COMPOSITE MATERIAL FABRICATION SYSTEM AND METHOD
20210308969 · 2021-10-07
Inventors
Cpc classification
B29C70/545
PERFORMING OPERATIONS; TRANSPORTING
B29C70/40
PERFORMING OPERATIONS; TRANSPORTING
B29C70/44
PERFORMING OPERATIONS; TRANSPORTING
B29C70/541
PERFORMING OPERATIONS; TRANSPORTING
B29C33/0038
PERFORMING OPERATIONS; TRANSPORTING
International classification
B29C70/54
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A composite fabrication system for fabricating a cured composite structure from a first composite layup comprising a matrix of resin and fiber reinforcement, the matrix configured upon a first supporting membrane, the matrix having a percentage of voids value (PCT-V) and a volumetric resin-to-fiber reinforcement ratio value (R:F), the system comprising: a fluid control delivery system; a layup structure having a layup support surface; the first composite layup positioned on the layup support surface; a second composite layup formed of the first composite layup with a second supporting membrane spread upon the matrix, the matrix positioned between the first and second supporting membranes; a roller; a form; and a removable seal configured to seal the form over the second composite layup; wherein the pressurized fluid introduced by the fluid control delivery system serving to expand and bias the second composite layup intimately against the form.
Claims
1. A composite fabrication system for fabricating a cured composite structure from a first composite layup comprising a matrix of resin and fiber reinforcement, the matrix configured upon a first supporting membrane, the matrix having a percentage of voids value (PCT-V) and a volumetric resin-to-fiber reinforcement ratio value (R:F), the system comprising: a. a fluid control delivery system having a pressurized fluid at a pressure exceeding one atmosphere; b. a layup structure having a layup support surface, the layup structure having a fluid inlet passage penetrating the layup support surface and connected to the fluid control delivery system; c. the first composite layup positioned on the layup support surface with the first supporting membrane contacting the layup support surface and a vibrational element mechanically attached to the layup structure, with operation of the vibrational element serving to lower PCT-V; d. a second composite layup formed of the first composite layup with a second supporting membrane spread upon the matrix, the matrix positioned between the first and second supporting membranes; e. a roller configured to displace excess resin in the matrix and lower R;F; f. a form having an internal, volumetric shape corresponding to a shape of the final composite structure, the form positioned over the second composite layup and the layup support surface, but substantially not contacting the second composite layup; and g. a removable seal configured to seal the form over the second composite layup; wherein the second composite layup is initially in contact with the form only at the removable seal, the pressurized fluid introduced by the fluid control delivery system serving to expand and bias the second composite layup intimately against the form.
2. The composite fabrication system according to claim 1, wherein the layup surface is substantially flat and horizontal and has at least one sealing element configured thereupon, located substantially at a periphery of the layup support surface.
3. The composite fabrication system according to claim 2, wherein the supporting membranes have an extended sheet shape and are formed from at least one material chosen from the list including: silicone rubber and vulcanized rubber.
4. The composite fabrication system according to claim 3, wherein the second composite layup extends over the entire layup support surface and over the at least one sealing element.
5. The composite fabrication system according to claim 4, wherein the removable seal is configured to seal the second composite layup against the at least one sealing element.
6. The composite fabrication system according to claim 5, wherein the pressurized fluid introduced by the fluid control delivery system is vented when the second composite layup is substantially completely cured.
7. The composite fabrication system according to claim 1, wherein the pressurized fluid is at least one chosen from the list including: a gas; water, and oil.
8. A method of fabricating a cured composite structure using the composite fabrication system according to claim 6, the method comprising the following steps: a. laying up the first composite layup by: i. spreading the first supporting membrane upon the layup support surface; ii. spreading the fiber reinforcement over the first supporting membrane; and iii. applying resin to the fiber reinforcement; b. activating the vibrational element to outgas voids and to reduce PCT-V; c. spreading the second supporting membrane upon the matrix to form the second composite layup; d. applying uniform pressure to the second composite layup using a roller to displace excess resin and lower R:F; e. placing a form over the second composite layup; f. sealing the form onto the second composite layup with a removable seal, the second layup substantially not in contact with the form; g. opening a main inlet fluid valve of the fluid control delivery system to introduce the pressurized fluid in the fluid inlet passage and beneath the second composite layup to expand the second composite layup and to bias it intimately against the form; h. closing the main inlet fluid after the second composite layup has substantially cured, thereby yielding a cured composite structure, and then opening a fluid venting valve of the fluid control delivery system to vent the fluid; i. removing the removable seal and the form from the cured composite structure once curing is completed, after any necessary cooling to ambient/near ambient conditions; and j. removing the supporting membranes from the cured composite structure.
