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Wood-Filled Feedstocks
Published in Antonio Paesano, Handbook of Sustainable Polymers for Additive Manufacturing, 2022
Since China is one of the leading countries in forested area (2 million sq. km), it is not surprising that Chinese researchers (Xu et al. 2016) developed a brass nozzle featuring a variable diameter of 2−5 mm, and mounted on a printer built to process wood powder and adhesive (volume ratio 2:1, respectively), mixed together by the rotating blades of the mixer included in the printer. The diameter was controlled by a magnetostrictive material called Terfenol-D made of TbxDy1Fe2 (x≈0.3) that is capable to reach a strain of 0.002 m/m in response to a magnetic field. Terfenol-D outperforms other piezoelectric ceramics: it is more deformable, it withstands greater stress values, and it has a shorter response time to changes in the magnetic field. Other printer’s key components are the system to convey the mix of powder and adhesive to the nozzle (consisting in pump, suction pipe, plunger, and pipe valve), and extrusion screw.
Glass
Published in Arthur Lyons, Materials for Architects and Builders, 2019
Terfenol-D is a magnetostrictive material that, when stimulated by a magnetic field, expands and contracts rapidly, producing a large physical force. If a device containing Terfenol-D is attached to the smooth surface of glass and an audio input is fed into the system, then the whole sheet of glass will vibrate, acting as a loudspeaker. Thus, shop windows can be turned into loudspeakers, producing across their surface a uniform sound that can be automatically controlled to just greater than the monitored street noise level, thus avoiding sound pollution. Two devices, appropriately positioned, will generate stereo sound. Magnetostrictive devices will operate similarly on any flat rigid surfaces such as tabletops, work surfaces and rigid partitions. Terfenol-D is named from the metallic elements iron, terbium and dysprosium from which it is manufactured.
Current Trends for Actuators and Micromechatronics
Published in Kenji Uchino, Micro Mechatronics, 2019
The displacement of an actuator element must be controllable by changes in an external parameter such as heat, magnetic field, electric field, or light irradiation. Actuators activated by changes in temperature generally operate through the thermal expansion or dilatation associated with a phase transition, such as ferroelectric and martensitic transformations. Shape memory alloys, such as Nitinol, are of this type. Magnetostrictive materials, such as Terfenol-D, respond to changes in an applied magnetic field. Piezoelectric and electrostrictive materials are typically used in electric field-controlled actuators. In addition to these, we will consider light-activated actuators (for which the displacements occur through the photostrictive effect or a photo-induced phase transformation) and electro/magnetorheological fluids.
Nonlinear vibration suppression of S-S and C-C laminated composite cylindrical shells with magnetostrictive strips
Published in Mechanics Based Design of Structures and Machines, 2023
Shahin Mohammadrezazadeh, Ali Asghar Jafari
Vibration phenomenon is generally undesirable and can cause resonance and fatigue in mechanical structures (Rao 2011). When large amplitude vibration takes place, the possibility of vibration damage increases; therefore, finding a way for its damping seems to be attractive. Smart materials can be used in order to suppress the vibration in mechanical structures. Magnetostrictive materials are from smart materials which can be used for active vibration control. Terfenol-D, which is one of the magnetostrictive materials, has wide bandwidth, high density of energy as well as relatively high displacement (Goodfriend and Shoop 1992).
Nonlocal and magneto effects on dispersion characteristics of Love-type waves in piezomagnetic media
Published in Waves in Random and Complex Media, 2022
Cobalt Ferrite is a well-known hard magnetic material with high coercivity, high electromagnetic performance, excellent chemical stability, mechanical hardness, and moderate saturation magnetization. These properties make nanoparticles suitable for the electronic components used in computers, magnetic cards and recording devices such as audio and videotape, high-density digital recording disks, etc.The vast application of nano ferrites in permanent magnets, ferrofluids, storage devices, targeted drug delivery and other uses, has attracted much attention in their way of synthesizing these nano materials.Terfenol-D is an alloy and is a magnetostrictive material. It has the highest magnetostriction of any alloy and it expands and contracts in a magnetic field. It bears a large magnetostriction force, high energy density, low sound velocity, and a low Young's modulus. In its most pure form, it also has low ductility and a low fracture resistance. It has wide application in magnetomechanical sensors, actuators, and acoustic and ultrasonic transducers, due to its high energy density and large bandwidth capabilities, e.g. in the SoundBug device.Compared with piezoelectric sensors, the piezomagnetic sensor has simple structure, large output power, convenient manufacture, low cost, strong signal and good anti-interference performance. In piezomagnetic sensor signal amplifier circuit is simple without charge amplifier, and is suitable for static and dynamic force measurement. Experimental data is stable and can be directly measured with general wire.The force-sensitive film is the most stable and sensitive one among the current piezomagnetic force-sensitive films. To achieve high performance and sensitivity in sensors, a thin film of piezomagnetic material embedded on a substrate is adopted.