A Multi-objective Simulation Based Tool: Application to the Design of High Performance LC-VCOs

Part 16: Optimization Techniques in EnergyInternational audienceThe continuing size reduction of electronic devices imposes design challenges to optimize the performances of modern electronic systems, such as: wireless services, telecom and mobile computing. Fortunately, those design challenges can be overcome thanks to the development of Electronic Design Automation (EDA) tools. In the analog, mixed signal and radio-frequency (AMS/RF) domains, circuit optimization tools have demonstrated their usefulness in addressing design problems taking into account downscaling technological aspects. Recent advances in EDA have shown that the simulation-based sizing technique is a very interesting solution to the ‘complex’ modelling task in the circuit design optimization problem. In this paper we propose a multi-objective simulation-based optimization tool. A CMOS LC-VCO circuit is presented to show the viability of this tool. The tool is used to generate the Pareto front linking two conflicting objectives, namely the VCO Phase Noise and Power Consumption. The accuracy of the results is checked against HSPICE/RF simulations

Recent advances in residual stress simulation caused by the welding process

The purpose of the present paper is to improve the description of residual stress field characteristics generated after welding. The behavior of the material both in the liquidand solid states and during all heating and cooling stages including the solidification in the mushy zone is considered, as well as the surface tension effects in the liquid phase.Simulations are conducted on the finite element software SYSWELD®. A displacement/pressure mixed formulation, based on the linear tetrahedral element of type P1/P1 in the context of elasto-viscoplastic formulation, is used. As regards the structure behaviour,thecontinuous transition between the liquid and the solid phases during the welding is ensured using a mixture law behavior. Numerical simulations were carried out in the context of Lagrangian approach. In this approach the material over the liquidus temperature is modelled as a Newtonian fluid but the flows in the weld pool are not accounted for.Concerning surface tension modelling,the standard method usually adoptedis to apply an externalloadon the freesurface of the weld pool. In the present study, a surfacespherical stress state is directly imposed on the surface in membrane elements incorporated in the meshand representing the interface.Since tetrahedral mesh is easily adapted to complex geometry, a discretization of type P1/P1 is used in the case of welding simulation. It shows the relevance of such tetrahedral finite element for the mechanical analysis of elasto-viscoplastic solid metal.A representative simulation of a laser welding case is processed. The material considered in H. Sallem, E.Feulvarch, H.Amin El Sayed, B.Souloumiac, J-B Leblond, J-M Bergheau this study is the Inconel 600 alloy. Computed residual stress distribution revealsthe ability of such approaches topredictresidual stress states in assessing the integrity of welded components

Simulation numérique de soudage avec un maillage en tétraèdres P1/P1

National audienceLe but de cet article est de montrer la pertinence de l’élément fini P1/P1 pour l’analyse mécanique des métaux solides présentant un comportement élasto-viscoplastique. Une simulation représentative d’un cas de soudage est traitée. Les résultats obtenus se comparent favorablement à ceux obtenus avec un maillage de référence utilisant des éléments hexaédriques du premier ordre à intégration sélective

Recent advances in residual stress simulation caused by the welding process

The purpose of the present paper is to improve the description of residual stress field characteristics generated after welding. The behavior of the material both in the liquidand solid states and during all heating and cooling stages including the solidification in the mushy zone is considered, as well as the surface tension effects in the liquid phase.Simulations are conducted on the finite element software SYSWELD®. A displacement/pressure mixed formulation, based on the linear tetrahedral element of type P1/P1 in the context of elasto-viscoplastic formulation, is used. As regards the structure behaviour,thecontinuous transition between the liquid and the solid phases during the welding is ensured using a mixture law behavior. Numerical simulations were carried out in the context of Lagrangian approach. In this approach the material over the liquidus temperature is modelled as a Newtonian fluid but the flows in the weld pool are not accounted for.Concerning surface tension modelling,the standard method usually adoptedis to apply an externalloadon the freesurface of the weld pool. In the present study, a surfacespherical stress state is directly imposed on the surface in membrane elements incorporated in the meshand representing the interface.Since tetrahedral mesh is easily adapted to complex geometry, a discretization of type P1/P1 is used in the case of welding simulation. It shows the relevance of such tetrahedral finite element for the mechanical analysis of elasto-viscoplastic solid metal.A representative simulation of a laser welding case is processed. The material considered in H. Sallem, E.Feulvarch, H.Amin El Sayed, B.Souloumiac, J-B Leblond, J-M Bergheau this study is the Inconel 600 alloy. Computed residual stress distribution revealsthe ability of such approaches topredictresidual stress states in assessing the integrity of welded components