• Composites Research
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• 제31권6호
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• pp.317-322
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• 2018

다양한 산업군에서 복합재료를 적용한 제품개발을 진행하고 있는 상황이며, 재활용이 가능한 장점으로 인해 열가소성 복합재료에 대한 개발이 활발하다. 장섬유 강화 열가소성 플라스틱(Long fiber thermoplastic, LFT)의 형태도 있지만, 연속섬유를 이용한 열가소성 복합재료(Continuous fiber thermoplastic, CFT)에 대한 활용도 증가하고 있다. 본 연구에서는 CFT를 제작할 때 사용되는 강화섬유의 제직 패턴에 따른 영향으로 CFT의 인장, 굴곡, 충격 강도의 변화를 확인하고자 하였다. 복합재료의 물성이 강화섬유의 제직 패턴에 의해 달라지는 원인을 기계적인 물성으로도 평가하였고, CT 촬영기법을 이용하여 내부 기공발생과 섬유 제직패턴과의 상관관계를 분석하였다. CFT의 경우 열가소성 필름이 섬유 로빙 내로 함침되는 수준이 낮기 때문에, 공극의 발생률이 높은 문제가 있다. 섬유 로빙과 로빙사이의 계면이 $100{\mu}m$ 수준으로 조밀하게 형성될 수 있는 평직 섬유 패턴이 CFT의 성형성 및 기계적 물성을 안정화시키는 강화섬유의 조직임을 검증하였다.

• 한국기계가공학회지
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• 제16권5호
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• pp.25-30
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• 2017

Carbon-fiber-reinforced plastic (CFRP) composite materials have been widely used in various industrial fields because the design variables can be adjusted according to the application of the required structure. Thermosetting and thermoplastic resins are used as the base materials of CFRP composites for the lightweight construction of automotive components. Thermoplastics have several advantages such as no curing and recyclability compared to thermosetting resin. In this study, CFRP composites were made using the Long-Fiber Thermoplastic-Direct (LFT-D) process. The LFT-D process includes an in-line production system that directly impregnates a thermoplastic resin, extrudes the composite material, and molds it. This process increases the strength and decreases the molding time. The tensile strength characteristics on the mechanical properties of CFRP were analyzed according to the parameters of LFT-D based on thermoplastics. To analyze the properties of CFRP, the specimens were prepared based on the tensile test standard ASTM 3039 of composite materials.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.261-264
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• 2000

The objective of this work was to characterize mechanical properties of thermoplastic composites for various forming condition in compression molding. Randomly oriented long glass fiber reinforced polypropylene(PP) was used in the work. The composite materials contained 20%, 30%, and 40% glass fiber by weight. Compression molding was conducted to make the test specimen. Dimensional stability was measured on each forming condition with the spring-forward angle. Tensile test was conducted to characterize mechanical properties of formed parts in various forming conditions.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.29-32
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• 2001

The objective of this work was to optimize processing parameters of hybrid thermoplastic composites in compression molding. The mechanical properties of the composites manufactured with various forming conditions were measured to characterize processing parameters. Polypropylene(PP) composites containing randomly oriented long carbon fiber and carbon black were used in this work. The composite materials contained 5%, 10%, 15%, and 20% carbon fiber and 5%, 10%, 15%, 20%, and 25% carbon black by weight. Compression molding was conducted at various mold temperatures. The temperature of the material in the mid-plain was monitored during the forming. Crystallinity was also measured by using XRD. The tensile modulus of the composites increase, with increasing the mold temperature. However, the impact strength of the composites decreases as mold temperature increases.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.67-70
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• 2000

This study was performed to investigate the material behavior of hybrid thermoplastic composites contained glass fiber and calcium carbonate. The composite was prepared with each combination ratio of calcium carbonate, and the content of glass fiber was fixed with 10% by weight. In order to investigate the material behavior for various combination ratio, tension test, flexural test, and impact test were performed. Microscopic observation were conducted to examine the fractured surface of specimen for tension test. And the material behavior of the hybrid thermoplastic composite immersed in salt water with definite time was investigated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.513-517
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• 1997

