WO2019108127A1

WO2019108127A1 - Method of manufacturing a composite sandwich structure

Info

Publication number: WO2019108127A1
Application number: PCT/SG2017/050586
Authority: WO
Inventors: Guo Ying ZHENG
Original assignee: ST Engineering Aerospace Ltd.
Priority date: 2017-11-29
Filing date: 2017-11-29
Publication date: 2019-06-06

Abstract

A method of manufacturing a composite sandwich structure. The method may include individually providing a plurality of planar materials to form a stack. The plurality of planar materials may be free from physical interconnection from each other, and at least one of the plurality of planar materials may include one or more substantially continuous fiber layer as a constituent material of a plurality of constituent materials of the composite sandwich structure. The method may further include simultaneously applying heat and compression to the stack between a male mold and a female mold to form the composite sandwich structure.

Description

METHOD OF MANUFACTURING A COMPOSITE SANDWICH

STRUCTURE

Technical Field

[0001] Embodiments generally relate to a method of manufacturing a composite sandwich structure. In particular, a method of manufacturing a thermoplastic composite sandwich structure.

Background

[0002] Thermoplastic composites are gaining popularity for used in various applications because of its unique properties such as recyclability, ease of repair, etc.. However, adoption of its application is hindered by the hefty upfront investment required for implementation. For example, thermoplastic composites generally require heating during the process of consolidation before curing. Further, thermoplastic composites sandwich structure manufacturing, typically, also requires multiple forming steps to prepare, pre-form, pre-process, pre-profile, pre-treat or pre impregnate the raw materials before using said prepared, pre-formed, pre-processed, pre-profiled, pre-treated, or pre-impregnate materials in the final consolidation process. Thus, thermoplastic composites sandwich structure manufacturing would usually involve significant upfront investment for the process, tooling and fabrication systems. Such investment is generally only justifiable when production volume reaches a certain scale. Thus, such investment definitely does not make economical sense at the beginning of a new product manufacturing cycle.

[0003] As an example, EP 2607075 Al discloses a method of manufacturing a sandwich laminate comprising a sandwich core material and an upper laminate part and a lower laminate part, wherein the upper laminate part and the lower laminate part comprise a thermoplastic matrix material and heating elements. However, before the process of molding to form the sandwich, each of the upper laminate and the lower laminate has to be prepared or preformed into a mat wherein the electrically conductive fibers are located substantially in the inner part of the thermoplastic matrix material. Otherwise, the electrically conductive fibers would have to be manually placed fiber by fiber into a granulated or powdered matrix material such that the fibers are fully encompassed by the thermoplastic material. Preparing or pre-forming of the mat would require additional steps of pre-processing which would mean substantial upfront investment. On the other hand, manually placing fiber by fiber would be time-consuming and inefficient, as well as induces variations

[0004] As another example, EP2527139 Bl discloses a method of producing a sandwich structure wherein prepreg component is first obtained by impregnating matrix resin into continuous reinforcing fibers. Afterwhich, a lamination step of disposing thermally adhesive substrate on both surfaces of the core component and disposing each prepreg component onto the thermally adhesive substrate to form a laminate. Lastly, the laminate is disposed into a mold for molding. The steps of preparing prepreg component and the lamination step of preparing a laminate for molding are additional pre-processing steps which would again incur upfront investment. Furthermore, prepreg components are typically stiff and poor in drape- ability. Thus, the resultant sandwich structure is typically only in the form of flat panel structures.

[0005] As a further example, US2010/0215887 Al, discloses a method of forming molded thermoplastic-resin composite material wherein a multilayer thermoplastic- resin-reinforced sheet material is first produced by joining reinforcing-fiber sheet material to thermoplastic-resin sheet material such that the reinforcing-fiber sheet material and the thermoplastic-resin sheet material are integrated in a manner that they do not come apart. For example, the reinforcing-fiber sheet material and the thermoplastic -resin sheet material are integrated by bonding, or applying adhesive, or stitching. Subsequently, the multilayer thermoplastic-resin-reinforced sheet material is then molded. Pre-forming of the multilayer thermoplastic-resin-reinforced sheet material would require additional steps of pre-processing which would mean substantial upfront investment.

