Material for magnetostrictivesensors and otherapplicationsbased on ferritematerials
The present invention provides magnetostrictive composites that include an oxide ferrite and metallic binders which provides mechanical properties that make the magnetostrictive compositions effective for use as sensors and actuators.
substituting the transition metals foriron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferritematerial effective for use as sensors andactuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications.
J. E. Snyder b 兲 and D. C. Jiles b 兲
Materials and Engineering Physics Program, Ames Laboratory, U.S. Dept. of Energy, Ames, Iowa 50011 共Received 2 August 2004; accepted 4 November 2004; published online 21 January 2005兲 Metal bonded cobalt ferrite composites have been shown to be promising candidate materials for use in magnetoelastic stress sensors, due to their large magnetostriction and high sensitivity of magnetization to stress. However previous results have shown that below 60 ° C the cobalt ferritematerial exhibits substantial magnetomechanical hysteresis. In the current study, measurements indicate that substituting Mn for some of the Fe in the cobalt ferrite can lower the Curie temperature of the material while maintaining a suitable magnetostriction for stress sensing applications. These results demonstrate the possibility of optimizing the magnetomechanical hysteresis of cobalt ferrite-based composites for stress sensor applications, through control of the Curie temperature.
There are two primary failure modes for composites: fibre rupture in tension or fibre buckle in compression , both of which result in an increase stress in the material. Thus the stress state of the composite material is the most important determinant of the structure safety . However, it is difficult to obtain a direct reading of the stress within the material, so a measure of the strain, which is the deformation of a solid due to stress is used instead. There are a number of different sensors being developed for composite damage detection, these include self-sensing in the carbon fibres , glass fibre optical sensors  and piezoelectric sensors . Each method has advantages and disadvantages, i.e. self-sensing in carbon fibres requires no added materials, but is limited to carbon composites, while piezoelectric sensors require the sensors to be attached to the composite surface, but multiple readings can be obtained simultaneously.
In order to analyze the magnetostriction properties of metal-bonded Co-ferrite composites, the hysteresis loops were measured. The metal-bonded Co-ferrite composites generally exhibited coercivities in a range of 6–8 kA/m. This was much lower than that 共 160 kA/m 兲 reported for Co ferrite. 14–16 The bonding metal may make it easier to nucle- ate reverse magnetic domains at the surface of the Co-ferrite particles, either by reacting with the ferrite and producing regions of reduced anisotropy, or by producing regions of a second magnetic material with lower anisotropy 共 e.g., Ni or Co 兲 at the surface. From the magnetostriction point of view, this will increase the initial permeability, the initial piezo- magnetic coefficient, and hence the sensitivity to stress. At the same time, the maximum magnetostriction of the com- posites is observed to decrease with increasing amounts of Co in the bonding metal, or increasing Ni in the Ag/Ni bond- ing metal mixture. There are two possible mechanisms at work here. First, the Co or Ni could diffuse into the Co ferrite, changing the stoichiometry and thus the magneto- striction. Although the literature references on this effect are limited, Co-rich Co ferrite is reported to have lower magne- tostriction and magnetic anisotropy. 17 One would also expect that addition of Ni to Co ferrite would also lower the mag- netostriction. As the magnetostriction is also dependent on the porosity and the mechanical strength of the bonding of the composite, it is possible that the changes in magnetostric- tion result from the mechanical properties of the composites.
An advantage of the magnetostrictive sensor, over other types of linear position sensors, is the ability to read the position magnet even when there is a barrier between the position magnet and the sensing rod. For example: the barrier can be the cylinder wall when the position magnet is part of a piston, or a transmission case when measuring gear position, etc. This is possible whenever the material directly between the position magnet and the rod can be a non-magnetic material. Common materials for this duty include plastics, ceramics, aluminum and non-ferrous metals, and many stainless steels.
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a low-cost method of producing films with thicknesses in excess of 100 m. The process is based upon a screen print- ing technique that is believed to have been in use for over a thousand years as a form of graphic art reproduction. The processing equipment used in this study is designed for use in the fabrication of electronic circuits and sensors. With thick-film technology, the target film material is mixed with a binder material, often a devitrifying glass frit, and suit- able solvents to produce a printable paste. This paste is then screen printed through a patterned screen onto a suitable substrate, typically alumina, insulated steel or silicon. The printed paste is then allowed to settle prior to drying, which is necessary to remove the solvents within the composition.
