외연적 유한요소법을 이용한 자동차 Hub Bearing의 Orbital forming 해석

조현직(Hyunjik Cho),구정서(Jeongseo Koo),배원락(Wonrak Bae),임종순(Jongsoon Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

In this paper was analysed the orbital forming of an automotive hub bearing using the explicit finite element method. To find an efficient solution technique on the orbital forming, axisymmetric finite element model s and 3D solid element models were solved and compared numerically. The time scaling and mass scaling techniques were used to reduce long computational time for fine element models in case of using the explicit finite element method. It was found from the numerical results that the axisymmetric element models showed the similar results to the 3D solid element models in forming loads whereas the deformations of them caused by O/F were quite different.

외연적 유한요소법을 이용한 항공기 착륙장치 Spin-up, Spring -Back 하중해석

박일경(Ill-Kyung Park),김성준(Seung-Jun Kim),안석민(Seok-Min Ahn),송정헌(Jung-Heon Song) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

The spin-up and the spring-back are most severe load cases in the aircraft landing gear design. These load cases are caused by reciprocal action of complex physical phenomenon such as the friction between a tire and ground, inertia of the rotation of a tire and the flexibility of a landing gear structure. Generally, the empirical formula or the theoretical formula is used to calculate the spin-up and spring-back load in the early stage of the development program of the aircraft landing gear. After the materialization of the design of a landing gear, spin-up and spring-back load are acquired by the free drop test. In this study, the spin-up and the spring-back load of the rubber shock absorber type aircraft nose landing gear are calculated by the explicit finite element analysis. Through this analysis, more accurate and realistic spin-up and spring back loads could be applied to the early phase of the development of the aircraft landing gear.

외연적 유한요소법을 이용한 자동차 Hub Bearing의 Orbital Forming 해석에 관한 연구

조현직(Hyunjik Cho),구정서(Jeongseo Koo),배원락(Wonrak Bae),임종순(Jongsoon Lim) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.1

FRP-콘크리트 합성보의 휨거동에 관한 외연적 비선형 유한요소해석 연구

유승운,강가람 대한토목학회 2017 대한토목학회논문집 Vol.37 No.2

본 연구는 철근콘크리트구조를 대신할 FRP-콘크리트 합성구조의 극한 휨 거동에 관한 것으로, FRP-콘크리트 합성보의 구조적 성능 및 거동 특성을 수치 해석적으로 규명하고자 범용 해석프로그램인 ABAQUS를 사용하여 외연적 비선형 유한요소해석을 실시하고 기 수행한 실험과 비교 분석하였다. 콘크리트의 재료모델은 콘크리트 손상 소성모델을 사용하였으며, 콘크리트 압축응력은 유로코드를 사용하였다. 4가지 종류의 FRP-콘크리트 합성보에 대해 비선형해석을 수행하고 극한하중 및 균열 형태를 비교 분석하였다. 본 모델의 경우 극한 하중 및 균열 형태를 잘 모사할 수 있었기 때문에 앞으로 다양한 FRP-콘크리트 합성구조의 정밀한 구조거동 해석 및 분석에 사용 가능할 것으로 판단된다. In order to study ultimate flexure behavior of FRP-concrete composite structures which can replace reinforced concrete structures,ABAQUS, a general purpose analysis program, was utilized for numerical nonlinear analysis of structural performance and behavior characteristics of FRP-concrete composite beams. Explicit nonlinear finite element analysis was conducted and the numerical results were compared with previous experiments. Concrete damaged plasticity model was adopted as material properties of concrete and Euro code was used as compressive stress state. Nonlinear analysis was performed for four different types of FRP-concrete composite beams, and ultimate load and cracking pattern was compared and analyzed. The model suggested in this research was able to simulate ultimate load and cracking pattern properly, it is expected to be utilized in study of precise structural and behavioral characteristics of various FRP-concrete composite structures.

연강 판재에 대한 연강 구의 고속경사충돌 수치해석

유요한,장순남,정동택,Yu, Yo-Han,Jang, Sun-Nam,Jeong, Dong-Taek 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.3

