KR20230082285A - Microwave absorbing form based sandwich composite with metallic lightning protection layer - Google Patents

Microwave absorbing form based sandwich composite with metallic lightning protection layer Download PDF

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KR20230082285A
KR20230082285A KR1020210170066A KR20210170066A KR20230082285A KR 20230082285 A KR20230082285 A KR 20230082285A KR 1020210170066 A KR1020210170066 A KR 1020210170066A KR 20210170066 A KR20210170066 A KR 20210170066A KR 20230082285 A KR20230082285 A KR 20230082285A
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metal layer
electromagnetic wave
wave absorbing
fiber
lightning protection
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KR1020210170066A
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KR102635644B1 (en
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남영우
권진회
명노신
최원호
송운형
신준형
김민준
김윤곤
황반토
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경상국립대학교산학협력단
주식회사 대한항공
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Priority to KR1020210170066A priority Critical patent/KR102635644B1/en
Priority to PCT/KR2022/002751 priority patent/WO2023101102A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/025—Electric or magnetic properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/046—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of foam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B32B5/245—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it being a foam layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/007—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with means for controlling the absorption
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H05K9/0084—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising a single continuous metallic layer on an electrically insulating supporting structure, e.g. metal foil, film, plating coating, electro-deposition, vapour-deposition
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2605/00—Vehicles
    • B32B2605/18—Aircraft

Abstract

본 발명은, 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재 및 이의 제조방법에 관한 것으로서, 특히 전자기파 흡수 성능을 발휘하고 낙뢰 피격 후에도 금속층 아래 구조물을 보호하는 복합재에 관한 것이다. 본 발명은 유리 섬유, aramid 섬유 또는 케블라 섬유 중 적어도 어느 하나를 포함하는 유전체 섬유; 상기 유전체 섬유의 표면에 전자기적 손실 또는 전자파 흡수를 구현하기 위해 금속 무전해(無電解) 도금 처리한 도금 유전체 섬유; 상기 유전체 섬유 및 상기 도금 유전체 섬유의 하부에 적층되는 폼코어; 및 상기 폼코어의 하부에 적층되며 레이더포착면적(RCS, Radar Cross Section) 감소 및 낙뢰보호를 위해 주기적인 원형 패턴이 적용된 금속층을 포함하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재를 제공한다.The present invention relates to an electromagnetic wave absorbing foam-based sandwich composite for aircraft in which a lightning protection metal layer is inserted and a method for manufacturing the same, and in particular, to a composite material that exhibits electromagnetic wave absorbing performance and protects a structure under a metal layer even after being struck by lightning. The present invention relates to a dielectric fiber including at least one of glass fiber, aramid fiber or Kevlar fiber; Plated dielectric fibers treated with metal electroless plating to implement electromagnetic loss or electromagnetic wave absorption on the surface of the dielectric fibers; a foam core laminated under the dielectric fiber and the plated dielectric fiber; And an electromagnetic wave absorbing foam-based sandwich composite for aircraft in which a lightning protection metal layer including a metal layer laminated on the lower portion of the foam core and having a periodic circular pattern applied thereto to reduce a radar cross section (RCS) and protect lightning strikes is inserted. to provide.

Description

낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재{MICROWAVE ABSORBING FORM BASED SANDWICH COMPOSITE WITH METALLIC LIGHTNING PROTECTION LAYER}MICROWAVE ABSORBING FORM BASED SANDWICH COMPOSITE WITH METALLIC LIGHTNING PROTECTION LAYER}

본 발명은 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재 및 이의 제조방법에 관한 것으로서, 특히 전자기파 흡수 성능을 발휘하고 낙뢰 피격 후에도 금속층 아래 구조물을 보호하여 스텔스 성능을 유지할 수 있는 전자기파 흡수 폼 기반 샌드위치 복합재에 관한 것이다.The present invention relates to an electromagnetic wave absorbing foam-based sandwich composite for aircraft in which a lightning protection metal layer is inserted and a method for manufacturing the same, and in particular, an electromagnetic wave absorbing foam capable of exhibiting electromagnetic wave absorbing performance and maintaining stealth performance by protecting a structure under the metal layer even after being struck by lightning It relates to a based sandwich composite.

항공기가 운항할 때 발생하는 낙뢰는 고온의 열에너지, 강한 전자기장을 유발하여 항공기에 직, 간접적으로 영향을 미친다. 항공기 운항 관점에서 낙뢰는 매우 위험한 요소이기 때문에 낙뢰 보호 시스템은 필수적으로 요구된다. 이를 대비하기 위해 항공기 기업들은 CM (Copper mesh), EMF (Expanded metal foil)과 같은 낙뢰 보호 시스템을 항공기에 적용하고 있다. 낙뢰는 크게 직접 영향과 간접 영향으로 구분되며, 직접 영향은 최대 200 kA에 이르는 고전류에 의한 열에너지와 전기적 충격에 의해 항공기 스킨, 윈드실드, 레이돔 등에 용융, 파손, 천공 등과 같은 영구적 손상을 발생시켜 안전성에 큰 영향을 미친다. Lightning that occurs when an aircraft is operating directly or indirectly affects the aircraft by causing high-temperature thermal energy and a strong electromagnetic field. Since lightning is a very dangerous factor in terms of aircraft operation, a lightning protection system is essential. To prepare for this, aircraft companies are applying lightning protection systems such as CM (Copper mesh) and EMF (Expanded metal foil) to aircraft. Lightning is largely divided into direct and indirect effects, and direct impact causes permanent damage such as melting, damage, and perforation to aircraft skin, windshield, and radome due to thermal energy and electrical shock caused by high currents of up to 200 kA, resulting in safety. have a great influence on

