저자명 허지향 
년도 2007 
The sheet metal forming is an effective process which is widely used in many industries. In sheet metal forming processes, the quality of deformed parts are influenced by many process parameters, such as the shape of the dies, the shape and the thickness of the initial blank, the material properties, blank holding force, friction, and so on. These process parameters are determined by intuition and experience through trial and error. Recently, a more systematic approach such as finite element analysis is applied in the initial and final design stage. This approach has shortcomings. One is that general finite element analysis is carried out with given initial blank shape and process parameters, but the contour of initial blank and the geometry of the tools are unknown in the preliminary product design stage. The other is that it needs tremendous computation time and cost to perform the incremental analysis.
In order to overcome those problems, some simplified approaches such as the finite element inverse analysis are developed to calculate initial blank shape and process parameters within the small amount of time in the preliminary design stage. In the finite element inverse analysis, initial shape and thickness or strain distributions of the final state is calculated by comparing the desired final shape and initially flat blank. In most of researches on the inverse analysis, bending effects were neglected since membrane effects are dominant in many cases of sheet metal forming processes. But there are a number of industrial applications such as deep drawing operations in which bending effects are significant. In these sheet metal forming processes, resulting error may increase in case of disregarding bending effects. Therefore, it needs to consider bending effects for more accurate result. There are many researches to consider bending effects in the inverse analysis using shell elements. However, we cannot consider bending effects on the region where bending and unbending occurs by using conventional approaches because there is no information on the deformation path. In this paper, a new approach is proposed to consider bending-unbending effects. Bending-unbending effects are considered by adding the bending-unbending energy using modified membrane elements. Bending-unbending region can be predicted from the geometry of the final shape and tools. Bending-unbending energy was calculated by assuming that the blank contacts with the die completely when it passes over the die radius. The present algorithm has been implemented in a finite element code and applied to several numerical examples for the demonstration of its validity. The algorithm was applied to a drawing of cylindrical cup to verify its validity and effectiveness. Blank shapes and thickness strain distributions were obtained with and without considering bending-unbending effects. The results are compared to the result of the incremental finite element analysis. The finite element inverse analysis of a cylindrical cup drawing process is carried out to inspect the effect of the thickness of the initial sheet by changing the initial thickness. Simulation for S-rail forming was carried out to demonstrate the program’s capability and versatility. The amount of errors was reduced when bending-unbending effects were considered. Furthermore, resulting errors reduces more largely as the thickness of the initial blank increases. Consequently, these examples fully demonstrate that the finite element inverse analysis with the proposed algorithm for considering bending-unbending effects is useful to obtain more accurate results especially when bending effects are significant.
번호 제목 저자명 날짜 조회 수
49 Structural Design and Evaluation for Improvement of the Roof Strength of a Three-Wheel Vehicle(삼륜차의 루프 강도 향상을 위한 구조 설계 및 평가) file Jesung Yoo  2017.06.07 1326
48 Tension/Compression Hardening Behavior of Auto-body Steel Sheets at Intermediate Strain Rates Ranging from 0.1/s to 50/s(중 변형률속도 0.1/s ~ 50/s 영역에서의 차체 강판의 인장/압축 경화 거동에 관한 연구) 주근수  2014.01.16 4507
47 Tensile Properties of Nugget Region in a Spot Weld at Various Strain-Rates (점용접 너겟부의 변형률속도에 따른 인장 물성에 관한 연구) 박문수  2014.01.16 4256
46 Validation of Dynamic Hardening Models at High Strain Rates Using Taylor Impact Tests (테일러 충격시험을 이용한 고 변형률속도 조건에서의 동적 경화모델 검증) 박명준  2013.09.02 4956
45 Tensile Material Properties of Carbon/epoxy Composite Laminates at High Strain Rates (탄소섬유강화 복합재료의 변형률 속도에 따른 인장물성의 평가) 최재영  2013.02.12 7442
44 Design and Dynamic Simulation of a New Shock Absorbing Device with a Bending Strap in a Helicopter Pilot Seat (헬리콥터 조종석의 굽힘 판재를 이용한 새로운 충격흡수장치의 설계 및 동적 모사해석에 관한 연구) [1] 박주형  2013.02.12 8062
43 Anisotropy Effect on the Fracture Forming Limit Diagram of DP980 Sheets Considering the Loading Path (DP980 강판의 하중경로를 고려한 파단성형한계도에 미치는 이방성의 영향) 박남수  2013.02.12 6857
42 Study on the Dynamic Failure Model of Structural Adhesive Joints under Combined Loading Conditions(차량 구조용 접착제를 이용한 접합부의 복합하중조건에서 동적 파단 특성 연구) 임승찬  2013.01.24 5853
41 Study on the Strain-Rate Dependent Tensile Properties of Micro-Scale Aluminum Specimens(알루미늄 마이크로시편의 변형률속도에 따른 인장 특성 연구) 권준범  2012.03.01 8142
40 Study on the Fracture Strain of DP780 Sheets Considering the Strain Rate and Loading Path (변형률속도와 하중경로를 고려한 DP780 강재의 파단변형률에 관한 연구) 박근환  2012.02.20 11958
39 Evaluation of Ultimate Buckling Strength of Stiffened Plates for Marine Structures (해양구조물용 보강판구조의 좌굴한계강도 평가) Waseem Gul  2010.07.13 8844
38 Study on Design of Stress Wave Micro Sensor for High Speed Transportation Safety System (고속운송기구의 안전시스템을 위한 마이크로 응력파 센서 설계 연구) 임성준  2010.07.13 7834
37 Study on the Anisotropy of Auto-body Steel Sheets considering the Strain Rate(변형률속도를 고려한 차체강판의 이방성에 관한 연구) 이창수  2010.07.13 9085
36 Reliability Based Design Optimization for Crashworthiness of a Spot Welded Hat Type Member (점용접 모자형 사각관의 충돌성능에 대한 신뢰도 기반 최적설계) 김유종  2010.07.13 7401
35 Upper Bound Analysis of Dynamic Buckling Phenomenon of Circular Tubes Considering Strain Rate Effect (변형률 속도를 고려한 원형 튜브의 동적 좌굴 현상의 상계 해석에 관한 연구) 박충희  2008.08.02 7330
34 Study on the Crash Energy Absorption and Dynamic Local Buckling of the Expansion Tubes (확관튜브의 충돌에너지 흡수성능 및 동적 국부좌굴에 관한 연구) 안광현  2008.01.28 6510
33 Dynamic Material Properties of the Heat-Affected Zone (HAZ) in a Resistance Spot Weld(점용접 열영향부의 동적 물성특성에 관한 연구) 하지웅  2008.01.25 7931
32 Cross-section Shape Design of an Aluminum Crash Box for Crashworthiness Enhancement (충돌성능 향상을 위한 알루미늄 크래쉬 박스의 단면 형상 설계) [1] 이경호  2008.01.25 8129
» Finite Element Inverse Analysis of the Sheet Metal Forming Process Considering Bending History (굽힘 이력을 고려한 박판성형공정의 유한요소 역해석) 허지향  2008.01.25 6212
30 Study on the 3-D finite element modeling of fiber reinforced rubber composite using the rebar element (리바요소를 이용한 섬유강화 고무기저 복합재료의 3차원 유한요소 모델링기법 연구) 정세환  2006.08.18 7024