Summary

[0006] According to various embodiments, there is provided a method of manufacturing a composite sandwich structure. The method may include individually providing a plurality of planar materials to form a stack. The plurality of planar materials may be free from physical interconnection from each other, and at least one of the plurality of planar materials may include one or more substantially continuous fiber layer as a constituent material of a plurality of constituent materials of the composite sandwich structure. The method may further include simultaneously applying heat and compression to the stack between a male mold and a female mold to form the composite sandwich structure.

Brief description of the drawings

[0007] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments are described with reference to the following drawings, in which:

FIG. 1 shows a schematic diagram of a method of manufacturing a composite sandwich structure according to various embodiments;

FIG. 2 shows a photograph of an actual example of a stack of a plurality of planar materials;

FIG. 3A shows a schematic diagram of a composite sandwich structure manufactured by the method according to the various embodiments;

FIG. 3B shows a photograph of an actual composite sandwich structure of FIG. 3 A manufactured by the method according to the various embodiments;

FIG. 4 shows a schematic diagram of a stack of a plurality of planar materials according to various embodiments;

FIG. 5 shows a schematic diagram of a method of manufacturing a composite sandwich structure according to various embodiments.

Detailed description

[0008] Embodiments described below in context of the apparatus are analogously valid for the respective methods, and vice versa. Furthermore, it will be understood that the embodiments described below may be combined, for example, a part of one embodiment may be combined with a part of another embodiment.

[0009] It should be understood that the terms “on”, “over”, “top”, “bottom”, “down”,“side”,“back”,“left”,“right”,“front”,“lateral”,“side”,“up”,“down” etc., when used in the following description are used for convenience and to aid understanding of relative positions or directions, and not intended to limit the orientation of any device, or structure or any part of any device or structure. In addition, the singular terms“a”,“an”, and“the” include plural references unless context clearly indicates otherwise. Similarly, the word“or” is intended to include “and” unless the context clearly indicates otherwise.

[00010] Various embodiments of a method of manufacturing a composite sandwich structure have been provided to address at least some of the issues identified earlier.

[00011] Various embodiments have provided a general formation process of thermoplastic composite sandwich, which may consolidate a stack-up material into an end-product, e.g. a thermoplastic composite sandwich structure, in one step, using a close mold that may include a female mold and a male mold. The molding system may be equipped with a heating system to achieve the desired thermal cycle during the consolidation or molding process for forming the thermoplastic composite sandwich structure. Pressure may also be applied during the consolidation or molding process. Various embodiments have also provided a method that may be able to achieve high quality thermoplastic composite sandwich panel which may be of any shape and which may include sheets or layers or skins sandwiching a core layer. Rather than using prepared, pre-formed, pre-processed, pre-profiled, pre-treated, or pre-impregnated materials for the purpose of consolidation, e.g. reinforced sheet material whereby resins have been impregnated into fibers, the sheets or the layers or the skins according to various embodiments may include independent thermoplastic resin films/sheets and fiber films/sheets, wherein each film/sheet consists essentially of either resins or fibers, and wherein the thermoplastic resin films/sheets and fiber films/sheets, and core layers may be individually and separately provided for direct usage or application. According to various embodiments, the thermoplastic resin films/sheets and fiber films/sheets individually provided to form the stack-up material may be free of physical interconnections from each other. By having separate thermoplastic matrix (either film or sheet) and fiber (either film or sheet), one may have the freedom to choose a desired fiber such as type of the fiber material, pattern of the wave, fiber orientation, and/or core layers etc., and select a desired resin such as composition of the resin, resin film thickness, resin film texture and resin film surface condition in accordance to the end product requirements, so as to produce high quality end-product (or composite sandwich structure) with the desired performance requirements. Using individually provided thermoplastic resin films/sheets and fiber films/sheets, which are free of being prepared, pre-formed, pre-processed, pre profiled, pre-treated, or pre-impregnated, may also enhance the drape-ability of the material during the consolidation or molding process for better quality end-product. The independency of the thermoplastic resin films/sheets selection may also allow flexibility in the material combinations, resin infusion configuration and consolidation/molding cycle configuration. This may be especially beneficial during the composite sandwich structure development stage.

