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Abstract: In this paper, numerical results of a drop weight impact test examining the dynamic response of a clamped steel beams struck transversely at the centre by a mass with a rectangular indenter are presented. The numerical simulation showed that the results are very sensitive to the way in which the supports are modelled and thus this paper studies the modelling of the structural supports used to clamp the specimen beam in the experiment. The first approach simplifies the structural support as boundary condition on the nodes; the second model represents the entire support as the real approximation; the last approach uses simplified support plate model acting with the beam to simulate the experimental set up. The complete force–displacement curve is used to compare the plastic deformation of the impacted beams, thus the best approximation is selected for further calculations. The finite element model was performed using the LS-DYNA non-linear, dynamic finite element software. The numerical calculations can predict accurately the response of deflections, forces and absorbed energies, when proper boundary conditions are applied, in this case with shell elements representing the support plates. [Copyright &y& Elsevier]

Abstract: Thermoplastic composite materials offer new perspective in the mechanical industry, especially in aeronautic industry. The assembly of huge structures by welding is made possible by the ability of the matrix to melt. This paper focuses on ultrasonic welding process where heating is confined at the welding interface. This is achieved thanks to a local mechanical dissipation in triangles specially located at the interface, called energy director. In order to better understand the phenomena that occur at the energy director scale, we propose to model and simulate the polymer flow at the interface. Based on a previous work, the flow under vibration is modeled using three coupled boundary value problems. A specific simulation tool is then developed for solving those three problems. It entails specific numerical methods: a level set method allows to handle the large geometry change, and an iterative solver manages the multiphysical aspects. The novel simulation obtained is validated with a qualitative comparison to experiments. Then, an analysis of the numerical results allows to understand the phenomena that enable welding. A thermomechanical localization heats the tip of the energy director. This initiates a fold of polymer that progressively fills the gap between the two plates to weld, and ensures conditions for adhesion. [Copyright &y& Elsevier]

This paper introduces a new spontaneous potential log model for the case in which formation resistivity is not piecewise constant. The spontaneous potential satisfies an elliptic boundary value problem with jump conditions on the interfaces. It has been shown that the elliptic interface problem has a unique weak solution. Furthermore, a jump condition capturing finite difference scheme is proposed and applied to solve such elliptic problems. Numerical results show validity and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]