In this paper, a study based on experimental and numerical simulations is performed to analyze fatigue cracks in clinched joints. An experimental investigation is conducted to determine the failure modes of clinched joints under cyclic loading at different load amplitudes with single-lap shear tests. In addition, numerical FEM simulations of clinching process and subsequent shear loading are performed to support the experimental investigations by analyzing the state of stresses at the location of failure. An attempt is made to explain the location of crack initiation in the experiments using evaluation variables such as contact shear stress and maximum principal stress.

The new generation of three roll mills is able to monitor occurring process loads while dispersion. This paper focuses on the interpretation of the gathered data to find criteria quantifying the dispersion state online. The aim is process time reduction. We used impedance spectroscopy to identify the dispersion state and correlated it with the occurring process loads. The dispersion process of a wide spectrum of carbon based nano particles, namely carbon black, single walled carbon nanotubes, multi walled carbon nanotubes, a few-layer graphene powder, electrochemically exfoliated graphite and a functionalized electrochemically exfoliated graphite was investigated. The filler content was varied along the material’s electrical percolation threshold. The criteria found led to a reduction of processing time and revealed the prevalent mechanisms during dispersion.