[00012] Various embodiments seek to achieve a one-step consolidation or molding process of thermoplastic composite sandwich structure or panel which may be formed with different contour and curvature three-dimensionally, and which may have random or varied or non-uniform thickness across the sandwich structure or panel. According to various embodiments, the random or the varied or the non-uniform thickness may be within a pre-determined range.

[00013] According to various embodiments, the one-step consolidation or molding process without using pre-profiled, pre-processed, prepared, pre-formed, pre-treated, pre-impregnated layers, or sheets, or films, or skins may minimize investment and simplify setup for low volume production, may enhance the flexibility for optimising the process and increase manufacturing efficiency and make the low volume production/prototype affordable, and may reduce lead time of development cycles.

[00014] According to various embodiments, the flexibility of resin film section may provide opportunity for better integration of different core in the same part, such as foam, honeycomb cores.

[00015] According to various embodiments, the thermoplastic components may allow easy recycling and may have potential for easy repair without degrading adjustment existing materials.

[00016] According to various embodiments, consolidation or molding using a two- pieces close mold with pressure and heat control may allow flexibility to make panels with varied thickness and contour in any directions, may allow good quality surface finish through the same consolidation or molding process, may enable local core stack up with different core such as different thickness and different material, and may enable local fibre cloth reinforcement. [00017] According to various embodiments, the tailorable thermoplastic film may enable flexibility to select different materials for different layers, both thermoplastic sheet/film and fiber sheet/film, to achieve desired bonding and finishing.

[00018] To form a composite sandwich structure with varying thickness and contour, the method according to various embodiments may not require pre-forming, preparing, pre-processing, pre-profiling the individual layer, or sheet, or film, or skin to the shape, before consolidating or molding them together. In the method according to various embodiments, because individual layer, or sheet, or film, or skin may not be required to be pre-pro filed, pre-formed, pre-processed, prepared, the consolidation or molding process may be completed in one step using a closed mold with the heat and pressure controls.

[00019] FIG. 1 shows a schematic diagram of a method of manufacturing a composite sandwich structure. As shown, the method of manufacturing the composite sandwich structure may utilize a compression molding system 110 comprising a two- piece mold for consolidation or molding. The two-piece mold of the compression molding system 110 may include a female mold 112 and a male mold 114. As shown, the female mold 112 may be mounted on a stationary stage 116 and the male mold 114 may be mounted to a plunger 118 movable relative to the stationary stage 116. Accordingly, the female mold 112 and the male mold 114 may be movable relative to each other. According to various embodiments, the female mold 112 and the male mold 114 may be configured to define a mold cavity with a non-uniform thickness, when the female mold 112 and the male mold 114 are in a clamped state, such that the composite sandwich structure formed has a non-uniform thickness. According to various embodiments, at least one of a molding surface of the male mold 114 or a molding surface of the female mold 112 may include a contoured surface such that the composite sandwich structure formed has a contoured surface. According to various embodiments, the female mold 112 and the male mold 114 may be configured to be heated, for example by having heater element embedded in the female mold 112 and the male mold 114 respectively such that the female mold 112 and the male mold 114 may conduct heat to the stack-up material during the consolidation or molding process. According to various embodiments, the molding system 110 may include temperature and pressure control such that a desired temperature and a desired compression pressure may be set for the consolidation or molding process. [00020] In the method according to various embodiments, a plurality of planar materials 120 including at least one resin sheet material such as a thermoplastic resin film or sheet, at least one fiber sheet material such as a dry fibre cloth, and at least one slab of core material such as a thermoplastic core plate may firstly be individually positioned or provided to form a stack 121 (or a stack-up material). The stack 121 may then be positioned or placed on the female mold 112 (e.g. lower half mold) and subsequently be covered with the male mold 114 (e.g. upper half mold). Accordingly, the plurality of planar materials 120 may be piled up to form the stack 121 which may be simultaneously compressed and heated between the female mold 112 and the male mold 114.

