastic deformation. This implies that modifications to the alloy composition or processing that change the fracture mode from intergranular to transgranular could increase the ductility of the alloy. This paper examines the effect of small additions of tertiary alloying elements (C, Cr, Al) and mixing with low carbon steel (with and without V additions) on the tensile properties and fracture mode of Galfenol. Generally, the addition of alloying elements increased both strength and ductility and changed the fracture mode from intergranular to transgranular fracture. © 2015, Her Majesty the Queen in Right of Canada.


Restorff J.B.,U.S. Navy | Wun-Fogle M.,U.S. Navy | Summers E.,Etrema Products, Inc.
Journal of Applied Physics | Year: 2011

Measurements of d 33 (major and minor loops) and d33 (major loops) were made on three Fe81.6Ga18.4 (Galfenol) highly textured polycrystalline rods, one of which had a small amount of 1002 steel substituted for the iron. Seven δT's between 25 and 0.5 MPa at 100 Oe were used for the minor loops. These measurements are useful for energy harvesting, which is the generation of energy by utilizing vibrations present in the environment. For magnetostrictive materials d 33 B / T H is the relevant parameter, where B is the magnetic flux density, T is the stress and H is held constant. Since real energy harvesting devices will not have active H control, B / T was also measured where H was not held constant. The d 33 's and d 33's (d 33 S / H T) for both binary samples with δT ≥ ± 5 MPa were well fit by a Gaussian plus a constant. Peak amplitudes for d33 and d 33 were ∼80 and ∼60 nm/A, respectively. At smaller δT's, d 33 vs. T was flat or showed a broad peak. The steel containing sample had a larger cubic anisotropy which resulted in a double peaked d 33 curve with a maximum amplitude of ∼100 nm/A. At the points where the d 33 and d33 measurements overlap, the two d-coefficients are within 5 to 50 of one another at 100 Oe. The hysteresis in the S-T and B-H loops was ∼2 and ∼0.9 kJ/m3, respectively. © 2011 American Institute of Physics.


Meloy R.,Etrema Products, Inc. | Summers E.,Etrema Products, Inc.
Journal of Applied Physics | Year: 2011

Recent results in the area of galfenol (iron-gallium) alloy rolled sheet have yielded significant Goss ({110} < 001 > rolling direction [RD]) texture development and large strain values, 250 > ppm. Goss-textured grain growth is promoted by the use of a grain boundary pinning second-phase particle. After multistage rolling and subsequent heat treatment, Goss grain areas as large as 125 cm2 develop in the RD-transverse direction (TD) plane. Goss grain < 100 > directions are typically within 15 of the RD inside these grains. Fully processed sheets were sectioned and bonded together to produce laminated stacks. Grain oriented and nongrain oriented stacks were characterized magnetically. Plotting strain data against H-field for both an Oriented Stack (OS) and a Nonoriented Stack (NonOS) yielded saturation stain values of 215 ppm and 70 ppm, at 48.3 MPa prestress, respectively. Magnetostrictive strain coefficient, d33, values of 20 nm/A and 4 nm/A were calculated for the OS and NonOS, respectively. Saturation magnetization values were found to be 1.3 T and 1.2 T for the OS and NonOS. Electron Backscatter Diffraction (EBSD) analysis was performed on cross sections of each laminated stack. EBSD mapping showed a large relative disparity in average grain size, taken from cross sections, of 470 μm and 84 μm for the OS and NonOS. Pole figures, contoured at a half-width of 10°, were analyzed and clearly show a high degree of Goss texture in the OS and a lack of any strong texture in the NonOS. The OS generated a maximum Multiple of Mean Uniform Density value > 16 while the NonOS produced a value < 2. © 2011 American Institute of Physics.


Patent
Etrema Products, Inc. | Date: 2013-01-31

A product, such as one or more thin sheets, each containing a single or near-single crystalline inclusion-containing magnetic microstructure, is provided. In one embodiment, the inclusion-containing magnetic microstructure is a Galfenol-carbide microstructure. Various methods and devices, as well as compositions, are also described.


