Tagungsbeiträge

One way to minimize the energy consumption of production processes is to reduce moving masses in machinery. This reduction of mass can be carried out through the exchange of solid material, like steel or aluminum, with hybrid materials. These hybrid materials combine application-oriented different type of materials and their properties. This paper deals with the RTM manufacturing process and FEM simulation of such a hybrid material. By using the sandwich design method two tensile-stiff carbon fiber reinforced plastic (CFRP) layers are connected to a low-density aluminum foam (AF) core in order to produce hereafter parts with high weight-specific bending stiffness. At the beginning of this paper an analytical calculation method on the basis of the beam theory is developed, which allows an estimation of the achievable mechanical properties of the composite. The bending stiffness of such a composite is mainly determined by the outer layer modulus and the gravity axis distance of the outer layers. These findings are incorporated into the development of a FEM model, which allows the simulation of various load cases with selectable composite structure. The challenge in developing this model is the implementation of the material-specific peculiarities. These include the anisotropy of the CFRP layers and the core structure of the AF. An experimental plan is developed by using the DoE method. It allows the determination of the RTM process parameters, which will lead to components with the highest weight-specific bending stiffness. On this account preliminary tests are carried out to identify the usable range of injection pressure, mold temperature and compression pressure of the press. This paper can demonstrate, that the production of CFRP/ AF hybrid material by means of the RTM process is feasible. The first manufactured specimens exhibit no displacement of the fibers and almost no air inclusions. The simulation of CFRP/ AF hybrid material could be implemented. The anisotropy of the CFRP layers can be simulated with the ANSYS fiber fracture software ACP. The structure of the AS core can be mapped with great computational effort. The next step is the execution of the developed experimental plan with an especially designed RTM mold for sandwich composites.

This report studies the fundamental parameters affecting the wash-off and the warpage of parts manufactured in in-mold decoration process (IMD). The purpose is to derive a process model for describing the wash-off and the warpage of the parts as a function of the main influencing parameters based on a dimensional analysis. In order to investigate the influence of the materials and various processing conditions, a test mold was created for experiments and simulations were carried out. First of all the main influencing factors have been identified. To quantify the influence of each factor, a full factorial design was used. A DOE of process parameters including injection speed, injection pressure, melt temperature, mold temperature, post-injection pressure and the material were designed and executed. Based on the DOE specimens with a 250 [my]m and 375 [my]m thick PC film and a part thickness of 2 mm and 3 mm made from different thermoplastics were produced. In addition, the results of the experiment were compared with the simulation.