| 1. |
- Mark, Andreas, 1980, et al.
(författare)
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Optimisation of Robotised Sealing Stations in Paint Shops by Process Simulation and Automatic Path Planning
- 2014
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Ingår i: International Journal of Manufacturing Research. - 1750-0591 .- 1750-0605. ; 9:1, s. 4-26
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Tidskriftsartikel (refereegranskat)abstract
- Application of sealing materials is done in order to prevent water leakage into cavities of the car body, and to reduce noise. The complexity of the sealing spray process is characterised by multi-phase and free surface flows,multi-scale phenomena, and large moving geometries, which poses great challenges for mathematical modelling and simulation. The aim of this paper is to present a novel framework that includes detailed process simulation andautomatic generation of collision free robot paths. To verify the simulations, the resulting width, thickness and shape of applied material on test plates as a function of time and spraying distance have been compared to experiments. The agreement is in general very good. The efficient implementation makes it possible to simulate application of one meter of sealing material in less than anhour on a standard computer, and it is therefore feasible to include such detailed simulations in the production preparation process and off-line programming of the sealing robots.
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| 2. |
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| 3. |
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| 4. |
- Tafuri, Sebastian, et al.
(författare)
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Improved Spray Paint Thickness Calculation From Simulated Droplets Using Density Estimation
- 2012
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Ingår i: Proceedings of the ASME 2012 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE. - 9780791845011 ; 2, s. 339-347
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Konferensbidrag (refereegranskat)abstract
- Advancements in the simulation of electrostatic spray painting make it possible to evaluate the quality and efficiency of programs for industrial paint robots during Off-Line Programming (OLP). Simulation of the spray paint deposition process is very complex and requires physical simulation of the airflow, electric fields, breakup of paint into droplets, and tracking of these droplets until they evaporate or impact on a surface. The information from the simulated droplet impacts is then used to estimate the paint film thickness. The current common way of measuring paint thickness on complex geometrical shapes is to use histogram based methods. These methods are easy to implement but are dependent on good quality meshes. In this paper, we show that using kernel density estimation not only gives better estimates but it also is not dependent on mesh quality. We also extend the method using a multivariate bandwidth adapted using estimated gradients of the thickness. To show the advantages of the proposed method, all three methods are compared on a test case and with real thickness measurements from an industrial case study using a complex automotive part.
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| 5. |
- Andersson, Björn O, 1982, et al.
(författare)
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A Modified TAB Model for Simulation of Atomization in Rotary Bell Spray Painting
- 2013
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Ingår i: Journal of Mechanical Engineering and Automation. - 2163-2413. ; 3:2, s. 54-61
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Tidskriftsartikel (refereegranskat)abstract
- The Rotary bell spray applicator technique is commonly used in the automotive industry for paint application because of its high transfer efficiency and high-quality result. The bell spins rapidly around its axis with a tangential velocity at the edge in the order of 100 m/s. The paint falls off the edge and enters the air with a large relative velocity, driving the atomization into small droplets where the resulting size distribution depends on the process conditions. Especially the rotation speed of the bell is an important parameter governing the size distribution. The main research question in this work is to investigate if the Taylor Analogy Breakup (TAB) model can be used to predict the resulting droplet size distributions in spray painting. As the paint is a viscous fluid a modification of the TAB model taking non-linear effects of large viscosity into account is proposed. The parameters in the breakup model are tuned by optimization to match droplet size distributions obtained in CFD simulations with measured ones. Results are presented for three cases with rotation speeds from 30 to 50 thousand RPM where the full droplet size distributions are compared with measurements. Good results are obtained for all three cases where the simulated size distributions compare well to measurements over a wide range of droplet sizes. The TAB method is able to quantitatively predict the result of the breakup process and can be used in a preprocessing stage of a full spray painting simulation, thereby reducing the need for costly and cumbersome measurements.
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| 6. |
- Andersson, Björn O, 1982, et al.
(författare)
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Modified TAB Model for Viscous Fluids applied to Breakup in Rotary Bell Spray Painting
- 2012
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Ingår i: ICLASS 2012 - 12th International Conference on Liquid Atomization and Spray Systems.