최근의 항공기 구조는 경량화 및 연료 효율을 높이기 위해 복합재 구조가 많이 사용되고 있는데 특히 복합재는 전기 전도도가 낮기 때문에 금속보다 낙뢰에 더 취약하다. 복합재의 높은 전기 저항은 순간적으로 열에너지(Joule 가열)로 변환되는 더 많은 전기 에너지를 흡수한다. 결과적으로 극도의 낙뢰 전류가 빠르게 전도되는 것을 방해하여, 아크 스파크, Joule 가열, 자기력 또는 절연 파괴를 초래한다. 또한 복합재를 구성하는 수지 매트릭스는 낮은 열 안정성 때문에 낙뢰 저항 열 또는 스파크에서 열화, 균열 또는 연소된다. 따라서 복합재 사용 비중이 증가함에 따라 항공기의 안전을 위해 고효율 낙뢰 보호시스템을 설계하는 것은 반드시 고려되어야 한다. In recent aircraft structures, composite structures are widely used to reduce weight and increase fuel efficiency. In particular, composite materials are more vulnerable to lightning strikes than metals because of their low electrical conductivity. The high electrical resistance of the composite absorbs more electrical energy which is instantly converted to thermal energy (Joule heating). As a result, extreme lightning currents are prevented from conducting quickly, resulting in arc sparks, Joule heating, magnetic force or dielectric breakdown. In addition, the resin matrix constituting the composite material deteriorates, cracks, or burns in lightning-resistant heat or sparks because of its low thermal stability. Therefore, as the proportion of composite materials increases, designing a high-efficiency lightning protection system for aircraft safety must be considered.

복합재 항공기 구조에서 낙뢰 보호 시스템을 적용하기 위해서는 일반적으로 두께가 얇은 금속층을 복합재 구조 외부에 적층하는 방법을 사용한다. 낙뢰가 복합재 구조물에 피격되었을 때 낙뢰 전류가 상대적으로 전기전도도가 높은 금속층을 따라 흘러나가게 되므로 복합재 구조물과 내부의 파손을 방지할 수 있다.In order to apply a lightning protection system in a composite aircraft structure, a method of laminating a thin metal layer on the outside of the composite structure is generally used. When lightning hits the composite structure, the lightning current flows along the metal layer with relatively high electrical conductivity, so damage to the composite structure and its interior can be prevented.

이와 관련, 종래의 한국공개특허 제10-2016-0110648호는 메탈 와이어 메쉬 및 장섬유 보강 열가소성 플라스틱 시트를 포함하는 복합재를 개시한다.In this regard, conventional Korean Patent Publication No. 10-2016-0110648 discloses a composite material including a metal wire mesh and a long fiber reinforced thermoplastic sheet.

하지만, 메탈 메쉬(Metal mesh)를 전자기파 흡수 구조에 적용할 경우, 낙뢰 피격으로 인한 구조적인 손상은 예방할 수 있으나 복합재 구조 외부에 위치한 메탈 메쉬로 인해 입사된 전자기파를 대부분 반사 시키기 때문에 전자기파 흡수 구조의 역할을 제대로 수행할 수 없는 문제점이 있다.However, when a metal mesh is applied to an electromagnetic wave absorbing structure, structural damage caused by lightning strikes can be prevented, but the metal mesh located outside the composite structure reflects most of the incident electromagnetic wave, so the role of the electromagnetic wave absorbing structure There is a problem that cannot be performed properly.

한국공개특허 제10-2016-0110648호Korean Patent Publication No. 10-2016-0110648

본 발명은 우수한 전자파 흡수성능을 발휘하고, 전기전도도가 높은 금속층을 적용한 낙뢰보호 시스템을 통해 낙뢰 피격 후에도 하중지지 및 전자기파 흡수성능을 유지할 수 있는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재를 제공하는 것을 목적으로 한다.The present invention is an electromagnetic wave absorbing foam-based sandwich composite for aircraft with a lightning protection metal layer capable of maintaining load bearing and electromagnetic wave absorption performance even after being struck by lightning through a lightning protection system using a metal layer with excellent electromagnetic wave absorption performance and high electrical conductivity. is intended to provide

상기 목적을 달성하기 위하여 본 발명은, 유리 섬유, aramid 섬유 또는 케블라 섬유 중 적어도 어느 하나를 포함하는 유전체 섬유; 상기 유전체 섬유의 표면에 전자기적 손실 또는 전자파 흡수를 구현하기 위해 금속 무전해(無電解) 도금 처리한 도금 유전체 섬유; 상기 유전체 섬유 및 상기 도금 유전체 섬유의 하부에 적층되는 폼코어; 및 상기 폼코어의 하부에 적층되며 레이더포착면적(RCS, Radar Cross Section) 감소 및 낙뢰보호를 위해 주기적인 원형 패턴이 적용된 금속층을 포함하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재를 제공한다.The present invention in order to achieve the above object, a dielectric fiber comprising at least one of glass fiber, aramid fiber or Kevlar fiber; Plated dielectric fibers treated with metal electroless plating to implement electromagnetic loss or electromagnetic wave absorption on the surface of the dielectric fibers; a foam core laminated under the dielectric fiber and the plated dielectric fiber; And an electromagnetic wave absorbing foam-based sandwich composite for aircraft in which a lightning protection metal layer including a metal layer laminated on the lower portion of the foam core and having a periodic circular pattern applied thereto to reduce a radar cross section (RCS) and protect lightning strikes is inserted. to provide.

실시 예에 따라, 상기 복합재는, 상기 유전체 섬유, 도금 유전체 섬유, 폼코어, 금속층 순으로 적층되고, 상기 금속층 하부에 추가적인 도금 유전체 섬유, 유전체 섬유, 폼코어가 적층되어 형성될 수 있다.According to an embodiment, the composite material may be formed by stacking the dielectric fiber, the plated dielectric fiber, the foam core, and the metal layer in that order, and further plating the dielectric fiber, the dielectric fiber, and the foam core under the metal layer.

실시 예에 따라, 상기 금속층은, 기 설정된 정사각형 내부에 소정의 지름을 갖는 원형 패턴이 소정의 간격으로 배치될 수 있다.According to an embodiment, in the metal layer, a circular pattern having a predetermined diameter may be disposed at predetermined intervals inside a predetermined square.

실시 예에 따라, 상기 금속층은, 상기 정사각형의 한 변이 11.67mm이고, 상기 원형 패턴은 지름이 10.67mm로 형성되며, 상기 간격은 1mm 이하로 형성될 수 있다.According to an embodiment, in the metal layer, one side of the square is 11.67 mm, the circular pattern is formed to have a diameter of 10.67 mm, and the interval may be formed to 1 mm or less.

실시 예에 따라, 상기 금속층은, 0.102mm의 두께로 형성되며 전기 전도도는 1.25×106 S/m 일 수 있다.According to an embodiment, the metal layer may be formed to a thickness of 0.102 mm and have an electrical conductivity of 1.25×10 6 S/m.

