A coupled plasticity-damage model of K418 nickel-based superalloy with pressure and temperature dependence

The issue of containment stems from the aero-engine field, and there is little research in the turbocharger field. In order to reduce the number of tests, development cycle and cost, it is necessary to predict the burst speed of the turbine accurately. In response to this problem, a coupled plasticity-damage model is developed for turbine materials according to the stress state and operating temperature of the turbine. The effect of stress triaxiality, temperature are considered in the plastic constitutive and the failure criterion. The stress update algorithm of plasticity-damage model is given. According to the operating temperature and stress state of the turbine, the experimental scheme of K418 nikel-base superalloy is designed to calibrate the plasticity-damage model. Finally, the coupled plasticity-damage model is verified by the specimens with the notch radius R6 at 550 degrees C and 600 degrees C. The results show that the maximum error of proposed model is about 7.3%, which is better than the 14.2% prediction error of the constitutive model without any corrections. Moreover, the failure displacement can be predicted by the proposed constitutive model (the maximum error is about 8.2%), which is beyond the ability of traditional model. The location of failure initiation, fracture pattern in numerical studies have also showed close correspondence to the experimental results.

Automated summary

A coupled plasticity-damage model is developed for predicting the burst speed and failure displacement of turbine materials under different stress states and operating temperatures. Experimental validation demonstrates that the proposed model performs better than traditional constitutive models in terms of prediction accuracy.