Tensile Properties of Auto-body Plastic with Various Strain Rates for FEM by Using The DIC Method and The Force Equilibrium Grid Method

Abstract

This paper is concerned with tensile properties of auto-body plastic by using the DIC(Digital Image Correlation) method and the FEGM(Force Equilibrium Grid Method) with various strain rates ranging from 0.001/sec to 100/sec. In recent years, the amount of auto-body plastic used is being increasing for the light weight, crashworthiness and its good formability. Due to non-uniform elongation at gauge section during tensile test of auto-body plastic, it is important to analyze material properties by using the FEGM. Although the FEGM is a good solution which compensates characteristics of non-uniform deformation on auto-body plastic, it is complicated to conduct the FEGM by analysis of grids on each part of the gauge section. The DIC is alternative method to resolve the difficulty of the FEGM. The DIC method is technique to acquire strain distribution on the gauge section by capturing image series of irregular speckle pattern on the gauge section of the auto-body plastic specimen during tensile test. High speed tensile test is conducted by using HSMTM(High Speed Material Testing Machine) at KAIST. Image series of the gauge section is captured by using high speed camera with various strain rates. Analysis of strain distribution at each image series is calculated for applying the FEGM. Obtained material properties of auto-body plastic enable FE analysis of auto-body plastic to be more accurate.