3-차원 보강 복합재 체결부의 피로강도 특성 연구
A Study on the Fatigue Strength of the 3-D Reinforced Composite Joints
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초록
복합재 체결부는 뛰어난 물성과 가벼운 구조의 수요로 널리 사용되고 있다. 하지만 두께 방향의 취약한 물성으로 인해 체결부 파손이 쉽게 발생한다. 이를 극복하기 위하여 체결부 끝단의 집중되는 응력을 완화시켜주는 Z-피닝, 스티칭 등 다양한 공법들이 적용되고 있다. Z-피닝 공법은 프리프레그의 두께 방향으로 금속 핀이나 카본 핀을 적용하여 보강하는 공법이고, 스티칭 공법은 프리폼에 상부 및 하부 섬유를 교차시켜 두께방향으로 기계적 강도를 향상시키는 방법이다. I-fiber 스티칭 공법은 Z-pinning 공법과 Stitching 공법을 보완한 유망한 공법이다. 본 논문에서는 I-fiber 스티칭 공법으로 보강된 Single-lap joint 시편을 오토클레이브 진공백 성형법으로 제작하여, 모재의 두께와 스티칭 각도에 따른 인장강도 및 피로강도 특성을 평가하여, I-fiber 보강 복합재 체결부 구조물의 보강효과를 검증하였다. 실험결과, 복합재 체결부의 두께가 얇을수록 I-fiber 보강효과가 더 높게 나타났으며 Ifiber로 보강된 복합재 체결부는 파손강도에서 약 52%, 피로강도에서 약 118% 우수한 특성을 나타냄을 확인하였다.
Abstract
Composite lap joints have been extensively used due to their excellent properties and the demand for light structures. However, due to the weak mechanical properties in the thickness direction, the lap joint is easily fractured. various reinforcement methods that delay fracture by dispersing stress concentration have been applied to overcome this problem, such as z-pinning and conventional stitching. The Z-pinning is reinforcement method by inserting metal or carbon pin in the thickness direction of prepreg, and the conventional stitching process is a method of reinforcing the mechanical properties in the thickness direction by intersecting the upper and lower fibers on the preform. I-fiber stitching method is a promising technology that combines the advantages of both z-pinning and the conventional stitching. In this paper, the static and fatigue strengths of the single-lap joints reinforced by the I-fiber stitching process were evaluated. The single-lap joints were fabricated by a co-curing method using an autoclave vacuum bag process and I-fiber reinforcing effects were evaluated according to adherend thickness and stitching angle. From the experiments, the thinner the composite joint specimen, the higher the I-fiber reinforcement effect, and Ifiber stitched single lap joints showed a 52% improvement in failure strength and 118% improvement in fatigue strength.
참고문헌 (17)
- Wang, P., "An Investigation of the Stitching Effect on Single Lap Shear Joints in Laminated Composites", Science Engineering Composite Materials, 26, pp.509~516 (2019)
- Andrew, F., "Failure Analysis of Adhesively Bonded GFRP", aluminum Matrix Single Composite Lap Joint with Cold Worked Penetrative Reinforcements, 2019, pp.161, 96~106
- Fu, M., "Failure Analysis of 2D C", SiC Composite z-pinned, Ceramics International, pp.2020, 46(13)[DOI]
- Ito, A., "Experimental Investigation of Interlaminar Mechanical Properties on Carbon Fiber Stitched CFRP Laminates", Advanced Composite Materials, 16(2), pp.95~113 (2007)
- Yoshimura, A., "Improvement of Out-of-Plane Impact Damage Resistance of CFRP Due to Through-the-Thickness Stitching", Advanced Composite Materials, 18(2), pp.121~134 (2009)
- Park, Y. B., "The Strength of Composite Bonded T-joints Transversely Reinforced by Carbon Pins", Composite Structures, 94, pp.625~634 (2012)
- Son, H. G., "Fatigue Behavior of Metal Pin-reinforced Composite Single-lap Joint in a Hygrothermal Environment", Composite Structures, 108, pp.151~160 (2014)
- Kim, C. H., "Failure Strength of Composite T-joints Prepared Using a New 1-thread Stitching Process", Composite Structures, 178, pp.225~231 (2017)
- An, W. J., "Static Strength of RTM Composite Joint with I-fiber Stitching Process", Composite Structures, 210, pp.348~353 (2019)
- An, W. J., "Process Variables of I-fiber Stitching in Mode I Failure", Composite Structures, 240, pp.112082~ (2020)
- Jonathan, T., "Analysis and Experiment on DCB Specimen Using I-fiber Stitching Process", Composite Structures, 220, pp.521~528 (2019)
- Jonathan, T., "Characterization of Mode II Specimen Using I-fiber Stitching Process", Composite Structures, 255, pp.112863~ (2021)
- Jonathan Tapullima, "Unit Cell FEM Analysis Using I-Fiber Single Stitch with Different Thickness", Composites Research, 34(1), pp.30~34 (2021), 한국복합재료학회[DOI]
- 송상훈, "I-fiber Stitching 공법을 적용한 복합재료 Single-lap Joint의 Stitching 패턴과 각도에 따른 정적 강도 연구", Composites Research, 33(5), pp.296~301 (2020), 한국복합재료학회
- 최성현, "I-fiber 스티칭 공법이 적용된 Single-lap Joint의 강도 특성 및 파손 신호 검출 연구", Composites Research, 34(5), pp.317~322 (2021), 한국복합재료학회[DOI]
- Kim, C. H., "Impact Characteristics of Composite Panel Stitched by I-fiber Process", Composites Part A : Applied Science and Manufacturing, 127, pp.105644~ (2019)
- Feng, Y. P., "The Fatigue Behavior of Carbon Fiber-reinforced Composite T300", Epoxy under Tension-tension and Bending Fatigue Loading, 2014, pp.941-944, 1522~1527