• Composites Research
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• v.23 no.4
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• pp.1-6
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• 2010

The dynamicresponse of biomimetic composites mimicking nacre under low velocity impact is investigated. The composites have hierarchical structures with a staggered pattern consisting of a protein and a mineral. To analyze the impact response of the composites, the finite element method is used. The effects of the hierarchical structures of the compositeson the dynamic response are examined. It is shown that the maximum stress, displacement and contact force in the composite subjected to low velocity impact decrease as the level of structural hierarchy increases.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.48.2-48.2
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• 2009

Ti와 Ti-6%Al-4%V합금은 내 부식성 및 생체 적합성이 매우 우수하기 때문에 현재 생체재료로써 널리 사용되고 있다. 하지만 Ti-6%Al-4V합금에 포함된 Al과 V이 신체에 좋지 않은 영향을 줄 수 있다는 연구 결과가 보고되면서 새로운 생체재료의 연구가 활발히 진행되고 있다. 본 연구에서는 생체에 무해한 Ti-Nb와 hydroxyapatite(HAp)를 복합 첨가하여 고에너지볼밀링(high-energy mechanical milling, HEMM)으로 나노 합금분말을 제조 후 급속소결에 의하여 Ti-Nb/HAp 생체재료를 제조 하였다. 제조한 Ti-Nb/HAp 생체용 복합재료에서 HAp 첨가량과 분말의 밀링, 믹싱에 따른 조직 변화와 소결체의 생체적합성의 변화 및 기계적 특성의 변화를 분석하였다. 이때 Ti-42%Nb에 HAp의 첨가량을 0%, 5%, 10%, 15%로 변화를 주었고, 밀링은 고에너지볼밀링기를 이용하여 0~8시간 동안 실시하였다. 그 결과 밀링 시간이 증가할수록 합금 분말의 크기가 미세해졌으며, 특히 8시간 밀링시 분말의 크기가 나노 크기로 감소하여 기계적 특성(경도 및 강도)이 우수해지는 것을 알 수 있었다.

• Rubber Technology
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• v.18 no.1
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• pp.1-12
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• 2017

• Composites Research
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• v.22 no.4
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• pp.41-49
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• 2009

Natural fiber reinforced composites are emerging as low-cost, lightweight, recyclable, and eco-friendly materials. These are biodegradable and non-abrasive. Due to eco-friendly and biodegradable characteristics of natural fibers, they are being considered as potential candidates to replace the conventional fibers. The chemical, mechanical, and physical properties of natural fibers have distinct features depending upon the cellulose content of the fibers which varies from fiber to fiber. The mechanical properties of composites are influenced mainly by the adhesion between matrix and fibers. Several chemical and physical modification methods of fiber surface were incorporated to improve the tiber-matrix adhesion resulting in the enhancement of mechanical properties of the composites. This paper outlines the works reported on natural tiber reinforced composites with special reference to the type of fibers, polymer matrix, processing techniques, treatment of fibers, and fiber-matrix interface.

• 기계와재료
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• v.23 no.4
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• pp.36-44
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• 2011

생체모방 경량 나노복합 에코소재기술은 자연계에 존재하는 물질의 구조를 모방하여 저온 저에너지 소모공정을 통하여 고경량 및 고강도를 갖는 나노복합체를 제조하는 친환경 신소재 기술이다. 고효율 저공해 성능에 초점을 맞추어 $CO_2$ 배출 및 지구온난화를 억제하고 웰빙사회에 적합한 차량을 개발하는 것이 현재 전세계 자동차회사들의 주된 관심사이다. 이러한 상황에 생체모방기술은 에너지 환경산업분야의 소재로 응용하는 원천기술로 기대된다. 이 생체모방기술은 자연 친화적 재료를 개발하여 하이브리드/전기 자동차의 내/외장재, 고효율 건축자재, 첨단 항공우주 신소재에도 응용이 가능하다. 최근에 보고된 생체모방 경량 나노 복합 에코소재 기술을 조사하였다.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1288-1296
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• 2011

Effective elastic constants of bone-like biocomposites are investigated numerically. The bone-like materials are composed of strong layers and weak layers, and hierarchically structured. The unit cell model is employed to obtain the effective elastic constants. The effective anisotropic elastic constants of bone-like composites are obtained by using the potential energy method and finite element analysis. The effects of the Poisson's ratio, elastic modulus, hierarchical level, volume fraction and aspect ratio of the strong layer composed of the composites on the effective elastic constants are discussed.

• Composites Research
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• v.32 no.1
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• pp.50-55
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• 2019

In this study, we investigated the effect of fiber alignment in helicoidal structure on the mechanical properties of biomimetic fiber-reinforced composites. Using finite element analysis, circular biomimetic fiber composites were designed and studied. Various amounts of pressure loads were applied to a surface of the composites, and then bending and failure behaviors of the composites were analyzed. The results showed various failure morphologies according to the orientation of the fibers, and it turned out that the fiber alignment in helicoidal structure significantly improved the bending strength of the composite under pressure loading. This was because the fiber alignment in various directions for each layer dispersed effectively the fracture energy from the external load into multiple directions.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.136.2-136
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.909-910
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• 2010

• Journal of Biomedical Engineering Research
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• v.23 no.2
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• pp.119-130
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• 2002

The nonlinear finite element program has been developed to analyze the design performance of an artificial hip prosthesis and long term behavior of a treated femur with stems made of composite material after cementless total hip arthroplasty(THA). The authors developed the three dimentional FEM models of femoral bone with designed composite stem which was taken with elliptic cross section of 816 brick elements under hip contact load and muscle farce in simulating single leg stand. Using the program, density changes, stress distributions and micromotions of the material femoral bone were evaluated by changing fiber orientation of stems for selected manufacturing method such as plate cut and bend mold. The results showed that the composite materials such as AS4/PEEK and T300/976 gave less bone resorption than the metallic material such as cobalt chrome alloy, titanium alloy and stainless steal. It was found that increasing the long term stability of the prosthesis in the femur could be obtained by selecting the appropriate ply orientation and stacking sequence of composite.