A three-dimensional Lagrangian explicit time-integration finite element code for analyzing the dynamic impact phenomena was developed. It uses four node tetrahedral elements. In order to consider the effects of strain rate hardening, strain hardening and thermal softening, which are frequently observed in high-velocity deformation phenomena, Johnson-Cook model is used as constitutive model. For more accurate and robust contact force computation, the defense node contact algorithm was adopted and implemented. In order to evaluate the performance of the newly developed three-dimensional hydrocode NET3D, numerical simulations of the oblique impact of mild steel plate by mild steel sphere were carried out. Ballistic limit about various oblique angle between 0 degree and 80 degree was estimated through a series of simulations with different initial velocities of sphere. Element eroding by equivalent plastic strain was applied to mild steel spheres and targets. Ballistic limits and fracture characteristics obtained from simulation were compared with experimental results conducted by Finnegan et al. From numerical studies, the following conclusions were reached. (1) Simulations could successfully reproduce the key features observed in experiment such as tensile failure termed "disking"at normal impacts and outwards bending of partially formed plus segments termed "hinge-mode"at oblique impacts. (2) Simulation results fur 60 degrees oblique impact at 0.70 km/s and 0.91 km/s were compared with experimental results and Eulerian hydrocode CTH simulation results. The Lagrangian code NET3D is superior to Eulerian code CTH in the computational accuracy. Agreement with the experimentally obtained final deformed cross-sections of the projectile is excellent. (3) Agreement with the experimental ballistic limit data, particularly at the high-obliquity impacts, is reasonably good. (4) The simulation result is not very sensitive to eroding condition but slightly influenced by friction coefficient.

외연적 시간영역 탄성파 해석을 위한 안정적 비분할 PML 기법

김보영(Kim, Boyoung),강준원(Kang, Jun Won) 대한토목학회 2021 대한토목학회 학술대회 Vol.2021 No.10

스프링백 특성에 영향을 미치는 수치변수의 분석을 위한 다구치 실험계획법의 응용

김형종,전태보 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.A

It is desirable but difficult to predict springback quantitatively and accurately for successful tool and process design in sheet stamping operations. The result of springback analysis by the finite element method (FEM) is sensitively influenced by numerical factors such as blank element size, number of integration points, punch velocity, contact algorithm, etc. In the present work, a parametric study by Taguchi method is performed in order to evaluate the influence of numerical factors which gives the best approximation to experimental data. Since springback is determined by the residual stress after forming process, it is important to evaluate stress distribution accurately. The oscillation in the time history curve of stress obtained by the dynamic-explicit finite element variability study is also carried out in this study in order to assess the stability of implicit springback analysis starting from the stress solution by explicit forming simulation. The U-draw bending process, one of the NUMISHEET '93 benchmark problems, is adopted as an application model because it is most popular one for evaluation the springback characteristic.

외연 유한요소 기법을 사용한 고속충돌 및 관통해석

백승훈,김승조,Paik, Seung-Hoon,Kim, Seung-Jo 한국군사과학기술학회 2005 한국군사과학기술학회지 Vol.8 No.4

The impact of a long-rod penetrator into oblique plates with combined obliquity and yaw is investigated. The study was done using a newly developed three dimensional dynamic and impact analysis code, which uses the explicit finite element method. Through the comparison of simulation result with experimental result and other code's result, the adaptability and accuracy of the developed code is evaluated under the complex situation in which yaw angle and oblique angle exist simultaneously. As a result of comparison, it has found that deformed shape, residual length and velocity, rotational velocity of long-rod show good agreement with experimental data. Through this study, the applicability and accuracy of the code as a metallic armour system design tool is verified.

스프링백 특성에 영향을 미치는 수치변수의 분석을 위한 다구치 실험계획법의 응용

김형종(Kim Hyung Jong),전태보(Jeon Tae Bo) 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.1

It is desirable but difficult to predict springback quantitatively and accurately for successful tool and process design in sheet stamping operations. The result of springback analysis by the finite element method (FEM) is sensitively influenced by numerical factors such as blank element size, number of integration points, punch velocity, contact algorithm, etc. In the present work, a parametric study by Taguchi method is performed in order to evaluate the influence of numerical factors which gives the best approximation to experimental data. Since springback is determined by the residual stress after forming process, it is important to evaluate stress distribution accurately. The oscillation in the time history curve of stress obtained by the dynamic-explicit finite element variability study is also carried out in this study in order to assess the stability of implicit springback analysis starting from the stress solution by explicit forming simulation. The U-draw bending process, one of the NUMISHEET ’93 benchmark problems, is adopted as an application model because it is most popular one for evaluation the springback characteristic.

홉킨슨 압축봉에서의 동적 재료특성에 관한 수치해석적 연구

이승우,홍성인,Lee, Seung-U,Hong, Seong-In 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.6

To determine dynamic characteristics of materials, a program was developed under base of stress wave propagation theory for SHPB with explicit finite element method. Through the program, all kinds of quasi-static stress-strain curves can be directly converted to dynamic stress-strain curves at any strain rate. This simulation results were compared with experimental results in the references and they are in a good agreement with each other.