• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2005년도 추계학술대회 논문집
• /
• pp.460-462
• /
• 2005

Asymmetrical rolling was performed with different working roll speeds of upper and lower rolls. In order to promote the shear deformation during asymmetrical rolling, various deformation parameters of initial sheet thickness, rolling reduction, roll speed ratio and roll radius are considered. The evolution of texture during asymmetrical rolling was shown by the calculation of orientation distribution function (ODF). The effect of deformation parameters on shea. deformation were investigated by simulations with the finite element method (FEM). Asymmetrical rolling gave rise to the development of pronounced strain gradients throughout the thickness layers which resulted in the formation of strong texture gradients in the sheet.

• 한국지반공학회지:지반
• /
• 제9권1호
• /
• pp.21-30
• /
• 1993

본 연구에서는 지반해석을 위한 여러 방법중 유한요소법에 의한 연성해석 및 역해석기법을 이용하여, 지반변형해석과 토질정수의 추정방법 등에 대하여 연구하였다. 토질정수의 정확한 산정의 필요성을 알기 위하여, 지반의 탄성해석에서의 탄성계수, 투수계수, 포아송비 등에 따른 민감도를 분석 고찰하였고, 여러가지의 점토질 흙에 대한 압밀실험결과를 이용하여 역해석기법에 의한 토질정수의 산정을 실시하고, 이 토질정수를 이용한 탄성해석에 의하여 지반의 변형과 간극수압을 구하여, 다음과 같은 결과를 얻었다. 탄성해석에 있어서, 지반의 탄성계수에 따른 지반변형량과 간극수압의 민감도가 비교적 크게 나타나므로, 탄성계수의 산정은 매우 중요하며, 재하하중이 클수록 탄성계수의 산정을 정확히 하여야 한다. 작은 하중단계에서의 짧은 시간의 실측치를 이용한 역해석을 통하여 토질정수를 산정함으로 4, 비교적 단순한 탄성해석을 통하여서도, 더욱 큰 하중 재하시 또 장기간의 변형량을 실제와 가잠게 예측할 수 있으며, 역해석에서의 반복계산 회수를 줄이고 더욱 좋은 결과를 얻기 위해서는, 초기치 실측 절점의 개수를 증가시키고 초기 실측치의 더욱 정확한 산정이 필요하다.

• 한국공간구조학회논문집
• /
• 제5권1호
• /
• pp.91-98
• /
• 2005

연성구조물의 일종인 막구조물은 대공간 구조물을 보다 효과적으로 구축할 수 있다. 연성구조물은, 축강성은 강하고 휨강성이 매우 작은 재료를 주 구조재로 사용하므로 초기강성에 매우 약한 구조체이다. 초기강성을 확보하기 위해서는 초기응력의 도입이 필수적이고, 초기강성을 갖기 전에는 불안정현상을 나타내지만, 초기강성의 도입과 함께 안정상태가 된다. 초기 불안정 구조물에 초기강성을 도입함으로써 야기되는 대변형 현상을 파악하기 위해서는 기하학적 비선형을 고려한 형상해석이 요구된다. 본 연구에서는 비선형 해석프로그램인 NASS를 이용하여 해석을 수행한다. 해석모델은 Barrel Vault형 지붕 막구조물을 대상으로 하며, 직교이방성을 고려한 형상해석 및 응력-변형해석을 수행한 후 안정성을 검토한다.

• 한국전산유체공학회지
• /
• 제18권3호
• /
• pp.20-25
• /
• 2013

In various manufacturing industries, an in-mold decoration (IMD) process for plastic objects is widely utilized because a film forming and an injection molding processes run simultaneously. In the present study, the deformation of polymer film and filling of resin in the IMD process were numerically investigated to evaluate the quality of the plastic object formed by the IMD process, which consists of thermoforming and injection molding processes. To obtain the initial shape of the polymer film during the injection molding process, the deformation of the polymer film in the thermoforming process was pre-formed using the vacuum conditions to attach the film to a cavity. Since the properties and deformation of polymer film are greatly affected by the behavior of polymer resin being injected into a mold cavity, numerical simulations for the injection molding and film forming were performed with one-way coupling method. The results showed that the injected resin could lead to the tearing of the polymer film in local regions near the corners. In order to verify the proposed numerical methodology, the numerical results of the deformation patterns printed on the initial polymer film were compared with the experimental data. The proposed methodology to couple film forming analysis with injection molding analysis can be used to predict the deformation of film in IMD process.

