An Acoustic Reception Ability Analysis of SONAR Multilayer Structures by Using Elastic Theory

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Ǧ ȗȗȗǡǦȗȗȗȌ

Դڐʂॡİ३ت֨֟ࢰėॡٍĵՙ ԴڐʂॡİܓԸ३تėॡę ۻǫʂॡİ३تşցॡҙ Ķѓęॡٍĵՙ

ۿսێۙțښێս܁ێۙțښێ޽࢘ێۙțښێ

ొ ߧ: սܼИşߕćقەرՙǣ࢒ݓՁɠڹԦܕՁॳԜںڦॢܼڅॢۍۙۋɰ. ՙǣۆڼॳս֪Ձɠںࣷ؊ॠ şڦ३Դ࢏Ձۋ΁ںۋڌॠيՙǣɰࠗĵܓۆڼॳՁɠں३Եॠٕɰ. ɳտĵܓНقʂॠي࢏Ձۋ΁ںۺڌॠي

صڹ҆३ԵĀęεԜڌ३Ե॒ͿŔ͖ۍANSYSٮҼİॠٕČ, χܔॣχॢĀęεصؽɰ. êݒʽ࢏Ձۋ΁ںۋڌ ॠيՙǣɰࠗĵܓۆࠗѻ˃ƍѺজق˰δڼؓфъॳڼÇՙ३Եںսॱॠٕɰ. Иъॳ(anechoic)ࠗۆ˃ƍÀ

ݒÀॣս΀ܳࣷսق˰δڼؓۋČβóқपॠČъॳڼÇՙ͟ۋأÂݒÀॠəìںঝۍॠٕɰ. ҼĀ० (decoupling)ࠗęࣲ֟(steel)ࠗۆąڍ˃ƍق˰δڼؓۆѺজəäۆػڷǣ˃ƃڗݗս΀ъॳڼۋأÂÇՙॠ əĀęεǣࢍǴؽɰ. ࢏ՙÌজࣰ॔͆֟(Carbon Reinforced Platic, CRP)ࠗۆ˃ƍѺজəڼؓęъॳڼÇՙ͟ق

ٖॳۋػəìںঝۍॠٕɰ. ˰͆ԴՙǣɰࠗĵܓۆڼॳՁɠںȭۋşڦ३ԴəИъॳࠗں˃ƉóॠČ, ҼĀ०

ࠗ, ࣲ֟ࠗę࢏ՙÌজࣰ॔͆֟ࠗڹ߯ՙজॠəìۋц͊ݔॣìڷͿٚԜʽɰ.

ෑਕ૳ઘ: ɰࠗĵܓ, ࢏Ձۋ΁, ڼؓ३Ե, ъॳڼÇՙ

ABSTRACT: SONAR detection performance is one of the key survivability factors in underwater weapon systems. In order to catch the acoustic ability of SONAR, multilayer SONAR structures are analyzed using the elastic theory. The applied results for the simple models are compared with those from commercial program, ANSYS, and the reliable results are obtained. The analysis of sound pressure level (SPL) and echo reduction (ER) by the thickness change of multilayer SONAR structures are performed using the verified elastic theory. As the thickness of anechoic layer is increased, SPL is distributed evenly and ER is increased slightly with the frequency.

In decoupling layers and steel layers, SPL are hardly changed and ER is slightly decreased with the thickness increase of those layers. SPL and ER are not affected by the thickness change of the carbon reinforced plastic (CRP) layer. Therefore, to improve the acoustic ability of multilayer SONAR structures, the thickness increase of the anechoic layer and minimization of the decoupling layer, steel layer and CRP layer are desirable.

Keywords:Multilayer structure, Elastic theory, Sound press level (SPL), Echo redution (ER) PACS numbers:43.30.Ky

Department of Naval Architecture and Ocean Engineering, College of Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of Korea (Tel: 82-2-880-8757, Fax: 82-2-888-9298)

*Դ΁

ইʂИşߕćقەرԴԜʂѓقʂॢ࢒ݓɠ

ͳڹԦܕՁॳԜںڦॢܼڅॢۍܼۙۆॠǣۋ ɰ. ۋεڦ३࢒ݓɠͳۋ̬رǦՙǣۆÒьʪܼ

څॠݓχՙǣÀڙॠə֪঒À؉ɨՙڼۆٖॳ ںܶيՙǣÀ߯ۺۆڏڌՁɠںь৅ॣսەʪ

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(2)