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Konferensbidrag (refereegranskat)abstract
- The Taylor Analogy Breakup (TAB) model is applied to droplet breakup in rotary bell spray painting commonly used in the automotive industry. The bell spins rapidly around its axis with a tangential velocity at the edge in the order of 100 m/s. The paint falls off the edge and enters the air with a large relative velocity, driving the atomization. The paint is a viscous fluid and a modification of the TAB model taking non-linear effects of large viscosity into account is described. The parameters in the breakup model are tuned to match droplet size distributions obtained in CFD simulations with measured ones. Results are presented for three cases with rotation speeds from 30 to 50 thousand RPM where the full droplet size distributions are compared with measurements. Good results are obtained for all three cases where the simulated size distributions compare well to measurements over a wide range of droplet sizes. The obtained results can be used in a preprocessing stage of a full spray painting simulation thereby reducing the need for costly and cumbersome measurements.
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| 7. |
- Edelvik, Fredrik, 1972, et al.
(författare)
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Math-Based Algorithms and Software for Virtual Product Realization Implemented in Automotive Paint Shops
- 2017
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Ingår i: Math for the Digital Factory. - 2198-3283. ; 27, s. 231-251
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Tidskriftsartikel (refereegranskat)abstract
- We present a simulation framework that makes it possible to accurately simulate spray painting of e.g. a truck cab in only a few hours on a standard computer. This is an extreme improvement compared to earlier approaches that require weeks of simulation time. Unique algorithms for coupled simulations of air flows, electrostatic fields and charged paint particles make this possible. In addition, we demonstrate that the same framework can be used to efficiently simulate the laydown of sealing or adhesive material. In the virtual paint factory the production preparation process can be performed in the computer, which allows the engineers to replace physical prototypes with virtual ones to shorten the lead time in product development, and avoid future unforeseen technological and environmental problems that can be extremely costly if they are discovered at the end of the production line, or even worse by the costumer.
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| 8. |
- Edelvik, Fredrik, 1972, et al.
(författare)
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Numerical homogenization of spatial network models
- 2024
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - 0045-7825 .- 1879-2138. ; 418
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Tidskriftsartikel (refereegranskat)abstract
- We present and analyze a methodology for numerical homogenization of spatial networks models, e.g. heat conduction and linear deformation in large networks of slender objects, such as paper fibers. The aim is to construct a coarse model of the problem that maintains high accuracy also on the micro-scale. By solving decoupled problems on local subgraphs we construct a low dimensional subspace of the solution space with good approximation properties. The coarse model of the network is expressed by a Galerkin formulation and can be used to perform simulations with different source and boundary data, at a low computational cost. We prove optimal convergence to the micro-scale solution of the proposed method under mild assumptions on the homogeneity, connectivity, and locality of the network on the coarse scale. The theoretical findings are numerically confirmed for both scalar-valued (heat conduction) and vector-valued (linear deformation) models.
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| 9. |
- Edelvik, Fredrik, 1972, et al.
(författare)
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SelfPaint-A self-programming paint booth
- 2018
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 72, s. 474-479
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a unique Fraunhofer approach that aims towards a vision to automate the product preparation in paint shops by automatically generating robot paths and process conditions that guarantee a certain wanted paint coverage. This will be accomplished through a combination of state-of-the-art simulation technology, inline quality control by novel terahertz thickness measurement technology, and surface treatment technology. The benefits of the approach are a shortened product preparation time, increased quality and reduced material and energy consumption. The painting of a tractor fender is used to demonstrate the approach.
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| 10. |
- Gleeson, Daniel, 1988, et al.
