JPS58209791A - Front sheet for sound absorbing panel, manufacture thereof and acoustic energy attenuator therewith - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound absorption (ξ) channel, an acoustic energy attenuation device using the same, and particularly a noise attenuation device and a sound absorption/ξ channel manufacturing method. In order to reduce i, so-called "linear" acoustic panels have already been proposed (UK patent application no.
st, 16th Rim Specification Co.).

(-) a non-porous backing layer; (b) a sheet with a number of through apertures of predetermined and directed dimensions and spacing, such that the apertures define the aperture area characteristics; (C) a multivesicular layer fixed between the nonporous layer and the open layer;
In this case, all the vesicle bodies/ends are covered by the non-porous layer and closed by the λ-th end of the opposite deposit 11 or the aperture layer, and many openings communicate with each of the vesicles, thereby forming a Helmholtz resonance cavity. , (mountain) On the opposite side of the surface to which the porous layer is adhered: a porous layer that is adhered to the surface of the white layer and constitutes the outer surface of the panel onto which airborne noise is incident, the dimensions of its pores being the size of the aperture. The opening in the layer is substantially smaller.

In such panels, both the honeycomb and porous layers achieve the required wide range noise attenuation, and I, i? = The white layer is a structural member that constitutes a support for the other layers, and by means of this stiffening material the panel is fixed to the cypress structure of the aircraft. The performance of the panel is impaired when the percentage of the surface area of the open layer that is open between the porous layer and the cells of the multivesicular layer changes substantially from a predetermined value.

On the one hand, layer separation of the panel during and before use should occur as little as possible, and on the other hand, it should be avoided that the active area of the aperture layer is lost and the efficiency of sound damping is impaired The layers of such panels may be joined together in such a way that the joining step is accomplished without creating a large number of openings and holes or occlusions such as is not easy. The purpose of the invention is to eliminate these difficulties.

Another purpose is to provide a lighter panel than traditional brakes.

Another object of the present invention is to provide a panel structure and a method for assembling the same, which facilitate the formation of panels with complex shapes.

According to one aspect of the present invention, there is provided a front sheet comprising an open layer and a porous layer, wherein the open layer is made of string and the solid wood is made of a base material. Ru.

According to the present invention, in terms of w2, a synthetic phase of the fiber/resin matrix is formed by forming a plurality of through openings of predetermined and specified dimensions and spacing, and the opening area is determined by such openings. Prepare an aperture 1-, and bond the aperture layer and the porous layer facing each other to form a front sheet. A method for manufacturing a front sheet for an acoustical panel is provided, the method comprising each step.

This use of a synthetic material in place of the conventional material, which is aluminum, provides several advantages.

In kl, the apertures can be formed when the synthetic material matrix is in a partially cured state. This is probably a sufficiently low-friction method to form the same number of apertures in the goblet sheet.

In addition, synthetic material - another resin matrix is 1. It becomes an adhesive medium by itself, which allows the porous layer to adhere to the open layer.

At W3, the fiber fraction of the synthetic material can be arranged in the pattern, for example by means of a ferrule, which itself forms the required number of apertures, thus eliminating the need for a separate aperture formation step at all.

First, the special problems associated with electrolytic corrosion are eliminated.

One conventional panel has an open layer of aluminum and a porous layer of stainless steel woven into a mesh or felt.

If these two layers were to come into electrical contact, electrolytic corrosion could occur in wet conditions. Conventional build-up methods may include extra steps to minimize the risk that portions of the netting or felt in the finishing assembly come into contact with the underlying open layer. The carbon fiber/epoxy resin composite material has essentially the same electrode potential as the upper stainless copper porous layer, so there is no possibility of electrical corrosion and no contact between the porous layer and the open layer. No special steps are required during assembly.

When the resin is not completely cured, one of the adjacent layers is held in contact with the Japanese synthetic material layer, and both layers held in contact are cured and the two layers are fixed together with the resin. It is advantageous to employ as a method of manufacturing the noise attenuating device according to the invention a method characterized by the step of fixing the layer of synthetic material to one of the adjacent layers. Desirable resins are so-called "controlled flow" resins, ie resins of sufficiently high viscosity that they remain jelly-like rather than completely fluid during the early stages of curing. It is preferable to provide a "skin layer" as described below to absorb excess resin.