9. A composite fabrication system for fabricating a cured composite structure from a composite layup comprising a matrix of resin and fiber reinforcement, the matrix configured between a first and a second supporting membrane, the matrix having a percentage of voids value (PCT-V) and a volumetric resin-to-fiber reinforcement ratio value (R:F), the system comprising: a. a fluid control delivery system having a pressurized fluid at a pressure exceeding one atmosphere; b. a layup structure having a first layup support surface, the layup structure having a fluid inlet passage penetrating the first layup support surface and connected to the fluid control delivery system; c. the composite layup positioned on a second layup support surface with the first supporting membrane contacting the layup support; d. a roller configured to displace excess resin in the matrix and lower R;F and PCT-V; e. a form having an internal, volumetric shape corresponding to a shape of the final composite structure, the form positioned over the composite layup and the layup support surface, but substantially not contacting the second composite layup; and f. a removable seal configured to seal the form over the composite layup and against the second layup support surface; wherein the composite layup is initially in contact with the form only at the removable seal, the pressurized fluid introduced by the fluid control delivery system serving to expand and bias the composite layup intimately against the form.
10. The composite fabrication system according to claim 9, wherein the second layup support surface has an elongated cylindrical shape having a first and a second end, respectively, the second end closed, having a substantial semispherical closure, and the first end open, having a substantially right-angle truncation.
11. The composite fabrication system according to claim 9, wherein the second layup support surface is positioned substantially vertically, with the first end opening onto the first layup support surface, centered substantially above inlet passage, and sealed at the first end onto the first layup support surface.
12. The composite fabrication system according to claim 11, wherein the supporting membranes have an extended sheet shape and are formed from at least one material chosen from the list including: silicone rubber and vulcanized rubber.
13. The composite fabrication system according to claim 12, wherein the composite layup extends over the entire second layup support surface, towards the first layup support surface.
14. The composite fabrication system according to claim 13, wherein the removable seal is positioned at an end of the form, towards the first end, the removeable seal configured to seal the composite layup between the form and the second layup surface.
15. The composite fabrication system according to claim 14, wherein the pressurized fluid introduced by the fluid control delivery system is vented when the composite layup is substantially completely cured.
16. The composite fabrication system according to claim 9, wherein the pressurized fluid is at least one chosen from the list including: a gas; water, and oil.
17. A method of fabricating a cured composite structure using the composite fabrication system according to claim 15, the method comprising the following steps: a. laying up the composite layup by: i. spreading the first supporting membrane upon the layup support surface; ii. spreading the fiber reinforcement over the first supporting membrane; and iii. applying resin to the fiber reinforcement; iv. spreading the second supporting membrane upon the matrix; b. applying uniform pressure to the composite layup using a roller to displace excess resin and lower R:F and to reduce PCT-V; c. placing a form over the second composite layup; d. sealing the form onto the second composite layup with a removable seal, the composite layup substantially not in contact with the form; e. opening a main inlet fluid valve of the fluid control delivery system to introduce the pressurized fluid in the fluid inlet passage and inside the composite layup to expand the composite layup and to bias it intimately against the form; f. closing the main inlet fluid after the composite layup has substantially cured, thereby yielding a cured composite structure, and then opening a fluid venting valve of the fluid control delivery system to vent the fluid; g. removing the removable seal and the form from the cured composite structure once curing is completed, after any necessary cooling to ambient/near ambient conditions; and h. removing the supporting membranes from the cured composite structure.
Description
LIST OF FIGURES
[0022] The invention is described herein, by way of example only, with reference to the accompanying drawings, wherein:
[0023]
[0024]
[0025]
[0026]
DETAILED DESCRIPTION
[0027] Embodiments of the current invention relate to the field composite materials and specifically to a composite material fabrication system and method.
[0028] Reference is currently made to
[0029] Layup structure 8 includes: a substantially flat and horizontal layup support surface 20, a fluid inlet passage 22 shown leading from the fluid delivery piping configuration and penetrating layup support surface 20; at least one sealing element 24 configured on the layup support surface, substantially at a periphery of the layup support surface; and a vibrational element 26 mechanically connected to a support 28 of the layup support surface, the vibrational element shown schematically connected to an electrical power source. Support 28 may be a set of four legs, typical for a table support, or any other similar structure allowing the layup support surface to be stably positioned for placing first composite layup 6 and additional elements thereupon, as further described hereinbelow.