• 대한기계학회논문집A
• /
• 제26권4호
• /
• pp.644-652
• /
• 2002

Increasing demands for Electric Resistance Welded pipes of high quality with thick wall require c lose investigations in edge deformation by slitting, strip deformation during break down farming, and difference of circumferential length. In order to obtain good quality of a welding zone, it is necessary to predict the edge shape of the initial strip. The modeling of the multi-pass thick tube roll forming process with rigid plastic finite element method ultra the edge shape prediction of an initial strip with 2nd-degree polynomial regression method are presented. Edge shapes of initial strip have been analyzed by the finite element method and designed by the regression method to satisfy the requirements in target fin pass. It is concluded that the proposed edge design method results in optimal edge shapes sat string the design requirements.

• 대한토목학회논문집
• /
• 제35권1호
• /
• pp.129-139
• /
• 2015

차수기능을 점토 코아 대신 상류사면의 콘크리트 슬래브로 수행하는 콘크리트 표면차수벽형 석괴댐의 설계는 이론보다는 사례와 경험에 크게 의존한다. 본 연구에서는 두 개의 CFRDs에서 준공 후 초기 담수기간에 계측된 데이터를 근거로 콘크리트 슬래브와 누수량 거동을 분석하였다. 분석결과 슬래브의 변형률과 수직이음부의 수평변위는 미미하게 계절적인 온도 변화와 저수위면 증가에 의한 담수하중의 영향을 받고, 주변이음부의 변형은 온도 변화의 영향은 미미하고 담수하중의 영향을 크게 받는 것으로 나타났다. 그리고 누수량은 담수하중에 따른 주변이음부의 변형에 의한 영향을 크게 받는 것으로 나타났다.

• 소성∙가공
• /
• 제15권5호
• /
• pp.382-386
• /
• 2006

Preform design is an effective means of achieving the homogeneous deformation of workpiece materials and decreased load in metal forming. However, this approach has not been applied to equal channel angula. pressing (ECAP). In this paper, plastic deformation behavior of workpieces having four different preform shapes during ECAP was investigated using finite element analyses. The results indicated that a preform design of the workpiece head has a beneficial effect on homogeneous deformation, reducing the maximum pressing load at the initial stage and eliminating folding defects at strain concentration points.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 춘계학술대회논문집
• /
• pp.74-79
• /
• 2003

When workability at the a certain bulk deformation process is defined as the maximum plastic deformation capability that the workpiece can sustain without causing any cracks or fracture, the workability is dependent on the microstructure, initial workpiece shape, stress state developed during the deformation process, strain rata and presence of the interfacial friction between workpiece and tool. For a review purpose, the workability definition and test methods are summarized depending on the applied stress state at bulk deformation process in Table 1 at the text. In this study, the cold workabilities of as-cast A16061 bulk material have been measured and comparatively analyzed at the primary tensile stress state by using tensile specimens, the primary compressive stress state by using cylindrical specimens, and the forming limit diagram by ductile fracture.

• ETRI Journal
• /
• 제38권6호
• /
• pp.1095-1103
• /
• 2016

We present a method for transferring deformation weights of a human character to three-dimensional (3D) scanned clothes. First, clothing vertices are projected onto a character skin. Their deformation weights are determined from the barycentric coordinates of the projection points. For more complicated parts, such as shoulders and armpits, continuously moving planes are constructed and employed as projection reference planes. Clothing vertices on a plane are projected onto the intersection curve of the plane with a character skin to achieve a smooth weight transfer. The proposed method produces an initial deformation for physically based clothing simulations. We demonstrated the effectiveness of our method through several deformation results for 3D scanned clothes.

• 대한조선학회논문집
• /
• 제49권3호
• /
• pp.222-226
• /
• 2012

When ship blocks are erected or pre-erected, most blocks will be at outdoors where they are not protected from weather and exposed to ray of the sun. A deck plate compared to those in radiation heat transfer from the sun will have higher temperature than it of ambient air, and will expand more than lower laying structures whose temperatures are similar with air. But deck plates and under-structures are connected, so the deck plate will be under out-of-plane deformation rather than expand in length. In this study, we considered the temperature difference between air and plate as a major parameter of out-of-plane deformation, and analyzed how much additional deformation would take place. In addition, when a deformation could take place was also analyzed based on the initial deformed shape of deck plate. Because the accuracy inspections of deck plate will be done during daytime, conventional accuracy check results on sunny day could make us feel unfair. Thus resonable datum about momentary additional out-of-plane deformation due to environmental effects have been determined. The real deformation values can be specified even under enlarged deformations by radiation-expansion.