Scalable fabrication process for multi-spectral camouflage systems with adaptive concealment capabilities

Abstract

Aspects of present disclosure relate to a scalable fabrication process(100) for multi-spectral camouflage systems with adaptive concealment capabilities The process(100) comprising preparing a first or top layer including at least one fabric printed with a prespecified optical camouflage pattern for mitigation in Visual & IR bands(101); preparing a second layer using a fabric substrate with a plurality of conductive ink circuits(102); preparing a third layer using a laminated dielectric material to provide thermal insulation(103); preparing MSCS core sandwich with jointing the second layer and the third layer by industrial cold gluing(104); preparing a bottom layer having water resistant and fire-retardant properties(105); treating the top layer for superior water resistant and high fire-retardant properties(106); and preparing a composite sandwich of the layers by layering and stitching together with quilting(107).

Description

DESCRIPTIONSCALABLE FABRICATION PROCESS FOR MULTI-SPECTRAL CAMOUFLAGE SYSTEMS WITH ADAPTIVE CONCEALMENT CAPABILITIES TECHNICAL FIELD

[0001] The present disclosure relates to multi-spectral camouflage systems, and particularly relates to a scalable fabrication process for multi-spectral camouflage systems with adaptive concealment capabilities.BACKGROUND ART

[0002] A radiation-absorbing composite is primarily composed of a resin matrix reinforced with fibre cloth. A metamaterial absorber is a type of engineered material designed to efficiently absorb electromagnetic radiation. These metamaterials, when used as absorbers, offer several advantages over traditional absorbers, such as greater miniaturization, enhanced versatility, and improved efficiency. Metamaterial absorbers are employed in a wide range of applications, including infrared emitters, photodetectors, sensors, spatial light modulators, infrared camouflage, wireless communication devices, solar photovoltaic systems, and thermophotovoltaic devices.

[0003] Traditional metamaterial composites mainly consist of a resin matrix reinforced with fibre cloth. However, these absorbers suffer from electrical and magnetic losses, leading to poor performance in absorbing lower-frequency bands and limited absorption bandwidths. Additionally, highly absorbing metamaterial surfaces have been developed for specific frequency ranges, from microwave to infrared and visible light. For example, microwave absorbers are commonly made using printed copper circuit board technology, but these metamaterials tend to have narrow bandwidths and lack flexibility.

[0004] Current camouflage systems are often limited by their inability to adapt to different spectral ranges or environmental conditions. Various techniquesand solutions, have been developed for fabrication of effective camouflage systems.

[0005] For instance, Patent application US8340358B2 discloses visual camouflage with thermal and radar suppression and methods of making the same. A visual camouflage system that provides at least one of thermal or radar suppression is described. The system includes a vinyl layer having a camouflage pattern on a front surface of the vinyl layer. The camouflage pattern includes a site-specific camouflage pattern. A laminate layer is secured over the front surface of the vinyl layer coating the camouflage pattern to provide protection to the camouflage pattern and strengthen the vinyl layer. One or more nanomaterials are disposed on at least one of the vinyl layer, camouflage pattern, or the laminate to provide at least one of thermal or radar suppression.

[0006] Patent application CN109862769A discloses a kind of absorbing material and preparation method thereof of ultra-thin ultra-wide spectrum. The invention provides an absorbing material includes metal base plate, absorbent structure layer is provided on the metal base plate, the absorbent structure layer is formed by multiple wave-absorber periodic arrangements, each wave-absorber includes the ring resistance film of dielectric substrate layer with the upper surface that the dielectric substrate layer is arranged in, and the dielectric substrate layer is arranged on the upper surface of the metal base plate. The absorbing material of ultra-thin ultra-wide spectrum of the invention is based on resistive film absorbent structure, using isotropic ring resistance film.

[0007] These disclosures provides camouflage systems which relies on fixed patterns and materials that may be effective in specific wavelengths, such as visible light or infrared, but fail to provide comprehensive, adaptive concealment across a broader spectrum. Therefore, there is a growing need for a scalable, versatile, and cost-effective fabrication process that can produce multi-spectral camouflage systems with adaptive capabilities to provide improved concealment and stealth features.

[0008] Keeping this in mind, the present disclosure overcomes the above mentioned problems associated with the conventionally available fabricationprocess and camouflage systems. The present invention discloses a scalable fabrication process for multi-spectral camouflage systems with adaptive concealment capabilities.