This paper addresses the modeling of Villari-effect sensors whose active element is a magnetostric- tive element operated under mechanical and magnetic bias conditions. The proposed model is sufficiently general to provide characterization of actuation and sensing effects. In actuation mode, strains and ensuing forces arise as a result of magnetization changes which are brought about by the application of magnetic fields. Conversely, elastic deformations lead to measurable changes in mag- netization thus providing a mechanism for sensing. Both modes of operation are inherently coupled through the magnetomechanical coupling and hence methods for addressing this form of coupling must be considered in models to be used in high performance transducers. Only by addressing magnetic hysteresis and magnetoelastic coupling effects in a manner consistent with the physi- cal properties of magnetostrictivematerials will models for intelligent structures based on these materials be sufficiently accurate to characterize the performance space of existing and expected applications. It is emphasized that transducer models able to characterize the magnetomechanical coupling lend themselves to the design of collocated actuators and sensors. Demonstration of the use of magnetostrictivematerials for sensoriactuation applications can be found in [18, 21].
CoFe 2 O 4 -graphene nanocomposite has been prepared by hydrothermal method and employed as an anode material for lithium-ion batteries (Figure 2) . Pure CoFe 2 O 4 electrode (a) offered the first discharge and charge capacity values of 1606 and 960 mAh g -1 , respectively. On the other hand pure graphene electrode exhibited 1200 and 426 mAh g -1 of discharge and charge capacities respectively. CoFe 2 O 4 -graphene (10 wt% of graphene) nanocomposite offered the discharge and charge capacities of 1531 and 952 mAh g -1 . Similarly, CoFe 2 O 4 -G (20 wt% of graphene) exhibited the discharge and charge capacity values of 1388 and 906 mAh g -1 respectively. Here, CoFe 2 O 4 -graphene composite having 20 wt% of graphene has high reversible capacity of 1082 mAh g -1 along with excellent cyclic stability. This could be due to the facilitation of extra lithium storage attributed to the large surface area of incorporated graphene. High content of graphene in CoFe 2 O 4 -graphene (20 wt%
The applications of magnetostrictivematerials can be found in various disciplines. Due to their excellent actuation performance characteristics, magnetostrictivematerials are employed as smart actuators in aerospace applications. As the technology of adaptive structures is favoring the use of smart actuators and sensors, magnetostrictive smart materials have justified their employment in morphing applications. The morphing aircraft technology presents new challenges in terms of actuation characteristics; these material actuators provide higher frequency and higher actuation efficiency. Also, the magnetostrictivematerials can provide mechanisms both for actuation and sensing due to their property of bidirectional energy exchange between magnetic and elastic states. This paper presents an overview of magnetostrictivematerials, their characteristic features and the applications with the aim to inspire morphing structures in aircraft. The challenges and trends in the applications of magnetostrictivematerials have also been discussed.
Magnetostrictivematerials have potentials for applica- tions in stress/torque sensors development and composite mag- netoelectric device fabrication. For applications in chemically or thermally challenging environments, or where it is desirable to avoid losses due to eddy current, oxide basedmaterials are more appropriate. Among the oxides, materialsbased on cobalt ferrite have both sufficient magnetostriction amplitude and strain derivative for many applications, considering that 30 ppm obtainable for Ni is sufficient for applications. 1 Cation substitution, high pressure processing and heat treatment have been investigated for optimizing the magnetostrictive proper- ties of cobalt ferrite. 2–4 It was recently shown, for nanopar- ticles derived from auto-combustion method, that initial particle sizes affect the magnetostrictive properties of cobalt ferrite. 5 Since most ceramics oxides, such as cobalt ferrite are often fabricated via the traditional ceramic processing technique, it is desirable to investigate the extensibility of the importance of initial particle sizes to micron-size powders of- ten obtained from the traditional ceramic method. In this work, the dependence of the magnetostrictive properties of cobalt ferrite on the distribution of the initial powder particle sizes, derived from the traditional ceramic synthesis, is presented.
Wireless sensors continually or intermittently monitor the surrounding environment to gather useful information and transmit that information to a remote base station using radio frequency (RF) transmission for further processing. Because of their small size and wireless communication capability, networks formed by wireless sensor nodes play a significant role in the structural health monitoring of civil infrastructures, aircrafts, process control systems, temperature monitoring in buildings, military surveillance, personal tracking devices, industrial process monitoring, environment and habitat monitoring, healthcare applications, home automation, traffic control, and so on. Such pervasive networks of wireless sensors significantly impact society and create large market opportunities. For these networks to achieve their full potential and autonomy, the source of power supply is an important consideration.
Ferrite temperature sensors for biological applications have been developed, which can monitor human body temperature  and also have biochemical applications [8, 9].
