A two-scale model for damage processes during the machining of carbon fiber reinforced plastics

This project includes an experimental characterization of the carbon-fiber-reinforced plastic (CFK) composite and its components, material modeling, CFK machining tests, and simulation-supported analyses of CFK machining. Its main objective is the simulation-supported prediction of machining damage mechanisms of CFK. Four basic relevant damage types form the working hypothesis: fiber failure, matrix failure, fiber-matrix failure, and delamination. On the basis of the damage mechanisms, this project considers the following themes:

• Experiments: The experimental characterization concentrates on the measurement of the temperature-dependent mechanical properties and the failure parameters of the four basic damage types of single components and the composite. The necessary tests for the matrix material and the composite are implemented with a strain rate up to = 1000 s^-1 and a workpiece temperature up to T = 100°C to get closer to the process of machining.

• Simulation: The material modeling is based on a micromechanical two-scale model. The four relevant basic damage types and further mechanical material properties are considered through experimental characterization. The machining simulation is a time-consuming process. To minimize computing time and simulation costs, the mean-field method is exclusively used for homogenization.

• Validation: In the CFK machining tests, the necessary data are measured to evaluate the damage types, cutting force components, and other process data. Orthogonal turning tests and simple milling tests enable the validation of FE simulation models. This validation occurs through an ongoing evaluation of numerical data with respect to the experiment data, with the objective of obtaining a better understanding of the phenomena of CFK turning and milling.