9 results for Kelly, Piaras, Conference item, 2010

  • A 2.5 Simulation of the Resin Infusion Process addressing complex reinforcement compaction response

    Verleye, B; Kelly, Piaras; Bickerton, Simon (2010)

    Conference item
    The University of Auckland Library

    The simulation of composite manufacturing processes is a great aid to obtaining efficient production and high quality parts. The mould and process design must allow for fast filling times as well as dry-spot free parts. In previous work we presented our software SimLCM for the simulation of force and velocity controlled Resin Transfer Moulding (RTM) and Compression RTM. These are two examples of the general Liquid Composite Moulding (LCM) group of processes. Another recently popular subclass is Resin Infusion (RI), also know as Vacuum Assisted RTM. The simulation of RI adds an extra difficulty to the simulation process, as the height of the preform will change locally because of the filling. In contrast to CRTM, this change of height is not imposed, and thus not known beforehand. This paper describes the extension of SimLCM to the simulation of RI processes. The results of the simulations are compared with results from other programs that use different techniques, and also with experimentally obtained data found in literature. The comparison between simulation and experiment is found to be excellent.

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  • Simulation and tooling forces exerted on rigid non-planar LCM tools

    Walbran, W; Verleye, B; Bickerton, Simon; Kelly, Piaras (2010)

    Conference item
    The University of Auckland Library

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  • A Rate-independent thermomechanical Constitutive Model for Fibrous Reinforcements

    Cheng, Jonathan; Kelly, Piaras; Bickerton, Simon (2010)

    Conference item
    The University of Auckland Library

    In Liquid Composite Moulding (LCM) processes, the constitutive behaviour of fibrous reinforcements has a strong bearing on the choice of manufacturing parameters and final part properties. In many LCM processes, the fibrous preform is subjected to loading and unloading, the latter also occurring during filling and post-filling phases of the manufacturing process. Fibrous materials display inelastic behaviour with rate-dependent and rate-independent components and this must be modelled accurately over several load-unload cycles in order to accurately simulate such processes. An important feature of the material behaviour is its unchanging response to successive load cycles once a large number of load cycles have been applied. Inelastic effects such as fibre-fibre frictional sliding occur during loading as well as unloading and the inelastic deformation remaining after successive cycles appears unchanged. The model presented is developed within a thermomechanical framework and reproduces such behaviour using a single internal variable to account for inelasticity. It is compared to cyclic loading experiments and serves as a starting point for the incorporation of effects such as cyclic softening and rate-effects through additional internal variables.

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  • Observations from the filling and post-filling stages of axisymmetric liquid composite moulding with flexible tooling

    Timms, J; Govignon, Quentin; Bickerton, Simon; Kelly, Piaras (2010)

    Conference item
    The University of Auckland Library

    This paper presents experimental observations from the filling and postfilling stages of 1D axisymmetric Resin Infusion (VARTM) and RTM Light. A series of experiments have been performed to investigate the influence of mould flexural stiffness and fill mode on fluid pressure, cavity thickness, filling stage time, and postfilling stage time. Observations are also made on the effect of those parameters on the repeatability of nominally identical experiments.

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  • Optimisation of mould filling parameters of the compression resin transfer moulding process

    Hsu, S; Ehrgott, Matthias; Kelly, Piaras (2010)

    Conference item
    The University of Auckland Library

    The Compression Resin Transfer Moulding Process (CRTM) is a popular type of Liquid Composite Moulding Process (LCM) commonly used for manufacturing composite materials. In this paper we consider the optimisation of the manufacturing processing time and the machine tooling force for the CRTM process. Since this process requires large forces during compression, force evaluation and prediction provides great advantages for the industry as it enables structural analysis of the moulds. Not only it does lead to cost effective tooling design, it also allows for proper selection of cost effective moulds and supporting equipment. The tooling force, moreover, is in conflict with manufacturing time, which is another objective of particular interest in the industry. In recent years, the advancement of CRTM simulation software allows accurate prediction of the processing objectives thus making it unnecessary to run through the expensive experiments physically. In this process, we use such a simulation software called SimLCM and combine it with a popular NSGA-II evolutionary multi-objective optimisation (EMO) algorithm to optimise maximum tooling force and processing time with respect to three manufacturing parameters. The EMO algorithm uses SimLCM as a black box to evaluate the objective function values for a population of solutions. We report results on a simple rectangular plate model (for calibration) and an industrial example.

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  • Simulation and experimental validation of force controlled compression resin transfer moulding

    Verleye, B; Walbran, William; Bickerton, Simon; Kelly, Piaras (2010)

    Conference item
    The University of Auckland Library

    The simulation of composite manufacturing processes is a great aid to obtaining efficient production and high quality parts. The mould and process design must allow for fast filling times as well as dry???spot free parts. Besides an accurate simulation of the resin flow through the reinforcement, the compaction response of the preform is also needed. The stress response of the textile to compaction has an influence on the local and global forces exerted on tooling. The numerical prediction of the clamping force helps to trade off fast production times against affordable machinery. This article describes the accurate simulation of force controlled Resin Transfer Moulding RTM and Compression RTM, and compares results of simulations with experimental data. A parametric study is performed in order to minimise the simulation time without compromising the accuracy of the results. The controlled force algorithms have been implemented within SimLCM, a code under development at the University of Auckland to address the liquid composite moulding LCM family of manufacturing processes. With these new tools the trade???off between production process time and equipment cost can be considered, and optimal process design solutions found.

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  • Optimisation of mould filling parameters during the compression resin transfer moulding process

    Kam, W; Kelly, Piaras; Ehrgott, Matthias; Verleye, B; Bickerton, Simon (2010)

    Conference item
    The University of Auckland Library

    manufacture of composite materials. In this process, a fibrous preform is first placed in a mould and then the mould is partially closed. The resin is then injected, before the mould is finally closed fully, driving the fluid through any remaining dry regions in the fabric. Finally, the resin is allowed to cure and the part is de-moulded. A number of manufacturing parameters affect the efficiency and cost of the CRTM process. Principal amongst these are the fluid injection pressure, the velocity at which the mould is closed and the thickness of the preform at which the resin is first injected. The goal of this study was to optimise the choice of the manufacturing parameters, such that the process time was kept short and the maximum force necessary to close the mould was kept low. This non-linear non-convex multi-objective optimisation problem was solved using a genetic algorithmic approach, with the algorithm interacting with SimLCM, a composites manufacturing process simulation software developed at the University of Auckland. Full-scale analyses were carried out, providing valuable information, regarding process parameters to use, for manufacturers.

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  • Deviation from Darcy's Law During the Post-filling Stage of Resin Infusion

    Govignon, Quentin; Timms, J; Bickerton, Simon; Kelly, Piaras (2010)

    Conference item
    The University of Auckland Library

    To allow for a better control of the quality of parts produced through the resin infusion process, it is necessary to understand the phenomenon happening during the post-filling stage of the process. This paper investigates the causes of the residual pressure gradient that can be observed at the end of the post-filling stage of the resin infusion and RTMLight processes. A modified formulation of Darcy???s law is presented along with experimental evidence in an attempt to verify and quantify the existence of a threshold pressure gradient in the case of flow through porous media.

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  • A 2.5D Model of the Resin Infusion Process, Experiments and Simulation

    Govignon, Quentin; Verleye, B; Bickerton, Simon; Kelly, Piaras (2010)

    Conference item
    The University of Auckland Library

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