[0009] Advantageously, this process utilizes simple and time saving fabrication process. The process provides fabrication of user friendly multi-spectral camouflage systems. It enables variation in the printed structure to change the absorption bandwidth. The camouflage wearable fabricated by the process provides replacement of metallic layers like copper or aluminium with conductive ink printed cloth which eliminates detection under metal detectors and increases flexibility.DISCLOSURE OF THE INVENTION OBJECTS OF THE INVENTION

[0010] It is an object of the present disclosure which provides a scalable fabrication process for multi-spectral camouflage systems with adaptive concealment capabilities.

[0011] It is an object of the present disclosure which provides production of lightweight, flexible, and cost-effective multi-spectral camouflage systems for applications in security, stealth technology and other sectors requiring adaptive concealment.

[0012] It is an object of the present disclosure which provides a versatile camouflage solution that can adapt to varying environmental conditions and electromagnetic spectrum, including microwave bands.SUMMARY

[0013] The present disclosure is directed towards a scalable fabrication process for multi-spectral camouflage systems with adaptive concealment capabilities. The process comprising of preparing a first or top layer including at least one fabric printed with a prespecified optical camouflage pattern formitigation in Visual & IR bands; preparing a second layer using a fabric substrate with a plurality of conductive ink circuits; preparing a third layer using a laminated dielectric material to provide thermal insulation; preparing an MSCS core sandwich with jointing the second layer and the third layer by industrial cold gluing; preparing a bottom layer having water resistant and fire-retardant properties; treating the top layer for superior water resistant and high fire-retardant properties; and preparing a composite sandwich of the plurality of layers by layering and stitching together with quilting.

[0014] In an aspect of the present disclosure, the process further including preparing Edge-bands, Tie-bands, and Cords and affixing to the composite sandwich for fabricating final MSCS wearable.

[0015] In an aspect of the present disclosure, the fabricating the final MSCS wearable in predefined dimensions to cover at least a portion of a subject, and wherein the prespecified optical camouflage pattern is configured to mimic environment of the subject.

[0016] In an aspect of the present disclosure, the process optionally including fabricating Visual & IR camouflage compliant 3D garnishing net layer and attaching to the top layer.

[0017] In an aspect of the present disclosure, the preparing the first layer including at least one fabric selected from a UV protection PVC layer with Polyvinylidene fluoride (PVDF) & TFL / TFX lacquer, and a polyester layer including Taffeta polyester.

[0018] In an aspect of the present disclosure, the UV protection PVC layer having a Tensile strength and Tear strength of 4215 N and 600 N for warp, and 4125 N and 550 N for weft weave, respectively, and wherein the polyester layer is 150 GSM polyester fabric.

[0019] In another aspect of the present disclosure, the preparing the second layer using the second fabric substrate by printing of the conductive ink circuits and lamination of the substrate with air-gap and conducting foil.

[0020] In another aspect of the present disclosure, the preparing the MSCS core sandwich configured to provide electrical conductivity and absorb or redirect electromagnetic radiation at multiple spectral bands.

[0021] In another aspect of the present disclosure, the preparing the bottom layer with high tensile & shear strength Rip-Stop Nylon fabric treated for water resistant and fire-retardant properties, and wherein the Rip-Stop Nylon fabric having 330 GSM with a Tensile strength and a Tear strength of 3000 N and 210 N for warp, and 2500 N and 210 N for weft weave, respectively.

[0022] In another aspect of the present disclosure, the preparing the composite sandwich configured to have multi spectral properties with UV, near IR absorption and microwave absorption more than 90% in the frequency band ranging from 8-18 GHz.

[0023] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawing is included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawing illustrates exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0025] FIG. 1 illustrates a flowchart of scalable fabrication process (100) for multi-spectral camouflage systems with adaptive concealment capabilities in accordance with an embodiment of the present disclosure.

[0026] FIG. 2 illustrates a diagram of layer architecture of multi-spectral camouflage systems (MSCS) in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION

[0027] Aspects of the present disclosure relate to a scalable fabrication process for multi-spectral camouflage systems with adaptive concealment capabilities.

[0028] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

[0029] Figure 1 discloses a flowchart of a scalable fabrication process (100) for multi-spectral camouflage systems with adaptive concealment capabilities. The process (100) comprising of preparing a first or top layer including at least one fabric printed with a prespecified optical camouflage pattern for mitigation in Visual & IR bands (101); preparing a second layer using a fabric substrate with a plurality of conductive ink circuits (102); preparing a third layer using a laminated dielectric material to provide thermal insulation (103); preparing an MSCS core sandwich with jointing the second layer and the third layer by industrial cold gluing (104); preparing a bottom layer having water resistant and fire-retardant properties (105); treating the top layer for superior water resistant and high fire-retardant properties (106); and preparing a composite sandwich of the plurality of layers by layering and stitching together with quilting (107).

