• Title/Summary/Keyword: high strength materials

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Investigation of the Prediction Accuracy for the Stamping CAE of Thin-walled Automotive Products (고강도강 차체 박판부품 프레스성형 CAE의 예측 정확도 고찰)

  • Jung, D.G.;Kim, S.H.;Rho, J.D.
    • Transactions of Materials Processing
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    • v.23 no.7
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    • pp.446-452
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    • 2014
  • In the current study finite element forming analysis is performed to understand the final geometric accuracy limitations for the stamping of an automotive S-rail from four different steel sheets having tensile strengths of 340MPa, 440MPa, 590MPa and 780MPa. Comparisons between the analysis and the experiments for both springback and formability as measured by the amount of edge draw-in and the thickness distribution were conducted. The springback modes were classified according to a scheme proposed in the current investigation and the error was calculated using the normalized root mean square error method. While the analysis results show fairly good agreement with the experimental data for deformation and formability, the simulation accuracy is lower for predicting wall curl, camber and section twist as the UTS of steel sheet increases.

Characteristic Strength of $\delta$-Al$_2$O$_3$/Aluminum Composite by Rheo-compocasting (반용융 가공법에 의한 $\delta$-Al$_2$O$_3$/Aluminum 복합재료의 강도 특성)

  • 이상필;김만수;김석호;윤한기
    • Proceedings of the KWS Conference
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    • 1995.04a
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    • pp.155-159
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    • 1995
  • A16061 alloy reinforced with 10 vol% $\delta$-A1$_2$O$_3$ short fiber have been fabricated by Rheo-compocasting and squeeze casting and extruded at high temperature using conical shape die and curved shape die with various extrusion ratios.. Tensile and hardness tests were carried out to examine mechanical properties of extruded materials and SEM observation of fractured surface was capable of accounting for fracture mechanism and bonding state of fiber and matrix.

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A study on the mirror like machining of Al-Si alloy for extraction of Si particle (Al-Si합금의 Si석출 경면가공에 관한 연구)

  • 이은상;김정두
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.12
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    • pp.2279-2286
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    • 1992
  • A hypereutectic Aluminum-Silicon Alloy is widely used in the parts of autombile because of high-resistance and good strength. In this study, the cutting of a hypereutectic Al-Si alloy (A390) for extraction of Si particle was experimentally investigated. By proper selection of cutting tool materials and optimization of cutting conditions, economical machining of this alloy is achieved. The surface roughness relates closely with the feed rate and cutting speed.

Strain Hardening Behaviour of PM Alloys with Heterogeneous Microstructure

  • Straffelini, Giovanni
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.928-929
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    • 2006
  • Tensile stress-strain and dynamic acoustic resonance tests were performed on Fe-C-Ni-Cu-Mo high-strength steels, characterized by a heterogeneous matrix microstructure and the prevalence of open porosity. All materials display the first yielding phenomenon and, successively, a continuous yielding behavior. This flow behavior can be described by the Ludwigson equation and developes through three stages: the onset of localized plastic deformation at the pore edges; the evolution of plastic deformation at the pore necks (where the austenitic Ni-rich phase is predominant); the spreading of plastic deformation in the interior of the matrix. The analytical modeling of the strain hardening behavior made it possible to obtain the boundaries between the different deformation stages.

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A Study on the Fracture Characteristics of 7075 Aluminum Alloy (7075 Al 합금의 파괴특성에 관한 연구)

  • Joung, Tai-Seoung;Kang, In-Chan
    • Journal of Korea Foundry Society
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    • v.12 no.1
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    • pp.32-39
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    • 1992
  • In this study, electron microscopy, Fractography and $J_{IC}$ test have been used to investigate the fracture behaviour in the scope of aging temperature which 7075 Al-alloy can have high strength. Conclusions obtained on this study are as followed. 1) When the 7075 Al-alloy was aged for 24hrs at $120^{\circ}C$, it's mechanical properties was excellent but fracture toughness decrement resulted from intergranular fracture was emerged. 2) The state of aged for 24hrs at $100^{\circ}C$, had the highest fracture toughess. 3) We could infer that intergranular fracture occurred because preferrential precpitated precipitates in the grain boundary growed in the form of colinear along the grain boundary.

