Rethinking SMC Process Simulation and Increasing Component Quality: Analysis and Prediction of Fiber Orientation

At the Fraunhofer ITWM, we develop simulation methods that help to better understand and optimize production processes. One current example is our new solution for the simulation of Sheet Molding Compounds (SMC), which we use to precisely model the production of fiber-reinforced plastics. SMC is a versatile material made of glass or carbon fibers and resin that is frequently used in the automotive industry, but also in many other industries. The core of our approach is the realistic prediction of the orientation of fiber bundles in the material, a decisive factor for the strength and quality of the finished component.

SMC have been among the most established fiber composite materials for decades and are well suited for lightweight construction. The orientation of the fibers largely determines the stiffness and the strength of the finished product. Long fibers in a thermosetting resin make the material stable, lightweight and suitable for series production. Carbon fiber-reinforced variants (C-SMC), which can be processed with fiber content of up to 60 percent, are currently gaining in importance. In the automotive industry in particular, SMCs help to make vehicle structures lighter – which reduces both energy consumption and environmental impact.

Fiber Orientation in View: Polarization Imaging Complements the Simulation

In addition to model-based prediction, we also rely on innovative imaging methods to make the orientation of fiber bundles visible – directly on the material surface. Carbon fibers reflect light in a characteristic way: They polarize it. The polarization camera developed by the Fraunhofer Institute for Integrated Circuits IIS uses precisely this effect to show the fibre orientation in carbon fibre-reinforced sheet molding compounds (C-SMC). This is done in real time, without contact and without time-consuming sample preparation. The method is suitable both for quality control in ongoing production and for validating simulation data. We are developing methods for this together with IVW in the IGF project »Machine Vision for Carbon Composites«.

Outlook: Structural Simulation of SMC Components for Efficient Materials

A realistic simulation of the SMC process is possible if resin and fiber behavior are considered separately – and the results are checked with high-resolution image data. The method improves the predictability of component properties and helps to use materials more efficiently.

»Our solution provides robust and industrially practicable input data for the structural simulation of SMC components,« explains project manager Dr. Hannes Grimm-Strele from Fraunhofer ITWM. »This enables an end-to-end digital process chain – from the material model to the virtual component test.«

The new method is a further step towards more efficient materials, optimized production processes and lighter, more efficient components, especially in lightweight automotive construction.