Squeeze flow rheometry and data analysis of carbon fiber sheet molding compounds

The compression molding process of carbon fiber sheet molding compounds (CF-SMC) is characterized by a squeeze flow of the material. There are no standardized measurement methods to characterize the flow behavior of CF-SMC and conventional methods of shear-flow dominated plastics processing are not suitable to describe the elongational deformation mode during compression molding. The objective of this work was to develop a methodology to determine the rheological properties of two CF-SMC materials. This included the development of the squeeze flow measurement device and the necessary software tools to efficiently analyze the data. The experimental findings were used to calibrate rheological power law models for both materials and validated with numerical compression molding simulations.