Abstract
It is very important to get to know the mechanical behavior of structure because of the health monitoring of structure. Industrially, a strain gage is used for a stress analysis on the surface of an object. In order to carry out full field measurement in a certain region, many gages and supporting equipment are required, as well as time. Hence, there is the strong need for the development of a stress analysis system by an optical, real time and non-contact measurement method. Digital image correlation (DIC) is suitable to this aim and has been adopted to analyze the displacement on the surface of the specimen. DIC has been successfully applied mainly to metallic materials which are homogeneous and isotropic. On the other hand, recently fiber reinforced composites are developed and are used as structural materials, especially in various fields including an aerospace field. Fiber reinforced composites are heterogeneous and anisotropic. The applicability of the stress analysis methods on such heterogeneous and anisotropic materials is not well known. In this study, the displacement, stress and strain analysis of carbon fiber reinforced plastic (CFRP) laminate that was an anisotropic material were carried out by combining digital image correlation with two-dimensional linear/nonlinear intelligent hybrid method. A material used was carbon/epoxy system. Laminate configuration was unidirectional. Tensile load was applied in off-axis (45 degrees) direction as well as longitudinal (0 degree) and transverse (90 degrees) directions on a CFRP laminate. The constitutive equation considering material anisotropy was built into the intelligent hybrid method used at the time of analyses. The validity of algorithm was verified by the comparison between the results of the present method, experimental results from the strain gage method, and the analytical results from finite element method (FEM).
