Temperature-dependent anisotropic material modeling of the sheet metal component within the polymer injection forming process
In the course of this work, an extended material model for a carbon steel sheet metal has been developed based on Hill’48 yield criterion, considering temperature-dependent plastic anisotropy coefficients. This material model is applied on a polymer injection forming process in which the sheet metal heats up to a critical forming temperature through the contact with the plastic melt. At this temperature range blue brittleness occurs. The elastic properties, the yield stress as well as the plastic anisotropy coefficients of the sheet material become significantly different compared to those at room temperature. It should be emphasized that especially temperature-dependent anisotropy coefficients are not yet considered in most common material models. With the help of the presented modelling approach a more precise modelling of the temperature-dependent carbon steel material behavior can be realised.
Development of a Combined Process of Organic Sheet forming and GMT Compression Molding
Abstract This research describes the development of a combined one-step process of complex organic sheet forming and GMT (Glass Mat Thermoplastics) compression molding which can be integrated in processes using conventional stamping technology. Hence, no additional injection molding step is required. Compression molding allows adding a third dimension to the two-dimensional organic sheet. Thus, reinforcements or screw connection points can be produced out of complex 3D-structures with fiber lengths up to 40 mm. While forming simulations for both separate processes already exist to a certain degree of maturity, the coupling of organic sheet forming and GMT compression molding in one software tool involves major challenges. This paper presents a solution approach that depicts the combined process in a single FE-based forming simulation carried out with LS Dyna. The investigation was mainly focused on the interaction between the two materials and the temperature distribution which largely influences the forming effects and the bonding of the materials to one another.
Methods and programs for analysis of fluid-structure systems
Abstract Computational algorithms for the analysis of fluid and structural dynamics are reviewed, with particular emphasis on methods that are employed or of potential benefit in reactor safety analysis, where coupled fluid-structure analyses are of interest. The fluid dynamics algorithms are classified according to time integration methods, mesh descriptions, and compressible/incompressible flow, while the structural dynamics algorithms are summarized from the view-points of time integration and the types of nonlinearities which can be treated. Alternative means of coupling these various fluid and structures algorithms are examined. Finally the principal features of some existing programs are summarized.