Transactions of the Korean Society of Automotive Engineers (한국자동차공학회논문집)

The Korean Society of Automotive Engineers (한국자동차공학회)
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Numerical Analysis to Predict the Time-dependent Behavior of Automotive Seat Foam

자동차용 시트 폼의 시간 의존적 거동 예측을 위한 수치해석

  • Kang, Gun (Polymeric Materials Research Team, Advanced Technology Center R&D Division for Hyundai Kia Motors Department) ;
  • Oh, Jeong Seok (Polymeric Materials Research Team, Advanced Technology Center R&D Division for Hyundai Kia Motors Department) ;
  • Choi, Kwon Yong (Polymeric Materials Research Team, Advanced Technology Center R&D Division for Hyundai Kia Motors Department) ;
  • Kim, Dae-Young (Department of Mechanical Biomedical Engineering, Kangwon National University) ;
  • Kim, Heon Young (Department of Mechanical Biomedical Engineering, Kangwon National University)
  • 강건 (현대자동차 고분자재료연구팀) ;
  • 오정석 (현대자동차 고분자재료연구팀) ;
  • 최권용 (현대자동차 고분자재료연구팀) ;
  • 김대영 (강원대학교 기계의용공학과) ;
  • 김헌영 (강원대학교 기계의용공학과)
  • Received : 2014.03.14
  • Accepted : 2014.05.09
  • Published : 2014.09.01
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Abstract

Generally, numerical approaches of evaluation for vehicle seat comfort have been studied without considering time-dependent characteristics and the only seating moment have been considered in seat design. However, the comfort not only at the seating moment but also in the long-term should be evaluated because the passengers are sitting repeatedly on the seat to drive the vehicle for hours. So, the aim of this paper is to carry out a quantitative evaluation of the time-dependent mechanical characteristics of seat foams and to suggest a process for predicting the viscoelastic deformation of seat foam in response to long-term driving. To characterize the seat materials, uniaxial compression and tension tests were carried out for the seat foam and stress relaxation tests were performed for evaluating the viscoelastic behavior of the seat foam. A unit solid element model was used to verify the reliability of the material model with respect to the compression behavior of the seat foam. It is not straightforward to evaluate the time-dependent compression of foams using the explicit solver because the viscoelastic material model is limited. To use the explicit solver, the material model must be modified using stress-degradation data. Normalized stress relaxation moduli were added to the stress-strain curves obtained under static conditions to achieve a time-dependent set of stress-strain relations that were compatible with the implicit solver. There was good agreement between the analysis results and experimental data.

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References

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