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| 2. |
- Alnersson, Gustaf, et al.
(författare)
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3D-flow and and fibre orientation modelling for compression moulding of SMC
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Two different numerical models for compression moulding of Sheet Moulding Compound are discussed and compared, with one being a more traditional flow model implemented in the 3DTimon commercial software, and the other being a more advanced flow model implemented in more general fluid dynamics software. The focus will be on comparing the resulting fibre orientations.
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| 4. |
- Alnersson, Gustaf, et al.
(författare)
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3D flow and fibre orientation modelling of compression moulding of A-SMC: simulations and experimental validation in squeeze flow
- 2023
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Ingår i: Functional Composite Materials. - : Springer Nature. - 2522-5774. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Sheet Moulding Compound (SMC) based composites have a large potential in industrial contexts due to the possibility of achieving comparatively short manufacturing times. It is however necessary to be able to numerically predict both mechanical properties as well as manufacturability of parts.In this paper a fully 3D, semi-empirical model based on fluid mechanics for the compression moulding of SMC is described and discussed, in which the fibres and the resin are modelled as a single, inseparable fluid with a viscosity that depends on volume fraction of fibres, shear strain rate and temperature. This model is applied to an advanced carbon-fibre SMC with a high fibre volume fraction (35%). Simulations are run on a model of a squeeze test rig, allowing comparison to experimental results from such a rig. The flow data generated by this model is then used as input for an Advani-Tucker type of model for the evolution of the fibre orientation during the pressing process. Numerical results are also obtained from the software 3DTimon. The resulting fibre orientation distributions are then compared to experimental results that are obtained from microscopy. The experimental measurement of the orientation tensors is performed using the Method of Ellipses. A new, automated, accurate and fast method for the ellipse fitting is developed using machine learning. For the studied case, comparison between the experimental results and numerical methods indicate that 3D Timon better captures the random orientation at the outer edges of the circular disc, while 3D CFD show larger agreement in terms of the out-of-plane component. One of the advantages of the new image technique is that less work is required to obtain microscope images with a quality good enough for the analysis.
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| 6. |
- Alnersson, Gustaf, et al.
(författare)
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Numerical Study of the 3D-Flow Characteristics During Compression Moulding of SMC
- 2019
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Ingår i: Proceedings of the 2019 International Conference on Composite Materials. - : RMIT University. ; , s. 1571-1581
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A numerical model for compression moulding of Sheet Moulding Compound is presented. The model is based on fluid mechanics and the SMC charge is modelled as a fluid with a viscosity that is dependent on the charge temperature, the fibre volume fraction of the material and the shear strain rate. Trends observed in the simulations regarding the shape of the flow front agree with experimental observations in previous studies. The simulations also yield that the type and magnitude of initial heating effects the initial flow to a large extent.
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| 7. |
- Alnersson, Gustaf, et al.
(författare)
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Review of the Numerical Modeling of Compression Molding of Sheet Molding Compound
- 2020
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Ingår i: Processes. - : MDPI. - 2227-9717. ; 8:2
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Forskningsöversikt (refereegranskat)abstract
- A review of the numerical modeling of the compression molding of the sheet molding compound (SMC) is presented. The focus of this review is the practical difficulties of modeling cases with high fiber content, an area in which there is relatively little documented work. In these cases, the prediction of the flows become intricate due to several reasons, mainly the complex rheology of the compound and large temperature gradients, but also the orientation of fibers and the micromechanics of the interactions between the fluid and the fibers play major roles. The details of this during moldings are discussed. Special attention is given to the impact on viscosity from the high fiber volume fraction, and the various models for this. One additional area of interest is the modeling of the fiber orientation.