[0030] In an embodiment of the present invention, the process (100) further includes preparing Edge-bands, Tie-bands, and Cords and affixing to the composite sandwich for fabricating final MSCS wearable (108). The final MSCS wearable is fabricated in predefined dimensions to cover at least a portion of a subject. The prespecified optical camouflage pattern is configured to mimic environment of the subject which is to be covered or camouflaged.

[0031] Figure 2 illustrates a diagram of multi-spectral camouflage systems (MSCS) layer architecture. In an embodiment of the present invention, the process (100) optionally including fabricating Visual & IR camouflage compliant 3D garnishing net layer and attaching to the top layer. The garnishing net layer can be made up of polyester coated with advanced NIR and TIR-compliant plasmonic nanoparticle plasmonic coatings to achieve very low thermal infrared emissivity and minimize infra-red signatures, and blend seamlessly with natural environments under varying solar loading conditions. The garnishing net layer is a 3-D NIR- Visual, TIR camouflage.

[0032] The first layer includes at least one fabric selected from a UV protection PVC layer with Polyvinylidene fluoride (PVDF) & TFL coating, and a polyester layer. The UV-protective top layer can be used for customized applications. The UV protection PVC layer having a Tensile strength and Tear strength of 4215 N and 600 N for warp, and 4125 N and 550 N for weft weave respectively. The UV-protective top layer can be PVDF & TFL Coated 900 gsm PVC. The UV-protective layer has superior Tensile strength, Flame-retardant, Water-resistant, Radar-Transparent PVC fabric integrated with advanced NIR and TIR-compliant plasmonic nanoparticle-based coatings to minimize thermal infrared signatures, and blend seamlessly with natural environments under varying solar loading conditions. It is finished with a TFL / TFX lacquer (a multilayer finish with a UV-filter and a weldable Hyper-PVDF lacquer) for guaranteed excellent durability of the product. UV Stabilization is achieved through a stabilized PVC molecular structure, high-quality colour pigments and UV light inhibitors. The anti-wick yarn treatment polyester multifilament base knitted fabric prevents penetration of microorganisms into the base fabric of the coated membrane and ingression of water inside fabric through fibres capillary action. Higher yarn density yields higher tensile strength, by up to 16% compared to a Panama fabric.

[0033] The UV-protective layer is selected to be 2-D NIR-Visual, TIR compliant camouflage. The UV-protective layer has multilayer finish with a UVshield for customised shaped profiling of multi-spectral camouflage systems. This demands higher degree of homogenous elastic behaviour in warp and weft than that afforded by conventional fabrics. It ensures minimal elongation difference between warp and weft of the membrane, without constriction to a desirable flexibility and elasticity in textile architecture. When used as the topmost cover in specialised applications, it provides 2-D NIR- Visual, TIR camouflage.

[0034] The polyester layer can be Hydrophobic Fire-retardant fabric. The polyester layer is a 150 GSM polyester fabric. Taffeta Polyester with high Tensile Strength is used to ensure durability and resistance to tearing or mechanical stress. It facilitates ease of deployment over varied surfaces, including irregular and contoured structures and enhances longevity when exposed to harsh environmental conditions. It affords high temperature stability, low specular reflection, UV & weather resistance, and is treated for low thermal emissivity.

[0035] The second layer is prepared using the second fabric substrate by printing of the conductive ink circuits and lamination of the substrate with air-gap and conducting foil. The high viscosity of conductive ink is instrumental in suppressing ink-flaring post-printing, thereby enhancing the resolution and precision of printed circuit patterns. However, this increased viscosity also promotes particle agglomeration, leading to rapid coagulation, a progressive decline in electrical conductivity, and inconsistent performance in continuous large-format printing. These challenges pose significant hurdles in automated industrial screen printing, where frequent screen clogging disrupts production throughput and limits operational efficiency.

[0036] To mitigate these issues, conductive polymers were strategically incorporated into the ink formulation. The selection process entailed rigorous materials research to identify polymer candidates exhibiting optimal rheological stability and electrical conductivity. This was followed by precise experimental tuning of the polymer-to-conductive filler ratios, validated through systematic anechoic chamber testing of the MMA sandwich structure. This iterative refinement process achieved an optimal balance between viscosity, printability,and functional performance, ultimately enhancing industrial scalability, manufacturing reliability, and electromagnetic effectiveness of the conductive ink system.

