Rotary braiding is a cost effective method to manufacture near net shaped preforms that generally have a closed section and may have an arbitrary shape if braiding is performed over a shaped mandrel. The reinforcement architecture can be varied by the number and spacing of active bobbins, and by the speeds used to 'take-up' the braid and move the circumferential bobbins. Analytical methods are available that can reliably predict yarn paths and the final braid meso-structure for simple regular sections, and further analytical methods have been proposed to estimate composite braid elastic mechanical properties. A full simulation chain using the explicit Finite Element (FE) technique is presented for composite braid manufacture and mechanical stiffness prediction of the final composite. First simulation of the braiding process provides detailed information on yarns paths and braid meso-structure, from which Representative Volume Elements (RVE) of the braid may be constructed for analysis of stiffness properties. The techniques are general and can be applied to any braid geometry. A specific problem of meshing the yarn structure and interspersed resin volumes is overcome using conventional solid elements for the yarns and Smooth Particle Hydrodynamics for the resin, with link element to join the two constituents. Details of the background theory, braid simulation methods, meso-model analysis and validation again analytical and test measurements are presented.

Two-dimensional braiding of a generic preform has been undertaken using test, analytical and advanced explicit finite element simulation methods. The generic preform selected incorporates several important features including two cylindrical and one square section, a tapered cone and two dissimilar flanges. The analytical method has been shown to be computationally fast, but has limited accuracy and cannot directly predict braiding imperfections. Conversely, the explicit finite element method does require a complex model description, but has the capability to detect manufacturing imperfections and accurately predict yarn paths and yarn interactions. A detailed evaluation and comparison of the two methods is made against test results from the generic preform, which was deliberately manufactured to have both good and imperfect yarn architecture.

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The purpose of this paper is to present an approach to model, analyze and visualize online production systems, such as Wikipedia, open source software development processes, and Flickr. While the final result of the production in these systems depends on the type of product (e.g., content, software, and tags), there are similarities in their modes of actions. The approach taken is to interpret online production systems as social information spaces, and to describe them with a generic vocabulary that is implemented in software. One scenario for open content production is presented using data from the online encyclopedia Wikipedia. The generic vocabulary is extended by wiki-specific vocabulary; the value of the approach is illustrated with two selected network presentations. The main insight is that key processes in online production systems can be reduced to two basic items and three fundamental relations. Various kinds of online production systems can be mapped onto this vocabulary and the same software solution can be applied for analyzing them. The approach presented here has two practical implications: first, available data from online production systems can be obtained and evaluated more easily. Second, results are comparable because the generic vocabulary serves as a shared understanding of online production systems.

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