(författare)
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Generating Optimized Trajectories for Robotic Spray Painting
- 2022
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Ingår i: IEEE Transactions on Automation Science and Engineering. - 1558-3783 .- 1545-5955. ; 19:3, s. 1380-1391
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Tidskriftsartikel (refereegranskat)abstract
- In the manufacturing industry, spray painting is often an important part of the manufacturing process. Especially in the automotive industry, the perceived quality of the final product is closely linked to the exactness and smoothness of the painting process. For complex products or low batch size production, manual spray painting is often used. But in large scale production with a high degree of automation, the painting is usually performed by industrial robots. There is a need to improve and simplify the generation of robot trajectories used in industrial paint booths. A novel method for spray paint optimization is presented, which can be used to smooth out a generated initial trajectory and minimize paint thickness deviations from a target thickness. The smoothed out trajectory is found by solving, using an interior point solver, a continuous non-linear optimization problem. A two-dimensional reference function of the applied paint thickness is selected by fitting a spline function to experimental data. This applicator footprint profile is then projected to the geometry and used as a paint deposition model. After generating an initial trajectory, the position and duration of each trajectory segment are used as optimization variables. The primary goal of the optimization is to obtain a paint applicator trajectory, which would closely match a target paint thickness when executed. The algorithm has been shown to produce satisfactory results on both a simple 2-dimensional test example, and a non-trivial industrial case of painting a tractor fender. The resulting trajectory is also proven feasible to be executed by an industrial robot.
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| 11. |
- Gleeson, Daniel, 1988, et al.
(författare)
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Robot spray painting trajectory optimization
- 2020
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Ingår i: IEEE International Conference on Automation Science and Engineering. - 2161-8070 .- 2161-8089. ; 2020-August, s. 1135-1140
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Konferensbidrag (refereegranskat)abstract
- In the manufacturing industry, spray painting is often an important part of the process. Especially in the automotive industry, the perceived quality of the final product is closely linked to the exactness and smoothness of the painting process. For complex products or low batch size production, manual spray painting is often used. But in large scale production with a high degree of automation, the painting is normally performed by industrial robots. There is a need to improve and simplify the generation of robot trajectories used in industrial paint booths. A method for spray paint optimization is presented, which can be used to smooth out an initial trajectory and minimize paint thickness deviations from a target thickness. By fitting a spline function to experimental data, an applicator footprint profile is determined, which is a two-dimensional reference function of the applied paint thickness. This footprint profile is then projected to the geometry and used as a deposition model at each point along the trajectory. The positions and durations of all trajectory segments are used as optimization variables. They are modified with the primary goal to obtain a paint applicator trajectory, which will closely match a target paint thickness when executed. The algorithm is shown to produce satisfactory results on both a simple 2-dimensional test example, and a nontrivial industrial case of painting a tractor render. The final trajectory shows an overall thickness close to the target thickness, and the resulting trajectory is feasible to execute directly on an industrial robot.
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| 12. |
- Jareteg, Cornelia, 1986, et al.
(författare)
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Geometry Assurance Integrating Process Variation with Simulation of Spring-in for Composite Parts and Assemblies
- 2014
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Ingår i: Proc. of ASME 2014 International Mechanical Engineering Congress & Exposition. - 9780791846438 ; 2A
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Konferensbidrag (refereegranskat)abstract
- Geometrical variation and deviation in all manufacturing processes affect quality of the final product. Therefore geometry assurance is an important tool in the design phase of a new product. In the automotive and aviation industries where the use of composite parts is increasing drastically, new tools within variation simulations are needed. Composite parts tend to deviate more from nominal specification compared to metal parts. Methods to simulate the manufacturing process of composites have been developed before. In this paper we present how to combine the process variation simulation of composites with traditional variation simulations. The proposed method is demonstrated on a real complex subassembly, representing part of an aircraft wing-box. Since traditional variation simulation methods are not able to capture the spring-in and the special deviation behavior of composites,the proposed method adds a new feature and reliability to the geometry assurance process of composite assemblies.
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| 13. |
- Jareteg, Cornelia, 1986, et al.
(författare)
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Geometry Assurance Integrating Process Variation with Simulation of Spring-In for Composite Parts and Assemblies
- 2016
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Ingår i: Journal of Computing and Information Science in Engineering. - : ASME International. - 1530-9827 .- 1944-7078. ; 16:3
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Tidskriftsartikel (refereegranskat)abstract
- Copyright © 2016 by ASME.Geometrical variation and deviation in all the manufacturing processes affect the quality of the final product. Therefore, geometry assurance is an important tool in the design phase of a new product. In the automotive and aviation industries where the use of composite parts is increasing drastically, new tools within variation simulations are needed. Composite parts tend to deviate more from nominal specification compared to metal parts. Methods to simulate the manufacturing process of composites have been developed before. In this paper, we present how to combine the process variation simulation of composites with traditional variation simulations. The proposed method is demonstrated on a real complex subassembly, representing part of an aircraft wing-box. Since traditional variation simulation methods are not able to capture the spring-in and the special deviation behavior of composites, the proposed method adds a new feature and reliability to the geometry assurance process of composite assemblies.