Grant
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 79.92K | Year: 2011

Etrema proposes to develop a free-flooded Galfenol split-ring transducer that will provide 50-75 Hz of bandwidth on a 200 Hz carrier wave capable of operating at depths up to 1000 m with a source level greater than 190 dB re 1uPa @ 1m. While there are no specifications on size, the desire expressed by the technical point of contact is for a source that will fit on a standard pallet. By combining the depth-independence and bandwidth of a free-flooded magnetostrictive ring with the compact size of a split-ring, the resulting transducer should meet the objectives for the communications application. Design options which decrease size and improve performance will be explored.


Grant
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase II | Award Amount: 742.97K | Year: 2011

Etrema is developing an acoustic projector that provides broad bandwidth, high source level, directional output, high duty cycle, and high reliability in a compact package. Specific objectives of the Phase II effort are: demonstrate performance of a prototype projector, optimize the full-scale projector design, and demonstrate performance of the full-scale projector. Fabrication and testing of the full-scale hardware will demonstrate its readiness for transition to the fleet. Etrema plans to partner with Ultra Electronics Ocean Systems in the development of the Vector Projector. Advantages of the proposed work will be a high power, high duty cycle, directional acoustic projector that meets requirements for ASW and CTDCL missions.


Grant
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 99.87K | Year: 2011

Etrema proposes to develop a modified acoustic projector design that provides broad bandwidth, high source level, directional output, high duty cycle, and high reliability in a compact package. The design will target the same acoustic source levels as the baseline Vector Projector with higher duty cycle, lower frequency bandwidth, and a smaller package size. Specific objectives of the effort are: identify specific improvements to the existing Vector Projector to improve source level and duty cycle; develop a notional projector design by performing a trade-off analysis of different projector designs; and, in the Option, develop a proof-of-concept design that demonstrates the performance goals. Technical feasibility of the projector will be demonstrated by using a combination of equivalent circuit-based models and finite element models to develop a design that meets the performance goals. Long-term performance and reliability will be assessed by identifying areas of greatest risk in the design and developing mitigation plans to address them. Etrema plans to partner with Ultra Electronics Ocean Systems in the development of the Vector Projector. Advantages of the proposed work will be an improved design that meets requirements for ASW and CTDCL missions.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase II | Award Amount: 741.62K | Year: 2011

Development of an energy harvesting system utilizing the magnetostrictive material, Galfenol, will be completed in this effort. The energy harvesting system will consist of Galfenol plates or sheets, magnetic circuit components, coupling structure, power conditioning electronics, sensor, and wireless transmitter. Lab testing and relevant environment testing through sea-trials will be completed on the system and compared to the predicted performance of FEA and analytical models. In addition, Galfenol wire fabrication efforts will be advanced with the primary goal of developing a Galfenol alloy and process capable of producing wire with the appropriate texture to maximize energy harvesting properties for future 1D devices.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 99.82K | Year: 2010

Energy harvesting devices utilizing magnetostrictive materials are a logical choice for harvesting the high impedance (high force, low displacement) vibrations found aboard Navy ships. Force-based devices, enabled by magnetostrictive materials, can harvest energy over an extremely large bandwidth, approximately ±35 and ±70 Hz currently, making them more desirable in situations aboard Navy ships were transient vibration conditions created by varying ship speeds is present. This broader bandwidth also means easier installation of the devices without the need for exact placement on the vibration source and eliminating tuning requirements typical of the displacement based devices. The robustness and formability that Galfenol alloys exhibit allow 1-dimensional (1D), 2-dimensional (2D), and 3-dimensional (3D) energy harvesting devices to be developed and optimized for the identified need and vibration coupling scheme. A 1D Galfenol device could consist of wire(s) bundled together to form an energy harvesting cable that could be wrapped around a vibrating column; a 2D Galfenol device could consist of a single Galfenol sheet attached to a vibrating panel; and a 3D Galfenol device could consist of structural support on-which the vibration source is mounted. The proposed work will investigate 1D and 2D Galfenol energy harvesting devices in Navy ship environments.

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