Sharif Digital Repository

In this article, both experimental and numerical approaches are conducted to present a constitutive equation for 5052 aluminum diaphragms under quasi-static strain rate loadings. For this purpose the stress-strain curves at different strain rates are obtained using tensile tests. Brittle behavior during tensile tests is observed due to samples thin thicknesses. Employing Johnson-Cook constitutive equation no yields in reasonable agreement with these tensile tests results. Therefore, developing a more suitable constitutive equation for aluminum diaphragms is taken into consideration. This equation is then implemented into the commercial finite element software, ABAQUS, via a developed user... 

This study develops the governing equations and characterizes the mechanical properties of a new orthotropic accordion morphing honeycomb structure containing periodic arrays of U-type beams reinforced with glass fibers. Castigliano’s second theorem is modified to develop the analytical equations to predict the deformation behavior of a single orthotropic ply under a combined axial, bending, and shear loadings. Accordingly, the elastic properties of the orthotropic structure including elastic stiffness, shear stiffness, and in-plane Poisson’s ratios are calculated by the developed equations. The honeycomb structure is manufactured by 3D printing, and the samples are subjected to tensile... 

In the present study, a novel theoretical model is developed, based on the energy method, to predict the equivalent mechanical properties of a new morphing structure with zero Poisson's ratio, which is composed of continuous fiber reinforced composite struts. Due to the employing glass fiber in fabricating the proposed cruciform honeycomb, higher strength than the structures made of pure isotropic materials is obtained. The use of cells with a zero Poisson's ratio also increases the flexural strength of the structure. In the continuation of the paper, by examining the geometric effects on the equivalent properties, a parametric study is performed. Then, using the appropriate failure...