Models of Tet-On System with Epigenetic Effects

International audienceWe present the first results of ongoing work investigating two models of the artificial inducible promoter Tet-On that include epigenetic regulation. We consider chromatin states and 1D diffusion of transcription factors that reveal, respectively, stochastic noise and a memory effect

Element activation method and non-conformal dynamic remeshing strategy to model additive manufacturing

peer reviewedModeling of Additive Manufacturing (AM) at the part scale involves non-linear thermo-mechanical simulations. Such a process also imposes a very fine discretization and requires altering the geometry of the models during the simulations to model the addition of matter, which is a computational challenge by itself. The first focus of this work is the addition of an additive manufacturing module in the fully implicit in-house Finite Element code Metafor [1] which is developed at the University of Liège. The implemented method to activate elements and to activate and deactivate boundary conditions during a simulation is adapted from the element deletion algorithm implemented in Metafor in the scope of crack propagation [2]. This algorithm is modified to allow the activation of elements based on a user-specified criterion (e.g. geometrical criterion, thermal criterion, etc.). The second objective of this work is to improve the efficiency of the AM simulations, in particular by using a dynamic remeshing strategy to reduce the computational cost of the simulations. This remeshing is done using non-conformal meshes, where hanging nodes are handled via the use of Lagrange multiplier constraints. The mesh data transfer used after remeshing is based on projection methods involving finite volumes [3]. The presented model is then compared against a 2D numerical simulation of Direct Energy Deposition of a High-Speed Steel thick deposit from the literature [4]

Addition of a finite element activation method in an existing thermomechanical finite element code to model additive manufacturing

With the rise of Additive Manufacturing (AM) technologies in the industry, it becomes more and more important to have a good understanding of such processes. However, there is still a crucial lack of fundamental knowledge regarding AM. Hence, there is a high demand for the implementation of a model to accurately simulate an AM process. The complexity of such a simulation comes from multiple sources. Firstly, from the nature of the process. Indeed, it requires geometrically non-linear thermo-mechanical simulations. Secondly, the modeling of the material law is complex. Lastly, the geometry of the process imposes a very fine discretization (layers can be as small as a few μm). This creates models that are computationally costly. Moreover, the process requires altering the geometry of the model during the simulation to model the addition of matter, which is a computational challenge by itself. This work presents the addition of additive manufacturing in the fully implicit in-house Finite Element code “Metafor”, which considers large strains and includes thermo-mechanical simulations and crack propagation simulations. The focus of the work is to add an “additive manufacturing module” to the existing thermomechanical code Metafor. The implemented method to activate elements and to activate and deactivate boundary conditions during a simulation is adapted from the element deletion algorithm implemented in Metafor in the scope of crack propagation. Indeed, in crack propagation the deactivation of an element in a simulation was already possible, i.e. an element could be deactivated based on a certain crack propagation criterion. This algorithm is modified to allow the activation of elements based on a criterion (which can, in the case of AM, be the presence or not of the element in a certain “activation volume” modeling the moving laser). After implementing other AM specificities (heat source model, annealing temperature for alloys, etc), an effective thermomechanical simulation of Additive Manufacturing is obtained. The model is then compared against the literature, including numerical and experimental results from a thermal experimental calibration and a thermo-mechanical analysis of blown powder laser solid forming of Ti-6Al-4V. Temperature, deformation and stress fields are analyzed as well as the influence of different process parameters

Don d'ovocyte: aspects éthiques liés à la donneuse.

SCOPUS: re.jinfo:eu-repo/semantics/publishe

Analysis of couples attitudes concerning spare embryos destiny through a cryopreservation consent questionnaire

info:eu-repo/semantics/nonPublishe

Finite Element activation strategy in the numerical simulation of Additive Manufacturing Processes

Additive Manufacturing (AM) is currently enjoying a tremendous boom. However, there is still a crucial lack of fundamental knowledge regarding AM. Hence, there is a high demand for the implementation of a model to accurately simulate an AM process. The complexity of such a simulation comes from multiple sources. Firstly, from the nature of the process. Indeed, it requires a large deformation thermo-mechanical simulation. Secondly, the modeling of the material law is complex. Lastly, the geometry of the process imposes a very fine discretization (layers can be as small as a few µm). This creates models that are computationally costly. Moreover, the process requires altering the geometry of the model during the simulation to model the addition of matter, which is a computational challenge by itself. This work presents a first implementation of a three-dimensional thermal Finite Element Analysis (FEA) of AM in the fully implicit in-house Finite Element code “Metafor”. The main focus of the work is on mesh management. The method to activate elements and to activate and deactivate boundary conditions during a simulation is adapted from the element deletion algorithm (erosion method) implemented in Metafor in the scope of crack propagation. The final model is compared against literature results, in particular to numerical and experimental results from a thermal experimental calibration of blown powder laser solid forming of Ti-6Al-4V. The model shows a reasonable agreement between the simulations

Efficient Roll-Forming Simulation Using Non-Conformal Meshes with Hanging Nodes Handled by Lagrange Multipliers

peer reviewedSimulations of industrial roll-forming processes using the finite element method typically require an extremely fine discretization to obtain accurate results. Running those models using a classical finite element method usually leads to suboptimal meshes where some regions are unnecessarily over-refined. An alternative approach consists in creating non-conformal meshes where a number of nodes, called hanging nodes, do not match the nodes of adjacent elements. Such flexibility allows for more freedom in mesh refinement, which results in the creation of more efficient simulations. Consequently, the computational cost of the models is decreased with little to no impact on the accuracy of the results. Handling the generated hanging nodes can, however, be challenging. In this work, details are first given about the implementation of these particular meshes in an implicit finite element code with a special focus on the treatment of hanging nodes using Lagrange Multipliers. Standard and non-conformal meshes are then compared to experimental measurements on the forming of a U-channel. A more complex roll-forming simulation—a tubular rocker panel—is then showcased as proof of the potential of the method for industrial uses. Our main results show that the proposed method effectively reduces the computational cost of the roll-forming simulations with a negligible impact on their accuracy

Element activation strategy for Additive Manufacturing, based on the element deletion algorithm

With the rise of Additive Manufacturing (AM) technologies in the industry, it is becoming more and more crucial to have a good understanding of those processes. This leads to a high need for the implementation of a model that can accurately simulate such a process. The difficulties of simulating AM can come from multiple sources. Firstly, from the nature of the process. Indeed, it requires a large deformation thermo-mechanical simulation. Secondly, the modeling of the material law is complex. Lastly, the geometry of the process imposes a very fine discretization (layers can be as small as a few μm). This creates models that are very computationally costly. Moreover, the process requires altering the geometry of the model during simulations to model the addition of matter, which is a computational challenge by itself. This poster presents the implementation of a three-dimensional thermal Finite Element Analysis (FEA) of AM in the fully implicit in-house Finite Element code “Metafor”. The main focus of the work is on mesh management techniques. The method to activate elements during a simulation is adapted from the element deletion algorithm (erosion method) implemented in Metafor in the scope of crack propagation. The final model is compared against literature results with a good agreement

Models of Tet-On System with Epigenetic Effects

International audienceWe present the first results of ongoing work investigating two models of the artificial inducible promoter Tet-On that include epigenetic regulation. We consider chromatin states and 1D diffusion of transcription factors that reveal, respectively, stochastic noise and a memory effect