A two scale model for damage mechanisms during machining of carbon fibre reinforced plastics

由于其低密度和由此产生的机械性能，碳纤维增强塑料（CFRP）适用于创新的轻量化设计概念。部分非均相和各向异性的纤维基体结构不仅影响加工结果，而且影响加工过程中不同工件的性能，如纤维失效（FF）、基体失效（MF）、纤维基体失效（FMF）和分层。为了更详细地识别这些复杂的损伤机制，将在研究项目中开发一个两比例模型。双尺度模型在平均场方法的框架内捕获了各种损伤机制FF， MF和FMF。在不同的应变速率和温度下，使用合适的测试方法分别确定各自类型的失效所需的机械特性，从而考虑加工操作期间的实际应力负荷。采用内聚带模型进行分层，并通过实验数据进行了验证。随后，在有限元程序Abaqus中实现完整的模型，以实现切割过程的宏观模拟，包括由此产生的损伤。通过实际加工对仿真模型进行了调整和验证。所建立的模型详细描述了CFK加工过程中的工作关系。

Due to their low density and the resulting mechanical properties, carbon fiber reinforced plastics (CFRP) are suitable for innovative lightweight design concepts. The partly heterogeneous as well as anisotropic fiber matrix structure not only influences the resultant processing result but also the different workpiece properties during the machining operation, e.g. fiber failure (FF), matrix failure (MF), fiber matrix failure (FMF) and delamination. In order to identify these complex damage mechanisms in more detail, a two scale model will be developed within the research project. The two-scale model captures the various damage mechanisms FF, MF and FMF within the framework of a mean-field method. The required mechanical characteristics of the respective type of failure are determined separately using suitable test methods at different strain rates and temperatures, thus accounting for the real stress load during the machining operation. A cohesive zone model is used for delamination which is verified based on experimental data. Subsequently, the complete model is implemented in the finite element program Abaqus to enable a macroscopic simulation of the cutting process, including the resulting damage. The simulation model is successively adapted and validated by means of real machining. A detailed description of the working relationships in the machining of CFK is provided by the developed model.