Patent Application
20190031292
This invention generally relates to the field of ship construction. It relates more particularly to a method for manufacturing plates reinforced/stiffened by stiffening elements comprising laminated composite materials as well as the plate obtained by the method. The reinforced plates are intended for the creation of ship walls. More specifically, the invention relates to a method for stiffening plates intended for the creation of ship walls and comprising laminated composite materials.
In ships, flat regions must be reinforced or rigidified/stiffened, with these terms considered to be equivalents in the context of the invention, in order to resist the stresses that the ship is subjected to. This also relates to inside partitions which are more preferably manufactured with relatively light materials, in particular composite materials, in order to reduce the weight of the ship. Among the latter, the inside separating partitions, in particular those comprised of separating plates between two levels of the ship (typically the floors and decks), must more particularly be reinforced due to the fact that they are substantially horizontal and the loads and stresses that they are subjected to and which are primarily applied according to a perpendicular to the surface of the panel forming the plate.
As such, in the case of reinforcing floors and decks of ships, one is led to create stiffening elements on the lower surface of the panel of the plate. Conventionally, for this, manufacturing is carried out on-site, directly on the panel itself, of a network of stiffeners comprising forms in foam or wood that are covered with one or several layers of composite fibre/resin. These layers create an over-thickness on the panel to be stiffened, on either side of the base of the form made of foam or wood. This “over-measure” method is relatively long and tedious since it requires beforehand installing forms on the panel then, afterwards, covering them with composite. Furthermore, this method leads to leaving in the plate foreign material in terms of the composite comprised of layers of fibres and of resin.
In the field of aviation, means are known for reinforcing partitions in documents U.S. Pat. No. 4,786,343, US-2012/282441 and US-2007/277470.
In order to overcome the aforementioned disadvantage of prior art, this invention proposes to use as stiffening elements pre-manufactured profile members and separately from the panel to be reinforced, profile members which are made from a laminated composite material and which are then added and fastened onto the panel itself, with the panel being made from a laminated composite material or containing it on the surface. These pre-manufactured profile members are rigid when they are assembled to the panel. Thanks to this method, one is no longer constrained to use composite in the conventional “wet” manner in order to create the reinforced plate comprised of the panel and of its stiffening element or elements. Furthermore, the creation of the reinforced plate is greatly accelerated. The same applies for manufacturing beforehand (=pre-manufacturing) profile members that can be standardized given in that in most cases, the panels are flat and the arrangement of the stiffening elements is predictable and regular. Finally, the reinforced plate created no longer includes the “foreign” materials that were used in the conventional method described hereinabove and which do not participate in the mechanical resistance of the whole. It is therefore possible to create reinforced plates made of composite material exclusively comprised of stacks of layers of fibres impregnated with resin and therefore without any “foreign” material which would be there only for giving a shape to the stiffener.
As such, the invention relates to a method for stiffening plates intended for the creation of ship walls and comprising laminated composite materials, the laminated composite materials being constituted of stacks of layers of fibres impregnated with resin.
According to said method:
on the one hand, at least one elongate profile member made from laminated composite material is pre-manufactured having a transverse cross-section of a predetermined shape over the length thereof, the pre-manufactured profile member and obtained being rigid due to the polymerization/solidification of the resin that has impregnated the layers of fibres that the profile member comprises, and,
on the other hand, a panel is used having two main surfaces and comprising at least on the surface of at least one of its two main surfaces a laminated composite material, with the resin that has impregnated the layers of fibres that the panel contains being polymerized/solidified, and
said at least one pre-manufactured profile member is assembled and fixed together on one of the main surfaces of said panel, with the main surface of the panel receiving the profile member comprising laminated composite material, and the pre-manufactured profile member has a transverse cross-section of a determined shape that comprises three continuous portions: two flanges and a web, with the two flanges and the web being substantially straight in the transverse cross-section of the profile member, the web connecting to the flanges along its two opposite lateral edges, and the two flanges and the web are longitudinally extended over three separate planes, with the plane over which extends the web crossing the two separate planes over which extend the flanges, with the two planes over which extend the two flanges being parallel to each other and crossing the plane over which the web extends with an angle of about 90°, each flange having two main surfaces, a main inner surface on the side of the web and a main outer free surface opposite the preceding one, one of the two flanges of the pre-manufactured profile member being applied by its main outer free surface on the panel.
