Investigation of the forming behavior of carbon fiber yarns on microscopic scale with detailed statistical volume elements

Simulations at microscopic scale are subject of research in many fields of continuous fiber reinforced materials. They allow the virtual characterization with clearly defined boundary conditions and the investigation of effects that cannot easily be observed in experimental tests, such as crack initiation. While the influence of differently detailed modeling, such as variable fiber radii, is well investigated for consolidated composite materials, that influence is not well investigated for dry yarns. The effect of different modeling aspects on the shearing of statistical volume elements (SVE) is object of this study. Those aspects are in particular the SVE’s size and side ratio, the deformation velocity, the friction coefficient and the initial stress of the elements. The investigations have shown that the deformation of the SVEs is very sensitive to changes of the named parameters. Especially parameters that influence the number of fiber contacts or the friction forces have a noticeable effect on the shear stress. In addition, changes in the velocity have a significant impact on the deformation. Therefore, it is necessary to characterize the fiber and yarn parameters precisely and transfer them into the simulation model to obtain a realistic deformation behavior.