실시 예에 따라, 상기 금속층은, 8.2GHz 내지 12.4GHz의 주파수 대역에서 -10Db 이하의 전자기파 흡수 성능이 구현될 수 있다.According to an embodiment, the metal layer may have an electromagnetic wave absorption performance of -10 Db or less in a frequency band of 8.2 GHz to 12.4 GHz.

실시 예에 따라, 상기 복합재는 낙뢰 발생시 상기 금속층 하부는 보호될 수 있다.Depending on the embodiment, the lower portion of the metal layer of the composite material may be protected when lightning strikes.

전술한 바와 같은 구성을 갖는 본 발명에 따르면, 특정 주파수 대역 전자기파를 흡수하고, 낙뢰 발생 시 복합재 구조물과 내부의 파손을 줄여주는 이점이 있다.According to the present invention having the configuration as described above, there is an advantage in absorbing electromagnetic waves of a specific frequency band and reducing damage to the composite structure and the interior when lightning strikes.

도 1은 전자기파 흡수 폼 기반 샌드위치 복합재를 나타내며, 도1(a)는 종래의 복합재, 도1(b)는 본 발명의 복합재를 나타낸다.
도 2는 유전체 섬유와 니켈 무전해 도금된 유전체 섬유의 복소 유전율을 나타낸다.
도 3은 본 발명의 실시 예에 따라 니켈 무전해 도금된 도금 유전체 섬유의 SEM image, EDS, XPS를 나타낸다.
도 4는 본 발명의 실시 예에 따른 원형 패턴이 적용된 얇은 금속층이다.
도 5는 본 발명의 실시 예에 따라 낙뢰 보호 금속층 유무에 따른 전자기파 흡수 성능 설계 결과를 나타낸다.
도 6은 본 발명의 실시 예에 따른 복합재의 제작 과정을 나타낸다.
도 7은 본 발명의 실시 예에 따른 복합재의 전자기파 흡수성능을 평가하기 위해 자유공간 측정장비를 이용하여 Return loss 및 1D scan을 수행하는 모습이다.
도 8은 금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 전자기파 흡수성능을 나타낸다.
도 9는 본 발명의 실시 예에 따라 금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 전자기파 흡수성능을 나타낸다.
도 10은 본 발명의 실시 예에 따라 Impulse current generator 및 낙뢰시험 set-up을 나타낸다.
도 11은 본 발명의 실시 예에 따른 낙뢰 시험 전류 파형을 나타낸다.
도 12는 본 발명의 실시 예에 따른 낙뢰 시험 후 금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 (a) 파손 사진, (b) 이미지 프로세싱으로 얻은 손상 영역, (c) 3D X-ray CT 측정 결과(시편 단면)
도 13은 본 발명의 실시 예에 따른 낙뢰 시험 후 금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 (a) 파손 사진, (b) 이미지 프로세싱으로 얻은 손상 영역, (c) 3D X-ray CT 측정 결과(시편 단면)
도 14는 본 발명의 실시 예에 따른 금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 낙뢰 시험 후 전자기파 흡수 성능을 비교한 모습이다.
도 15는 본 발명의 실시 예에 따른 금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 낙뢰 시험 후 전자기파 흡수 성능을 비교한 모습이다.1 shows an electromagnetic wave absorbing foam-based sandwich composite, FIG. 1(a) shows a conventional composite, and FIG. 1(b) shows a composite of the present invention.
2 shows the complex permittivity of a dielectric fiber and a nickel electroless plated dielectric fiber.
3 shows SEM images, EDS, and XPS of nickel electroless plated dielectric fibers according to an embodiment of the present invention.
4 is a thin metal layer to which a circular pattern is applied according to an embodiment of the present invention.
5 shows electromagnetic wave absorption performance design results according to the presence or absence of a lightning protection metal layer according to an embodiment of the present invention.
6 shows a manufacturing process of a composite material according to an embodiment of the present invention.
7 is a view of performing return loss and 1D scan using free space measuring equipment to evaluate the electromagnetic wave absorption performance of a composite material according to an embodiment of the present invention.
8 shows the electromagnetic wave absorbing performance of the electromagnetic wave absorbing foam-based sandwich composite structure in which no metal layer is inserted.
9 shows electromagnetic wave absorbing performance of a sandwich composite structure based on electromagnetic wave absorbing foam in which a metal layer is inserted according to an embodiment of the present invention.
10 shows an impulse current generator and a lightning test set-up according to an embodiment of the present invention.
11 shows a lightning test current waveform according to an embodiment of the present invention.
12 shows (a) a picture of damage, (b) a damaged area obtained by image processing, and (c) a 3D X-ray CT of an electromagnetic wave absorbing foam-based sandwich composite structure without a metal layer inserted after a lightning test according to an embodiment of the present invention. Measurement result (specimen section)
13 shows (a) a photograph of damage, (b) a damaged area obtained by image processing, and (c) 3D X-ray CT measurement of an electromagnetic wave absorbing foam-based sandwich composite structure in which a metal layer is inserted after a lightning test according to an embodiment of the present invention. Results (specimen section)
14 is a comparison of electromagnetic wave absorbing performance after a lightning test of an electromagnetic wave absorbing foam-based sandwich composite structure in which a metal layer is not inserted according to an embodiment of the present invention.
15 is a comparison of electromagnetic wave absorbing performance after a lightning test of an electromagnetic wave absorbing foam-based sandwich composite structure in which a metal layer is inserted according to an embodiment of the present invention.

이하, 본 명세서에서 사용되는 용어에 대해 간략히 설명하고, 본 발명을 실시하기 위한 구체적인 내용으로서 본 발명의 바람직한 실시 예의 구성과 작용에 대해 구체적으로 설명하기로 한다.Hereinafter, terms used in this specification will be briefly described, and the configuration and operation of a preferred embodiment of the present invention will be described in detail as specific contents for carrying out the present invention.