Other non-limiting and advantageous characteristics of the method in accordance with the invention, taken individually or according to any technically permissible combinations, are as follows:
The invention also proposes a reinforced plate for a ship wall comprising laminated composite materials and specifically obtained by the method described. The reinforced plate therefore results from the method of stiffening plates and it is comprised of at least one pre-manufactured profile member fixed on a panel.
The invention also proposes a ship comprising at least one reinforced plate according to the invention, said ship being a surface craft or a semi-submersible or submersible craft.
Among the advantages of the invention, it makes it possible to respond to the specificities of this type of vehicle/ship: high resistance to fatigue and to cyclical stresses, as well as to corrosion in wet environments, and a low radar echo. This type of structure does not require any specific maintenance, contrary to the structures used in aeronautics, primarily comprised of carbon epoxy composite.
Other non-limiting and advantageous characteristics of the reinforced plate, can be taken individually or according to all technically permissible combinations using the means described in this application.
The following description with respect to the accompanying drawings, given as non-limiting examples, will indeed facilitate the understanding of what the inventions consists of and how it can be carried out.
In the accompany drawings:
In relation with
The stiffening elements which are, in the scope of the invention, pre-manufactured profile members made of composite material, are arranged for example in strips or alignments that are parallel or not on the panel and according to a periodicity that depends on the desired resistance for the plate. These strips or alignments that are periodic or not can also be crossed between them.
Generally, the profile members are elongate elements that have a transverse cross-section of a determined shape comprising three continuous portions: two flat flanges in a straight profile member, straight if the section of the profile member is considered, and connected together by a flat web in a straight profile member, straight if the section of the profile member is considered. The flanges and the web when they are viewed as a transverse cross-section of the profile member are carried by separate axes, with the axis carrying the web crossing the two axes carrying the flanges typically at 90° and the two axes carrying the flanges are parallel to one another.
In
The flange 7, on the panel side 2, is fastened to the latter via structural gluing 4. As an alternative or a complement, a fastening via over-laminating and therefore with the adding of layers of fibres and resin, is possible. The gluing and/or the bonding with resin of the pre-manufactured profile members on the plate can use all the known techniques, in particular with regards to the adding of resin and/or of adhesive, with these elements being identical or not: the gluing of the pre-manufactured profile member that can be done with a compound corresponding to the resin used for creating the composite or another specific compound for gluing. For the taking of the resin and of the glue the same technique (for example heating, radiation, hardener/catalyst) can be used or a different technique. The profile members can, for example, be created via infusion, contact, “pre-preg” where the layers of fibres used are pre-impregnated with resin or, “pultrusion” of extrusion-drawing of the layers of fibres.
In
As an alternative embodiment, on the plate 1 of
In
Finally, in certain embodiments, through-openings can be pre-manufactured in the web in order to allow for the passage of ducts or cables through the web of the profile member.
A preferred embodiment of the pre-manufacturing of profile members of the invention shall now be described.
The base shape for the manufacturing of profile members is the U-shaped traverse cross-section, with the two flanges of the same lateral side of the web, with these three portions being substantially perpendicular between them. This U-shaped profile member is created via stacking of layers of fibres, more preferably of orientations crossed between them for the oriented layers. The layers are also continuous from one flange to the other for most of the layers or, better, all the layers. Once the resin soaking the fibres of the layers is polymerized/solidified, the pre-manufactured U-shaped profile member and which is rigid is obtained.
