• 제목/요약/키워드: cohesive elements

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Identity Formation and Self-Reflection Strategies in the Development of Apparel Design ePortfolios

  • Seifert, Christin;Chattaraman, Veena
    • Fashion, Industry and Education
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    • 제14권2호
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    • pp.60-69
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    • 2016
  • Visual literacy, a key element of a design portfolio, is achieved by communicating a consistent visual aesthetic with respect to design elements, design principles and individual style. Yet, students often feel challenged in articulating their personal aesthetic or design philosophy in order to create a unifying design identity within a body of artifacts. This paper shares some best practices on overcoming this challenge through students' engagement in self-reflection and identity formation processes. The implemented innovative strategy in a senior-level portfolio development course for apparel designers involved four different phases: 1) one-on-one meetings to self-reflect on previous design work, 2) selection and revision of artifacts, 3) peer-review and critiques of revised portfolio artifacts, and 4) development of a final ePortfolio to showcase a unified design identity. It was evident that recording students' initial self-reflection in the form of a metacognitive oral report encouraged and motivated identity development in their portfolio. Further, students expressed their satisfaction in the ability to participate in the selection process of artifacts by self-reflecting about what they wanted to highlight about themselves and why. Overall, student outcomes from this strategy exceeded expectations and the portfolios developed were successful in creating a cohesive design identity.

Performance of High Strength Self-Compacting Concrete Beams under Different Modes of Failure

  • Harkouss, Raya Hassan;Hamad, Bilal Salim
    • International Journal of Concrete Structures and Materials
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    • 제9권1호
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    • pp.69-88
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    • 2015
  • Self-consolidating concrete (SCC) is a stable and cohesive high consistency concrete mix with enhanced filling ability properties that reduce the need for mechanical compaction. Limited standards and specifications have been reported in the literature on the structural behavior of reinforced self-compacting concrete elements. The significance of the research presented in this paper stems from the need to investigate the effect of enhanced fluidity of SCC on the structural behavior of high strength self-consolidating reinforced concrete beams. To meet the objectives of this research, twelve reinforced concrete beams were prepared with two different generations of superplasticizers and designed to exhibit flexure, shear, or bond splitting failure. The compared beams were identical except for the type of superplasticizer being used (second generation sulphonated-based superplasticizer or third generation polycarboxylate-based superplasticizer). The outcomes of the experimental work revealed comparable resistance of beam specimens made with self-compacting (SCC) and conventional vibrated concrete (VC). The dissimilarities in the experimental values between the SCC and the control VC beams were not major, leading to the conclusion that the high flowability of SCC has little effect on the flexural, shear and bond strengths of concrete members.

Cementing failure of the casing-cement-rock interfaces during hydraulic fracturing

  • Zhu, Hai Y.;Deng, Jin G.;Zhao, Jun;Zhao, Hu;Liu, Hai L.;Wang, Teng
    • Computers and Concrete
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    • 제14권1호
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    • pp.91-107
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    • 2014
  • Using the principle of damage mechanics, zero-thickness pore pressure cohesive elements (PPCE) are used to simulate the casing-cement interface (CCI) and cement-rock interface (CRI). The traction-separation law describes the emergence and propagation of the PPCE. Mohr-coulomb criteria determines the elastic and plastic condition of cement sheath and rock. The finite element model (FEM) of delamination fractures emergence and propagation along the casing-cement-rock (CCR) interfaces during hydraulic fracturing is established, and the emergence and propagation of fractures along the wellbore axial and circumferential direction are simulated. Regadless of the perforation angle (the angle between the perforation and the max. horizontal principle stress), mirco-annulus will be produced alonge the wellbore circumferential direction when the cementation strength of the CCI and the CRI is less than the rock tensile strength; the delamination fractures are hard to propagate along the horizontal wellbore axial direction; emergence and propagation of delamination fractures are most likely produced on the shallow formation when the in-situ stresses are lower; the failure mode of cement sheath in the deep well is mainly interfaces seperation and body damange caused by cement expansion and contraction, or pressure testing and well shut-in operations.