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ՙǣۆɰࠗĵܓε۞ĵՁॠşڦ३Դəՙǣ ۆɰࠗĵܓقۆ३ьԦॠəڼॳս֪Ձɠق

ʂॢٚࠑۋज़څॠɰ. ɰتॢɰࠗĵܓقʂॢ

ڼॳս֪ՁɠٚࠑںࣀॠيՙǣÀ߯ۺۆڏ ڌՁɠںь৅ॣսەəՙǣɰࠗĵܓεĵՁ

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ĶǴٽۺڷͿՙǣۆɰࠗĵܓقʂॢٍĵə࣢

ՁԜ֖óۿŖॣսػڷдͿҙқۺۍ܁҃χս ݚÀɠॠ϶, ३ԵۆşߣÀʼəѕąۋ΁˞قʂ

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ory)ںۺڌ^[4-6]ॠيथϸࣷ(plane wave)ÀۓԐॠٕ

ں˺قʂ३ٍĵÀݕॱʼؽɰ. ɰتॢÀݕͳق

ʂ३ԴʪٍĵÀݕॱʼرşćۺÀݕ(mechanical excitation), ɳŕÀݕ(monopole excitation)قʂॢɰ

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ɰࠗĵܓÀێъۺۍ঍ԜںÀݓəąڍۋ΁ۺ ۍ३ԵںۺڌॠşقəॢćÀەڷдͿ࠻ौࢢε

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ʂًۆ३ԵقԐڌʼəşѪ˞Ϳ׆, ܳࣷսÀݒÀ

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ॢɰࠗथࣺϿʝق࢏Ձۋ΁ںۺڌॠٕɰ. սܼ॥

ۆԸࠑقţۋѓॳڷͿҙ޳ʼəՙǣۆąڍИ

ॢɰࠗथࣺڷͿϿʝτॠəìۋমęۺۋČ, ɰࠗ

ĵܓۆąڍ३ԵʂԜۋئڹथࣺۋ΁(thin plate theory)ںۺڌॠşقə˃ƉČ, ড়ڼۦۆäʴںश ইॠşقʪ࢏Ձۋ΁ۋʌۺ०ॠş˺Лۋɰ. Ǧ Ϊڮʴՙڼ३ԵقəCorcos ϿʝںԐڌॠٕɰ.

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ࡿ෉ۗ౾ඌൡଭ஺ࢼࢺ୨ਐ

SkeltonڹࠗۆąćقԴٍ՚ܓæںۺڌॢɰࠗ

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ս঍ࢗͿɰڼ֩ڷͿशইʽɰ.

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ćŞƎÞķìĸìƘß áŇŎŞƘ ^ÏƓƘÞķìĸìƘß. (2)

Ƙ á ƆٮƘ á ×قԴ֟घ࣡ͤؓͳƎÞķìĸìƘßٮą ćۆսݔѺڦƓ_ƘÞķì ĸì ƘßəɰڼęÏɰ.

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(3)

anechoic coating

steel plate water

GRP CRP plane wave water

Ň_ÏìƁ_Ïì_Ï Ň_ÐìƁ_Ðì_Ð Ň_ÑìƁ_Ñì_Ñ Ň_ÒìƁ_Òì_Ò Ň_ÎìƁ_Îì_Î

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order

Fluid or

Material E[Pa] Ń Ň [kg/m³] ^Ľ

h [mm]

c [m/s]

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1 CRP 9.8×10¹⁰ 0.3 2860 0.02 10

2 water 1000 1500

3 anechoic

material 6.2×10⁷ 0.48 1616 0.54 45 4 GRP 6.9×10¹⁰0.28 2520 0.02 12 5 steel plate 2.1×10¹¹ 0.3 7800 0.01 25

lower air 1.21 340

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Ɠ á x âx Z ©, (7)

ڦۆܓæںχܔॠə࢏ՁߕقԴۆԸ঍Ѻڦѓ

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ەɰ.

