LOEWE-Zentrum AdRIA | Teilprojekt: Umformen funktional bedruckter Bleche

LOEWE-Centre AdRIA (Adaptronics – Research, Innovation, Application)

Subproject: forming of functional printed sheets

 

During the integration of sensor elements into formed sheet metal parts the functional elements have to be connected by electrical conductors for energy and data transmission. This connection typically takes place subsequently to the forming process causing an increased economic effort of time-consuming assembly processes. Therefore, approaches are being developed aiming to reduce these additional costs. The integration of the electrical conductors prior to the forming process appears especially promising, since subsequent assembly processes can be eliminated. [Figure 1] illustrates a multifunctional component with integrated flat copper conductors and insulating polymer layers, which are applicated onto the sheet metal surface prior to the hydroforming process.

In Addition, printed sensors can be printed onto the sheet metal parts prior to the forming process, too. In this way functional sheet metal components with integrated electrical conductors and sensor elements can be manufactured economically.

Figure 1: Functional sheet metal component with integrated electrical conductors,. Manufactured by hy-droforming
Figure 1: Functional sheet metal component with integrated electrical conductors,. Manufactured by hy-droforming

The resulting multi-functional components consist of insulating polymer layers, metallic conductors, the sheet metal and sensors based on conductive printing inks. All these elements are joined together before the forming process is accomplished.

Deep drawing is a suitable forming process for the production of multifunctional components with integrated electronics like printed sensors or flat copper conductors. In addition, bending is also a viable forming process. The components, which are depicted [Figure 2], were manufactured by a multi-stage bending method.

The analysis and the characterization of the forming behavior of functional sheet metal components various testing methods are necessary to describe the mechanical behavior of the different layers. The objective is the initiation of one-, two- and multi-axial stress states in the composite in order to study the strain distribution and to develop design methods for functional multi-layer sheet metal composites. Furthermore, it should be considered that the functional elements have to possess the desired electrical properties after the forming process, such as a certain electrical resistance.

Figure 2: Sensor rings with screen printed strain gages manufactured by bending (silver or graphite ink on an insulating base layer)
Figure 2: Sensor rings with screen printed strain gages manufactured by bending (silver or graphite ink on an insulating base layer)

In particular, the numerical representation of this forming process and the analysis of the behavior of the different layers during the forming process are main objectives of this research field. Another challenge is the integration of the different constitutive laws of the used materials in the mechanical considerations.

In collaboration with the Fraunhofer LBF, the Technische Universität Darmstadt and the University of Applied Sciences Darmstadt methods for the achievement of the described project objectives are developed.

Parts of the present and still ongoing research in this field are funded by the German federal state of Hesse (project “LOEWE-Zentrum AdRIA: Adaptronik – Research, Innovation, Application”, grant number III L 4 – 518/14.004 (2008)). This financial support is gratefully acknowledged.