Numerical analysis on tensile properties of composite hybrid bonded/bolted joints with flanging

  • Cheng, Xiaoquan;Zhang, Jie;Zhang, Jikui;Liu, Peng;Cheng, Yujia;Xu, Yahong
    • Steel and Composite Structures
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    • 제26권3호
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    • pp.265-272
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    • 2018
  • A detailed study was carried out on the tensile properties of the single-lap joint of a steel panel bolted/bonded to a composite laminate with a flanging. Finite element model (FEM) was established to predict the strength and to analyze the damage propagation of the hybrid joints by ABAQUS/Standard, which especially adopted cohesive elements to simulate the interface between the laminate and adhesive. The strength and failure mode predicted by FEM were in good agreement with the experimental results. In addition, three influence factors including adhesive thickness, bolt preload and bolt-hole clearance were studied. The results show that the three parameters have effect on the first drop load of the load-displacement curve, but the effect of bolt-hole clearance is the largest. The bolt-hole clearance should be avoided for hybrid joints.

카본블랙 첨가 PMC(Polyethylene Matrix Composites)의 문턱스며들기(Percolation Threshold)와 절연파괴 강도 임계지수 (Percolation Threshold and Critical Exponent of Dielectric Breakdown Strength of Polyethylene Matrix Composites added Carbon Black)

  • 신순기
    • 한국재료학회지
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    • 제21권9호
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    • pp.477-481
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    • 2011
  • Composites of insulating polyethylene and carbon black are widely used in switching elements, conductive paint, and other applications due to the large gap of resistance value. This research addresses the critical exponent of dielectric breakdown strength of polymer matrix composites (PMC) made with carbon black and polyethylene below the percolation threshold (Pt) for the first time. Here, Pt means the volume fraction of carbon black of which the resistance of the PMC is transferred from its sharp decrease to gradual decrease in accordance with the increase of carbon-black-filled content. First, the Pt is determined based on the critical exponents of resistivity and relative permittivity. Although huge cohesive bodies of carbon black are formed in case of being less than the Pt, a percolation path connecting the conducting phases is not formed. The dielectric breakdown strength (Dbs) of the PMC below Pt is measured by using an impulse voltage in the range from 10 kV to 40 kV to avoid the effect of joule heating. Although the observed Dbs data seems to be well fitted to a straight line with a slope of 0.9 on a double logarithm of (Pt-$V_{CB}$) and Dbs, the least squares method gives a slope of 0.97 for the PMC. It has been found that finite carbon-black clusters play an important role in dielectric breakdown.

Parametric study of laterally loaded pile groups using simplified F.E. models

  • Chore, H.S.;Ingle, R.K.;Sawant, V.A.
    • Coupled systems mechanics
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    • 제1권1호
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    • pp.1-7
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    • 2012
  • The problem of laterally loaded piles is particularly a complex soil-structure interaction problem. The flexural stresses developed due to the combined action of axial load and bending moment must be evaluated in a realistic and rational manner for safe and economical design of pile foundation. The paper reports the finite element analysis of pile groups. For this purpose simplified models along the lines similar to that suggested by Desai et al. (1981) are used for idealizing various elements of the foundation system. The pile is idealized one dimensional beam element, pile cap as two dimensional plate element and the soil as independent closely spaced linearly elastic springs. The analysis takes into consideration the effect of interaction between pile cap and soil underlying it. The pile group is considered to have been embedded in cohesive soil. The parametric study is carried out to examine the effect of pile spacing, pile diameter, number of piles and arrangement of pile on the responses of pile group. The responses considered include the displacement at top of pile group and bending moment in piles. The results obtained using the simplified approach of the F.E. analysis are further compared with the results of the complete 3-D F.E. analysis published earlier and fair agreement is observed in the either result.

의미네트워크 분석법을 이용한 근대 건축문화유산의 보존과 활용에 관한 사회적 논의 분석 - 부산광역시 근대건조물 구)한성은행 부산지점(청자빌딩)을 중심으로 - (An Analysis of Social Discussion on Preservation and Utilization of Modern Architectural Heritage using Semantic Network Analysis - Focussed on the former Busan Branch of Hansung Bank(Cheong-Ja Bldg) as a Modern Heritage -)

  • 안재철
    • 대한건축학회논문집:계획계
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    • 제35권7호
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    • pp.101-108
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    • 2019
  • In this research, I conducted a semantic network analysis centering on media articles on purchasing, revitalizing, and utilizing the former Busan branch of Hansung Bank, a modern architectural heritage. We sought the most efficient analysis elements for the analysis of the social arguments about preservation and utilization embedded in media articles. For this reason, Degree Centrality measures how many connections the word described in the media article has, and Betweenness Centrality measures the influence that controls the flow of information through correlation I examined. In addition, keyword that express the theme well examined the aggregation structure in each sub-network. In this research, in theoretical terms, it makes sense in that the social discussion embedded in the article of the mass media is grasped empirically through semantic network analysis of words. Methodological aspect is best when it includes nouns and adjectives and the distance between words is more than four words in the analysis of the cohesive structure of the semantic network to determine whether the influence of social discussions is best assessed through the connection between words to media articles.