Preferably, the H-shaped pre-manufactured profile member with two flanges is obtained from the preceding U-shape form by joining/fastening web-against-web of two U-shaped profile members. For this it is possible, either to use two pre-manufactured U-shaped profile members and therefore rigid and joining and fastening together which makes it possible to obtain the H-shaped profile in two steps, or creation via stacking of layers of fibres with two U-shaped forms joined web-against-web and of which the resin is then polymerized, which makes it possible to directly obtain the rigid H-shaped profile member, in a single step. Given this embodiment wherein the layers of fibres are wholly separated into two sets belonging to the two lateral portions (each one as a U) of the H-shaped profile member, complementary extended layers of fibres are added between these two lateral portions and therefore extended at least on the main free outer surface of the flange. These complementary layers being of course also taken in the resin in order to form the pre-manufactured H-shaped profile member.
Alternatively, two U-shaped pre-manufactured profile members, instead of being joined web-against-web in order to form an H-shaped profile member, can be joined by the lateral ends of their respective flanges in order to form a tubular profile member with a substantially square or rectangular section according to the initial shapes of the U-shaped profile member, with complementary layers of layers of fibres being preferably created on these joined flanges in order to reinforce the fastening of the two U-shaped profile members.
Equivalently, a T-shaped or Z-shaped profile member can be manufactured from two joined L-shaped profile members and an H-shaped profile member can be manufactured from four joined L-shaped profile members. Other combinations are possible, for example to manufacture an H-shaped profile member it is possible to take a Z-shaped profile member and two L-shaped profile members. However, it is preferably chosen the embodiment that makes it possible to obtain the pre-manufactured profile member which is the more resistant in the application under consideration and this is in particular the case with H-shaped profile members obtained from two U-shaped profile members and with complementary layers of fibres on the flanges.
It is understood that the invention can be broken down in many other ways in the framework of the claims of this application. It is possible for example to create pre-manufactured T-shaped or L-shaped profile members with a single flange and it is fixed to the panel via this flange. Likewise, certain configurations of profile members, in particular U or L-shaped, allow for a fastening of the pre-manufactured profile member via application of the web on the panel instead of using the flange. For example, it is possible to pre-manufacture connecting profile members with an X or T or V shape as seen from above or from below or according to other shapes that correspond to a crossing or a connection between stiffening elements arranged according to longitudinal orientations that lead them to cross each other. As such, at the foreseen location of the crossing the pre-manufactured connection in the shape of an X will be arranged and its arms/branches will be extended by the pre-manufactured linear profile members described. Preferably, the transverse cross-sections of the arms of the pre-manufactured connection and of the pre-manufactured profile members that pursue them will be identical, for example all in H.
Moreover, particular shapes of the longitudinal ends of the profile members and/or connections can be provided, these forms being complementary between two ends of two profile members placed end-to-end, for example via partial overlapping or nest of ends. These shapes can, in particular, make it possible to provide a certain maintaining between the two profile members. Alternatively, or as a complement, pre-manufactured composite splice bar connectors can be fastened to the two longitudinal ends placed end-to-end of two profile members. Alternatively, pre-manufactured splice bars of a suitable shape, in particular an L, can be created for the perpendicular fastening between a longitudinal end of a first profile member and a full field, laterally, of a second profile member. In certain alternatives, one or several splice bars can be fastened or created at the origin on the pre-manufactured profile member.
By way of example of a pre-manufactured combination of connection or crossing and of complementary longitudinal ends, a crossing or a connection is created of which the longitudinal ends of arms are hollow and wherein the longitudinal ends of the profile members are nested are inserted.
Finally, although examples of applications with flat panels have been given, the invention can perfectly be applied to panels with a curved shape, the pre-manufactured profile members then being created curved with a shape complementary to that of the panel.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1650144 | Jan 2016 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2017/050029 | 1/5/2017 | WO | 00 |
