고 변형률 속도에서 폴리프로필렌 및 열가소성 올레핀 소재의 기계적 거동에 대한 연구

Abstract

Polypropylene-glass long fiber material (PP-LGF) and thermoplastic olefin (TPO) are materials that improve the function of polypropylene. They are promising materials for automobile interior components and building insulation because of their excellent heat resistance, impact resistance, and formability. In order to develop reliable automotive parts using these materials, it is very important to predict the damage behavior and mechanical properties of materials under impact load because material shows different behavior depending on strain rate. In this study, the strain rate dependent compressive properties of PP-LGF and TPO was investigated under the high strain rate by using the Split Hopkinson Pressure Bar (SHPB). The SHPB is the most widely usedapparatus to characterize dynamic mechanical behavior of materials at high strain rates between 100 �ିଵ and 10,000 �ିଵ. The SHPBtest applies wave propagation theory which was developed to calculate the stress, strain and strain rate of the specimen using thestrains measured in the incident and transmission bars. The size of the specimen for the high-speed compression test was determined according to ASTM D695. The strain data obtained through the high-speed camera and Digital Image Correlation (DIC) were compared and verified during the high strain compression test of the PP and TPO specimen. As a result, it was found that both PPLGF and TPO materials had higher compressive strength than the static compression test, and the strain verified through DIC showed similar results from the SHPB strain values. The results imply that the strain dependent properties should be considered when designing automotive components and we will apply it to evaluate and design airbag.