본 명세서에서 사용되는 용어는 본 발명에서의 기능을 고려하면서 가능한 현재 널리 사용되는 일반적인 용어들을 선택하였으나, 이는 당 분야에 종사하는 기술자의 의도 또는 판례, 새로운 기술의 출현 등에 따라 달라질 수 있다. 또한, 특정한 경우는 출원인이 임의로 선정한 용어도 있으며, 이 경우 해당되는 발명의 설명 부분에서 상세히 그 의미를 기재할 것이다. 따라서 본 발명에서 사용되는 용어는 단순한 용어의 명칭이 아닌, 그 용어가 가지는 의미와 본 발명의 전반에 걸친 내용을 토대로 정의되어야 한다. The terms used in this specification have been selected from general terms that are currently widely used as much as possible while considering the functions in the present invention, but these may vary depending on the intention of a person skilled in the art, precedent, or the emergence of new technologies. In addition, in a specific case, there is also a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, not simply the name of the term.

명세서 전체에서 어떤 부분이 어떤 구성요소를 "포함"한다고 할 때, 이는 특별히 반대되는 기재가 없는 한 다른 구성요소를 제외하는 것이 아니라 다른 구성요소를 더 포함할 수 있음을 의미한다. 또한, 명세서에 기재된 "~부", "모듈" 등의 용어는 적어도 하나의 기능이나 동작을 처리하는 단위를 의미하며, 이는 하드웨어 또는 소프트웨어로 구현되거나 하드웨어와 소프트웨어의 결합으로 구현될 수 있다. 또한, 명세서 전체에서 어떤 부분이 다른 부분과 "연결"되어 있다고 할 때, 이는 "직접적으로 연결"되어 있는 경우뿐 아니라, "그 중간에 다른 구성을 사이에 두고" 연결되어 있는 경우도 포함한다.When it is said that a certain part "includes" a certain component throughout the specification, it means that it may further include other components without excluding other components unless otherwise stated. In addition, terms such as “~unit” and “module” described in the specification refer to a unit that processes at least one function or operation, and may be implemented as hardware or software or a combination of hardware and software. In addition, when a part is said to be "connected" to another part throughout the specification, this includes not only the case of being "directly connected" but also the case of being connected "with another component in between".

아래에서는 첨부한 도면을 참조하여 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자가 용이하게 실시할 수 있도록 본 발명의 실시 예를 상세히 설명한다. 그러나 본 발명은 여러 가지 상이한 형태로 구현될 수 있으며 여기에서 설명하는 실시 예에 한정되지 않는다. 그리고 도면에서 본 발명을 명확하게 설명하기 위해서 설명과 관계없는 부분은 생략하였으며, 명세서 전체를 통하여 유사한 부분에 대해서는 유사한 도면 부호를 붙였다.Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice with reference to the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

본 발명은 낙뢰 보호 금속층이 포함된 항공기용 전자기파 흡수 샌드위치 복합재에 관한 것으로, 유전체 섬유, 도금 유전체 섬유, 폼코어 및 금속층을 포함한다. 특히 전자기적 손실을 부여하기 위해 금속 무전해 도금 기법을 활용하여 X 밴드(8.2-12.4 GHz)에서 RCS 감소 효과를 보이도록 설계된 전자기파 흡수체에 전기전도도가 높은 금속층(Metallic layer)을 적용시켜 낙뢰 보호 성능도 발휘되는 항공기용 샌드위치 구조물에 관한 것을 포함한다.The present invention relates to an electromagnetic wave absorbing sandwich composite for aircraft including a lightning protection metal layer, and includes a dielectric fiber, a plated dielectric fiber, a foam core, and a metal layer. In particular, lightning protection performance by applying a metallic layer with high electrical conductivity to the electromagnetic wave absorber designed to show RCS reduction effect in the X band (8.2-12.4 GHz) by utilizing metal electroless plating technique to impart electromagnetic loss. It also includes those related to aircraft sandwich structures that are also exhibited.

도 1은 전자기파 흡수 폼 기반 샌드위치 복합재를 나타내며, 도1(a)는 종래의 복합재, 도1(b)는 본 발명의 복합재를 나타낸다.1 shows an electromagnetic wave absorbing foam-based sandwich composite, FIG. 1(a) shows a conventional composite, and FIG. 1(b) shows a composite of the present invention.

도 1(b)를 참고하면, 본 발명의 복합재는 유리 섬유, aramid 섬유 또는 케블라 섬유 중 적어도 어느 하나를 포함하는 유전체 섬유; 상기 유전체 섬유의 표면에 전자기적 손실 또는 전자파 흡수를 구현하기 위해 금속 무전해(無電解) 도금 처리한 도금 유전체 섬유; 상기 유전체 섬유 및 상기 도금 유전체 섬유의 하부에 적층되는 폼코어; 및 상기 폼코어의 하부에 적층되며 레이더포착면적(RCS, Radar Cross Section) 감소 및 낙뢰보호를 위해 주기적인 원형 패턴이 적용된 금속층을 포함한다.Referring to Figure 1 (b), the composite material of the present invention is a dielectric fiber including at least one of glass fiber, aramid fiber or Kevlar fiber; Plated dielectric fibers treated with metal electroless plating to implement electromagnetic loss or electromagnetic wave absorption on the surface of the dielectric fibers; a foam core laminated under the dielectric fiber and the plated dielectric fiber; And a metal layer laminated on the lower portion of the foam core and having a periodic circular pattern applied thereto to reduce a Radar Cross Section (RCS) and to protect against lightning strikes.

본 발명은 입사된 전자기파 흡수 성능을 나타냄과 동시에 낙뢰 보호 금속층이 삽입된 항공기용 폼 기반 샌드위치 평판형 구조로, 낙뢰 보호 금속층은 주기 원형 패턴이 적용된 얇은 금속 막이며, 이는 전자기파 흡수 성능에 영향을 미치지 않고, 낙뢰로부터 복합재 구조물을 보호하는 역할을 한다.The present invention is a foam-based sandwich plate-type structure for aircraft in which a lightning protection metal layer is inserted while exhibiting incident electromagnetic wave absorption performance. The lightning protection metal layer is a thin metal film to which a periodic circular pattern is applied, which does not affect the electromagnetic wave absorption performance. It also serves to protect composite structures from lightning strikes.

상기 복합재는, 유전체 섬유, 도금 유전체 섬유, 폼코어, 금속층 순으로 적층되고, 금속층 하부에 추가적인 도금 유전체 섬유, 유전체 섬유, 폼코어가 적층되어 형성될 수 있다.The composite material may be formed by stacking dielectric fibers, plated dielectric fibers, a foam core, and a metal layer in this order, and further plated dielectric fibers, dielectric fibers, and a foam core are laminated under the metal layer.

