3D geometric modelling of discontinuous fibre composites using a force-directed algorithm

A geometrical modelling scheme is presented to produce representative architectures for discontinuous fibre composites, enabling downstream modelling of mechanical properties. The model generates realistic random fibre architectures containing high filament count bundles (>3k) and high (~50%) fibre volume fractions. Fibre bundles are modelled as thin shells using a multi-dimension modelling strategy, in which fibre bundles are distributed and compacted to simulate pressure being applied from a matched mould tool. FE simulations are performed to benchmark the in-plane mechanical properties obtained from the numerical model against experimental data, with a detailed study presented to evaluate the tensile properties at various fibre volume fractions and specimen thicknesses. Tensile modulus predictions are in close agreement (less than 5% error) with experimental data at volume fractions below 45%. Ultimate tensile strength predictions are within 4.2% of the experimental data at volume fractions between 40%-55%. This is a significant improvement over existing 2D modelling approaches, as the current model offers increased levels of fidelity, capturing dominant failure mechanisms and the influence of out-of-plane fibres

Mission impossible? The paradoxes of stretch goal setting

© 2016, © The Author(s) 2016. Stretch goal setting is a process involving multiple and nested paradoxes. The paradoxical side of stretch is attractive because it holds great promise yet dangerous because it triggers processes that are hard to control. Paradoxes are not readily managed by assuming a linear relation between the here and now and the intended future perfect. Before adopting stretch goal setting, managers should thus be prepared for the tensions and contradictions created by nested or interwoven paradoxes. Achieving stretch goals can be as difficult for the managers seeking to direct the process as for designated delegates. While the increasing popularity of stretch goal setting is understandable, its unexpected consequences must be taken into account. The inadequate use of stretch goals can jeopardize the social sustainability of organizations as well as their societal support systems

Voxelization of Free-Form Solids Represented by Catmull-Clark Subdivision Surfaces

www.cs.uky.edu/∼cheng Abstract. A voxelization technique and its applications for objects with arbitrary topology are presented. It converts a free-form object from its continuous geometric representation into a set of voxels that best approximates the geometry of the object. Unlike traditional 3D scan-conversion based methods, our voxelization method is performed by recursively subdividing the 2D parameter space and sampling 3D points from selected 2D parameter space points. Moreover, our voxelization of 3D closed objects is guaranteed to be leak-free when a 3D flooding operation is performed. This is ensured by proving that our voxelization results satisfy the properties of separability, accuracy and minimality.

A marching method for computing intersection curves of two subdivision solids

This paper presents a marching method for computing inter- section curves between two solids represented by subdivision surfaces of Catmull-Clark or Loop type. It can be used in trimming and boolean op- erations for subdivision surfaces. The main idea is to apply a marching method with geometric interpretation to trace the intersection curves. We first determine all intersecting regions, then find pairs of initial in- tersection points, and trace the intersection curves from the initial inter- section points. Various examples are given to demonstrate the robustness and efficiency of our algorithm

A Suite of Computationally Expensive Shape Optimisation Problems Using Computational Fluid Dynamics

This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.PPSN2018: 15th International Conference on Parallel Problem Solving from Nature, 8-12 September 2018, Coimbra, PortugalIn many product design and development applications, Computational Fluid Dynamics (CFD) has become a useful tool for analysis. This is particularly because of the accuracy of CFD simulations in predicting the important flow attributes for a given design. On occasions when design optimisation is applied to real-world engineering problems using CFD, the implementation may not be available for examination. As such, in both the CFD and optimisation communities, there is a need for a set of computationally expensive benchmark test problems for design optimisation using CFD. In this paper, we present a suite of three computationally expensive real-world problems observed in different fields of engineering. We have developed Python software capable of automatically constructing geometries from a given decision vector, running appropriate simulations using the CFD code OpenFOAM, and returning the computed objective values. Thus, users may easily evaluate a decision vector and perform optimisation of these design problems using their optimisation methods without developing custom CFD code. For comparison, we provide the objective values for the base geometries and typical computation times for the test cases presented here.This work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) grant (reference number: EP/M017915/1)

Temporal development of the oral microbiome and prediction of early childhood caries

Human microbiomes are predicted to assemble in a reproducible and ordered manner yet there is limited knowledge on the development of the complex bacterial communities that constitute the oral microbiome. The oral microbiome plays major roles in many oral diseases including early childhood caries (ECC), which afflicts up to 70% of children in some countries. Saliva contains oral bacteria that are indicative of the whole oral microbiome and may have the ability to reflect the dysbiosis in supragingival plaque communities that initiates the clinical manifestations of ECC. The aim of this study was to determine the assembly of the oral microbiome during the first four years of life and compare it with the clinical development of ECC. The oral microbiomes of 134 children enrolled in a birth cohort study were determined at six ages between two months and four years-of-age and their mother’s oral microbiome was determined at a single time point. We identified and quantified 356 operational taxonomic units (OTUs) of bacteria in saliva by sequencing the V4 region of the bacterial 16S RNA genes. Bacterial alpha diversity increased from a mean of 31 OTUs in the saliva of infants at 1.9 months-of-age to 84 OTUs at 39 months-of-age. The oral microbiome showed a distinct shift in composition as the children matured. The microbiome data were compared with the clinical development of ECC in the cohort at 39, 48, and 60 months-of-age as determined by ICDAS-II assessment. Streptococcus mutans was the most discriminatory oral bacterial species between health and current disease, with an increased abundance in disease. Overall our study demonstrates an ordered temporal development of the oral microbiome, describes a limited core oral microbiome and indicates that saliva testing of infants may help predict ECC risk

A Critical Comparison of Two Creativity Methods for Fostering Participatory Innovation: Implications to Improve TRIZ

We present an empirical study in which we contrast two creativity methods, the lateral thinking method and the improvisational theatre method, to investigate their applicability for advancing participatory innovation. While both of the contrasted methods aim to increase creativity as a means of improving participative innovation, they differ in terms of their conceptualisations of creativity, goals and processes. We propose that these two methods could complement the weaknesses of the TRIZ method (theory of inventive problem solving), especially in cases in which diverse experts gather to innovate, solve problems and generate new knowledge for shared goals. We illustrate the utilisation of the methods by reporting two creative development workshops. The paper sheds light on methods for fostering creative participatory innovation and highlights the collective nature of co-creation in participatory innovation. In addition, the paper suggests how the studied participative co-creative methods could be useful in improving the TRIZ method.Post-print / Final draf