In temperature sensorsbased on the dependence of magnetic properties with temperature, the Curie temperature (T C ) of the ferrite is an important parameter to be established. Ni-Zn ferrimagnetic ferrites have T C ranging from −140 ◦ C to +570 ◦ C approximately , depending on the Ni : Zn proportion. Therefore, additions of Zn and Ni change the Curie temperature in a controllable manner, thus being possible to produce ferritematerial with a fine tuning of the Curie point. Cedillo et al.  have shown that, near T C , the magnetic permeability (µ) of a Ni-Zn ferrite increases reaching a maximum at the Hopkinson peak. The magnetic permeability decreases steeply above the temperature that corresponds to the Hopkinson peak (T H ). In the temperature range where a steep variation rate of µ occurs the ferrites may act as a temperature transducer, such as based on the inductance variation of a circuit’s component. The inductance (L) of a toroidal inductor may be calculated  by (1), where N is the number of coil’s turns; A is the cross-section area of the ferrite core; µ 0 is the magnetic permeability of vacuum; µ r (dimensionless) is the relative magnetic permeability of the core and r is the average radius of the ferrite core.
2. New Cork Materials and Applications
2.1. Cork Based Sandwich and Plywood Materials
Cork based agglomerates are being considered an interesting core material for sandwich components, mainly of lightweight, high-performance and low-maintenance structures with specific properties. Some consider that current core materials have low structural freedom and, in certain cases, high environmental burdens. Therefore, it has been suggested that benefits in performance and economic and environmental aspects could be achieved by hybrid sandwich panels comprising non-traditional materials as cork basedmaterials [4,5]. Cork has properties which allow a better performance regarding damage tolerance due to impact loads . For this, low speed impact tests were performed and residual strength characterization through four-point bending tests. Damage extension quantification was carried out showing evident advantages relatively to other types of core materials.
The main focus of this paper is to highlight some of the key criteria in successful utilization of magnetostrictivematerials within a cantilever based microelectromechanical system (MEMS). The behavior of coated cantilever beams is complex and many authors have offered solutions using analytical techniques. In this study, the FEMLAB finite-element multiphysics package was used to incorporate the full magnetostrictive strain tensor and couple it with partial differential equations from structural mechanics to solve simple cantilever systems. A wide range of geometries and material properties were solved to study the effects on cantilever deflection and the system resonance frequencies. The latter were found by the use of an eigen-frequency solver. The models have been tailored for comparison with other such data within the field and results also go beyond previous work.
Keywords: Fiber Bragg grating; carbon fiber reinforced polymer; strain field monitoring
Monitoring the internal strain state of fiber-reinforced polymer materials has become an important issue since in-service strain monitoring of civil engineering and aeronautic structures can lead to improved safety and better control over costs . Fiber Bragg grating (FBG) basedsensors are excellent candidates for that purpose as they can be embedded in different materials for smart structure applications. These sensors combine many advantages over conventional electrical sensor configurations, such as for example their small size, their immunity to electromagnetic interference, their multiplexing capabilities and self-referencing ability together with an often linear response that is encoded in the change of their reflected resonance wavelength.
(Received November 6, 2003; Accepted January 14, 2004)
Keywords: magnetostriction, high frequency, inductors, permeability, torque sensor
Highly sensitive sensors for strain or stress measurements are of increasing interest for industrial applications in areas like automotive, aerospace, process control, automation and biotechnology. In comparison to classical metallic or piezoresistive strain gauges, magnetostrictive thin ﬁlm sensors show a higher sensitivity, almost no substrate limitations, and allow the fabrication of small sensor elements. Furthermore, the LC circuit sensor design allows wireless operation using either radar reﬂectivity or inductive coupling.
En förlängd hållbarhet hos livsmedel har varit viktig i utvecklingen av nya för- packningsmaterial där ökad import och export har varit bidragande faktorer. Med i utvecklingen av nya barriärmaterial har även förnyelsebara källor och utveckling av material som är komposterbara och biologiskt nedbrytbara varit med. Där är ut- vecklingen av biobaserade material en viktig del. Dock finns det faktorer som för- svårar för utvecklingen av biomaterial, faktorer som höga produktionskostnader och mekaniska- och barriäregenskaper som inte kan konkurrera med konventionella bar- riärmaterial. Eftersom konventionell plast produceras i större utsträckning och har lägre produktionskostnad så är det svårt för bioplasterna att konkurrera med dem på marknaden. För att biobaserade material ska ha en plats på marknaden så skulle de behöva marknadsföras som ett medvetet, och kanske ett lyxigt alternativ till de kon- ventionella alternativen och därmed legitimera de högre kostnaderna.
Provenance: Continues to be critical to record all processing and data sources
Data Transport: Transport data between job components on Grids and Commercial Clouds respecting custom storage patterns like Lustre v HDFS
Program Library: Store Images and other Program material Blob: Basic storage concept similar to Azure Blob or Amazon S3