In sheet metal forming simulations using finite element method, the coefficient of friction according to Coulomb is normally assumed to be constant for the whole tool region. Recent research has demonstrated that under contact conditions typical for sheet metal forming, the coefficient of friction is strongly dependent on the contact pressure and the slip-rate between the interacting partners as well as on the contact temperature. A friction law based on the approach of Filzek is proposed in this research paper and implemented as a user subroutine in ABAQUS. Moreover, a novel user subroutine coupling is developed which enables the visualization of local coefficients of friction for every contact node. For the very first time, this enables the in situ visualization of local coefficients of friction in sheet metal forming simulations using the FE system ABAQUS. Multiple evaluation algorithms are presented as well. The presented friction model and the user subroutine coupling are validated using experimental data of an industrial deep drawing process. The proposed combination of the friction modeling and the in situ visualization of coefficients of friction enables the identification of friction hot spots. Based on such analysis, the tool and die making industry can realize tribologically optimized tools either by applying special coatings in areas of low or high friction, or by choosing different materials for tooling inserts, or by changing the type as well as the amount of the lubricant. Whereas the presented friction model is tailored to sheet metal forming and developed using the commercial code of ABAQUS, the visualization coupling methodology is transferable to any manufacturing process and various FE systems supporting FORTRAN programming language.

No abstract

No abstract

No abstract

Fibre reinforced plastics (FRP) are being increasingly used for advanced applications where an appropriate mechanical performance should be achieved at minimum weight. A substantial increase of the FRP usage is expected across various industries e.g. in automotive sector in the nearest future. This leads to the mass manufacturing of FRP components. Reduction of manufacturing costs of FRP components is regarded as the main enabler for the usage of this material in mass production. Although FRP components are manufactured near-net-shape, they often have to be pierced or trimmed in one of the last manufacturing steps. With rising production numbers blanking is a potentially more cost efficient technology for trimming and piercing of FRP components compared to the conventionally performed abrasive water jet cutting or machining. The mechanisms of FRP separation in blanking have not yet been researched. In particular, the influence of the fibre orientation relative to the cutting line on the cutting force is not known. In the scope of this work an experimental study of blanking of a unidirectional carbon fibre reinforced plastic with a thermoset resin at different fibre orientations to the cutting line was performed. It was shown that the cutting force decreases from the perpendicular to the parallel fibre orientation to the cutting line. A possible mechanical explanation of this dependency was formulated.