Browsing by Keyword "FEM"
Now showing 1 - 7 of 7
Results Per Page
Sort Options
Item 3D numerical simulation of slope-flexible system interaction using a mixed FEM-SPH model(2021) Jimenez Fernandez, Jose Carlos; Castanon-Jano, Laura; Gaute Alonso, Alvaro; Blanco-Fernandez, Elena; Gonzalez Fernandez, Juan Carlos; Centeno Gonzalez, Victor; Castro-Fresno, Daniel; Garcia-Sanchez, David; Tecnalia Research & Innovation; E&I SEGURAS Y RESILIENTESFlexible membranes are light structures anchored to the ground that protect infrastructures or dwellings from rock or soil sliding. One alternative to design these structures is by using numerical simulations. However, very few models were found until date and most of them are in 2D and do not include all their components. This paper presents the development of a numerical model combining Finite Element Modelling (FEM) with Smooth Particle Hydrodynamics (SPH) formulation. Both cylindrical and spherical failure of the slope were simulated. One reference geometry of the slope was designed and a total of 21 slip circles were calculated considering different soil parameters, phreatic level position and drainage solutions. Four case studies were extracted from these scenarios and simulated using different dimensions of the components of the system. As a validation model, an experimental test that imitates the soil detachment and its retention by the steel membrane was successfully reproduced.Item Accurate calculation of conductive conductances in complex geometries for spacecrafts thermal models(2016-02-15) Garmendia, Iñaki; Anglada, Eva; Vallejo, Haritz; Seco, Miguel; CIRMETAL; MAQUINASThe thermal subsystem of spacecrafts and payloads is always designed with the help of Thermal Mathematical Models. In the case of the Thermal Lumped Parameter (TLP) method, the non-linear system of equations that is created is solved to calculate the temperature distribution and the heat power that goes between nodes. The accuracy of the results depends largely on the appropriate calculation of the conductive and radiative conductances. Several established methods for the determination of conductive conductances exist but they present some limitations for complex geometries. Two new methods are proposed in this paper to calculate accurately these conductive conductances: The Extended Far Field method and the Mid-Section method. Both are based on a finite element calculation but while the Extended Far Field method uses the calculation of node mean temperatures, the Mid-Section method is based on assuming specific temperature values. They are compared with traditionally used methods showing the advantages of these two new methodsItem Design of Rotary Extrusion Process Using Simulation Techniques to Save Raw Material in Hollow Components(Trans Tech Publications, Switzerland, 2015) Mangas, Ángela; Santos, Maite; Zarazua, Jose Ignacio; Pérez, Iñaki; Ofenheimer, Aldo; Poletti, Cecilia; Schalk-Kitting, Daniela; Sommitsch, Christof; Tecnalia Research & Innovation; SG; PROMETALThe forging process plays an important role in the automotive industry thanks to the good mechanical properties of the forged parts. Nowadays, due to the European policy of increasing efficiency in raw material and energy usage, the metal forming sector is demanding new innovative technologies. In this context, rotary extrusion technology is a very promising metal forming alternative to the drilling techniques after forging processes. The presented work is focused on hollow shafts that are usually manufactured using a combination of forming and metal cutting techniques. Deep drilling is the most common technique to obtain internal holes in the automotive hollow parts, but it is an expensive process in terms of material usage. In this framework, rotary extrusion appears as an alternative technology that leads to the reduction of material usage and process time. The tubular shape is formed with the combination of two forming processes: flow forming and backward extrusion. This paper presents the development of a simulation methodology, the process design for a hollow part, the specifications of the experimental unit, and the manufactured prototypes in order to validate the simulation model. Also the incremental process is improved thanks to a sensitivity study of the rollers geometry. Rotary extrusion experiments are done using a modified flow forming machine and 20% material saving is achieved when obtaining the deep hole in comparison to the current deep drilling technology. The process design and numerical model tasks carried out try to provide the industry manufacturers an alternative technology to drilled parts considering the advantages of rotary extrusion parts.Item Metamodels’ Development for High Pressure Die Casting of Aluminum Alloy(2021-10-31) Anglada, Eva; Boto, Fernando; García de Cortazar, Maider; Garmendia, Iñaki; CIRMETAL; Tecnalia Research & Innovation; FACTORYSimulation is a very useful tool in the design of the part and