Damage assessment of composite plate structures with material and measurement uncertainty

Composite materials are very useful in structural engineering particularly in weight sensitive applications. Two different test models of the same structure made from composite materials can display very different dynamic behavior due to large uncertainties associated with composite material properties. Also, composite structures can suffer from pre-existing imperfections like delaminations, voids or cracks during fabrication. In this paper, we show that modeling and material uncertainties in composite structures can cause considerable problein in damage assessment. A recently developed C-0 shear deformable locking free refined composite plate element is employed in the numerical simulations to alleviate modeling uncertainty. A qualitative estimate of the impact of modeling uncertainty on the damage detection problem is made. A robust Fuzzy Logic System (FLS) with sliding window defuzzifier is used for delamination damage detection in composite plate type structures. The FLS is designed using variations in modal frequencies due to randomness in material properties. Probabilistic analysis is performed using Monte Carlo Simulation (MCS) on a composite plate finite element model. It is demonstrated that the FLS shows excellent robustness in delamination detection at very high levels of randomness in input data. (C) 2016 Elsevier Ltd. All rights reserved.

The impact of architectural uncertainty on product introduction in dispersed environments

This research addresses product introduction dispersed across locations and companies. Mechanisms appropriate to integrate activities in collocated teams may not serve dispersed teams well. A semiconductor design licensor was studied in depth to explore how dispersed product introduction varies with uncertainty. We found that autonomous teams focused on sub-products (micro-products) were used rather than cross-functional teams in departments with high architectural uncertainty. Both types of teams were effectively dispersed across locations and companies. This suggests that small high-technology companies may find it easier to expand into new geographies and product lines than was previously believed.