[00021] According to various embodiments, the individually provided plurality of planar materials 120 may be free from physical interconnection from each other. Accordingly, the plurality of planar materials 120 may not be joined, adhered, bind, attached, stitched, fused, coupled, fastened, meshed, mated, intermixed, or welded to each other. Rather, the plurality of planar materials 120 may be disjoined, separated, independent, unattached or unconnected from each other.

[00022] According to various embodiments, at least one of the plurality of planar materials 120 may consist essentially of one constituent material of a plurality of constituent materials of the composite sandwich structure to be formed. The plurality of constituent materials of the composite sandwich structure to be formed may include at least one of resins, fibers, or a core material. According to various embodiments, the at least one of the plurality of planar materials 120 may consist essentially of fibers as one constituent material of the plurality of constituent materials of the composite sandwich structure to be formed. Further, at least another one of the plurality of planar materials 120 may consist essentially of resins as another constituent material of the plurality of constituent materials of the composite sandwich structure to be formed. Furthermore, at least a further one of the plurality of planar materials 120 may consist essentially of a core material as a further constituent material of the plurality of constituent materials of the composite sandwich structure to be formed. Accordingly, the plurality of constituent materials of the composite sandwich structure may include the fibers, the resins and the core material. According to various embodiments, the at least one of the plurality of planar materials may comprise one or more substantially continuous fiber layer as one constituent material of the plurality of constituent materials of the composite sandwich structure to be formed. The at least another one of the plurality of planar materials 120 may comprise one or more substantially continuous resin layer as another as another constituent material of the plurality of constituent materials of the composite sandwich structure to be formed. The at least further one of the plurality of planar materials 120 may comprise one or more substantially continuous core material as a further constituent material of the plurality of constituent materials of the composite sandwich structure to be formed. Hence, each of the plurality of planar materials 120 may be in their respective original, initial, pristine, raw, unprocessed, or untreated form as available or supplied. Thus, the stack 121 may not need to be prepared, pre formed, pre-processed, pre-treated, pre-profiled, or pre-impregnated. Rather, the plurality of planar materials 120 may merely to piled up to form the stack 121 in their respective original, initial, pristine, raw, unprocessed, or untreated form.

[00023] According to various embodiments, the two-pieces mold compression molding system 110 may be equipped with a hot press system and may subject the stack 121 of the plurality of planar materials 120 to elevated temperature and pressure. Accordingly, for example, the thermoplastic sheets/films (or the at least one resin sheet material) may be melted by the heating from the mold, and may then impregnate into the dry fibre cloth (or the at least one fiber sheet material) as well as bind with the thermoplastic core plate (or the at least one slab of core material) to form the composite sandwich structure. Through pressure, the two-pieces mold compression molding system 110 may be closed and the stack 121 of the plurality of planar materials 120 may be consolidated or molded, and may then be cured through a cooling process. According to various embodiments, the stack 121 of the plurality of planar materials 120 may be formed into a desired shape with a desired performance through varying the female mold 112 and the male mold 114 profiles and configuration, varying or controlling or adjusting the heating and the pressure cycle.

[00024] FIG. 2 shows a photograph of an actual example of a stack 221 of a plurality of planar materials 220. As shown, each of the planar materials 220 may be a separate and independent item. Since each of the planar materials 220 may contain only one constituent material of the plurality of constituent materials of the composite sandwich structure to be formed and each of the planar materials 220 may be in their respective original, initial, pristine, raw, unprocessed, or untreated form as available or supplied, each of the independent planar materials 220 may not necessary be pre formed, prepared, pre-processed, pre-treated, pre-profiled, or pre-impregnated before consolidation or molding. Rather, each of the planar materials 220 may be used directly for piling into the stack 221 so as to be compressed and heated in the consolidation or molding process.