[0030] The first composite layup and elements of layup structure 8, namely: the layup support surface, the fluid inlet passage; and the at least one sealing element are all shown schematically in cross-section. Furthermore, layup support surface 20 and the at least one sealing element 24 has a geometric shape such as, but not limited to: rectangular, circular, square, triangular, and hexagonal, with the at least one sealing element 24 being configured mutatis mutandis to allow for a seal, as further described hereinbelow, corresponding to the shape of first composite layup 6, which typically extends over the entire layup support surface and beyond, as indicated in
[0031]
[0032] A first step in a first method to form a composite material using composite fabrication system 4 includes forming (or “laying up”) first composite layup 6 by spreading first supporting membrane 35 upon layup support surface 20, with the first supporting membrane closely complying with the layup support surface; followed by spreading fiber reinforcement 30 over the first supporting membrane. Embodiments of the current invention typically avoid and/or minimize cutting additional pieces of fiber reinforcement, but instead use complete and/or larger sheets of fiber, thereby generally saving time and fiber reinforcement material as part of the layup process. The term “matrix” used hereinbelow in the specification and in the claims which follow is intended to mean the combined mixture/structure of fiber reinforcement 30 and resin 32, with voids 38.
[0033] Resin 32 is then applied to fiber reinforcement 30 by means of resin infusion, such as, but not limited to: brush or other methods, as known in the art. A typical result following resin application, as shown in the figure, is a layer of the fiber reinforcement impregnated with the resin typically having voids 38, otherwise referred to as “bubbles”, as known in the art. As noted hereinabove, PCT-V represents the relative percentage of voids 38 in the matrix, whether measured volumetrically or by mass.
[0034] Following application of resin, vibrational element 26 is activated to effectively outgas some of voids 38 by introducing vibrations into layup support surface 20 having first composite layup 6 spread thereupon. Operating the vibrational element for a specified time (typically from at least 10 seconds to a few minutes) and with a range of vibrational frequencies of 10 to 500 Hz, with amplitudes of under a few millimeters serves to significantly reduce PCT-V.
[0035] Reference is currently made to
[0036] Apart from differences described below, composite fabrication system 4, layup structure 8, and fluid delivery system 10 of
[0037]
[0038] With second supporting membrane 35a spread upon the matrix as show in
[0039] Reference is currently made to
[0040]
[0041] The next step in a first method is to seal the form onto second layup 6a and at least one seal 24 using a removable seal 46, schematically shown as “C” clamps. Removable seal 46 make take the form of any mechanism and configuration thereof effecting a seal as described hereinabove. Except for contacting the form at the removable seal, second composite layup 6a is substantially not in contact with the form in the current step.
[0042] The next step in the first method is to open main inlet fluid valve 14 to introduce a pressurized fluid (the fluid and its direction of flow indicated by arrows in the figure) into fluid inlet passage 22. Examples of the pressurized fluid include, but are not limited to: air, any other gas, water, and oil. Pressure values of the pressurized fluid exceed one atmosphere and the values range to a number of multiples of atmospheric pressure. Typically, the pressurized fluid is heated above ambient temperature, the temperature and pressure of the fluid determined by resin curing qualities, as known in the art. Generally, higher fluid pressure and temperature yield faster curing times whereas lower fluid pressure and temperature yield slower curing times.
[0043] Introduction of the pressurized fluid into fluid inlet passage 22 and beneath second composite layup 6a serves to expand the second composite layup and to bias it intimately against form 40, as shown schematically in
[0044] The at least one vent opening 44 serves to allow any ambient air to escape the form (as shown schematically by the smaller arrows) as the second composite layup is inflated and biased against form 40. In
[0045] Once curing is completed, including any necessary cooling to ambient/near ambient conditions, removable seal 46 and form 40 are removed, and a cured composite structure 76, enclosed in first supporting membrane 35 and second supporting membrane 35a remains, as shown in
[0046] The first method of to form a composite material using composite fabrication system 4 is summarized by the following steps: [0047] a. Laying up the first composite layup by: [0048] a. spreading the first supporting membrane upon the layup support surface; [0049] b. spreading the fiber reinforcement over the first supporting membrane; and [0050] c. applying resin to the fiber reinforcement. [0051] b. Activating the vibrational element to outgas some of the voids and reduce PCT-V. [0052] c. Spreading the second supporting membrane upon the matrix to form the second composite layup. [0053] d. Applying uniform pressure to the second composite layup using a roller to displace excess resin and lower R:F. [0054] e. Placing a form over the second composite layup. [0055] f. Sealing the form onto the second composite layup with a removable seal, the second layup substantially not in contact with the form. [0056] g. Opening the main inlet fluid valve to introduce the pressurized fluid in the fluid inlet passage and beneath the second composite layup to expand the second composite layup and to bias it intimately against the form. [0057] h. Closing the main inlet fluid after the second composite layup has substantially cured, and thereby yielding a cured composite structure, and then opening the fluid venting valve to vent the fluid. [0058] i. Removing the removable seal and the form from the cured composite structure once curing is completed, after any necessary cooling to ambient/near ambient conditions. [0059] j. Removing the supporting membranes from the cured composite structure.