전자기파를 효과적으로 흡수하는 낙뢰 보호 금속층이 삽입된 폼 기반 샌드위치 구조를 해석프로그램(CST Studio)를 통해 설계하고, X-band(8.2-12.4 GHz) 대역에서 90% 이상의 전자기파 흡수 성능을 나타낼 수 있도록 설계 및 제작하였다.A foam-based sandwich structure with a lightning protection metal layer that effectively absorbs electromagnetic waves is designed through an analysis program (CST Studio), and it is designed to show more than 90% of electromagnetic wave absorption performance in the X-band (8.2-12.4 GHz) band. produced.

반사 손실(Return loss)을 측정하여, 전자기파 흡수체의 성능을 검증하도록 설계되고, 반사 손실(Return loss)은 다음과 같이 나타낼 수 있다. It is designed to verify the performance of the electromagnetic wave absorber by measuring the return loss, and the return loss can be expressed as follows.

반사 손실(Return loss) =

Figure pat00001
Return loss =
Figure pat00001

(여기서,

Figure pat00002
: 반사손실계수,
Figure pat00003
: 입사 임피던스,
Figure pat00004
: 자유공간 임피던스 = 377
Figure pat00005
)(here,
Figure pat00002
: Return loss coefficient,
Figure pat00003
: incident impedance,
Figure pat00004
: Free space impedance = 377
Figure pat00005
)

다층형 Dallenbach absorber의 입사 임피던스 =

Figure pat00006
Incident impedance of multilayer Dallenbach absorber =
Figure pat00006

(여기서,

Figure pat00007
: i번째 층의 특성 임피던스(
Figure pat00008
),
Figure pat00009
: i번째 층의 전파정수(
Figure pat00010
=
Figure pat00011
),
Figure pat00012
: i번째 층의 두께)(here,
Figure pat00007
: Characteristic impedance of the ith layer (
Figure pat00008
),
Figure pat00009
: Propagation constant of the ith layer (
Figure pat00010
=
Figure pat00011
),
Figure pat00012
: thickness of the ith layer)

Return loss 측정이 완료된 흡수체는 낙뢰 시험을 통하여 낙뢰 보호 성능을 평가한다. 본 발명의 복합재 구조는 Dallenbach layer로 구현되어 7층형 복합재 구조로 설계 및 제작되었다. 유리섬유/에폭시와 금속 무전해 도금된 유리섬유/에폭시, 원형 패턴이 에칭된 얇은 금속 막으로 구성되어 있고, 임피던스 정합을 일으키며 최적의 전자기파 흡수 성능을 갖는 두께 및 패턴의 형상을 설계하였다.The absorber for which the return loss measurement is completed evaluates the lightning protection performance through the lightning test. The composite structure of the present invention is implemented as a Dallenbach layer and designed and manufactured as a 7-layer composite structure. It is composed of glass fiber/epoxy, metal electroless plated glass fiber/epoxy, and a thin metal film etched with a circular pattern, and the thickness and shape of the pattern that produces impedance matching and has optimal electromagnetic wave absorption performance are designed.

본 발명의 실시 예에 따라, 아래 표 1과 같이 Layer 1 내지 7로 구성될 수 있다.According to an embodiment of the present invention, it may be composed of Layers 1 to 7 as shown in Table 1 below.

Layer 1Layer 1 0.250 mm (유리섬유/에폭시)0.250 mm (fiberglass/epoxy) Layer 2Layer 2 0.500 mm (금속 무전해 도금된 유리섬유/에폭시)0.500 mm (metal electroless plated fiberglass/epoxy) Layer 3Layer 3 2.000 mm (Foam core)2.000 mm (Foam core) Layer 4Layer 4 0.102 mm (얇은 금속층)0.102 mm (thin metal layer) Layer 5Layer 5 0.750 mm (금속 무전해 도금된 유리섬유/에폭시)0.750 mm (metal electroless plated fiberglass/epoxy) Layer 6Layer 6 0.250 mm (유리섬유/에폭시)0.250 mm (fiberglass/epoxy) Layer 7Layer 7 3.000 mm (Foam core)3.000 mm (Foam core)

도 2는 유전체 섬유와 니켈 무전해 도금된 유전체 섬유의 복소 유전율을 나타낸다.2 shows the complex permittivity of a dielectric fiber and a nickel electroless plated dielectric fiber.

도 2를 참조하면, 본 발명의 실시 예에 따라 10 GHz 에서 복소 유전율이 측정되었으며, 유전체 섬유와 니켈 무전해 도금된 유전체 섬유의 화학적 결정 분석이 상이한 점을 보여준다.Referring to FIG. 2, the complex permittivity was measured at 10 GHz according to an embodiment of the present invention, and the chemical crystal analysis of the dielectric fiber and the nickel electroless plated dielectric fiber show differences.

10 GHz에서 유전체 섬유의 복소 유전율은 4.57-j0.05이고, 니켈 무전해 도금된 유전체 섬유의 복소 유전율은 5.77-j6.60로 나타났다.At 10 GHz, the complex permittivity of the dielectric fiber was 4.57-j0.05, and the complex permittivity of the nickel electroless-plated dielectric fiber was 5.77-j6.60.

도 3은 본 발명의 실시 예에 따라 니켈 무전해 도금된 도금 유전체 섬유의 SEM image, EDS, XPS를 나타낸다.3 shows SEM images, EDS, and XPS of nickel electroless plated dielectric fibers according to an embodiment of the present invention.

도 3을 참조하면, 니켈 무전해 도금된 유전체 섬유의 화학적 결정 분석을 위해 SEM image(scanning electron microscope), EDS (energy-dispersive X-ray spectroscopy) 성분 분석, XPS(X-ray photoelectron spectroscopy)를 수행하였다.Referring to FIG. 3, SEM image (scanning electron microscope), EDS (energy-dispersive X-ray spectroscopy) component analysis, and XPS (X-ray photoelectron spectroscopy) are performed for chemical crystal analysis of nickel electroless plated dielectric fibers. did

SEM image를 통해 유전체 섬유 표면에 니켈이 균일하게 코팅된 것을 확인하였고, EDS 성분분석을 통해 섬유 표면의 Ni 성분 함량이 증가된 것을 확인하였다. XPS 측정을 통해 856.1 eV에서 Ni 성분 피크가 확인되었으며, 이는 855.6eV에서 857.9eV에 이르는 니켈 결합 에너지의 값과 일치하며, 2가 산화 상태를 유지한다.Through the SEM image, it was confirmed that nickel was uniformly coated on the surface of the dielectric fiber, and through EDS component analysis, it was confirmed that the content of the Ni component on the surface of the fiber was increased. The Ni component peak at 856.1 eV was confirmed through XPS measurement, which is consistent with the value of nickel binding energy ranging from 855.6 eV to 857.9 eV, maintaining the divalent oxidation state.

