SMC Simulation

To develop a better understanding of the manufacturing and processing of carbon fiber reinforced sheet molding compounds (C-SMC) and to thus improve the prediction of a finished part’s structural properties, knowledge regarding of fiber orientation, -length and content as well as the interaction between fibers and the resin is essential. Exploiting the polarizing effect of carbon fibers when incident light is reflected from their surfaces, localized fiber orientation can be captured during production with a polarization camera. The direct integration of the camera into the SMC production line allows the in-situ observation of the material’s fiber structure formation of a C-SMC semi-finished product. In a subsequent digitization process, the captured stack of 2D images is converted into a three-dimensional representation of the fiber structure for a complete roll of semi-finished product. The digital image is used for quality and process control of semi-finished product manufacturing and enables as input information numerical modeling of fiber movement and resin flow during SMC compression molding. In order to measure the resin flow through the fiber structure of C-SMC, test specimens with a comparable fiber structure in the form of dry carbon fiber mats are prepared on the same SMC production line and used for permeability tests. During these tests, the dry test specimen is impregnated with a resin-like material under vacuum and different cavity heights. The measurement of flow front position allows the determination of the permeability of the loose fiber structure. The precise observation of the flow front geometry also allows a qualitative evaluation of the influence of the fiber structure on the matrix flow.

The development of techniques to measure, digitize and analyze the structure and properties of C-SMC materials improves the prediction of structural properties of finished parts.