Composites Research

The Korean Society for Composite Materials (한국복합재료학회)
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A Constitutive Equation with Impulse-Momentum Theory for the Expanded Polypropylene

충격량-운동량 이론을 접목시킨 발포 폴리프로필렌의 구성방정식

  • Kim, Byeong Kil (Department of Mechanical Engineering, Kongju National University) ;
  • Cho, Jae Ung (Division of Mechanical & Automotive Engineering, Kongju National University) ;
  • Jeong, Kwang Young (Division of Mechanical & Automotive Engineering, Kongju National University) ;
  • Kim, Nam Hoon (Division of Mechanical & Automotive Engineering, Kongju National University) ;
  • Oh, Bum S. (Division of Mechanical & Automotive Engineering, Kongju National University) ;
  • Hahn, Youngwon (Dassault Systemes SIMULIA) ;
  • Cheon, Seong S. (Division of Mechanical & Automotive Engineering, Kongju National University)
  • Received : 2016.03.02
  • Accepted : 2016.06.27
  • Published : 2016.06.30
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Abstract

In this paper, impulse-momentum theory was coupled to a constitutive equation both for implementing quasi-static and impact characteristics of EPP (Expanded polypropylene). Also, parameters which have physical meanings were expressed as functions of relative density. Simultaneous nonlinear Newton-Raphson method was applied to find the proper values for parameters in the constitutive equation along with quasi-static test data. Results from the impulse-momentum theory coupled constitutive equation showed good agreement with experimental data and the potential to be applied to different material type polymeric foam.

본 연구에서는 EPP(Expanded polypropylene) 준정적 및 충격 하중에 대한 구성방정식을 표현하는 데 있어서, 충격량-운동량 이론을 연계하였다. 또한, 구성방정식을 이루는 물리적으로 의미있는 변수들에 대해, 상대밀도의 함수로 표현하였다. 이를 위해, 연립 비선형 뉴튼-랩손 방법을 사용하여, 준정적 시험결과에 맞는 구성방정식의 변수값을 선정하였다. 또한, 충격량-운동량 이론이 구성방정식과 연계되어, 충격시 응력-변형률 선도를 변형률 속도에 따라 구하였고, 충격시험결과와 비교하였다. 향후에는 다른 재질의 발포고분자에도 본 구성방정식이 적용될 수 있을 것으로 사료된다.

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References

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