In previously proposed panels, an aperture layer is used to secure the panel to an adjacent support structure. In one embodiment of the invention, a non-porous backing layer is used for such applications. It has been found that it is desirable for fixing with the aperture layer that the ratio of the open aperture area to the protruding surface area of the aperture layer is about 30 inches.

Such a high A-centage of open surface area and the desire to keep the panel as light as possible makes it unsuitable to use an open layer to attach the panel to a support structure.

Embodiments of the invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, a nonporous metal backing layer 1 of 10ri aluminum alloy is provided, to which a multicellular honeycomb layer 1 is fixed with 1 ml of epoxy resin adhesive. The six cells have at least seven drainage holes it. The other end of the honeycomb is covered with an open layer 13 or epoxy resin I as described in detail below. layer 1
A thin wire mesh made of stainless steel is glued to the outer surface of 3.

The aperture layer 13 and the mesh layer are herein collectively referred to as the front sheet of the panel/θ.

Panel IO forms part of the inward facing surface of the duct in the nose cowl of a turbofan aircraft engine, and the panel is one of several arcuate panels located just upstream of the engine's fan. It is therefore extremely important that the panel does not deteriorate during use, and in particular that there are no parts that become detached from its support structure. This structure has support 7 langes or support stringers, only one of which is shown at 15. The panels are fixed to the stringers by means of joining known to those skilled in the art, but it should be noted that the panel attachment of the stringers is fixed to the flange L, and the backing layer of the R flannel is attached to the panel. It is not the aperture layer 13. The space between the outer surface of the panel lθ and the surrounding sacrificial body may remain open, but may also be sealed or closed, for example using mastic.

Referring to FIG. 2, the single white layer 13 is formed from a woven material of three sets of threads, each of which contains many carbon fibers. Consisting of The three pairs Oe -27t JJ are arranged at 60 degrees to each other, thus forming many hexagonal openings. - As can be seen from the superimposed outline C of one of the honey vacuoles of the multivesicular layer I, there are a large number of openings H for one of the open ends of one vacuole C.

The fine fibers F are surrounded in the threads of the rutting material without blocking the uncured resin Rri openings H. During the production of the A-nel IO, the resin Rri is cured in an autoclave together with the aperture layer /3 which is supported and arranged in the shape required for the finished Sibanel, which may be curved in three dimensions.

Attaching a layer of woven nylon cloth (as a so-called "skin") to each side of the 18-hole layer/3 during the curing stage does not completely eliminate the "flash" of adhesive from within the opening. , a weave pattern is added to the surface of the sheet to which a subsequently applied adhesive adheres. Preferably, however, the pressure is maintained such that during the curing stage the outer layer 1 is in contact with 10 layers/J, so that the resin serves to adhere both layers of the front sheet of the panel 10 to each other.

One particular way of effectively carrying out such a method is described below with reference to FIG.

The forming tool Jθ, herein referred to as the tool, having a forming surface 31 with the shape of a portion of the panel IO, is typically cleaned using methyl ethyl ketone and then
Frf3kOte133 available from oteko nC+
Three coats of a mold release agent, such as 3 coats, are received at time intervals such that air drying can be achieved between coats. The mold release agent is then cured for 30 minutes at 121°C.

720 / which is wide enough to cover the work area of Tool JQ.
/50 stainless steel mesh 33 (The symbol 720//30 indicates the length of the fabric in the warp and top chick yarns, 1 inch, or approximately 5 cm, and the number of wires in each t).

Such rust-free steel nets are manufactured by, for example, [Robus+tak, Ri J, G, Bopp & N2, London, UK].
Co, Ltd. ) is subjected to active vapor degreasing treatment. This is then hung loosely over the tool JO, taking great care to avoid wrinkles, and secured in position by tape (not shown) applied around its circumference. If the tool 30 is curved in three dimensions, the mesh may be torn to cause it to assume the position ii specified in the design and manufacturing specifications. In order to improve the adhesion between the net and the fiber/resin composite material that is subsequently placed on the net, the wraps around the perimeter of the net and the cracks in the net are placed around the area and/or in any suitable manner. It would be desirable to apply a thin film of adhesive, but I don't know.