[0037] The second layer is configured to provide electrical conductivity within the MSCS wearable. The MSCS core sandwich provides electrical conductivity and absorb or redirect electromagnetic radiation at multiple spectral bands. A meticulously designed array of micro-sized circuits and resonators using conductive ink is defined on textiles that manipulate electromagnetic waves at sub -wavelength scales. The MSCS core manipulates electromagnetic waves at sub -wavelength scales to result in very high absorption. It works as inert spacer having reflective metallic surface.

[0038] The third layer is a laminated dielectric material which can be a laminated dielectric foam. The bottom layer is a high tensile & shear strength Nylon 66 / 6 Rip Stop fabric treated for water resistant and fire-retardant properties. The fabric enhances durability, preventing propagation of small tears, withstands rugged environments, ensuring long-term usability, and maintains its structural integrity under mechanical stress and environmental variations. The Rip-Stop Nylon fabric is a 330 GSM fabric with a Tensile strength and a Tear strength of 3000 N and 210 N for warp, and 2500 N and 210 N for weft weave respectively.

[0039] In a specific embodiment, the bottom layer is affixed with a metallic layer that involves the precise integration of a metallic material to enhance the system's protective and reflective properties across various spectra. This process typically entails material selection (consistent with the specific requirements for reflectivity, durability, and weight), surface preparation, selecting application method (such as laminating, vacuum-depositing, electroplating), and Adhesion & Bonding (environmental factors-compliant industrial adhesives or bonding agents).

[0040] The Metamaterial Absorber (MMA) is embedded between a top and bottom layer. The composite sandwich typically consists of the core layer comprising metamaterial with RF absorbing properties and a non-snagging innersurface sandwiched in high tenacity hydrophobic water-repellent top & bottom cover layers (with or without an additional outer garnish to give a 3D impression). The top cover shall have reflective camouflage properties from Visual to NIR wavelengths, physical properties. The perimeter of the composite sandwich shall be reinforced with an “edge band” ensuring that tensile strength demands are met. The perimeter of the edge band, in turn, shall be circumfered by the “edge cord”, being the interface with the fastening points, inter-MSCS coupling, and the outer garnishing layer.

[0041] Therefore, the MMA layers shall have camouflage properties in the RF Bands of military SAR and a non-snagging layer ‘sandwiched’ between a high abrasion-resistant, water-resistant, and fire-retardant top-cover and a lower surface backing made of very high tensile and tear strength rip-stop material which too shall be fire-retardant and water-resistant.

[0042] The conductive ink having bulk conductivity of ranging about 500 siemens per centimetre square to 800 siemens per centimetre square. In a specific embodiment, the second layer may be composed of a laminated metal foil.

[0043] The layers may be fabricated using a screen-printing technique. In one embodiment, the MSCS wearable may be designed to have 90 percent absorption in the frequency band stretching from 6 gigahertz to 18 gigahertz for 50 micrometre thickness.

[0044] The absorbing MSCS wearable described above enables a flexible wearable by using printed cloth for the second layer instead of commonly used copper or aluminium for making the absorber flexible. Additionally, the MSCS wearable uses laminated metallic foils for making the absorber flexible and its use in wearable is for cold climates as the large infra-red reflectivity of the metal provides for minimizing thermal losses by radiation. The use of conductive inks on a flexible substrate like textile-based cloth are used to make conductive circuits despite of the textured and rough surface for performance as absorbing multi-spectral camouflage wearable.

[0045] Moreover, replacement of metallic layers like copper or aluminium with conductive ink printed cloth eliminates detection under metal detectors and increases flexibility. In addition, wearable microwave absorber may be used in stealth technology by enabling radar absorbing clothing for personnel, vehicle skirtings, canopies, covers for radar equipment and other strategic installations. Evaluation of MSCS wearable

[0046] The MSCS wearable was evaluated for Visual, NIR & Thermal IR compliance. The results are as displayed in Table 1. The MSCS wearable demonstrates reduction in probability of recognition by up-to 75% in visual range when observed at 3000 m during daytime (ambient light condition in a clear day with bright sun) and 500 m during the night (ambient light condition of full moon night). The MSCS wearable demonstrates reduction in probability of recognition by 75% in NIR range when viewed through PNV devices at 1500 m in ambient light equivalent to full moon night.

