Component variation in the manufacture of hybrid composites by free kinematic forming

Hybrid lightweight technology enables new possibilities for the design and construction of structural components in automotive and aircraft construction. It is desirable to maintain economic production through an optimised combination of dissimilar materials. Production errors, such as air inclusions in metal-plastic hybrids, must be avoided. Free-kinematic forming is being researched as a manufacturing process that, as a press-based process with a flexible die path, is intended to enable this process condition. In the first phase of the project, it was shown that, in addition to the production of hybrid composites, variant flexibility is also possible by varying the component geometry. Thus, without modifying the die geometry, the component geometry can be changed locally by adapting the die path, which is accompanied by an increase in the flexibility of the pressing process. The optimisation of the component variants can be flexibly extended to the respective given requirements, such as stiffness or damping. The driving aspects for researching the manufacturing process are changing from an increase in process quality to increased process flexibility and thus flexible component variant production with little or no additional effort for die provision.

The overall objective of the joint research project of the IFUM (University of Hanover) and the IWF (Technical University of Braunschweig) is to provide increased process flexibility for local modification of the component geometry through process parameter variants with simultaneously short cycle times. However, influencing the component geometry by adapting the die path and the targeted procedure for generating a die geometry for component variants have not yet been methodically solved. The process properties and limits must be described both qualitatively and quantitatively to enable suitable model-based process planning methods. Also, the method for designing the die geometry must be extended to include the application of web shares for a spectrum of component variants.

In this project, a detailed material characterisation of a unidirectional tape (UD) is to be carried out by uniaxial tensile tests and a more precise determination of the heat transfer and friction coefficient of GMT (glass mesh reinforced thermoplastic). Subsequently, the simulation model of the free kinematic forming will be extended with the determined material data, so that the influence of the die path on the formation of variants of the component can be investigated. With these findings, a suitable component geometry is determined for the tests. Finally, a method is developed by means of FE simulation to develop desired component variants with the corresponding die path and geometry. The application tests for the production of component variants on a demonstration geometry will be carried out at the end of the project in order to validate the procedure for the variant formation as well as the prediction accuracy of the material flow simulation.