摘要:
Methods are provided for mechanically chopping nanotubes and other nanoscale fibrous materials. The method includes forming a macroscale article which include the nanoscale fibers, and then mechanically cutting the macroscale article into a finely divided form. In one embodiment, these steps are repeated. The nanoscale fibers may be carbon nanotubes, which optionally are aligned in the macroscale article. The macroscale article may be in the form of or include one or more buckypapers. In one embodiment, the macroscale article further includes a solid matrix material in which the nanoscale fibers are contained or dispersed. The forming step can include making a suspension of nanoscale fibers dispersed in a liquid medium and then solidifying the liquid medium to form the macroscale article. After the mechanical cutting step, the medium can be dissolved or melted to enable separation of the chopped nanoscale fibers from the medium.
摘要:
Passive solid-state magnetic sensors comprise a magnetostrictive material in contact with a piezoelectric material. The magnetostrictive material strains under the influence of an external magnetic field and imparts stress to the piezoelectric material to produce a detectable voltage signal indicative of the external field. Sensors have applications in rotor speed detection, electrical current measurements, magnetic imaging, magnetic field detection, read heads, and MRAM, for example.
摘要:
A system for in-situ and on-line monitoring of a preform layup process for liquid composite molding allows for gathering of permeability measurements of a fabric preform for use in a liquid composite molding process after situation of the preform within the mold wherein the molding process is to occur. The system uses a plurality of pressure sensors located within one of the mold sections of the liquid composite molding process mold. The sensors take pressure measurements which are processed to obtain a permeability profile of the preform. From such data, any local permeability variations that are caused from defects in the preform, deformation of the preform, or from mold misfit can be noted and acted upon before resin flow. The system is relatively simple to use and is easy to implement.
摘要:
Passive solid-state magnetic sensors are based on the combination of magnetorestrictive materials and piezoelectric materials. Sensors have applications in motor speed detection, magnetic field detection, read heads, and MRAM, for example.
摘要:
An apparatus for use in the production of fiber reinforced polymer composite structures includes a mold having a mold surface and a fiber construction on the mold surface including at least one layer of resin absorbing fibrous lay up material. A stiffener on the fiber construction is constructed of a resin absorbing material. A flexible, resin impervious vacuum bag lays over the mold surface and is marginally sealed to the mold surface to define an enclosure for the fiber construction and stiffener. The vacuum bag has a resin inlet to permit introduction of a resin into the enclosure. A vacuum is drawn upon the enclosure to draw the vacuum bag against the fiber construction and stiffener. The stiffener spaces the vacuum bag from the fiber construction when the vacuum bag is drawn against the fiber construction and stiffener to facilitate the distribution of resin uniformly throughout the fiber construction. The stiffener is integrated with the fiber construction upon curing of the resin.