[00025] FIG. 3A shows a schematic diagram of a composite sandwich structure 300 manufactured by the method according to the various embodiments. FIG. 3B shows a photograph of an actual composite sandwich structure 301 of FIG. 3 A manufactured by the method according to the various embodiments. As shown in FIG. 3B, after the one-step consolidation or molding process by the method according to various embodiments, the stack 221 of the plurality of planar materials 220 in FIG. 2 may be consolidated or molded into the composite sandwich structure 301 as shown in FIG. 3B. In contrast, in conventional manufacturing processes, the top face sheet/s, bottom face sheet/s and core of the composite sandwich structure 301 in FIG. 3B would need to be pre-formed separately before consolidation or molding.

[00026] FIG. 4 shows a schematic diagram of a stack 421 of a plurality of planar materials 420 according to various embodiments. As shown, the stack 421 of the plurality of planar materials 420 may include a first resin sheet material 422, a first fiber sheet material 424 on the first resin sheet material 422, a second resin sheet material 426 on the first fiber sheet material 424, a slab of core material 428 on the second resin sheet material 426, a third resin sheet material 430 on the slab of core material 428, a second fiber sheet material 432 on the third resin sheet material 430, and a fourth resin sheet material 434 on the second fiber sheet material 432.

[00027] According to various embodiments, each of the first resin sheet material 422, the second resin sheet material 426, the third resin sheet material 430 and the fourth resin sheet material 434 may include a thermoplastic resin film or thermoplastic resin sheet, which may be a substantially continuous resin layer or may consist essentially of thermoplastic resins. The first resin sheet material 422, the second resin sheet material 426, the third resin sheet material 430 and the fourth resin sheet material 434 may be of the same type of thermoplastic resin film/sheet or of different types of thermoplastic resin film/sheet.

[00028] According to various embodiments, each of the first fiber sheet material 424 and the second fiber sheet material 432 may include a dry fiber cloth, which may be a substantially continuous fiber layer or may consist essentially of fibers. According to various embodiments, the dry fibre cloth used may be of any type such as glass or carbon type fibers. [00029] According to various embodiments, the slab of core material 428 may include a thermoplastic core material, which may be a homogeneous material. The slab of core material 428 may also be a foam material or a honeycomb material. The slab of core material 428 may also include a light weight thermoplastic core material. According to various embodiments, the slab of core material 428 may include multiple layers of thermoplastic core material.

[00030] According to various embodiments, to ensure both good impregnation of the resins into the first fiber sheet material 424 or the second fiber sheet material 432 in the form of the dry fibre cloth, and good bonding between the impregnated first fiber sheet material 424 and second fiber sheet material 432 to the slab of core material 428 in the form of a foam core, two corresponding separate layers of resin sheet materials 422, 426, 430, 434 in the form of thermoplastic resin films/sheets may be used to sandwich respective first fiber sheet material 424 and second fiber sheet material 432. With reference to FIG. 4, the first and second resin sheet materials 422, 426, may impregnate the first fiber sheet material 424, and may bond the core material 428 to the impregnated first fiber sheet material 424. Similarly, the third and fourth resin sheet materials 430, 434, may impregnate the second fiber sheet material 432, and may bond the core material 428 to the impregnated second fiber sheet material 432.

[00031] According to various embodiments, to achieve the desired bonding strength and quality, the first, second, third and fourth resin sheet materials 422, 426, 430, 434 may be selected to be of a required thickness with a desired surface profile so as to impregnate well with the first fiber sheet material 424 and the second fiber sheet material 432 respectively as well as to bond well with the core material 428.

[00032] According to various embodiments, the stack 421 of the plurality of planar materials 420 may be extended, such as to repeat the layers of the first resin sheet material 422, the first fiber sheet material 424 and the second resin sheet material 426 with additional layers on one side of the slab of core material 428, and/or repeat the layers of the third resin sheet material 430, the second fiber sheet material 432 and the fourth resin sheet material 434 with additional layers on the other side of the slab of core material 428, and so on.

