A formulation for thick-walled composite blades is devised and implemented numerically. A parametric study which is focused on the influence of wall thickness on the structural behavior of blades, with an emphasize on the elastic couplings induced by composite materials is also presented. In contrast with models for thin-walled blades, the shear stresses perpendicular to the local wall direction are accounted for. The numerical solution is based on a finite-difference scheme where the displacement field is described by four global displacements for each cross-section and an out-of-plane warping function for each material point. Overall, the solution procedure employs an iterative scheme that enables the inclusion of a large number of independent variables. The results reveal and demonstrate the discrepancies between thick-walled modeling and thin-walled modeling as functions of the wall thickness for various loading modes, and supply a clear indication of regions where employing a thick-walled model is inevitable.

No abstract

We present algorithms for uniformly covering an unknown indoor region with a swarm of simple, anonymous and autonomous mobile agents. The exploration of such regions is made difficult by the lack of a common global reference frame, severe degradation of radio-frequency communication, and numerous ground obstacles. We propose addressing these challenges by using airborne agents, such as Micro Air Vehicles, in dual capacity, both as mobile explorers and (once they land) as beacons that help other agents navigate the region.The algorithms we propose are designed for a swarm of simple, identical, ant-like agents with local sensing capabilities. The agents enter the region, which is discretized as a graph, over time from one or more entry points and are tasked with occupying all of its vertices. Unlike many works in this area, we consider the requirement of informing an outside operator with limited information that the coverage mission is complete. Even with this additional requirement we show, both through simulations and mathematical proofs, that the dual role concept results in linear-time termination, while also besting many well-known algorithms in the literature in terms of energy use.