[0060] Reference is currently made to
[0061]
[0062] Layup support surface 130 is characterized by an elongated cylindrical shape having a first and a second end 131 and 132, respectively. Second end 131 is closed, having a substantial semispherical closure and first end 131 is open, having a substantially right-angle truncation. Layup support surface 130 is positioned substantially vertically with the first end opening onto layup support surface 20, centered substantially above inlet passage 22. A seal 136 is affixed at first end 131 and layup support surface 20. Layup support surface 130 has a plurality of holes 134 distributed therein to allow passage of a fluid, as described hereinbelow.
[0063] A first step in a second method to form a composite material using composite fabrication system 104 includes laying up composite layup 106, similar to the layup method described hereinabove with regard to second composite layup 6a, as follows: [0064] a. spreading the first supporting membrane upon the layup support surface; [0065] b. then spreading the fiber reinforcement over the first supporting membrane; [0066] c. applying resin to the fiber reinforcement; and [0067] d. spreading the second supporting membrane upon the matrix to form composite layup 106.
[0068] Referring to
[0069] The next step in a second method, referring to
[0070] As a result, pressurized fluid, introduced through fluid inlet passage 22, is constrained and sealed within the tubular support-form structure, as described further hereinbelow.
[0071] Referring to
[0072] Introduction of the pressurized fluid into fluid inlet passage 22 inside of tubular form 140 (as shown by the arrow) and beneath composite layup 106 serves to expand the composite layup and to bias it intimately against form 140, as shown schematically in
[0073] After a prescribed time (typically ranging a number of minutes, according to the curing characteristics of the resin) when the second composite layup has substantially completely cured, main inlet fluid valve 14 is closed, and then fluid venting valve 15 is opened to allow venting of the fluid to fluid vent outlet 16—all similarly to that shown as described hereinabove in
[0074] Once curing is completed, including any necessary cooling to ambient/near ambient conditions, removable seal 146 and form 140 (shown as two halves) are removed, and a cured composite structure 176 is enclosed in the supporting membranes as shown in
[0075] Fabricating cured composite structure 176 using the second method described hereinabove yields a fully formed structure—with all of the concomitant advantages of strength, lower cost, and reliability, as opposed to similar prior art structures typically fabricated in two half structures that must be subsequently joined together.
[0076] The second method of to form a composite material using composite fabrication system 104 is summarized by the following steps: [0077] 1. Laying up composite layup 106 by: [0078] a. spreading the first supporting membrane upon layup support surface 130; [0079] b. spreading the fiber reinforcement over the first supporting membrane; [0080] c. applying resin to the fiber reinforcement; and [0081] d. spreading the second supporting membrane upon the matrix to form composite layup 106. [0082] 2. Applying uniform pressure to composite layup 106 using a roller to displace excess resin and lower R:F and effecting reduction of PCT-V. [0083] 3. Placing form 140 over the composite layup. [0084] 4. Sealing form 140 onto composite layup 106 and layup support surface 130 with removable seal 146. [0085] 5. Opening main inlet fluid valve 14 to introduce a pressurized fluid into fluid inlet passage 22 and to expand composite layup 104 and to bias it intimately against form 140. [0086] 6. Closing the main inlet fluid valve after composite layup 140 has substantially cured and then opening fluid venting valve 15 to vent the fluid. [0087] 7. Removing removable seal 146 and form 140 from cured composite structure 176 once curing is completed, following any necessary cooling to ambient/near ambient conditions. [0088] 8. Removing the supporting membranes from cured composite structure 176.
[0089] While embodiments of the current invention, described hereinabove in the first and the second methods, are directed to exemplary wet layup FRP processes using the composite fabrication system, the composite fabrication system may be used for other processes and materials, such as, but not limited to: prepreg, and carbon fibers; mutatis mutandis.
[0090] A salient point in embodiments of the current invention is that substantially all of composite structure fabrication is performed on the same, unified platform and work setup—namely the composite fabrication system described herein.
[0091] It will be appreciated that the above descriptions are intended only to serve as examples, and that many other embodiments are possible within the scope of the present invention as defined in the appended claims.