When performing finite element analysis using materials with porosity the porosity shows different mechanical properties from the existing mechanical properties of the existing base materials. In this study the equivalent properties were calculated and verified by applying the representative volume element (RVE) method and assuming that the material with porosity is a 2D orthotropic material. In case of finite element analysis using porous material or composite material, it is inefficient to perform the analysis through material modeling. Based on the element volume and element stress values derived using the finite element analysis program, the representative stress values and elastic modulus matrix were calculated using Python. In addition, equivalent properties were derived using the calculated elastic modulus matrix. The pores were simulated by etching a thin plate specimen made of STS304 material in a certain pattern, and the elastic modulus and Poisson's ratio were measured through a UTM and compared with simulation results. It was confirmed that an error of 7.028% for elastic modulus and 10% for Poisson's ratio occurred, and through this, the validity of this simulation was verified.
The demand for materials with porosity is steadily increasing and the need for porous materials is increasing in fields such as chemical engineering and energy storage. In order to minimize trial and error, verifying design validity through finite element method at the design stage has the advantage to verify design validity with low cost. However there are limitations in finite element analysis using porous materials. In this study calculating the equivalent mechanical properties reflecting the porosity was carried out, and the first step was the isotropic elasticity in plane stress condition. The equivalent elastic modulus and the equivalent Poisson's ratio were derived through simulation. Assuming that the voids exist in a two-dimensional symmetrical shape and a constant distribution, the unit cell was defined and the equivalent mechanical properties were calculated. The specimen with same condition were measured through a universal test machine (UTM), the elastic modulus and Poisson's ratio were measured. The similarity between the value obtained through the simulation and the value measured through the experiment was under 5%, so the validity of this simulation was verified. With this result, FEM with porous materials will be used for design.
1997년 12월 이후 남한 중부지역에서 방생한 지진 중 13개 지진에 대하여, 지역에 따라 5개 그룹으로 구분하여 P 파 극성을 이용하여 구한 복합단층면해와 P, S파 극성 및 진폭비(SV/P, SH/P, SV/SH)를 이용하여 구한 결과를 비교 해석하였다. 지진원에서의 단층운동은 NNE-SSW와 WNW-ESE 방향의 단층면을 나타내며 주향이동 혹은 역단층성 주향이동운동이 우세하게 나타났다. 단층운동에 작용한 주압축응력방향은 ENE-WSW 방향, 혹은 NE-SW 방향을 나타내며, 이는 남한지역에 발생하는 주요 지진에 대하여 구해진 주압축 응력장 방향과 거의 일치한다.