[00033] According to various embodiments, each layer of the stack 421 may include two or more pieces of planar materials 420 laid side-by-side. For example, a layer of fiber material may include two or more pieces of fiber sheet materials laid side-by- side. A layer of resin material may include two or more pieces of resin sheet materials laid side-by-side. A layer of core material may include two or more slabs of core material laid side-by-side. Accordingly, different fiber sheet materials may be used in a same layer, and/or different resin sheet materials may be used in a same layer, and/or different core material may be used in a same layer. Hence, the composite sandwich structure formed may have different properties or performance at different portions of the composite sandwich structure formed.

[00034] According to various embodiments, each layer of the stack 421 may be of different dimensions. For example, a layer of fiber material may be smaller in dimension or size than a layer of resin material, or a layer of core material may be smaller in dimension or size than a layer of fiber material. Thus, the fibers may be localized in certain portions of the composite structure formed or the core materials may be localized in certain portions of the composite structure formed. Accordingly, some portions of the composite structure formed may not contain fibers or core materials. Hence, the composite sandwich structure formed may have different properties or performance at different portions of the composite sandwich structure formed.

[00035] FIG. 5 shows a schematic diagram of a method 500 of manufacturing a composite sandwich structure. At 502, a plurality of planar materials is individually provided to form a stack, wherein the plurality of planar materials are free from physical interconnection from each other, and wherein at least one of the plurality of planar materials comprises one or more substantially continuous fiber layer as a constituent material of a plurality of constituent materials of the composite sandwich structure. At 504, heat and compression are simultaneously applied to the stack between a male mold and a female mold to form the composite sandwich structure.

[00036] According to various embodiments, there is provided a method of manufacturing a composite sandwich structure. The method may include individually providing a plurality of planar materials to form a stack, wherein the plurality of planar materials may be free from physical interconnection from each other, and wherein at least one of the plurality of planar materials may include one or more substantially continuous fiber layer as a constituent material of a plurality of constituent materials of the composite sandwich structure. The method may further include simultaneously applying heat and compression to the stack between a male mold and a female mold to form the composite sandwich structure. [00037] According to various embodiments, the plurality of constituent materials of the composite sandwich structure may further include resins and a core material.

[00038] According to various embodiments, the one or more substantially continuous fiber layer may include a fiber sheet material.

[00039] According to various embodiments, the fiber sheet material may include a dry fiber cloth.

[00040] According to various embodiments, the fiber sheet material may be electrically non-conductive.

[00041] According to various embodiments, the plurality of planar materials may further include at least one resin sheet material, and at least one slab of the core material.

[00042] According to various embodiments, the at least one resin sheet material may include a thermoplastic resin sheet or a thermoplastic resin film.

[00043] According to various embodiments, the core material may include a thermoplastic core material.

[00044] According to various embodiments, the core material may include a foam material or a honeycomb material.

[00045] According to various embodiments, the at least one slab of core material may be free of at least one of the fibers or the resins, or a combination thereof.

[00046] According to various embodiments, the stack may include a first resin sheet material, a first fiber sheet material on the first resin sheet material, a second resin sheet material on the first fiber sheet material, a slab of core material on the second resin sheet material, a third resin sheet material on the slab of core material, a second fiber sheet material on the third resin sheet material, and a fourth resin sheet material on the second fiber sheet material.

[00047] According to various embodiments, the male mold and the female mold may be configured to define a mold cavity with non-uniform thickness in a clamped state such that the composite sandwich structure formed may have a non-uniform thickness.

[00048] According to various embodiments, at least one of a molding surface of the male mold or a molding surface of the female mold may include a contoured surface such that the composite sandwich structure formed may have a contoured surface.

[00049] According to various embodiments, simultaneously applying heat and compression may include setting a temperature and a compression pressure based on at least one of a property, a dimension, or a type of at least one of the plurality of planar materials.

[00050] According to various embodiments, simultaneously applying heat and compression may include setting a temperature and a compression pressure based on at least one of a desired property, a desired dimension, a desired performance, or a desired profile of the composite sandwich structure.

[00051] According to various embodiments, individually providing the plurality of planar materials may include selecting the plurality of planar materials based on at least one of a desired property, a desired dimension, a desired performance, or a desired profile of the composite sandwich structure.