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| 14. |
- Jareteg, Cornelia, 1986, et al.
(författare)
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Variation simulation for composite parts and assemblies including variation in fiber orientation and thickness
- 2014
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Ingår i: Procedia CIRP CATS 2014. 5th CATS 2014 - CIRP Conference on Assembly Technologies and Systems. - : Elsevier BV. - 2212-8271. ; 23, s. 235-240
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Konferensbidrag (refereegranskat)abstract
- All manufacturing processes are afflicted by geometrical variation, which can lead to defect products. A simulation tool for geometry assurance analysis is therefore important in the design process. The use of composites has recently increased drastically, but there is still a lack of understanding about the effects of variation in such parts. A method for predicting variation in subassemblies, including variation in fiber orientation and ply thickness for composites is presented. The approach is demonstrated on an industrial case and finite element analysis is used to calculate the deformation. In particular, contribution from variation in material properties to the variation in critical points is analyzed. The results indicate that material uncertainties have a small impact on the geometric variation for the test case.
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| 15. |
- Lorin, Samuel C, 1983, et al.
(författare)
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Simulating Geometrical Variation in Injection Molding
- 2010
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Ingår i: Proceedings of NordDesign2010 International Conference on Methods and Tools for Product and Production Development, August 25-27, Gothenburg, Sweden.. - 9789163370649 ; 8:2, s. 395-404
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Konferensbidrag (refereegranskat)
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| 16. |
- Mark, Andreas, 1980, et al.
(författare)
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Simulation of a Non-Newtonian Dense Granular Suspension in a Microfluidic Contraction
- 2013
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Ingår i: 8th International Conference on Multiphase Flow.
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Konferensbidrag (refereegranskat)abstract
- The success of a solder paste jet printer is based on an uninterrupted flow of fluid, specifically dense fluid suspensions, through a series of ducts inside the printing head. It is well known that the flow of dense suspensions is prone to jamming and sedimentation effects, both of which could entail detrimental failure modes in the printing heads. A thorough understanding of the fluid dynamics of suspensions as they flow through ducts and connections is of utmost importance. The purpose of this study is to propose a novel simulation framework and to show that it captures the main effects such as mass flow and partial jamming in a cylindrical duct test configuration. The granular suspension is a generic solder paste with solder particlesimmersed in a flux. The simulations are performed in the multi-phase flow solver IBOFlow. A two fluid model is used for the granular suspension and the discretization is done an Euler-Euler framework. The averaged momentum equations from Enwald et al. (1996) are solved together with the common continuity equation generating a shared pressure field. Explicit constitutive equations for the interfacial momentum transfer and particle pressure are employed. To capture the shear thinning effects of the non-Newtonian suspensions the standard Carreau rheology model is used. To study how the fluid flow affects the local volume fraction and partial jamming in the duct, simulations are performed for different applied pressure drops ranging from one to five bars. For both particle pressure models, the resulting mean bulk velocities are compared with experiments with good agreement, and partial jamming is observed. Hence, it is concluded that the proposed framework is suitable to model and simulate the granular suspension in a micro fluid contraction.
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| 17. |
- Mark, Andreas, 1980, et al.
(författare)
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Simulation of Electrostatic Rotary Bell Spray Painting in Automotive PAint Shops
- 2013
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Ingår i: Atomization and Sprays. - 1044-5110 .- 1936-2684. ; 23:1, s. 25-45
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Tidskriftsartikel (refereegranskat)abstract
- A new framework for simulation of electrostatic spray painting is proposed based on novel algorithms for coupled simulations of air flow, electromagnetic fields, and paint droplets. Particularly important for the computational efficiency is the Navier-Stokes solver. The incompressible solver is based on a finite volume discretization on a dynamic Cartesian octree grid and unique immersed boundary methods are used to model the presence of objects in the fluid. This enables modeling of moving objects at virtually no additional computational cost and greatly simplifies preprocessing by avoiding the cumbersome generation of a body-conforming mesh. To validate the simulation framework an extensive measurement campaign has been performed. Several test plates and car fenders were painted with different process conditions and robot paths. The same cases were then simulated and overall the agreement between simulations and experiments are remarkably good. The very efficient implementation gives a major improvement of computational speed compared to other approaches and makes it possible to simulate spray painting of a full car in just a few hours on a standard computer.
