CFRP and aluminum foam hybrid composites. - In: Shaping the future by engineering, (2014), insges. 9 S.
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.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-100:6
The influence of fiber undulation on the mechanical properties of FRP-laminates. - In: Shaping the future by engineering, (2014), insges. 8 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-099:3
Process parameters affecting the quality of functionalized in-mold decoration injection molded composites. - In: Shaping the future by engineering, (2014), insges. 9 S.
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.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-095:0
Integration of connecting elements in hybrid-composite components. - In: Shaping the future by engineering, (2014), insges. 7 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-089:1
Improvement of tribological properties of plastic compounds. - In: Shaping the future by engineering, (2014), insges. 7 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-084:0
Oxygen and water vapor permeability and required layer thickness for barrier packaging. - In: Shaping the future by engineering, (2014), insges. 11 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-076:8
Manufacturing hybrid lightweight compounds of closed-cell aluminium foam and thermosoftening plastics in injection moulding processes. - In: Shaping the future by engineering, (2014), insges. 8 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-053:0
Simulation of the resin transfer molding process (RTM) by analysis of the process fundamentals. - In: Shaping the future by engineering, (2014), insges. 8 S.
Fiber reinforces plastics (FRP) technologies enable the production of lightweight components. The RTM technique is attractive to obtain vehicle parts with little post-processing in industrial scales. The closed mold process provides a desired freedom in part-design combined with high and reproducible production rates compared to other FRP processes. However, the shorter the mold-closed time the higher the risk to run into quality consistency issues resulting from air entrapments. The acceleration of the process can only be achieved by the knowledge of the fundamental process parameters. The effects of void formation and process speed can be managed to reach progresses in both cycle time and void content. The major mechanism of void formation is the entrapment of air due to flow front inconsistencies. These are generated by the differences of the flow front as a result of advancing forces, viscosity and flow resistances. A faster flow front advancement in the fiber tows results in spherical voids, because air in the flow channel between the tows can be entrapped. On the other hand a faster advance in the flow channels results in cylindrical voids in the tows. Only a balanced flow front could enable a process with low void rates. The resin flow in the channels is primarily driven by the inlet pressure. The flow resistance is low in comparison to the fiber tows where the channel radius has a smaller order of magnitude. In the tows the resin flow is additively caused by the capillary pressure that occurs in the small channels between the fibers in the tow. So the flow behavior of the flow front depends on different factors. The established factors for influencing the RTM cycle are mold temperature, inlet pressure, application of vacuum, resin and fiber volume content. However, the impact of the capillary effect has not been examined sufficiently. Possible factors influencing the wicking are finish of the fiber, weave of the reinforcements and the radius of the tows. In addition all factors may have interdependencies on each other. Process trials were conducted using a DOE-approach under consideration of material and process parameters for simple 2D parts. The analysis shows the impact of principle process parameters on the achievable part quality.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-035:0
Analysis of the process behavior for planetary roller extruders. - In: Shaping the future by engineering, (2014), insges. 11 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-045:7
Influences with regard to the processing of conductive polymers. - In: Shaping the future by engineering, (2014), insges. 7 S.
Technical plastics products offer a high potential for light-weight construction techniques. The research activities for functionalized plastics components increasingly become focused. In complex plastics parts, the integration of materials with different properties plays a key role. Especially, conductive polymers offer the possibility to produce low cost complex plastic components in injection molding processes. Beside the functionalization of parts, conductive polymers are also interesting for the housing of electromagnetic compliance (EMC) devices. The conductivity of these plastics components strongly depends on its processing conditions. On consideration of each step of processing, such as the compounding of the plastic with fibers and a subsequent injection-molding, the main influences on the conductivity are carved out.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-062:9