process conditions of high pressure die casting (HPDC), due to the intrinsic complexity of this manufacturing process. Usually, physics-based models solved by finite element or finite volume methods are used, but their main drawback is the long calculation time. In order to apply optimization strategies in the design process or to implement online predictive systems, faster models are required. One solution is the use of surrogate models, also called metamodels or grey-box models. The novelty of the work presented here lies in the development of several metamodels for the HPDC process. These metamodels are based on a gradient boosting regressor technique and derived from a physics-based finite element model. The results show that the developed metamodels are able to predict with high accuracy the secondary dendrite arm spacing (SDAS) of the cast parts and, with good accuracy, the misrun risk and the shrinkage level. Results obtained in the predictions of microporosity and macroporosity, eutectic percentage, and grain density were less accurate. The metamodels were very fast (less than 1 s); therefore, they can be used for optimization activities or be integrated into online prediction systems for the HPDC industry. The case study corresponds to several parts of aluminum cast alloys, used in the automotive industry, manufactured by high-pressure die casting in a multicavity mold.Item More robust processes and more added value for foundries based on inverse modelling and tailor-made software tools(World Foundry Organization, 2014) Meléndez, A.; Anglada, E.; Maestro, L.; Domínguez, I.; Tecnalia Research & Innovation; CIRMETALWith this work the authors want to show how is possible to approach improved simulations to the results of the user's plants giving a good solution for the increasing needs of accuracy. In this sense, the authors want to present an innovative experience concerning to a recently finished R&D project, which involved the development of two solutions using and complementing a commercial simulation software. The first of them is an improvement of the conventional simulations based on the use of the inverse modelling and the second one consists of a new 'ad hoc' tool developed especially for the customer. Once the project was concluded, as planned, the 'new current' simulations resulted well correlated with the plant. The casting process involved in the project is the investment casting process or lost wax casting process.Item Performance of Optimization Algorithms in the Model Fitting of the Multi-Scale Numerical Simulation of Ductile Iron Solidification(Multidisciplinary Digital Publishing Institute (MDPI), 2020) Anglada, Eva; Meléndez, Antton; Obregón, Alejandro; Villanueva, Ester; Garmendia, IñakiThe use of optimization algorithms to adjust the numerical models with experimental values has been applied in other fields, but the efforts done in metal casting sector are much more limited. The advances in this area may contribute to get metal casting adjusted models in less time improving the confidence in their predictions and contributing to reduce tests at laboratory scale. This work compares the performance of four algorithms (compass search, NEWUOA, genetic algorithm (GA) and particle swarm optimization (PSO)) in the adjustment of the metal casting simulation models. The case study used in the comparison is the multiscale simulation of the hypereutectic ductile iron (SGI) casting solidification. The model fitting criteria is the value of the tensile strength. Four different situations have been studied: model fitting based in 2, 3, 6 and 10 variables. Compass search and PSO have succeeded in reaching the error target in the four cases studied, while NEWUOA and GA have failed in some cases. In the case of the deterministic algorithms, compass search and NEWUOA, the use of a multiple random initial guess has been clearly beneficious.Item Simulation And Experimental Results Of The Hot Metal Gas Forming Technology For High Strength Steel And Stainless Steel Tubes Forming(2007) Vadillo, L.; Santos, M. T.; Gutierrez, M.A.; Pérez, I.; González, B.; Uthaisangsuk, V.; Pérez, I.; González, B.; Tecnalia Research & Innovation; SG; PROMETALSimulation is a key topic within the development of the Hot Metal Gas Forming (HMGF) technology. In this work, tuve bulge tests and tubes forming processes using diez were simulated at high temperaturas by means of FEM. The tuve deformations is calculated by thenumerical simulations were compared to the results from experiments carried out at different heating conditions and using different input pressure curves. Flow curves for several stainless and high strength steels were experimentally determined in order to be used for the simualtion code. Ferritic stainless steel 1.4512 showed very high formability capabiliites at high temperatures. During tube bulge tests of the ferritic Steel a máximum expansión of tuve diameter up to 55% was recahed by using a pressure of only 14 bars.