도 4는 본 발명의 실시 예에 따른 원형 패턴이 적용된 얇은 금속층이다.4 is a thin metal layer to which a circular pattern is applied according to an embodiment of the present invention.

도 4를 참조하면, 금속층은 기 설정된 정사각형 내부에 소정의 지름을 갖는 원형 패턴이 소정의 간격으로 배치되어 있다.Referring to FIG. 4 , in the metal layer, circular patterns having a predetermined diameter are arranged at predetermined intervals within a predetermined square.

본 발명의 실시 예에 따라, 정사각형의 한 변이 11.67mm이고, 원형 패턴은 지름이 10.67mm로 형성되며, 간격은 1mm 이하로 형성될 수 있다. 이 경우, 원형 패턴을 적용하여 설계된 낙뢰 보호 기능의 금속층의 전기 전도도는 1.25 × 106 S/m 로 측정될 수 있다.According to an embodiment of the present invention, a side of a square is 11.67 mm, a circular pattern is formed with a diameter of 10.67 mm, and an interval of 1 mm or less may be formed. In this case, the electrical conductivity of the metal layer of the lightning protection function designed by applying the circular pattern may be measured as 1.25 × 10 6 S/m.

도 5는 본 발명의 실시 예에 따라 낙뢰 보호 금속층 유무에 따른 전자기파 흡수 성능 설계 결과를 나타낸다.5 shows electromagnetic wave absorption performance design results according to the presence or absence of a lightning protection metal layer according to an embodiment of the present invention.

도 5를 참조하면, 복합재 구조의 낙뢰 보호 금속층의 유무에 따른 전자기파 흡수 성능을 알 수 있다. Referring to FIG. 5 , electromagnetic wave absorption performance according to the presence or absence of the lightning protection metal layer of the composite structure can be seen.

전자기파 흡수 폼 기반 샌드위치 복합재 구조의 전자기파 흡수성능을 평가하기 위해 CST Studio 프로그램을 통해 설계하고 해석을 진행하였다. 복합재 구조는 8.2-12.4 GHz 대역에서 -10dB 이하의 흡수 성능(90% 이상의 흡수성능)을 보였다.In order to evaluate the electromagnetic wave absorbing performance of the electromagnetic wave absorbing foam-based sandwich composite structure, it was designed and analyzed through the CST Studio program. The composite structure showed an absorption performance of less than -10dB (over 90% absorption performance) in the 8.2-12.4 GHz band.

도 6은 본 발명의 실시 예에 따른 복합재의 제작 과정을 나타내며, 도 7은 반사 손실(Return loss)과 1D scan 과정을 보여준다.6 shows a manufacturing process of a composite material according to an embodiment of the present invention, and FIG. 7 shows a return loss and a 1D scan process.

도 6을 참조하면, 복합재의 제작 과정은 (a) lay up, (b) curing accessories (c)vacuum bagging (d)curing & curing cycle (e)specimen 과정으로 이루어져 있고, 도 7을 참조하면 본 발명의 실시 예에 따른 복합재의 전자기파 흡수성능을 평가하기 위해 자유공간 측정장비를 이용하여 Return loss 및 1D scan을 수행하는 모습을 알 수 있다.Referring to FIG. 6, the manufacturing process of the composite material consists of (a) lay up, (b) curing accessories (c) vacuum bagging (d) curing & curing cycle (e) specimen process, and referring to FIG. 7, the present invention It can be seen that return loss and 1D scan are performed using free space measuring equipment to evaluate the electromagnetic wave absorption performance of the composite material according to the embodiment of.

제작된 복합재 구조의 전자기파 흡수성능을 평가하기 위해 자유공간 측정장비를 이용한 Return loss 및 1D scan을 수행하였으며, 다. 금속층이 삽입된 복합재 구조는 10 GHz의 목표 주파수에서 측정하였고, 금속층이 삽입되지 않은 복합재 구조는 7.5 GHz의 목표 주파수에서 측정하였다.Return loss and 1D scan were performed using free space measurement equipment to evaluate the electromagnetic wave absorption performance of the fabricated composite structure. The composite structure in which the metal layer was inserted was measured at a target frequency of 10 GHz, and the composite structure in which the metal layer was not inserted was measured at a target frequency of 7.5 GHz.

도 8은 금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 전자기파 흡수성능을 나타내고, 도 9는 본 발명의 실시 예에 따라 금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 전자기파 흡수성능을 나타낸다.FIG. 8 shows the electromagnetic wave absorbing performance of the electromagnetic wave absorbing foam-based sandwich composite structure in which no metal layer is inserted, and FIG. 9 shows the electromagnetic wave absorbing performance of the electromagnetic wave absorbing foam-based sandwich composite structure in which the metal layer is inserted according to an embodiment of the present invention.

도 8 및 도 9를 참조하면, 금속층의 유무에 따른 전자기파 흡수 성능을 알 수 있다. 이 경우, 금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조와 금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 전자기파 흡수 성능을 자유공간측정장비를 이용하여 측정하였으며, Referring to FIGS. 8 and 9 , electromagnetic wave absorption performance according to the presence or absence of the metal layer can be known. In this case, the electromagnetic wave absorption performance of the electromagnetic wave absorbing foam-based sandwich composite structure with a metal layer inserted and the electromagnetic wave absorbing foam-based sandwich composite structure without a metal layer was measured using free space measurement equipment,

금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조는 8.2~12.4 GHz 대역에서 -10dB 이하(90% 이상 흡수)의 흡수성능을 보였으며, 공진 주파수(10.5 GHz)에서 최대 -40 dB 이하의 흡수성능을 나타내었다. 1D scan 결과 역시, 10 GHz의 목표 주파수에서 복합재 구조 전영역에서 5% 미만의 reflection magnitude를 나타내었다.The electromagnetic wave absorbing foam-based sandwich composite structure with a metal layer inserted showed an absorption performance of less than -10dB (more than 90% absorption) in the 8.2~12.4 GHz band, and an absorption performance of less than -40dB at the resonance frequency (10.5 GHz). showed up The 1D scan results also showed a reflection magnitude of less than 5% in the entire area of the composite structure at the target frequency of 10 GHz.