Ɠ_ƖÞķì ĸì Ƙßá Ƈķ_ÎÞ^ƇĹƊƘß^âƇķÏÞ^{à ƇĹ}ƊƘß âƇĸ_ÐÞ^ƇĹƑƘß^âƇĸÑÞ^{à ƇĹ}ƑƘß⁽⁹⁾ âķĹ_Ƒ_ÒÞ^ƇĹƑƘß^{à ķĹ}Ƒ_ÓÞ^{à ƇĹ}ƑƘß^,

Ɠ_ƗÞķì ĸì Ƙßá Ƈĸ_ÎÞ^ƇĹƊƘß^âƇĸÏÞ^{à ƇĹ}ƊƘß à Ƈķ_ÐÞ^ƇĹƑƘß^{à Ƈķ}ÑÞ^{à ƇĹ}ƑƘß⁽¹⁰⁾ âĸĹ_ƑÒÞ^ƇĹƑƘß^{à ĸĹ}ƑÓÞ^{à ƇĹ}ƑƘß^,

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֩(9)~(11)ęѺڦٮڿͳęۆěćεۋڌॠيɰ ڼڹڿͳ˞ںĵॣսەɰ.

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ň_ƘƘÞƖì Ɨì Ƙßá ŁxƓÞƖì Ɨì ƘßâÏłćŞƘ ŞƓ_ƘÞƖì Ɨì Ƙß

í (14)

***ۺڌ

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ɰ. ३ɾϿʝڹėşٮۿॠČەəÌࣺڦق2ࠗۆ

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ǴҙۆڮߕࠗŔνČՙǣʱۆٽĚࠗں঍Ձॠə

࢏ՁߕࠗęцŶޅڮߕࠗڷͿ঍Ձʼرەɰ. थϸ

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ԜডںԺ܁ॠيÁࠗقԴۆTL(Transmission Loss) ęSPL(Sound Pressure Level)ں३ԵॠٕČ, ANSYS

(4)

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ۆ३ԵĀęٮҼİॠٕɰ. TLڹۓԐࣷۆࡾşٮ

࣊ęࣷۆࡾşۆҼͿǣࢍǣə࣊ęćսۆًսق

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ٕɰ. Fig. 3ęFig. 4قԴ؎սەˢۋANSYSεটڌ

ॢ֨бͪۋՎ३ԵĀęÀۋ΁३ԵĀęٮ۞ێ

࠘॥ں؎սەɰ.

ANSYSٮۆҼİεࣀ३҆ۋ΁ۆ֪΋Ձںঝ

҃ॠٕş˺ЛقथϸࣷÀݕ֨ɰتॢܓæقʂ३

३Ե३҃ؕɰ. Fig. 5ۆϿʝقʂॠيÁࠗۆ˃ƍ

Ѻজق˰δ࣢Ձقʂ३ԕट҃ؕɰ. Fig. 6ę7ڹИ ъॳࠗۆ˃ƍÀ35T, 45T, 55T, 75Tێ˺ۆSPLę

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ࡾşٮъԐࣷۆࡾşۆҼͿǣࢍǣəъԐćսۆ

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ۋČβóǣࢍǣČ, 1 kHz~2 kHz ʂًۆъॳڼÇ

(5)

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ՙ͟ۋȭóǣࢍǦɰ. Fig. 8ę9ədecoupling ࠗۆ

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(6)

ęۋɰ. ڼؓقəsteelۆ˃ƍÀٖॳںй࠘ݕ؍ݓ χъॳڼÇՙۆąڍ۹ܳࣷսʂًقԴsteelۆ˃

ƍÀ˃ƃڐս΀ъॳڼÇՙ͟ۋǰڼںঝۍॣ

սەɰ.

7Ā΁

ɰࠗĵܓ३Եںڦॠي࢏Ձۋ΁ںۺڌॠٕɰ.

࢏Ձۋ΁ںࣀॢ३Եۆ֪΋ʪεঝ҃ॠşڦॠي

Ԝڌ३Ե॒ͿŔ͖ęҼİॠيێ࠘ʼəĀęεص ؽɰ. ֪΋Ձۋঝ҃ʽۋ΁ںц࢖ڷͿɰࠗĵܓϿ ʝقʂॠيɰتॢ˃ƍεÍəϿʝقʂ३३Ե ںսॱॠٕɰ.

