Stress Analysis of a Structure Subjected to Bending by the Three-dimensional Local Hybrid Method

We developed the 3-D local hybrid method that analyzes only the local model of a structure and can evaluate the interior stress field of it from surface data obtained by easy measurement. In previous studies, the good result was obtained with the surface cracked specimen subjected to uniform tension. In this study, we examined whether the 3-D local hybrid method could apply to the structure subjected to bending. The digital image correlation (DIC) method was adopted as measurement of the surface displacement data needed for the analyses by the 3-D local hybrid method. Although DIC can measure the in-plane displacement in sufficient accuracy, it cannot measure correctly the in-plane displacement accompanied by the out-of-plane displacement. A position is not constant as for the structure subjected to bending such as a cantilever, and the distance to a camera changes before and after loading. First, the influence of the out-of-plane displacement on the measurement accuracy of DIC was evaluated and how to eliminate the influence was examined. Secondly, the surface displacement was measured from the experiment of a cantilever subjected to bending, and whether the 3-D local hybrid method could evaluate an internal stress state was examined.