Glass fiber reinforced thermoplastic composite materials have considerable promise for increased use in low cost high volum applications because of the potential for processing by solid phase forming. However, the forming characteristics of these materials have not been well known. The primary focus of this research is the investigation of the bendability of these composites and spring-back phenomena in pure bending. The materials tested contained 10, 35, and 40 percent by weight of randomly oriented glass fiber in a polypropylene matrix. The bending tests were performed at temperatures ranging form 75 ".deg. c" to 150 ".deg. c" and at punch speeds of 2.54 mm/sec and 0.0254 mm/sec. The measured bendability and spring back angle in pure bending werw compared with the predictions based on the simple analyical models. Goog agreement between experimental and analytical results was observed.esults was observed.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 춘계학술발표대회 논문집
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• pp.91-94
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• 1999

• Design & Manufacturing
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• 제15권3호
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• pp.39-44
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• 2021

In molding of continuous fiber-reinforced thermoplastic composites, it is very difficult to impregnate between the reinforcements and the matrix since the matrix has a high melting temperature and high viscosity. Therefore, most of composite molding processes are divided in the manufacturing processes of intermediate materials called prepreg and the forming of products from intermediate materials. The divided process requires additional facilities and thermoforming, and they increase the cycle time and cost of composite products. These problems can be resolved by combining the continuous fiber-reinforced composite molding process with injection molding. However, when a composite material is manufactured by inserting woven fabric into the injection mold, poor impregnation occurs on the surface of the molded product. It affects the properties of the composites. In this paper, through an impregnation experiment using cores with different heat transfer rates and pore densities, the reason for the poor impregnation was confirmed, and molding experiments were conducted to produce composite with improved surface impregnation by inserting the mesh. And also, the surface impregnation and deformation of composites molded using different types of mesh were compared with each other.

• Composites Research
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• 제33권6호
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• pp.383-389
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• 2020

열가소성 복합재료를 적용하여 자동차 도어 임팩트 빔을 설계하고 시생산을 통해 생산성 및 성능을 검증하였다. 자동차 안전법규는 지속적으로 강화되어 왔으며 최근 자동차 산업에서 경량화가 필수 요건이 되면서 고성능 경량 부품에 대한 요구가 크게 증대되고 있다. 본 연구는 섬유강화 열가소성 복합소재를 도입하여 기존 탄소강 제품 대비 경량화 되면서 성능은 향상된 도어 임팩트 빔 개발을 목표로 하였다. 연속섬유 복합재료와 장섬유 복합재료(LFT)를 혼합 적용한 도어 임팩트 빔 제작 공정을 제시하며, 생산성이 우수한 인서트 사출 공정을 활용하여 구현하였다. 시생산된 도어 임팩트 빔은 3점 굽힘 시험을 통하여 성능을 평가하였다. 열가소성 복합재료는 경량화 설계와 함께 높은 생산성 구현이 가능하여 다양한 자동차 부품으로 복합소재의 적용을 확대시킬 것이다.

• Composites Research
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• 제37권3호
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• pp.186-189
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• 2024

본 연구는 나노필러가 혼합된 열가소성 탄소섬유강화 복합재료(Carbon fiber reinforced thermoplastic polymer, CFRTP)의 물성을 비교 평가하였다. Polyamide 6 (PA6) 수지에 Multi-wall carbon nano tube (MWCNT), Silicon oxide, Core shell rubber, Aramid nano fiber 등의 다양한 나노필러를 혼합한 후, 이를 기지재(Matrix)로 탄소섬유강화복합 재료(CFRP)를 제조하여 그 물성을 측정하였다. 나노필러의 종류와 혼합비율에 따라, 인장강도, 층간계면결합력 (Inter-laminar shear strength), Izod 충격 강도 등이 측정되었다. 인장 강도와 충격 강도의 경우 Core shell rubber를 혼합한 경우 가장 높은 물성을 가졌으나, 계면결합력은 silicon oxide를 1 wt.% 이하 혼합하였을 때 최적값을 가졌다.