Composites Research

The Korean Society for Composite Materials (한국복합재료학회)
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Application of the EPU Constitutive Equation to expanded Polypropylene under Dynamic Loading

동하중을 받는 발포 폴리프로필렌에 대한 EPU 구성 방정식 적용

  • Jeong, Kwang Young (Department of Mechanical Engineering, Kongju National University) ;
  • Kim, Byeong-Jun (Department of Mechanical Engineering, Kongju National University) ;
  • Cheon, Seong S. (Division of Mechanical and Automotive Engineering, Kongju National University)
  • Received : 2014.02.15
  • Accepted : 2014.08.06
  • Published : 2014.08.31
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Abstract

A constitutive equation, which was suggested for describing the compressive deformation behaviour of the expanded polyurethane, was applied to the expanded polypropylene under dynamic loading. This equation consists of seven parameters, five of which are obtained by fitting the stress strain curve obtained from the quasi-static compression test at the lowest base strain rate. The remaining two parameters are able to be determined by fitting the curve from the compression test at different two stage strain rates. In order to check the eligibility of the equation at high strain rate, the impact test was performed and the results were compared to the analytical constitutive equation results for the expanded polypropylene with expansion ratios of 30 and 40 times, respectively.

발포 폴리우레탄의 변형거동을 설명하기 위해 제안된 구성방정식을 발포 폴리프로필렌에 적용하였다. 이 방정식은 7개의 매개변수를 갖고 있으며, 그중 5개의 변수는 기준 변형률속도에서 준정적 압축시험을 하여 얻은 결과를 커브 피팅하여 구하고, 나머지 두 변수는 변형률 속도를 다르게 한 준정적 압축시험으로부터 얻은 결과를 커브 피팅하여 구한다. 이렇게 구한 응력-변형률 방정식이 높은 변형률속도에서도 유효한지 알기 위해 충격시험으로부터 얻은 결과와 비교하였으며 30배와 40배로 발포된 폴리프로필렌 폼 시편에 대하여 각각 시행하였다.

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References

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