Prediction of failure of cast iron with dynamic loading and high temperature

The fracture of compressor wheel in turbocharger leads wheel pieces impacting into the container. A design method is needed to assure full containment of turbocharger failures within the cast iron housings that operate at high temperatures. During the impacting the container of turbocharger is under critical condition: dynamic loading from wheel pieces and high temperature (in some cases it can reach 1000 °C). In this project the material of container is cast iron GGG400SiMo. To investigate the damage behaviour of the material, several groups of experiments were undertaken under specific conditions: quasi-static loading and room temperature, high strain rate dynamic loading and high temperature (up to 600 °C). The tests took a wide range of triaxiality (σm/σe; σm and σe are mean stress and equivalent stress) value into account. Extended Cast Iron model was adopted to simulate the elastoplastic property of the cast iron; Vöhringen model was used to consider the effect of strain rate; and proper failure criteria (including maximum and minimum limits) were proposed and applied into all the tests. The simulations with failure prediction mostly matched the experiment very well except for the ones under temperature of 200 °C and 400 °C with quasi static loading. In the end the finite element model of turbocharger was used to simulate the damage behaviour of the structure with proposed failure criteria.