A Methodology for Strength and Reliability Analysis of Carbon Nanofiber and Conventional Composite Plates

摘要

A methodology for predicting the nonlinear static response and the reliability of conventional composite and isotropic (metallic and nanocomposite) plates with initial imperfections is presented. The methodology consists of two tools. The first tool is a combined model for predicting the properties of conventional and carbon nanofiber composites from the properties of the fiber, matrix and their respective volume fractions. The combined model provides the material properties of the composite (conventional and nano) as input to a macro mechanics model for strength and reliability analysis of plates. The latter model will require as inputs the plate geometry and boundary conditions, and the material properties of the composite or isotropic material (metallic and nanocomposite). For composites, either the material properties of the orthotropic lamina, and the stacking sequence, can be supplied directly, or the composition of the composite can be given along with properties of the matrix and fiber. Output of the macro mechanic model includes the load-deflection data for a plate under axial or transverse loading, probability of failure by the important failure modes, and sensitivity of the failure probability of these failure modes to variation in each of the random input variables. The method accounts for the effects of geometric nonlinearity for composite and isotropic materials, as well as material nonlinearity for the latter. It also accounts for variability in the material properties, loading, and initial imperfections. The methodology is demonstrated on a rectangular plate subjected to an in-plane compressive load, with initial imperfections. The plate is made of carbon nanofiber composite material in which the nanofibers are straight and randomly oriented.