Failure and Phase Transformation Mechanism of Multi-Layered Nitride Coating for Liquid Metal Injection Casting Mold

  • Jeon, Changwoo;Lee, Juho;Park, Eun Soo
    • 한국재료학회지
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    • 제31권6호
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    • pp.331-338
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    • 2021
  • Ti-Al-Si target and Cr-Si target are sputtered alternately to develop a multi-layered nitride coating on a steel mold to improve die-casting lifetime. Prior to the multi-layer deposition, a CrN layer is developed as a buffer layer on the mold to suppress the diffusion of reactive elements and enhance the cohesive strength of the multi-layer deposition. Approximately 50 nm CrSiN and TiAlSiN layers are deposited layer by layer, and form about three ㎛-thickness of multi-layered coating. From the observation of the uncoated and coated steel molds after the acceleration experiment of liquid metal injection casting, the uncoated mold is severely eroded by the adhesion of molten metallic glass. On the other hand, the multi-layer coating on the mold prevents element diffusion from the metallic glass and mold erosion during the experiment. The multi-layer structure of the coating transforms the nano-composite structured coating during the acceleration test. Since the nano-composite structure disrupts element diffusion to molten metallic glass, despite microstructure changes, the coating is not eroded by the 1,050 ℃ molten metallic glass.

낙엽송 블록접착집성재의 접착 및 휨 강도 성능 (Bending and Bonding Strength Performances of Larix Block-glued Glulam)

  • 이인환;홍순일
    • Journal of the Korean Wood Science and Technology
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    • 제44권3호
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    • pp.315-322
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    • 2016
  • 2개 이상의 보부재 집성재 요소들의 측면접착으로 제작된 "블록접착집성재"는 대단면 목조건축물의 건축부재로 활용 가능한 구조용재다. 블록접착집성재의 측면은 접착제의 종류와 도포량 및 압체압력을 각기 다른 조합으로 접착하여 박리시험과 전단블록시험으로 접착성능을 검토하였다. 실험결과 레조시놀접착제 $500g/m^2$을 도포하고 압체압력 1.5 MPa의 조건으로 제작된 블록접착집성재의 측면접착성능이 가장 양호하였다. 양호한 측면접착조건으로 제작된 블록접착집성재는 동일단면계수의 대조군 집성재와 휨 강도 성능을 비교 검토하였다. 블록접착집성재의 휨 탄성계수는 대조군 집성재와 유사하였으며, 파괴계수는 대조군집성재 보다 27% 향상되었다. 할렬은 대조군집성재 보다 블록접착집성재에서 다량 발생하였으며, 블록접착집성재의 측면접착층에서 계면파괴나 응집파괴는 관찰되지 않았다.

Experimental study on the shear failure model for concrete under compression-shear loading

  • Shu, Xiaojuan;Luo, Yili;Zhao, Chao;Dai, Zhicheng;Zhong, Xingu;Zhang, Tianyu
    • Computers and Concrete
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    • 제29권2호
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    • pp.81-92
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    • 2022
  • The influence of normal stress perpendicular to the potential shear plane was always neglected in existing researches, which may lead to a serious deviation of the shear strength of concrete members in practice designs and numerical analyses. In this study, a series of experimental studies are carried out in this paper, which serves to investigate the shear behavior of concrete under compression shear loading. Based on the test results, a three-phase shear failure model for cohesive elements are developed, which is able to take into consideration the influence of normal stress on the shear strength of concrete. To identify the accuracy and applicability of the proposed model, numerical models of a double-noted concrete plate are developed and compared with experimental results. Results show that the proposed constitutive model is able to take into consideration the influence of normal stress on the shear strength of concrete materials, and is effective and accurate for describing the complex fracture of concrete, especially the failure modes under compression shear loadings.