저자명 강우종 
년도 2000 
The crashworthiness of auto-body structures is an indispensable issue in the automotive industry. The automotive industry has made an effort to develop light-weight auto-body structures to increase the fuel efficiency and to satisfy the emission gas regulation of vehicles. Since the weight reduction of an auto-body should not obstruct the safety improvement, the crash analysis has to be accurately conducted for efficient reducing of the auto-body weight. The vehicle body structures are generally composed of various members such as frames, stamped panels and deep-drawn parts from sheet metals. The strength of sheet metals depends on the rate of deformation and the dynamic behavior of sheet metals is a key to investigate the impact characteristics of the structure. As the dynamic behavior of a material is different from the static one due to the inertia effect and the stress wave propagation, an adequate experimental technique has to be developed to obtain the dynamic response for the corresponding level of the strain rate. To acquire the high strain-rate material properties of sheet metals, a tension type split Hopkinson bar apparatus specially designed for sheet metals was used. The tension split Hopkinson bar inevitably causes some errors in the strain at grips for the plate type specimens, since the grip and specimen disturb the one-dimensional wave propagation in bars. Validation of experiment is carried out with the error analysis that is estimated by comparing the waves acquired from experiments with the one from the Pochhammer-Chree solution. The optimum geometry of the specimen is determined to minimize the error from the loading equilibrium.
  The dynamic response of sheet metals at the high strain-rate is obtained from the tensile split Hopkinson bar test using plate type specimens. Experimental results from both quasi-static and dynamic tensile tests with the tensile split Hopkinson bar apparatus are interpolated to construct the Johnson-Cook and a modified Johnson-Cook equation as the constitutive relation that should be applied to simulation of the dynamic behavior of auto-body structures. The constitutive relation obtained is applied to simulation of thin-walled structures by an elasto-plastic explicit finite element method with shell elements incorporating with a contact algorithm. The present algorithm adopts the plastic predictor-elastic corrector (PPEC) scheme in stress integration in order to accurately keep track of the stress-strain relation for the rate-dependent model. To verify the finite element code developed with the dynamic constitutive relation, the dynamic crash experiment is conducted with square tubes made from the sheet metals. Comparison between the experimental and analysis results show that the dynamic mean crash loads of square tubes calculated with dynamic constitutive model are more accurate than the one with quasi-static model.
  To evaluate the crashworthiness of a car, the dynamic response of auto-body components has to be correctly simulated for various loading conditions. The crash analysis is performed for auto-body structures such as a hood and frontal frames of an automobile. The finite element model of an automobile is adopted from the web site of NHTSA (National Highway Traffic Safety Administration). The vehicle crashworthiness is greatly affected by side members and s-rails that are the energy absorbing structures with the axial and bending collapse mode. These structures are designed to effectively dissipate the vehicle kinetic energy in terms of plastic deformation in favor of the safety of passengers. Simulation is carried out with the dynamic and the quasi-static model of sheet metals in order to compare the results from both models. Results show remarkable difference in the reaction force and impact energy absorption. The reason is considered mainly due to the strain rate effect. Simulation results also provide the deformed shape and the deformation energy in order to predict and evaluate the crashworthiness of a car.