थϸࣷÀݕ֨ٽҙथϸࣷقۆ३ՅԴÀыə

ٖॳں؎şڦ३ՅԴڦ࠘قԴۆڼؓں३Եॠٕ

Č, ʴ֨قथϸࣷ঍ࢗͿۓԐʼəٽҙࣷۆъԐ

܁ʪε؎şڦ३ъॳڼÇկÉں३Եॠٕɰ.

Anechoicۆ˃ƍÀݒÀॣս΀ՅԴڦ࠘قۆڼ

ؓۋČδইԜۋǣࢍǮɰ. ŔνČ1 k~2 kHz ʂً

ۆъॳڼÇՙ͟ۋȭóǣࢍǣəìںঝۍॣս

ەؽɰ. ŔνČdecoupling ࠗęsteel ࠗقʂ३Դə

˃ƍѺজق˰δڼؓۆٖॳڹäۆػڷǣ۹ܳ

ࣷսʂًقԴۆъॳڼÇՙ͟ۋǰ؉ݓəìںঝ ۍॠٕɰ. CRP ࠗۆąڍ˃ƍۆѺজقڼؓęъ ॳڼÇՙ͟ۆѺজÀäۆػڼںঝۍॠٕɰ.

˰͆Դՙǣۆڼॳս֪Ձɠںȭۋşڦ३Դə

anechoic ࠗۆ˃ƍεɚνČ, decoupling ࠗęsteel ࠗ قʂ३Դə˃ƍεÇՙ֨ࢅəìۋज़څॠɰ. Ŕ

νČCRP ࠗۆąڍ˃ƍε߯ՙজॠəìۋমęۺ ڷͿٚԜʽɰ.

ÇԐۆŘ

ۋٍĵəĶѓęॡٍĵՙݓڙڷͿսॱʼؽ֥

ɦɰ.

޷ČЛॶ

1. S. H. Ko and C. H. Sherman, “Flexural wave baffling,” J.

Acoust. Soc. Am. 66, 566-570 (1979).

2. M. A. Gonzalez, “Analysis of a composite compliant baffle,” J. Acoust. Soc. Am. 64, 1509-1513 (1978).

3. G. Maidanik, “Acoustic radiation from a driven coated infinite plate backed by a parallel infinite baffle,” J. Acoust.

Soc. Am. 42, 32-35 (1967).

4. S. H. Ko, S. W. Pyo, and W. J. Seong, Structure-Borne and Flow Noise Reductions (Seoul National University Press, 2001).

5. E. A. Skelton and J. H. James, Theoretical Acoustics of Underwater Structures (Imperial College Press, London, 1997).

6. L. M. Brekhovskikh, Waves in Layered Media (Academic Press, New York, 1980).

7. C. A. Brebbia, J. F. C. Telles, and L. C. Wrobel, Boundary Element Techniques (Springer-Verlag, New York, 1984).

8. O. C, Zienkiewicz and R. L. Taylor, The Finite Element Method : Volume 1 The Basis (McGRAW-. Hill, London, 2000).

9. E. B. Becker, G. F. Carey, and J. T. Oden, Finite Elements (Prentice-hall, New Jersey, 1981).

۹ۙأͳ

֫෮૽ )ZVO8VOH,XPO

ԴڐʂॡİܓԸ३تėॡęॡԐ

ԴڐʂॡİܓԸ३تėॡęԵԐ

ԴڐʂॡİܓԸ३تėॡęчԐ

_ইۦԴڐʂॡİ३ت֨֟ࢰė ॡٍĵՙԸےٍĵڙ

กজଗ 4VL:PPO)POH

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ङ֬цɦ؉ܳςʂॡİڼॳॡ

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(7)

৉஺ผ +FF)VO4POH

߿ǫʂॡİԸч३تėॡęॡԐ

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_ইۦۻǫʂॡİ३تşցॡҙ İս

׌ন็ 4VOH)FF,JN

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_ইۦԴڐʂॡİܓԸ३تė ॡęчԐę܁

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ٍՃʂėʂşćęॡԐ

,"*45şćęԵԐ

,"*45şćęчԐ

_ইۦĶѓęॡٍĵՙսԵٍ

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ছઽ৤ :PVOH4PP4FP

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An Acoustic Reception Ability Analysis of SONAR Multilayer Structures by Using Elastic Theory

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