금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 경우, 5.8~12.0 GHz 대역에서 -10dB 이하의 흡수성능을 보였으며, 공진 주파수(7.5 GHz)에서 최대 -30 dB 이하의 흡수성능을 나타내었다. 1D scan 결과 7.5 GHz의 목표 주파수에서 복합재 구조 전영역에서 5% 미만의 reflection magnitude를 나타내었다.In the case of the electromagnetic wave absorbing foam-based sandwich composite structure without the insertion of a metal layer, the absorption performance was below -10 dB in the 5.8 to 12.0 GHz band, and the maximum absorption performance was below -30 dB at the resonant frequency (7.5 GHz). As a result of the 1D scan, the reflection magnitude was less than 5% in the entire area of the composite structure at the target frequency of 7.5 GHz.

도 10은 본 발명의 실시 예에 따라 Impulse current generator 및 낙뢰시험 set-up을 나타내고, 도 11은 본 발명의 실시 예에 따른 낙뢰 시험 전류 파형을 나타낸다.10 shows an impulse current generator and a lightning test set-up according to an embodiment of the present invention, and FIG. 11 shows a lightning test current waveform according to an embodiment of the present invention.

도 11과 같은 전류 파형을 적용하여 도 10의 낙뢰시험을 셋업하였다. 도 10과 같은 실험 과정에서 Impulse current generator를 이용하여8/40 ㎲ 의 전류 파형과 50 kA 수준의 전류를 인가하여 낙뢰 시험을 수행하였다.The lightning test of FIG. 10 was set up by applying the same current waveform as in FIG. 11 . In the experimental process as shown in FIG. 10, a lightning test was performed by applying a current waveform of 8/40 μs and a current of 50 kA using an impulse current generator.

도 12 및 도 13은 본 발명의 실시 예에 따라 각각 낙뢰 시험 후 금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 및 금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 (a) 파손 사진, (b) 이미지 프로세싱으로 얻은 손상 영역, (c) 3D X-ray CT 측정 결과(시편 단면)을 나타낸다.12 and 13 are (a) damage photographs and (b) of an electromagnetic wave absorbing foam-based sandwich composite structure without a metal layer inserted and an electromagnetic wave absorbing foam-based sandwich composite structure with a metal layer inserted after a lightning test, respectively, according to an embodiment of the present invention. Damaged area obtained by image processing, (c) 3D X-ray CT measurement results (specimen section) are shown.

도 12 및 도 13을 참조하면, 낙뢰에 의한 손상 정도를 평가하기 위해 이미지 프로세싱과 3D X-ray CT 촬영을 수행 결과를 알 수 있다.Referring to FIGS. 12 and 13 , results of image processing and 3D X-ray CT imaging can be seen to evaluate the degree of damage caused by lightning.

이미지 프로세싱은 낙뢰로 인해 손상이 발생한 구조의 표면에 대해 빛의 반사율을 이용한 2진화 기법으로 손상 면적을 평가하였으며, 두께 방향으로의 손상 정도를 측정하기 위해 3D X-ray CT 촬영을 진행하였다. For image processing, the damage area was evaluated using a binary evolution method using the reflectance of light on the surface of the structure damaged by lightning, and 3D X-ray CT was taken to measure the degree of damage in the thickness direction.

금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조는 상부층에서부터 하부층까지 전체적인 파손이 일어남을 확인하였다. 반면에 금속층이 삽입된 전자기파 흡수 폼기반 샌드위치 복합재 구조의 경우 금속층 아래로 파손이 일어나지 않음을 확인할 수 있었다.It was confirmed that overall damage occurred from the top layer to the bottom layer of the electromagnetic wave absorbing foam-based sandwich composite structure without a metal layer inserted. On the other hand, in the case of the electromagnetic wave absorbing foam-based sandwich composite structure with the metal layer inserted, it was confirmed that no damage occurred under the metal layer.

실험 과정을 통해, 본 발명의 복합재 구조물은 낙뢰 발생시 금속층 하부는 보호될 수 있음을 확인하였다.Through the experimental process, it was confirmed that the composite structure of the present invention can protect the lower part of the metal layer in the event of lightning.

도 14는 본 발명의 실시 예에 따른 금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 낙뢰 시험 후 전자기파 흡수 성능이고, 도 15는 금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 낙뢰 시험 후 전자기파 흡수 성능을 비교한 모습이다.14 is electromagnetic wave absorbing performance after a lightning test of an electromagnetic wave absorbing foam-based sandwich composite structure without inserting a metal layer according to an embodiment of the present invention, and FIG. 15 is an electromagnetic wave absorbing performance after a lightning test of an electromagnetic wave absorbing foam-based sandwich composite structure with a metal layer inserted. This is a comparison of absorption performance.

도 14 및 도 15를 참조하면, 낙뢰 시험을 수행한 후 손상을 입은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 return loss와 1D scanning 결과를 알 수 있다.14 and 15, it can be seen the return loss and 1D scanning results of the electromagnetic wave absorbing foam-based sandwich composite structure damaged after performing the lightning test.

금속층이 삽입되지 않은 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 경우 return loss 측정 결과와 1D scan 결과에서 낙뢰에 의한 손상 후에 흡수 성능의 변화가 크고, 부분적으로 전자기파 흡수 성능을 발휘하지 못하는 것으로 나타났다.In the case of the electromagnetic wave absorbing foam-based sandwich composite structure without a metal layer inserted, the return loss measurement results and 1D scan results show that the absorption performance changes significantly after lightning damage and partially fails to exhibit the electromagnetic wave absorption performance.

반면에 금속층이 삽입된 전자기파 흡수 폼 기반 샌드위치 복합재 구조의 경우, return loss 결과를 통해 낙뢰 손상 후에도 8.2~12.4 GHz 대역에서 -10dB 이하의 흡수 성능을 나타내는 것을 확인하였고, 1D scan 결과에서도 전체 영역이 5% 이하의 return loss의 변화를 나타내었다. On the other hand, in the case of the electromagnetic wave absorbing foam-based sandwich composite structure with a metal layer inserted, it was confirmed through the return loss result that the absorption performance was below -10 dB in the 8.2 to 12.4 GHz band even after lightning damage, and the entire area was 5 % or less change in return loss was shown.

