Multi-Material Additive Manufacturing Process for 3-Dimensional Circuit Device Fabrication

오성택(Sung Taek Oh),이인환(In Hwan Lee),김호찬(Ho-Chan Kim),조해용(Hae-Yong Cho) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.3

Recently, various attempts have been made to apply the additive manufacturing technology directly to fabricate a product. In this regards, the industry is focusing on the multi-material additive manufacturing technology that can processes multiple materials simultaneously. This study is about the fabrication of a 3-dimensional circuit device (3DCD), based on the multimaterial additive manufacturing technology, which is combination of the material extrusion and the direct writing processes. The multi-material additive manufacturing system was developed based on the commercial multi-head FDM system. In addition, a contact type nozzle for the dispensing of the conductive material in the direct writing process is proposed. The 3-dimensional circuit device in which circuit elements are arranged on several layers was fabricated successfully, based on the presented multi-material additive manufacturing system.

LS-DYNA 발파 모델링에서 현장암반의 특성을 반영하기 위한 Hoek-Brown 파괴기준과 Holmquist-Johnson-Cook 콘크리트 재료모델의 접목

최병희 ( Byung-hee Choi ),선우춘 ( Choon Sunwoo ),정용복 ( Yong-bok Jung ) 대한화약발파공학회 2020 화약발파 Vol.38 No.3

본 논문에서는 Hoek-Brown (HB) 파괴기준을 Holmquist-Johnson-Cook (HJC) 콘크리트 재료모델에 접목시킴으로써 LS-DYNA 상에서 암반발파를 모델링할 때 현장암반의 고유한 특성이 잘 반영될 수 있도록 도모하였다. 이것은 많은 지질학적 불연속면을 포함하고 있는 현장암반이 지니고 있는 독특한 특징을 강조하기 위함이다. 두 모델의 접목은 HB 파괴기준으로 HJC 재료모델의 정적 강도 부분을 교체함으로써 이루어지며, 교체과정은 통계학적 곡선적합기법에 의해 수행된다. 본 논문에서는 접목의 과정이 상세하게 소개되며, 획득된 HJC 재료모델의 사용에 대한 실례도 제시된다. 제시된 수치계산은 현장의 석회암 암반의 단일공 발파에 대한 평면변형률 모델링으로서 LS-DYNA가 제공하는 유체-구조물 상호작용(FSI) 기법과 다중재료 라그랑주-오일러(MMALE) 정식화 기법을 조합하여 수행된다. In this paper the Hoek-Brown (HB) failure criterion is integrated into the Holmquist-Johnson-Cook (HJC) concrete material model to reflect the inherent characteristics of field rock masses in LS-DYNA blast modeling. This is intended to emphasize the distinctive characteristics of field rock masses that usually have many geological discontinuities. The replacement is made only for the static strength part of the HJC material model by using a statistical curve fitting technique, and its procedure is described in detail. An example is also given to illustrate the use of the obtained HJC material model. Computation is performed for a plane strain model of a single-hole blasting on a field limestone by using the combination of the fluid-structure interaction (FSI) technique and the multi-material arbitrary Lagrangian Eulerian (MMALE) method in LS-DYNA.

초점탄성재료의 다중 압출에 의한 착륙선 충격완충 해석

이춘우,김인걸 항공우주시스템공학회 2017 항공우주시스템공학회지 Vol.11 No.6

As an alternative of the existing honeycomb shock absorbing device, the new approach on shock absorbing design using the extrusion of hyper-viscoelastic material such as silicon rubber is studied in this paper. The strain energy and stress-strain characteristic of viscoelastic material at extrusion process through the metered orifice has a similarity with the honeycomb core for maximizing shock absorbing capability. And in order to evaluate the design feasibility of this device and to understand the shock absorbing mechanism of energy transformation, finite element analysis and quasi-static compression test of the multi-stage extrusion shock absorber are examined in this paper. 기존 알루미늄 하니콤 코어를 이용한 착륙선 충격완충장치의 대체 방안으로서 실리콘 고무와 같은초점탄성 재료의 다중압출 특성을 이용한 새로운 개념의 충격 완충장치를 고찰하였다. 초점탄성재료가오리피스 단면을 통과하며 압출되는 과정에서 재료 변형에너지 및 하중-변위 특성이 기존 하니콤 코어특성과 유사하여 충격 완충 성능을 극대화 할 수 있는 측면에서 유사성을 가지고 있음을 알 수 있었다. 본 논문에서는 충격완충장치의 설계 구현가능성을 평가하고, 에너지 변환을 통한 충격흡수 매커니즘을이해하기 위하여 유한요소해석 및 준정적 압축시험 결과를 검토하였다

