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A stress induced supercritical non-linear microcracking model is employed as part of an incremental and iterative hierarchical modeling scheme aimed at investigating the evolution of damage in brittle matrix plain weave fabric composites subjected to uniaxial tension. The study focuses exclusively on matrix micro-damage and its effect on the macroscopic non-linear composite response. For a given load increment, the requisite micro-stresses and associated state of matrix microcracking are updated through an iterative converging scheme that employs the semi-analytical approximate model to compute micro-stresses and the discrete microcracking model to evaluate micro-damages. A wide range of non-linear stress–strain curves were obtained through parametric studies. Degradation of the in-plane effective properties of the unit-cell and evolution of the volumetric matrix damage were monitored throughout the simulations. The simulated predictions were then used to develop empirical in-plane effective property degradation laws in terms of the applied loading. Damage-induced macroscopic elastic anisotropies were predicted as was the formation of macroscopic damage zones consistent with discrete micro-fracture events such as inter-bundle matrix cracking, bundle mode-I cracking, and transverse bundle matrix cracking. Stress–strain curves obtained from the model were compared favorably with their experimental counterparts obtained from literature and commercial sources.

Recent growth in the business of unmanned air vehicles (UAVs) both in the US and abroad has improved their overall capability, resulting in a reduction in cost, greater reliability and adoption into areas where they had previously not been considered. Uses in coastal and border patrol, forestry and agriculture have recently been evaluated in an effort to expand the observed area and reduce surveillance and reconnaissance costs for information gathering. The scientific community has both contributed and benefited greatly in this development. A larger suite of light-weight miniaturized sensors now exists for a range of applications which in turn has led to an increase in the gathering of information from these autonomous vehicles. In October 2004 the first eruption of Mount St Helens since 1986 caused tremendous interest among people worldwide. Volcanologists at the U.S. Geological Survey rapidly ramped up the level of monitoring using a variety of ground-based sensors deployed in the crater and on the flanks of the volcano using manned helicopters. In order to develop additional unmanned sensing methods that can be used in potentially hazardous and low visibility conditions, a UAV experiment was conducted during the ongoing eruption early in November. The