Parallel three‐dimensional simulation of the injection molding process

Araújo, Billy Jácome de; Teixeira, José Carlos; Cunha, António M.; Groth, C. P. T.

doi:10.1002/fld.1852

Cited by 19 publications

(6 citation statements)

References 18 publications

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“…In this study, we utilized Moldflow™ for numerical simulation of thin parts molded with pure LLDPE. The governing equations for the filling phase in thin molding consist of continuity, momentum, and energy equations as given below [18, 20, 21]: where ρ is the density, u is the velocity vector, t is the time, T is the temperature, p is the pressure, τ is the shear stress, C p is the specific heat of the melt, g is the gravity vector, and η and ${\dot \gamma} $ are the viscosity and shear rate, respectively.…”

Section: Resultsmentioning

confidence: 99%

Feasibility study of thin microinjection molded components

Mahmoodi

Park

Rizvi

2011

Polymer Engineering & Sci

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The trend toward the miniaturization of parts has created a strong demand for the manufacturing of precision‐molded miniature polymeric components, due to their high productivity and cost‐effectiveness. The objective of this study is the investigation of the filling behavior and dimensional accuracy of thin microinjection‐molded components using chemical blowing agents and wood fibers. In order to investigate the dimensional stability of the miniature molded parts, a micromold was designed and manufactured using a precision micromilling machine. The flow pattern of the thin molded components was experimentally investigated using different materials: pure linear low‐density polyethylene (LLDPE), foamed LLDPE, and wood fiber LLDPE composite. The results indicate that viscosity significantly affects the flow patterns. Filling behavior of the molded parts was also investigated using commercial flow software. Dimensional accuracy and shrinkage of the molded parts were measured using various gauges. Controlling the cell size, cell density, and distribution of foamed parts was especially difficult for thin micro components; however, the results showed that use of chemical blowing agents can improve the flow ability of the thin components in the microinjection molding process. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

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Section: Resultsmentioning

confidence: 99%

Feasibility study of thin microinjection molded components

Mahmoodi

Park

Rizvi

2011

Polymer Engineering & Sci

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“…Considering, for example, the aforementioned Richtmyer-Meshkov instability case, with the DD approach we measured a raise of the VOF cost up to 84% when engaging 128 CPUcores while, with the new parallelization strategy presented in this paper, the percentage is kept at 24%. The parallel performance limitations of the standard DD approach can also be observed in the work by Aráujo et al [23] focused on the 3-D simulation of injection processes. Their tests show a maximum parallel efficiency of 50% with up to 80 CPU-cores, including both the momentum and the VOF solvers.…”

Section: Introductionmentioning

confidence: 85%

Parallel load balancing strategy for Volume-of-Fluid methods on 3-D unstructured meshes

Jofre

Borrell

Lehmkuhl

et al. 2015

Journal of Computational Physics

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UPCommonsPortal del coneixement obert de la UPC http://upcommons.upc.edu/e-prints Abstract: Volume-of-Fluid (VOF) is one of the methods of choice to reproduce the interface motion in the simulation of multi-fluid flows. One of its main strengths is its accuracy in capturing sharp interface geometries, although requiring for it a number of geometric calculations. Under these circumstances, achieving parallel performance on current supercomputers is a must. The main obstacle for the parallelization is that the computing costs are concentrated only in the discrete elements that lie on the interface between fluids. Consequently, if the interface is not homogeneously distributed throughout the domain, standard domain decomposition (DD) strategies lead to imbalanced workload distributions. In this paper, we present a new parallelization strategy for general unstructured VOF solvers, based on a dynamic load balancing process complementary to the underlying DD. Its parallel efficiency has been analyzed and compared to the DD one using up to 1024 CPU-cores on an Intel SandyBridge based supercomputer. The results obtained on the solution of several artificially generated test cases show a speedup of up to 12x with respect to the standard DD, depending on the interface size, the initial distribution and the number of parallel processes engaged. Moreover, the new parallelization strategy presented is of general purpose, therefore, it could be used to parallelize any VOF solver without requiring changes on the coupled flow solver. Finally, note that although designed for the VOF method, our approach could be easily adapted to other interface-capturing methods, such as the Level-Set, which may present similar workload imbalances. SUMMARY OF CHANGESAccordingly to the comments raised by the reviewer, the changes on the manuscript are:1. As suggested by Reviewer #1: (1) Eq. 3 is valid only for divergence-free velocity fields, hence, this condition has been introduced in the text; (2) the limits of the sum in the numerator of Eqs. 9 -11 were incorrect, therefore, they have been corrected to start at 0 and end at P-1; (3) the description of Fig. 10 has been improved.2. The reviewer observed that Alg. 4 did not scale in terms of memory, since vector WI gathered information from all processes and, thus, grew with the size of the problem and number of CPU-cores. This may had become a bottleneck on larger scale tests. Therefore, we have developed a new version of the algorithm overcoming such limitations. The new version is based on non-blocking point-to-point communications.The new algorithm has substituted the previous one on the manuscript, and all tests for the LB strategy have been repeated and the results updated. Since Alg. 4 represents only 5% of the algorithm time, its upgrading has provided rather small improvements on the results. Even so, the important point is that the memory bottleneck has been eliminated.3. Furthermore, we have corrected some minor errors and we have tried to improve the wording across all the manuscrip...

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“…Later, the work in Rajkumar et al [4] presented design guidelines to support die designers to obtain balanced flow distributions. For the numerical modeling of IM, Araújo et al [5] provided a parallel 3D unstructured non-isothermal flow solver, with both polymer and air being considered as incompressible fluids. Their results presented a good accuracy and reasonable parallel efficiency and scalability.…”

Section: Introductionmentioning

confidence: 99%

Verification and Validation of openInjMoldSim, an Open-Source Solver to Model the Filling Stage of Thermoplastic Injection Molding

Pedro

Ramoa

Nóbrega

et al. 2020

Fluids

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In the present study, the simulation of the three-dimensional (3D) non-isothermal, non-Newtonian fluid flow of polymer melts is investigated. In particular, the filling stage of thermoplastic injection molding is numerically studied with a solver implemented in the open-source computational library O p e n F O A M ® . The numerical method is based on a compressible two-phase flow model, developed following a cell-centered unstructured finite volume discretization scheme, combined with a volume-of-fluid (VOF) technique for the interface capturing. Additionally, the Cross-WLF (Williams–Landel–Ferry) model is used to characterize the rheological behavior of the polymer melts, and the modified Tait equation is used as the equation of state. To verify the numerical implementation, the code predictions are first compared with analytical solutions, for a Newtonian fluid flowing through a cylindrical channel. Subsequently, the melt filling process of a non-Newtonian fluid (Cross-WLF) in a rectangular cavity with a cylindrical insert and in a tensile test specimen are studied. The predicted melt flow front interface and fields (pressure, velocity, and temperature) contours are found to be in good agreement with the reference solutions, obtained with the proprietary software M o l d e x 3 D ® . Additionally, the computational effort, measured by the elapsed wall-time of the simulations, is analyzed for both the open-source and proprietary software, and both are found to be similar for the same level of accuracy, when the parallelization capabilities of O p e n F O A M ® are employed.

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Parallel three‐dimensional simulation of the injection molding process

Cited by 19 publications

References 18 publications

Feasibility study of thin microinjection molded components

Feasibility study of thin microinjection molded components

Parallel load balancing strategy for Volume-of-Fluid methods on 3-D unstructured meshes

Verification and Validation of openInjMoldSim, an Open-Source Solver to Model the Filling Stage of Thermoplastic Injection Molding

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