다중층 음향 재료의 투과손실 예측과 측정

박소희(Park, So-Hee),박철민(Park, Chul-Min),채기상(Chae, Ki-Sang),강연준(Kang, Yeon-June) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.11

In this paper, the predictions and measurements of sound transmission loss(STL) are discussed for various types of acoustical materials and carpets. Random incidence sound transmission losses are measured by the sound intensity method. The in-house software HONUS2005 is used to predict TL and estimate the various physical properties such as the flow resistivity, the structure factor, the porosity, the Possion's ratio, and etc. After this estimation, various multi-layered materials with a steel plate are measured and predicted. In particular, Carpets are assumed to be membranes to predict acoustical performance. To confirm this assumption, double and triple-layered cases are also observed including two different kinds of carpets.

다중벽 탄소나노튜브와 나노실리카를 혼입한 시멘트 복합체의 성능 평가

김성우 ( Kim Seong Woo ),손정진 ( Son Jeong Jin ),김지현 ( Kim Ji-hyun ),정철우 ( Chung Chul-woo ) 한국건축시공학회 2023 한국건축시공학회 학술발표대회 논문집 Vol.23 No.1

Recently, a lot of nano-scale material technology development and research have been conducted in construction fields to improve the compressive strength and durability of cement-based Composites. There are some studies that have confirmed the properties and application effects of cement-based complex using each nanomaterial, but development and research using both materials are relatively limited. This study sought to confirm the effect of multi-wall carbon nanotubes (MWCNT) and nanosilica, which are representative construction nanomaterials, on the compressive strength, voids, and microstructure formation of cement. The purpose was to produce a cement composite by changing the mixing rate of the two nanomaterials, and to find the optimal mixing amount considering its mechanical and rheological properties.

다중재료 광조형장치 개발

김호찬(Ho-chan kim),최재원(Jae-Won Choi),Ryan Wicker Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.3

Researchers continue to explore possibilities for expanding additive manufacturing (AM) technologies into direct product manufacturing. One limitation is in the materials available for use in AM that can meet the needs of end-use applications. Stereolithography (SL) is an AM technology well known for its precision and high quality surface finish capabilities. SL builds parts by selectively crosslinking or solidifying photo-curable liquid resins, and the resin industry has been continuously developing new resins with improved performance characteristics. This paper introduces a unique SL machine that can fabricate parts out of multiple SL materials. The technology is based on using multiple vats positioned on a rotating vat carousel that contain different photo-curable materials. To change the material during the process, the build platform is raised out of the current vat, a new vat with a different material is rotated under the platform, and the platform is submerged into the new vat so that the new material can be used. This paper introduces a new vat exchange mechanism, cleaning process, recoating process, resin leveling mechanism and process planning technologies for the implementation of multiple material SL. An overview of the system framework is provided and the system integration and control software is described. In addition, several multiple material test parts are designed, fabricated, and described.

CFRP와 금속 재료의 접합을 위한 epoxy/MWCNT의 특성 분석

유성훈 ( Sung-hun Yoo ),권일준 ( Il-jun Kwon ),신동우 ( Dong-woo Shin ),박성민 ( Sung-min Park ),염정현 ( Jeong-hyun Yeum ) 한국복합재료학회 2017 Composites research Vol.30 No.3