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| 18. |
- Mark, Andreas, 1980, et al.
(författare)
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Simulation of Electrostatic Rotary Bell Spray Painting in Automotive Paint Shops
- 2012
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Ingår i: Proceedings of 12th International Conference on Liquid Atomization and Spray Systems.
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Konferensbidrag (refereegranskat)abstract
- A new framework for simulation of electrostatic spray painting is proposed based on novel algorithms for coupled simulations of air flow, electromagnetic fields and paint droplets. Particularly important for the computational efficiency is the Navier-Stokes solver. The incompressible solver is based on a finite volume discretization on a dynamic Cartesian octree grid and unique immersed boundary methods are used to model the presence of objects in the fluid. This enables modeling of moving objects at virtually no additional computational cost, and greatly simplifies preprocessing by avoiding the cumbersome generation of a body conforming mesh. To validate the simulation framework an extensive measurement campaign has been performed. Several test plates and car fenders were painted with different process conditions and robot paths. The same cases were then simulated and overall the agreement between simulations and experiments are remarkably good. The very efficient implementation gives a major improvement of computational speed compared to other approaches and makes it possible to simulate spray painting of a full car in just a few hours on a standard computer.
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| 19. |
- Rundqvist, Robert, 1974, et al.
(författare)
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Modeling and Simulation of Sealing Spray Application Using Smoothed Particle Hydrodynamics
- 2011
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Ingår i: Fluid Dynamics and Materials Processing. - 1555-2578 .- 1555-256X. ; 7:3, s. 259-278
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Tidskriftsartikel (refereegranskat)abstract
- Multiphase flow simulation using Smoothed Particle Hydrodynamics (SPH)has gained interest during recent years, mostly due to the inherentflexibility of the method and the physically rather intuitiveformulation of extra constitutive equations needed when dealing withfor instance non-Newtonian flows. In the work presented here,simulations based on an SPH model implemented in the flow solverIBOFlow has been used for simulation of robotic application of sealingmaterial on a car body. Application of sealing materials is done inorder to prevent water leakage into cavities of the body, and toreduce noise. In off-line programming of the robots in the automotivepaintshop it is of great interest to predict shape and appearance ofsealing material without having to resort to trial and errorprocedures.The flow of sealing material in the air between applicator and target(car body) is relatively uncomplicated, as the material mostly movesat constant velocity until impact on target. The flow of the materialon the target is however more complex, applied material flows at thetarget surface due to inertia, gravity and pressure and in order topredict the appearance of the applied material, flow equations for anon-Newtonian fluid with an open surface needs to be solved. Thesealing material is both thixotropic and viscoelastic; the material isshear thinning but needs to be sheared for some time before thestructure of the material is broken down. Conversely, the regain ofstructure of the material, and thereby also the increase of viscositywhen shearing is stopped or reduced, is also connected to a delaytime. In the model used, the local viscosity is considered obeying afirst order differential equation where the stationary limit isdetermined by a Bingham relation.The simulation model was built by comparing simulations andexperiments at three different stages of complexity. In the mostfundamental stage the material properties were determined. Using arotational rheometer, yield stress, plastic viscosity and thixotropytime constant was determined and implemented in the simulation model.To verify the numerical behaviour of the rheology, simulated rheometerexperiments were carried out and compared with the physicalexperiments. In the second stage, simulation of application of sealingmaterial with a stationary hollowcone nozzle was carried out. Toverify the simulations, the resulting thickness, width and shape ofapplied material as a function of time were compared to experiments.In the third stage a moving applicator of the same type wasconsidered, here thickness width and shape of applied material as afunction of applicator to target distances were compared betweenexperiments and simulation. At all three stages the number of SPHparticles, /i.e./ grid points, in the simulations was varied in orderto verify that the simulations were resolution independent.Results of the simulations show good agreement between experiments andsimulations in all stages using no artificial tuning of the models,that is, all parameters used in the models are based on physicalconsiderations. Furthermore, simulation time on a desktop computerindicate that computational power required for industrially relevantcases is not prohibitively large, for the most complex cases in thiswork simulation time did not exceed six hours.