The openings Ptl between the warp and weft strands of the net 33 constitute the pores of this porous layer.

Next, a sufficiently wide open-weave carbon fiber cloth 3, as shown in FIG. 2, impregnated with a co-curing resin system is carefully placed on the screen 33. This cloth supports a layer 3 of the nine cloth as a "skin layer" on the surface of this carbon fiber cloth 31/L opposite the steel net 33.

Curing of the resin system is accomplished under reduced pressure in an autoclave cob. Depressurization is accomplished by overlaying the tool 30 and layer structure 33.3 with a nitrogen vacuum containment membrane 3S in a manner as illustrated in FIG. 3 and described below.

A band 36 of gas-permeable breathing material approximately 5 centimeters in width is provided around the periphery of the textile fabric.

A thin release film 37 suitable for high temperature use is placed on the exposed surface of the uncured fiber cloth 37, covering the band 36 by about /-/, Scm. Above the release film J6 and the band 36 is placed a breathing sheet 3g of the same material that forms the band 36. The vacuum membrane 35 surrounds the uncured workpiece and the breathing member covered with the resin. A sealing strip 33B of high temperature mastic sealant is provided around the circumference of the membrane 350 where it meets the tool 30.

Next, a test for leakage in the sealed portion of the vacuum membrane 3S and the tool 30 is carried out, during which the pressure inside the bag formed by the membrane is reduced by the vacuum pumper 0 to SOωHg at a gauge Dal. Next, the vacuum line octopus is cocked≠
3 and the pressure increase inside the bag is monitored. If the pressure rise for , S minutes is not more than / , 2 cm Hg, the test is passed.

Autoclave curing is then initiated while the air within the bag is still under vacuum. The atmospheric pressure outside the bag in the autoclave was 3.7±0. , / s bar + o, bq - bar. Is it the pressure inside the bag?1. When raised to q-, the bag is vented to the outside air, after which it is maintained at 0-f-0, 35°, /%-A/ after the residual v curing process.

As for the temperature, this is controlled by a temperature controller which receives temperature data from a thermocut puller S placed near the workpiece. As a result, 177±s
The rate of temperature rise of the object to be treated is increased from 1 to s C/min until the curing temperature C is reached, and this curing temperature is maintained for /20 min. After that, the object to be treated is heated at a rate of 5°C/min.
As a substitute for tearing the autoclave pressure wire J315, which can be cooled to below can be formed by welding the pieces together at their peripheries.

Other methods are also possible. The apertures can also be formed after weaving, but before hardening, by moving the rutting yarn and restraining it in a new position r1t, so that the required aperture is obtained. The porous layer can be attached to the aperture scrap after it has been hardened to the desired shape.

Referring to Figure i/, the unopened (but normally covered) synthetic material for layer/J can be cured to the desired shape;
Only then is the outer layer 13 attached, in which openings can possibly be formed by drilling into layer 13. However, the advantages of this invention may not be obtained by using this method.

The sheet of synthetic material can be perforated while flat, uncured or partially cured, and then brought into contact with the porous layer and cured to the desired shape.

A hardened corner front sheet is then bonded to the seven sides of the multicellular layer L using an epoxy adhesive as shown in FIG. A composite backing layer ll is glued to the other side. Adhesion of the front sheet is aided by the "skin" pattern remaining on the surface of the cured resin.

Nomex available from Multivesicular Layer/Co#-10iba-Geigy (% stated).

Wooden nylon paper material may be used. The cells are each sized to have the diameter of the largest circle inscribed in it.

The epoxy adhesive is 01ba-Ge from Cambridge, UK.
igy Plastlcs and Additive
The triaxially woven carbon fiber material is available from Ear Co., Ltd., Rockford, Illinois, USA.
ber-Colman Co. British Slurry Sciituota II! excel (U,
L) Lim1te4ri7ys93 "control section" Impregnate a cloth with resin, and make the impregnated cloth polythene (Po1
Serve between sheets of ythene).

As mentioned above, the porous weave layer was manufactured by British company G, Bopp.
Available from. As a substitute for Bo pp materials, Brunswick Corpo, DeHand, Florida, USA
A sintered stainless steel fiber product sold as Brunsmet J can be used. New woven carbon fiber mesh products are available from Brochiθr Industries, Villepin, France.