에폭시 수지의 열적 특성과 접합 특성에 대해 다중벽 탄소 나노 튜브 (MWCNT)의 효과가 이중 중첩 전단시험에 의해 연구되었다. Epoxy/MWCNT 복합 수지는 에폭시 수지(araldite 2011)에 다양한 질량 분율로 MWCNT를 분산하여 제조되었다. MWCNT의 효과를 확인하기 위해 접합강도 시험이 열특성 변형 만능재료시험기에 의해 진행되었고 충격강도 시험이 ASTM D256에 따라 진행되었다. 금속 판재와 탄소섬유강화복합재료가 실험 재료로써 사용되었으며, 열적 안정성 분석은 열 중량 분석기와 시차 주사 열량기에 의해 진행되었다. 또한 접합강도 시험 후 시편의 형태학적 특성은 주사전자현미경에 의해 관찰되었고 파괴거동을 알아보기 위하여 광학현미경을 사용하였다. 에폭시 수지와 비교하였을 때 epoxy/MWCNT 복합 수지가 물리적 특성이 향상되는 것을 나타내었다. The effect of a multi walled carbon nanotubes (MWNCT) on the adhesive properties and thermal properties of epoxy were studied by double lap-shear tests. Epoxy/MWCNT resins were prepared from a different amount of the MWCNT incorporated into the epoxy resins (araldite 2011). Steel plates and carbon fiber reinforced plastics (CFRP) were chosen as materials. Mechanical tests were performed by a universal testing machine (UTM). The analysis of thermal properties were conducted by a thermogravimetric analyzer (TGA) and a differential scanning calorimetry (DSC). The fracture surface morphology was examined using a scanning electron microscopy (SEM) and optical microscope. Compared to neat epoxy, it was found that the mechanical properties of epoxy/MWCNT resins are increased.

유리섬유 복합재료의 파괴인성치에 미치는 다중 벽 탄소 나노튜브와 진공의 영향

구천(Tian Gou),염영진(Young Jin Yum) 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.2

Chopped strand mat(M)과 Woven(W), 두 가지 형태의 유리섬유와 불포화 폴리에스터 수지를 혼합하여 6가지 적층 순서([M₄/M₄], [W₄/W₄], [M₄/W₄], [M/W]₄, [M/W/M/W]S, [W/M/W/M]S)를 갖는 복합재료를 제작하였다. 제작 시 진공을 적용하고 다중 벽 탄소 나노튜브(multi-walled carbon nanotube)를 첨가하여 파괴 인성치에 미치는 영향을 고찰하였다. DCB(Double Cantilever Beam) 시편과 ENF(End-Notched Flexure) 시편을 이용하여 각각 모드 I, II 파괴인성치를 구하였다. 시험 결과 [W/M/W/M]S 조합이 가장 파괴인성치가 큰 것으로 밝혀졌고 fiber bridge가 층간 파괴에 영향을 미침을 확인하였다. 또한 진공을 적용했을 경우와 MWCNT를 첨가하였을 경우 파괴인성치가 현저히 증가하는 것을 확인할 수 있었다. 따라서 여러 가지 제작 조건하에서 적절하게 설계된 복합재료 구조가 요구됨을 알 수 있었다. Two types of glass fiber, chopped strand mat (M) and woven (W), were combined together by using unsaturated polyester resin (UPR) in 6 different stacking sequences: [M₄/M₄], [W₄/W₄], [M₄/W₄], [M/W]₄, [M/W/M/W]S and [W/M/W/M]S. The effect of fabrication conditions such as vacuum and multi-walled carbon nanotubes (MWCNTs) on the fracture toughness of composites was investigated. Mode I and II fracture toughnesses were obtained from Double cantilever beam (DCB) test and the End-notched flexure (ENF) test respectively. As a result [W/M/W/M]S showed largest fracture toughness and it was found that fiber bridge had a great effect on the fracture behavior. Besides, the vacuum and MWCNTs showed a positive effect on fracture toughness in mode I and mode II tests. Consequently, properly designed structure is recommended under different fabrication conditions.

다상 레벨셋 모델을 이용한 다중재료 차체구조설계

황의상(Eysang Hwang),민승재(Seungjae Min) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

Weight reduction while maintain structural performance is one of the most challenging topics in automotive industry. Recent advances in manufacturing technology enable the automotive body structure to be built with multimaterial. In this paper, multiphase level set model is introduced to represent multi-material boundaries and the optimization problem for minimizing the strain energy is formulated. The proposed method is applied to the design of two-dimensional underbody structure and the usefulness is confirmed.

유리섬유복합재료의 파괴인성치에 미치는 제작조건의 영향

구천(Tian Gou),염영진(Young Jin Yum) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.5