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| 8. |
- Alnersson, Gustaf
(författare)
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Towards 3D modelling of Compression Moulding of SMC
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The automotive industry is facing ever increasing demands for reduced emissions, and lightweight solutions are thusly required. One field that has significant potential in this regard is composite materials, which can offer a good combination of weight reduction and mechanical properties. However, the rapid development cycles in the automotive industry mean that tools for numerical modeling are necessary, both regarding manufacturing processes and prediction of mechanical properties. The material that has been of interest for this work is Sheet Moulding Compound (SMC). SMC consists of sheets of resin and chopped fibres. When used for manufacturing the sheets are cut into appropriate size and shape. The cut sheets are then placed in a pre-heated mould. When this mould is closed, the sheets melt and the fibre-filled resin flows out and fills the mould cavity; the resin then cures and solidifies. A significant advantage of SMC compared to other composite solutions is that the process has comparatively short cycle times, which is a necessity for automotive applications. However, it is a rather complicated process to model numerically for a number of reasons, including the complex rheological properties of the charge, the often rather significant temperature gradients throughout the thickness, often complicated three-dimensional effects in the flow, and the chopped fibres present in the charge. These fibres will move and change orientation as the charge is pressed, which is a significant challenge to model properly.The first part of this work is a review and discussion of the difficulties described above, and some solutions that have been suggested. The second part concerns a suggestion for a three-dimensional flow model for the compression moulding process, which takes into account factors that have been suggested to influence the flow behavior, such as temperature distribution and shear strain rate. Some simulation results are presented along with comparison to previous experimental results, and similar flow patterns are observed serving as a qualitative validation. The third part concerns the expansion of this model to include the effects of the flow on the fibre orientation.
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| 9. |
- Altorkmany, Lobna, et al.
(författare)
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Effect of Working Parameters of the Plate Heat Exchanger on the Thermal Performance of the Anti-Bact Heat Exchanger System to Disinfect Legionella in Hot Water Systems
- 2018
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Ingår i: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 141, s. 435-443
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the current study is to analyze the effect of different working parameters on the thermal performance of the Anti-Bact Heat Exchanger system (ABHE). The ABHE system is inspired by nature and implemented to achieve continuous disinfection of Legionella in different human-made water systems at any desired disinfection temperature. In the ABHE system, most of the energy is recovered using an efficient plate heat exchanger (PHE). A model by Engineering Equation Solver (EES) is set-up to figure out the effect of different working parameters on the thermal performance of the ABHE system. The study shows that higher supplied water temperature can enhance the regeneration ratio (RR), but it requires a large PHE area and pumping power (PP) which consequently increase the cost of the ABHE system. However, elevate temperature in use results in a reduced PHE area and PP, which accordingly reduce the cost of the ABHE system. On the other hand, the EES-based model is used to study the effect of the length and the width of the plates used in the PHE on the RR and the required area of the PHE. Finally, taking into account the geometrical parameters, flow arrangement and the initial operating conditions of the PHE, the EES-based model is used to optimize the PHE in which its area is minimized, and the RR of the ABHE system is maximized.
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| 10. |
- Altorkmany, Lobna, et al.
(författare)
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Experimental and Simulation Validation of ABHE for Disinfection of Legionella in Hot Water Systems
- 2017
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Ingår i: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 116, s. 253-265
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Tidskriftsartikel (refereegranskat)abstract
- The work refers to an innovative system inspired by nature that mimics the thermoregulation system that exists in animals. This method, which is called Anti Bacteria Heat Exchanger (ABHE), is proposed to achieve continuous thermal disinfection of bacteria in hot water systems with high energy efficiency. In particular, this study aims to demonstrate the opportunity to gain energy by means of recovering heat over a plate heat exchanger. Firstly, the thermodynamics of the ABHE is clarified to define the ABHE specification. Secondly, a first prototype of an ABHE is built with a specific configuration based on simplicity regarding design and construction. Thirdly, an experimental test is carried out. Finally, a computer model is built to simulate the ABHE system and the experimental data is used to validate the model. The experimental results indicate that the performance of the ABHE system is strongly dependent on the flow rate, while the supplied temperature has less effect. Experimental and simulation data show a large potential for saving energy of this thermal disinfection method by recovering heat. To exemplify, when supplying water at a flow rate of 5 kg/min and at a temperature of 50 °C, the heat recovery is about 1.5 kW while the required pumping power is 1 W. This means that the pressure drop is very small compared to the energy recovered and consequently high saving in total cost is promising.
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