When a polyester rutted mesh is used as the non-metallic porous layer, it has the advantage that it is lighter than the equivalent gold-plated mesh. Adhesives and resins need not be epoxies, such as phenolic resins or polyimides.
de) Resin may be used. As an alternative to carbon fibers, other fibers can also be used if they have good mechanical properties: glass fibers and Kevlar.
is believed to produce inferior results to carbon fiber for this application.

[Brief explanation of the drawing]

1st IJ is a cross-sectional view transverse to the plane of the panel showing the edge area of the noise-damping sound-absorbing nonel; 1st IJ is one of the hexagonal cells of the lower multivesicular layer, with porous coral removed for clarity; Fig. 3 is an enlarged plan view of a part of the opening scrap of the panel shown in Fig. 1 showing its outline, and Fig. 3 shows the tool used to form the front sheet when manufacturing the front sheet of the sound-absorbing panel shown in Fig. 1 and Kiko. and a sectional view together with a vacuum bag. In the drawing, 10F'i sound absorption, J channel, 20. Ko/. Ko2ij 3 sets of threads, 13 and 3hiro are opening islands, 14L and j
Jri porous layer, Fri [fibers, HV'i openings, and Pt-j pores are shown.

Claims (1)

[Claims] l An aperture layer having a number of through apertures having predetermined and directed dimensions and spacing, such apertures defining the characteristics of the mortuary area, and an aperture in the aperture layer. In the sound-absorbing nonel front sheet, which comprises a porous layer having substantially small-sized pores and bonded to the surface of the aperture layer, the white layer is formed from a synthetic material of fiber/resin matrix. The front seat is characterized by: The front sheet according to claim 1, wherein the synthetic material is an open weave material, in which the openings are formed by holes between the rutted threads. , 3. A front sheet according to claim 1, wherein the hexagonal openings are provided by the weaving material being made of three sets of threads arranged at 60 degrees to each other. Hiroshi The front sheet according to any one of claims 1, 2, and 3, wherein the porous layer and the open layer have substantially the same electrode potential. Left: A front sheet according to claim 1, wherein the fibers of the synthetic material are made of a porous layer of carbon or stainless steel. Melon An aperture layer of a fiber-resin matrix composite material is provided with a number of through apertures of predetermined and directed dimensions and spacing such that the aperture area characteristics are defined by such apertures, and the apertures of the aperture layer are also controlled. A front sheet for sound absorption/channels, comprising the steps of preparing a porous layer having pores of substantially small size, and bonding the aperture layer and the porous layer facing each other to form the front sheet. Manufacturing method. 2. Claims in which the steps of adhering the aperture layer and the porous layer to each other and the step of curing the resin of the synthetic material are carried out simultaneously by using the resin to also act as an adhesive between the aperture layer and the porous layer. The method described in Section 6. The steps of adhering the KIA oral layer white layer to each other (recited in claim 6, in which the L-white layer is shaped on the tool and this layer is ossified into the desired shape on the tool) The method according to claim 6 or g, tL, in which the cut open area is determined before the curing of the resin of the synthetic material is completed. 10 The step of determining the open area is m multi-stage. Claim 7 or the method according to claim 7, wherein at least one surface of the open layer is brought into contact with the skin during the step of curing the resin of the synthetic material. 7
9. The method according to any one of the following items. /, 2. The method according to claim 1, wherein said at least one surface is the surface of the aperture layer of the cured face sheet that does not face the porous layer. /3. an aperture layer with a number of trace apertures having predetermined dimensions and spacings such that such apertures define the aperture area characteristics, and an aperture substantially smaller than the apertures in the aperture layer; A front sheet for a sound absorbing panel is provided, comprising a porous layer having holes of the same size and bonded to the surface of the aperture layer, and the front sheet is characterized in that the aperture layer is formed from a composite material of fiber/resin matrix. Acoustic energy attenuation device equipped with a front sheet for sound absorbing channels. 73. The acoustic energy attenuation device of claim 73, constructed as an edge-shaped sound-absorbing lξ channel with a backing layer for fixing to an adjacent support ladder.