번호 제목 저자명 날짜 조회 수
27 Study on Dynamic Tensile Tests of Auto-body Steel Sheet at the Intermediate Strain Rate for Material Constitutive Equations (차체강판의 중변형률 속도에서의 동적 인장시험 및 물성 구성방정식에 관한 연구) 임지호  2005.11.29 25430
26 Analysis of Elasto-Plastic Stress Waves by a Time Discontinuous Variational Integrator of Hamiltonian with a Second-Order Integration Scheme of the Constitutive Model (해밀토니안의 시간 불연속 변분적분기와 구성방정식의 2차 정확도 적분법을 이용한 탄소 조상순  2008.12.15 21646
25 Forming Limit Diagram of Auto-body Steel Sheets at High Strain Rates for Sheet Metal Forming and Crashworthiness (박판성형 및 충돌성능 향상을 위한 고변형률속도에서의 차체강판 성형한계도) 김석봉  2010.07.13 21585
24 A New Ductile Fracture Criterion for the Formability Prediction of Steel Sheets and Its Application to Finite Element Analysis (강판의 성형성 예측을 위한 새로운 연성 파괴 조건 및 유한 요소 해석에의 응용) [1] Yanshan Lou  2012.12.10 20976
23 A Study on the Tension/Compression Hardening Behavior of Auto-body Steel Sheets Considering the Pre-strain and the Strain Rate (초기 변형률 및 변형률 속도를 고려한 차체 강판의 인장/압축 경화 거동에 관한 연구) [1] 배기현  2011.01.11 20274
22 A Study on Material Properties of OFHC Copper Film at High Strain Rates using High-Speed Micro Material Testing Machine (고속마이크로재료시험기를 이용한 무산소동 박판의 고변형률속도 재료물성치 연구) 김진성  2010.07.13 20156
21 Finite Element Inverse Approach and Initial Guess Generation for Sheet Metal Forming Analysis of Complicated Auto-body Members (복잡한 차체부재의 박판성형공정을 위한 유한요소 역해석 및 초기추측치 계산) 김승호  2005.11.29 19050
20 A Study on the Dynamic Failure Model of a Spot Weld under Combined Loading Conditions for Auto-body Crash Analyses (차체용 부재의 충돌해석을 위한 복합하중조건에서 점용접부의 동적 파단모델 연구) [1] 송정한  2008.07.24 18508
19 Optimum Process Design in Sheet Metal Forming Processes using Finite Element Sensitivity Analysis (유한요소 민감도해석을 이용한 박판금속성형에서의 공정변수 최적설계) [1] 김세호  2005.11.29 18448
18 Strain-Rate Dependent Anisotropic Yield Criteria for Auto-body Steel Sheets (자동차용 강판의 변형률속도 의존 이방성 항복함수에 관한 연구) 허지향  2012.12.11 17976
17 Evaluation of a cast-joining process of dual metal crankshafts for heavy-duty engines with ductile cast iron and high strength forged steel(구상흑연주철과 고강도 단조강의 주조접합 이종금속을 이용한 중대형 엔진 크랭크샤프트의 평가) 한 신  2010.07.13 17828
16 Dynamic Formulation of Finite Element Limit Analysis for Impact Simulation of Structural Members (구조부재의 충돌해석을 위한 유한요소 극한해석의 동적 수식화) 김기풍  2005.11.29 17725
15 Measurement Uncertainty Evaluation for High Strain Rate Tensile Properties of Auto-body Steel Sheet (자동차용 강판 고속인장물성 데이터의 측정불확도 산출) 정세환  2012.12.10 17704
14 Development of a Nonlinear Degenerated Shell Element with the Drilling Degree of Freedom by the Cubic Polynomial Interpolation and the Assumed Strain Method (드릴링 자유도의 삼차 근사법과 대체변형률법을 이용한 비선형 감절점 쉘 요소의 개발) 이형욱  2005.11.29 17662
13 Rate Dependent Hardening Model for Pure Titanium Considering the Effect of Deformation Twinning (쌍정의 영향을 고려한 티타늄의 변형률속도 의존 경화 모델) 안광현  2012.12.12 17136
12 Finite Element Simulation of 3-dimensional Superplastic blow forming with diffusion bonding (유한요소법을 이용한 초소성 재료의 삼차원 확산 접합 및 압력 성형 해석) 이기석  2005.11.29 16942
11 Microscopic investigation of the strain rate hardening for auto-body steel sheet(차체강판 변형률속도 경화의 미시적 관찰) 윤종헌  2010.07.13 16887
» Crash Analysis of Auto-body Structures with an Explicit Finite Element Method ( 외연적 유한요소법을 이용한 차체 구조물의 충돌해석 ) 강우종  2005.11.29 16676
9 Shell Element Formulation for Limit Analysis of Thin-Walled Structures ( 박판부재의 붕괴거동해석을 위한 극한해석의 쉘요소 수식화 ) 김현섭  2005.11.29 14690
8 A Study on a Continuum Damage Yield Function to Predict Ductile Fracture of Materials (재료의 연성파단을 예측하기 위한 연속체 손상 항복 함수에 관한 연구) 고윤기  2012.12.10 14565