[00052] Various embodiments have provided a method that uses a one-step consolidation or molding process without pre-profiled, pre-formed, pre-processed, prepared, pre-treated or pre-impregnated layers of various thermoplastics (sheet/film, core/honey comb) while retaining integration ability of the stack of the plurality of planar materials according to the various embodiments.

[00053] According to various embodiments properties of the thermoplastic film such as material composition, thickness, surface profile, may be customised to achieve desired bonding with the flexibility to select fiber and combination of the stack of independent planar material.

[00054] According to various embodiments, the method of manufacturing may allow flexibility to make panels with varied thickness and changing contours in any directions.

[00055] According to various embodiments, good quality surface finish may be achieved through the same consolidation or molding by selecting the thermoplastic face sheet/film.

[00056] The method according to various embodiments may enable consolidation with different forms of cores such as honeycomb and foam cores, and localised core stack up with different core such as thickness and material without affecting external profile. The method according to various embodiments may also enable local fibre cloth reinforcement without affecting external profile.

[00057] While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes, modification, variation in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.

Claims

1. A method of manufacturing a composite sandwich structure, the method comprising:

individually providing a plurality of planar materials to form a stack, wherein the plurality of planar materials are free from physical interconnection from each other, and wherein at least one of the plurality of planar materials comprises one or more substantially continuous fiber layer as a constituent material of a plurality of constituent materials of the composite sandwich structure; and

simultaneously applying heat and compression to the stack between a male mold and a female mold to form the composite sandwich structure.

2. The method as claimed in claim 1, wherein the plurality of constituent materials of the composite sandwich structure further comprises resins and a core material.

3. The method as claimed in claim 1 or 2, wherein the one or more substantially continuous fiber layer comprises a fiber sheet material.

4. The method as claimed in claim 3, wherein the fiber sheet material comprises a dry fiber cloth.

5. The method as claimed in any one of claims 1 to 4, wherein the plurality of planar materials further comprises at least one resin sheet material, and at least one slab of the core material.

6. The method as claimed in claim 5, wherein the at least one resin sheet material comprises a thermoplastic resin sheet or a thermoplastic resin film.

7. The method as claimed in any one of claims 2 to 6, wherein the core material comprises a thermoplastic core material.

8. The method as claimed in any one of claims 2 to 7, wherein the core material comprises a foam material or a honeycomb material.

9. The method as claimed in any one of claims 5 to 8, wherein the at least one slab of core material is free of at least one of the fibers or the resins, or a combination thereof.

10. The method as claimed in any one of claims 5 to 9, wherein the stack comprises:

a first resin sheet material,

a first fiber sheet material on the first resin sheet material,

a second resin sheet material on the first fiber sheet material,

a slab of core material on the second resin sheet material,

a third resin sheet material on the slab of core material,

a second fiber sheet material on the third resin sheet material, and

a fourth resin sheet material on the second fiber sheet material.

11. The method as claimed in any one of claims 1 to 10, wherein the male mold and the female mold are configured to define a mold cavity with non-uniform thickness in a clamped state such that the composite sandwich structure formed has a non-uniform thickness.

12. The method as claimed in any one of claim 1 to 11, wherein at least one of a molding surface of the male mold or a molding surface of the female mold comprises a contoured surface such that the composite sandwich structure formed has a contoured surface.

13. The method as claimed in any one of claims 1 to 12, wherein simultaneously applying heat and compression comprises setting a temperature and a compression pressure based on at least one of a property, a dimension, or a type of at least one of the plurality of planar materials.

14. The method as claimed in any one of claims 1 to 13, wherein simultaneously applying heat and compression comprises setting a temperature and a compression pressure based on at least one of a desired property, a desired dimension, a desired performance, or a desired profile of the composite sandwich structure.

15. The method as claimed in any one of claims 1 to 14, wherein individually providing the plurality of planar materials comprises selecting the plurality of planar materials based on at least one of a desired property, a desired dimension, a desired performance, or a desired profile of the composite sandwich structure.