Evaluation and FE-Implementation of elastic properties and a failure criteria for an oxide Ceramic Matrix Composite material WHIPOX �

Kurzfassung

For many technical applications long term high temperature stability is required, as well as damage tolerant fracture behaviour, good thermal shock resistance and insensitivity against cyclic fatigue. Since most oxide/oxide Ceramic Matrix Composites (CMCs) do fulfill these requirements they are promising candidates for such applications, especially due to their inherent oxidation stability. In the last years the all oxide fibre reinforced ceramic matrix composite WHIPOX (Wound Highly Porous Oxide CMC) has been developed at the Institute of Materials Research of the German Aerospace Center (DLR) in Cologne. This material exhibits sufficient strength for many technical applications such as tubes, nozzles or combustion chambers for energy or aerospace applications and shows non brittle fracture behavior. Within this work simulation methods were developed for the selected WHIPOX material. With the help of inverse and classic laminate theory, the developed material models allow the calculation of any laminate structure with different fibre orientations. The focus of this work is the evaluation and adaption of failure criteria from fibre reinforced polymers (FRP) to CMC materials. In contrast to FRP the microstructure of CMC materials (fibre and matrix) is changing depending on the winding angle and therefore representative test results for UD-layers are not available. These effects have to be respected when using general laminate theory and failure criteria for CMCs. A failure model has been developed and verified for this oxide CMC material.