Abstract:
An acoustic structure that includes a septum having an acoustic opening which defines an open area that varies in response to changes in the velocity of noise-containing media passing through the acoustic opening. The septum includes a fixed portion and one or more movable flapper portions wherein the fixed portion and or the flapper portion(s) include surfaces that define an acoustic opening through the septum. The acoustic opening has an open area which varies due to movement of the movable flapper(s) in response to changes in velocity of the noise-containing media that passes through the acoustic opening. The resulting septum has a relatively low non-linearity factor (NLF).
Abstract:
A load-bearing composite structure for connection to a support body or structure. The load-bearing structure includes a load-bearing element that is made up of continuous reinforcing fibers and a resin matrix. The load-bearing element has an attachment portion for connection to the support body. The load-bearing composite structure further includes a connection element that is formed using a molding material which is composed of discontinuous fibers and a resin matrix. The molding material is molded over the surface of the attachment portion of the load- bearing element.
Abstract:
Honeycomb sections are bonded together with seams made up of an adhesive that is carried by a honeycomb seam support or a linked-segment seam support. The seams are particularly useful for splicing together curved honeycomb sections that contain acoustic septum. The curved acoustic honeycomb sections are spliced or seamed together to form engine nacelles and other acoustic dampening structures.
Abstract:
The solvent resistance of epo.xy resins toughened with polyethersulfone is improved by using low molecular weight polyethersulfone. The resulting thermoplastic toughened epoxy resins are useful for making prepreg for aerospace applications.
Abstract:
Composite materials that contain thermoplastic - toughened cyanate ester resins as the resin matrix. The composite materials exhibit low levels of heat release when burned. The matrix resins are composed of from 50 to 80 weight percent of a cyanate ester resin component. The matrix resin composition also includes from 10 to 40 weight percent of a thermoplastic blend that is composed of polyetherimide and polyamideimide. The cyanate ester resin composition may further include from 1 to 10 weight percent of a curative agent. The composite materials may be used for primary structures in aircraft and other load-bearing structures.
Abstract:
Epoxy resin compositions that include an epoxy resin component and a curative powder comprising particles of 4,4'-diaminobenzanilide (DABA) wherein the size of the DABA particles is less than 100 microns and wherein the median particle size is below 20 microns.
Abstract:
Methods and apparatus are provided for making a rotor blade spar from composite material wherein a multi-component mandrel is used to form the composite spar. The mandrel (10) is made using a number of components (38, 44, 50, 56, 62, 64), which are assembled to provide a structure that is sufficiently strong to maintain the spar shape during pre-cure lay up, compaction and curing of the composite material. The multiple components used to form the mandrel can be separated from each other and easily removed from the spar either before or after curing of the composite material. The mandrel components can then be re-assembled and re-used to form additional composite spars.
Abstract:
An acoustic structure that includes a honeycomb having cells in which septum caps are located. The septum caps are formed from sheets of acoustic material and include a resonator portion and a flange portion. An adhesive flow barrier is arranged along the outer edge of the resonator portion of the septum caps. The flange portion has an anchoring surface that provides frictional engagement of the septum caps to the honeycomb cells when the caps are inserted into the honeycomb during fabrication of the acoustic structure. An adhesive is applied to the anchoring surface of the septum caps after the caps have been inserted into the honeycomb cells to provide a permanent bond.
Abstract:
Reinforced concrete columns wherein the exterior surface of the concrete column is wrapped with a composite reinforcement layer. The composite reinforcement layer includes at least one fabric layer which is located within a resin matrix. The fabric layer has first and second parallel selvedges which extend around the circumferential outer surface of the column in a direction substantially perpendicular to the column axis. Specific weave patterns are disclosed. The composite reinforcement layer provides a quick, simple and effective means for increasing the resistance of concrete columns to failure during the application of asymmetric loads.