3D X-ray CT 통해 전자기파 흡수 폼 기반 샌드위치 복합재 구조에서 금속층 아래로 파손이 발생하지 않았음을 확인하였고, 낙뢰로 인한 파손 후에도 전자기파 흡수 성능을 유지하였다. 이를 통해 낙뢰 보호 금속층이 전자기파 흡수 폼 기반 샌드위치 복합재 구조에서 기계적 및 전자기적 손상 방지에 유효하다는 것을 확인하였다.Through 3D X-ray CT, it was confirmed that no damage occurred under the metal layer in the electromagnetic wave absorbing foam-based sandwich composite structure, and the electromagnetic wave absorbing performance was maintained even after damage caused by lightning. Through this, it was confirmed that the lightning protection metal layer is effective in preventing mechanical and electromagnetic damage in the electromagnetic wave absorbing foam-based sandwich composite structure.

이상에서 대표적인 실시예를 통하여 본 발명을 상세하게 설명하였으나, 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자는 상술한 실시예에 대하여 본 발명의 범주에서 벗어나지 않는 한도 내에서 다양한 변형이 가능함을 이해할 것이다. 그러므로 본 발명의 권리 범위는 설명한 실시예에 국한되어 정해져서는 안 되며, 후술하는 특허청구범위뿐만 아니라 특허청구범위와 균등 개념으로부터 도출되는 모든 변경 또는 변형된 형태에 의하여 정해져야 한다.Although the present invention has been described in detail through representative embodiments, those skilled in the art will understand that various modifications are possible to the above-described embodiments without departing from the scope of the present invention. will be. Therefore, the scope of the present invention should not be limited to the described embodiments and should not be defined, and should be defined by all changes or modifications derived from the claims and equivalent concepts as well as the claims to be described later.

Claims (7)

유리 섬유, aramid 섬유 또는 케블라 섬유 중 적어도 어느 하나를 포함하는 유전체 섬유;
상기 유전체 섬유의 표면에 전자기적 손실 또는 전자파 흡수를 구현하기 위해 금속 무전해(無電解) 도금 처리한 도금 유전체 섬유;
상기 유전체 섬유 및 상기 도금 유전체 섬유의 하부에 적층되는 폼코어; 및
상기 폼코어의 하부에 적층되며 레이더포착면적(RCS, Radar Cross Section) 감소 및 낙뢰보호를 위해 주기적인 원형 패턴이 적용된 금속층을 포함하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재.
a dielectric fiber including at least one of glass fiber, aramid fiber, and Kevlar fiber;
Plated dielectric fibers treated with metal electroless plating to implement electromagnetic loss or electromagnetic wave absorption on the surface of the dielectric fibers;
a foam core laminated under the dielectric fiber and the plated dielectric fiber; and
It is laminated on the lower part of the foam core and has a lightning protection metal layer including a metal layer applied with a periodic circular pattern to reduce the radar cross section (RCS) and lightning protection. Sandwich composite based on electromagnetic wave absorbing foam for aircraft.
 제 1 항에 있어서,
상기 복합재는,
상기 유전체 섬유, 도금 유전체 섬유, 폼코어, 금속층 순으로 적층되고,
상기 금속층 하부에 추가적인 도금 유전체 섬유, 유전체 섬유, 폼코어가 적층되어 형성되는 것을 특징으로 하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재.
According to claim 1,
The composite material,
The dielectric fiber, the plated dielectric fiber, the foam core, and the metal layer are laminated in this order,
An electromagnetic wave absorbing foam-based sandwich composite for aircraft with a lightning protection metal layer inserted, characterized in that additional plated dielectric fibers, dielectric fibers, and foam cores are laminated under the metal layer.
 제 1 항에 있어서,
상기 금속층은,
기 설정된 정사각형 내부에 소정의 지름을 갖는 원형 패턴이 소정의 간격으로 배치된 것을 특징으로 하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재.
According to claim 1,
The metal layer,
An electromagnetic wave absorbing foam-based sandwich composite for aircraft inserted with a lightning protection metal layer, characterized in that circular patterns having a predetermined diameter are arranged at predetermined intervals inside a predetermined square.
 제 3 항에 있어서,
상기 금속층은,
상기 정사각형의 한 변이 11.67mm이고,
상기 원형 패턴은 지름이 10.67mm로 형성되며,
상기 간격은 1mm 이하로 형성되는 것을 특징으로 하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재.
According to claim 3,
The metal layer,
One side of the square is 11.67 mm,
The circular pattern is formed to have a diameter of 10.67 mm,
The interval is an electromagnetic wave absorbing foam-based sandwich composite for aircraft inserted with a lightning protection metal layer, characterized in that formed to 1 mm or less.
 제 3 항에 있어서,
상기 금속층은,
0.102mm의 두께로 형성되며 전기 전도도는 1.25×106 S/m 인 것을 특징으로 하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재.
According to claim 3,
The metal layer,
Formed to a thickness of 0.102mm and having an electrical conductivity of 1.25×10 6 S/m A lightning protection metal layer is inserted for aircraft electromagnetic wave absorbing foam-based sandwich composite.
 제 1 항에 있어서,
상기 금속층은,
8.2GHz 내지 12.4GHz의 주파수 대역에서 -10Db 이하의 전자기파 흡수 성능이 구현되는 것을 특징으로 하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재.
According to claim 1,
The metal layer,
An electromagnetic wave absorbing foam-based sandwich composite for aircraft inserted with a lightning protection metal layer, characterized in that the electromagnetic wave absorption performance of -10Db or less is implemented in the frequency band of 8.2GHz to 12.4GHz.
 제 1 항에 있어서,
상기 복합재는 낙뢰 발생시 상기 금속층 하부는 보호되는 것을 특징으로 하는 낙뢰 보호 금속층이 삽입된 항공기용 전자기파 흡수 폼 기반 샌드위치 복합재.According to claim 1,
The composite material is an electromagnetic wave absorbing foam-based sandwich composite for aircraft inserted with a lightning protection metal layer, characterized in that the lower portion of the metal layer is protected when lightning occurs.
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