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A study on solidification of sewage sludge ash by chemical activation (화학 반응을 이용한 하수슬러지 소각재 고형화 연구)

  • Jo, Byung-Wan;Suh, Suk-Koo;Park, Jong-Bin
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.477-480
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    • 2005
  • The discharge of sewage sludge is rapidly increasing in Korea. But the most common sewage sludge disposal alternative is to incinerate and to deposit it in controlled landfills. However, space limitations on existing landfill sites, and increasing environmental concerns have prompted the investigation of alternative ash disposal routes. The utilization of sewage sludge ash would contribute to the elimination of an environmental problem and to the development of new high-performance materials. The purpose of this study is to apply to Alkali Activation into solidification of sewage sludge ash. It achieves leaching test, chemical composition and compressive strength test. As a result of tests, the sewage sludge ash has sufficient potential for use of pozzolanic raw material. However, it is judge to be available to construction material if research is continuously gone.

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Fabrication of Large-Size Alumina by Pressure-Vacuum Hybrid Slip Casting

  • Cho, Kyeong-Sik;Lee, Seung Yeul
    • Journal of the Korean Ceramic Society
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    • v.50 no.6
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    • pp.396-401
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    • 2013
  • The size of various alumina ceramics used in the semiconductor and display industries must be increased to increase the size of wafers and panels. In this research, large alumina ceramics were fabricated by pressure-vacuum hybrid slip casting (PVHSC) employing a commercial powder, followed by sintering in a furnace. In the framework of the PVHSC method, the consolidation occurs not only by compression of the slip in the casting room but also by suction of the dispersion medium from the casting room. When sintered at $1650^{\circ}C$ for 4 h, the fabricated large-size alumina ($1,550{\times}300{\times}30mm^3$) exhibited a dense microstructure corresponding to more than 99.2% of the theoretical density and a high purity of 99.79%. The flexural and compressive strengths of the alumina plate were greater than 340 MPa and 2,600 MPa, respectively.

A study on analysis of interfacial breakdown properties with variable temperalure in straight cable Joint modeling EPGXY/EPOM interface (온도에 따른 케이블 직선 접속재 모델링 EPOXY/EPDM 계면의 파괴 특성에 관한 연구)

  • 배덕권;정인재;김상걸;정일형;이준웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.05a
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    • pp.532-535
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    • 1999
  • In power cable joints, the interfaces of two different dielectric materials are inevitable. In addition, the interfacial breakdown between two internal dielectric surfaces represents one of the major causes of failure for power cable joints. We chose epoxy/EPDM interface, one of the interface in cable joints, and investigate dielectric interfacial breakdown phenomenon. First, design specimen with Flux 2D. Second, find interface condition which has high dielectric strength. Third, investigate interfacial breakdown properties with variable temperature.

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Analysis of Chemical Components and Microstructure Characteristics of CBS Dust (CBS-Dust의 화학성분 및 미세구조 특성 분석)

  • Han, Jun-Hui;Lee, Young-Jun;Hyun, Seung-Yong;Lee, Dong-Joo;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.05a
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    • pp.180-181
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    • 2019
  • In this study, in order to find new uses for CBS dust, the chemical components of CBS dust were analyzed and effectively proposed a method. Chemical analysis shows that CBS dust contains a large amount of alkali in addition to chloride therefore, if CBS dust is used for secondary concrete products that use high amounts of mixed materials without rebars, it will be found that it can be used effectively for enhancing strength by active alkali.

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Engineering Characteristics of Resource-Cycling Mortar according to the Variation of Illite Replacement Ratio and Fine Aggregate Type (일라이트 치환률 및 잔골재 종류 변화에 따른 자원순환형 모르타르의 공학적 특성)

  • Kim, Min-Yoyng;Song, Yuan-Lou;Kim, Sang-Sup;Yoon, Won-Geun;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.05a
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    • pp.46-47
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    • 2015
  • This study has analyzed the engineering characteristics of resource-cycling mortar according to the variation of fine aggregate type using illite with high development potentials by setting the goal as developing eco-friendly construction materials. As a result, while flow has increased if recycled fine aggregate and waste refractory are used separately or mixing them adequately in case of flow and compressive strength, the flow had somewhat declined followed by illite replacement. However, the possibility of such usage is determined to be adequate if used by mixing illite, recycled fine aggregate and waste refractory properly due to the dry shrinkage effect.

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