[0047] The process results in fabricating the MSCS wearable in which the Thermal Transmission is not more than 0.7% in the 3-5 pm and 8-12 pm wavelength bands. The radiation temperature in wavelength bands 3-5 pm & 8-12 pm due to solar loading / ambient cooling would not diverge more than ±8 °C from a black-body mean radiation temperature.Table 1: Visual, NIR & Thermal IR compliance of the MSCS wearable & &&

[0048] Absorption by the MSCS wearable is typically more than 90% over the 8-18 GHz bands with Transmittance < 1 % (transmittance loss > 20dB). Table 2 displays the RF compliance matrix of the the MSCS wearable. These values show that it is an effective material for RF shielding.Table 2: RF compliance matrix> > >> > >

[0049] The MSCS wearable can be formulated as panel-specific camouflage tiles that could be stitched or joined together to comprehensively cover the entire structure. The non-glossy structure, pattern, and colours of the multi-spectral camouflage wearable is capable of minimizing the contrast between an object and the background to degrade visual detection.

[0050] In an embodiment, the MSCS wearable feature patterns that are adjusted perfectly to match NIR reflections of the environment that behave differently depending on a variety of factors, including climate and its interactions with solar radiation. The MSCS wearable adapts to the background radiation of a natural environment such that it interacts with the surroundings through convection, reflection, radiation, and insulation to degrade the performance ofthermal devices in TIR. The camouflage wearable fabricated by the process can be designed as camouflage apparel for personnel, vehicles, aircraft, and equipment, providing enhanced stealth and protection against detection by infrared, visible, and radar-based systems.

[0051] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

Claims

CLAIMSWe Claim:

1. A scalable fabrication process (100) for multi-spectral camouflage systems (MSCS) with adaptive concealment capabilities, the process (100) comprising of:preparing a first or top layer including atleast one fabric printed with a prespecified optical camouflage pattern for mitigation in Visual & IR bands (101);preparing a second layer using a fabric substrate with a plurality of conductive ink circuits (102);preparing a third layer using a laminated dielectric material to provide thermal insulation (103);preparing an MSCS core sandwich with jointing the second layer and the third layer by industrial cold gluing (104);preparing a bottom layer having water resistant and fire-retardant properties (105);treating the top layer for superior water resistant and high fire- retardant properties (106); andpreparing a composite sandwich of the plurality of layers by layering and stitching together with quilting (107).

2. The scalable fabrication process (100) as claimed in claim 1, wherein the process (100) further including preparing Edge-bands, Tie-bands, and Cords and affixing to the composite sandwich for fabricating final MSCS wearable (108).

3. The scalable fabrication process (100) as claimed in claim 2, wherein the fabricating the final MSCS wearable in predefined dimensions to cover at least a portion of a subject, and wherein the prespecified optical camouflage pattern is configured to mimic environment of the subject.

4. The scalable fabrication process (100) as claimed in claim 1, wherein the process (100) optionally including fabricating Visual & IR camouflage compliant 3D garnishing net layer and attaching to the top layer.

5. The scalable fabrication process (100) as claimed in claim 1, wherein the preparing the first layer including atleast one fabric selected from a UV protection PVC layer with Polyvinylidene fluoride (PVDF) & TFL / TFX lacquer, and a polyester layer including Taffeta polyester.

6. The scalable fabrication process (100) as claimed in claim 5, wherein the UV protection PVC layer having a Tensile strength and Tear strength of 4215 N and 600 N for warp, and 4125 N and 550 N for weft weave respectively, and wherein the polyester layer is 150 GSM polyester fabric.

7. The scalable fabrication process (100) as claimed in claim 1, wherein the preparing the second layer using the second fabric substrate by printing of the conductive ink circuits and lamination of the substrate with air-gap and conducting foil.

8. The scalable fabrication process (100) as claimed in claim 1, wherein the preparing the MSCS core sandwich configured to provide electrical conductivity and absorb or redirect electromagnetic radiation at multiple spectral bands.

9. The scalable fabrication process (100) as claimed in claim 1, wherein the preparing the bottom layer with high tensile & shear strength Rip-Stop Nylon fabric treated for water resistant and fire-retardant properties, and wherein the Rip-Stop Nylon fabric having 330 GSM with a Tensile strength and a Tear strength of 3000 N and 210 N for warp, and 2500 N and 210 N for weft weave respectively.

10. The scalable fabrication process (100) as claimed in claim 1, wherein the preparing the composite sandwich configured to have multi spectral properties with UV-visible, near IR absorption and microwave absorption more than 90% in the frequency band ranging from 8-18 GHz.

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