• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 춘계학술대회 논문집
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• pp.149-158
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• 1994

Powder forged Connecting Rods have become attractive for use in automotive engines. The powder forging process offers beneficial material utilization as well as the minimization of finishing operations over that of conventionally forged rods. In the present work, the sintering behavior of Fe-2Cu-0.6C, optimum preform design and forgeability of various forging variables were investigated. Our data were generated using a newly proposed sub-scale con-rod developed specifically to simulate the powder forging process. We obtain optimum condition of sintering and powder forging process.

• 한국정밀공학회지
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• 제25권12호
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• pp.33-38
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• 2008

• 한국분말재료학회지
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• 제2권1호
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• pp.19-28
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• 1995

Powder forging is a combined technology of powder metallurgy and precision hot forging. Recently, the technology is developing rapidly because of its economic merits, especially in automotive part manufacturing. In the present study, the finite element technique was developed to predict density variation during P/M forging and the technique was applied to analysis of forging of a P/M connecting rod. Although deformation mode of the connecting rod was quite complex, several sections were selected and analyzed under an assumption of asymmetric or plane strain deformation. It was found that some modifications were necessary on the cross section of the beam portion. Therefore, the cross section was modified repeatedly until a satisfactory result of the analysis was obtained. On the other hand, no modifications were necessary in the ring and the pin portions. It is anticipated that the developed technique can be used to optimize preform design and manufacturing processes in P/M forging, which are highly critical to produce successful products in practice.

• Elastomers and Composites
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• 제57권4호
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• pp.138-146
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• 2022

Research on the reduction of plastic use to prevent environmental pollution is urgently needed. Accordingly, studies on reducing the weight of polyethylene terephthalate (PET) bottles are currently being conducted. PET bottles are fabricated by injection stretch blow molding. In this study, stretch blow molding for fabricating PET bottles using preform studied through a computer simulation. Blowing characteristics are analyzed by varying the start time of the pre-blow, which is one of the process conditions of stretch blow molding. Simulation results and the preform inflation process are presented, and the parameters of stretch ratio, stretching path, thickness distribution, and weight distribution of blown PET bottles are investigated.

• 한국산학기술학회논문지
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• 제13권5호
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• pp.1990-1995
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• 2012

본 연구에서는 다구찌 방법을 이용하고 유한요소해석을 통해 알루미늄 피스톤 제조에 큰 영향을 미치는 설계변수의 적합한 조건을 도출하였다. 단조 최대 성형하중을 목적함수로 하고 설계변수로서 예비성형체, 소재온도 및 빼기구배를 선정하였으며 마찰을 잡음인자로 하는 직교배열표를 작성하고 시뮬레이션별 유한요소해석을 통해 하중을 평가하였다. 이를 통해 설계 변수들이 미치는 영향을 분석한 결과를 바탕으로 설계변수의 최적조합조건은 제안하였다. 이러한 방법은 여러 가지 금속성형공정에서 최종 단조품 전단계에서 여러 예비성형체에서 적합한 예비성형체를 결정할 때 도움을 줄 수 있으며 특히, 최적의 설계조합을 결정할 때 쉽게 적용할 수 있을 것이다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.46-46
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• 2005

• Composites Research
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• 제33권3호
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• pp.115-124
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• 2020

적층복합재료, 특히 탄소섬유 복합재료는 금속에 비해 가벼우며 상대적으로 비강도 및 비강성이 뛰어나기 때문에 항공 우주 산업 및 자동차 산업 등과같이 광범위한 분야에서 사용되고 있다. 그러나, 적층 복합재료는 섬유의 배열이 모두 면내방향으로 배열되어있기 때문에 박리가 발생한다는 큰 단점이 있으며, 이는 적층복합재료의 응용분야를 제한한다. 본 연구에서는 먼저 π-빔과 평판이 결합된 형태의 적층복합재료 T-빔을 개발하고, 구조해석 및 기계적 물성평가를 통하여 설계변수를 최적화하였다. 이후 적층복합재료 T-빔의 설계변수를 3D 직조 프리폼에 동일하게 적용하여 T-빔을 개발하였으며, 적층구조에 비하여 향상된 기계적 강도를 달성할 수 있었다. 이러한 연구결과는 강도향상을 필요로 하는 기존의 적층복합재료 구조물에 적용 가능할 것으로 기대된다.

• 한국정밀공학회지
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• 제22권12호
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• pp.93-99
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• 2005

In this work, computer-aided process design is carried out to develop an optimal preform of a pressure vessel. Knowledge-based rules are employed to design the preform, and they are formulated using the handbooks of plasticity theories. In the FE-analysis, a commercial finite element code, ABAQUS was employed. Axisymmetric deep drawing of a hemisphere-bottomed cup has been analyzed fur various combinations of die design parameters. The length of the land of die, the clearance between punch and die and the clearance between the blank holder and die are optimized to minimize the forming load. The results of the simulations are verified with the experiments which are scaled down to one tenth of the actual size.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.113-116
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• 1998

A derivative based approach to process optimal design in powder forging is presented. The process model, the formulation for process optimal design, and the schemes for the evaluation of the design sensitivity, and an iterative procedure for the optimization are described in detail. The validity of the schemes for the evaluation of the design sensitivity is examined by performing numerical tests. The capability of the proposed approach to deal with diverse process parameters and objective functions is demonstrated through applications to some selected process design problems.

• Fibers and Polymers
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• 제4권3호
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• pp.135-144
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• 2003

Permeability of the preform is one of key factors in design of RTM (Resin Transfer Molding) mold, determination of processing conditions, and modeling of flow in the mold. According to previous studies, permeability measured in the unsaturated fiber mats are higher than that in the saturated fiber mats by about 20% because of the capillary pressure. In this study, permeabilities of several fiber preforms are measured for both saturated and unsaturated flows. A saturated experiment of radial flow has been adopted to measure the permeability of anisotropic fiber preforms with high fiber content, i.e., circular braided preforms. In this method, four pressure transducers are used to measure the pressure distribution. Permeabilities in different directions are determined and the experimental results show a good agreement with the theory. Since permeability is affected by the capillary effect, permeability should be measured in the unsaturated condition for the textile composites to be manufactured under lower pressure as in the Vacuum Assisted Resin Transfer Molding (VARTM).