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| 20. |
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| 21. |
- Rundqvist, Robert, 1974, et al.
(författare)
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Simulation of Spray Painting in Automotive Industry
- 2010
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Ingår i: Numerical Mathematics and Advanced Applications 2009 (Proceedings of ENUMATH 2009, the 8th European Conference on Numerical Mathematics and Advanced Applications, Uppsala, July 2009). - Berlin, Heidelberg : Springer Berlin Heidelberg. ; Part 2, s. 769-777
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Konferensbidrag (refereegranskat)
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| 22. |
- Rylander, Thomas, 1972, et al.
(författare)
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Advances in FEM-FDTD hybrid methods
- 2005
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Ingår i: Computational Electrodynamics: The Finite-Difference Time-DomaMethod (3rd edition) -- Allen Taflove and Susan C. Hagness.
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 23. |
- Svensson, M., et al.
(författare)
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Process Simulation and Automatic Path Planning of Adhesive Joining
- 2016
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Ingår i: Procedia CIRP. - : Elsevier B.V.. - 2212-8271. ; , s. 298-303
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Konferensbidrag (refereegranskat)abstract
- Adhesive joining is frequently used in the automotive industry. In the pursuit of reducing weight, adhesive joining is important due to the possibility of joining different types of materials. The process is often automatised in order to reduce cycle time. In this paper we aim to present a novel framework that includes detailed process simulation and automatic generation of collision free robot paths and in this way improve the quality of the joint and reduce both cycle time and processing time. To verify the simulations, the properties of the adhesive bead have been compared to experiments with good agreement. © 2016 The Authors.
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| 24. |
- Svensson, Martin, 1987, et al.
(författare)
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Simulation of Droplet Jetting of a Non-Newtonian Mixed Suspension
- 2016
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Ingår i: ICMF-2016 – 9th International Conference on Multiphase Flow May 22nd – 27th 2016, Firenze, Italy.
-
Konferensbidrag (refereegranskat)abstract
- The jet printing of a dense mixed non-Newtonian suspension is based on the rapid displacement of fluid through a nozzle, the forming of a droplet and eventually the break-off of the filament. The ability to model this process would facilitate the development of future jetting devices. The purpose of this study is to propose a novel simulation framework and to show that it captures the main effects such as droplet shape, volume and speed. In the framework, the time dependent flow and the fluid-structure interaction between the suspension, the moving piston and the deflection of the jetting head is simulated. The system is modelled as a two phase system with the surrounding air being one phase and the dense suspension the other. Hence, the non-Newtonian suspension is modelled as a mixed single phase with properties determined from material testing. The simulations were performed with two coupled in-house solvers developed at Fraunhofer-Chalmers Centre; IBOFlow, a multiphase flow solver and LaStFEM, a large strain FEM solver. Jetting behaviour was shown to be affected not only by piston motion and fluid rheology, but also by the energy loss in the jetting head. The simulation results were compared to experimental data obtained from an industrial jetting head.
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| 25. |
- Andersson, Björn O, 1982, et al.
(författare)
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Modeling Surface Tension in SPH by Interface Reconstruction using Radial Basis Functions
- 2010
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Ingår i: Proceedings of the 5th International SPHERIC Workshop, 22-25 June 2010, Manchester, U.K., edited by B. D. Rogers. ; , s. 7-14
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A novel method for reconstructing the interface between two fluids is described and evaluated. The method uses a different basis for approximating the color function than what is common practice in SPH simulations. The key feature of the new method is the ability to omit small length scale structures in order to obtain a smoother representation. A smoother interface is more suitable to derive a surface tension force from, as the magnitude of the force is proportional to the curvature which is related to the second derivative along the interface.
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