Yield behavior of open-cell rhombic dodecahedron Ti-6Al-4V lattice at elevated temperatures

The initial yield behavior of Ti-6Al-4V rhombic dodecahedron lattice structures under biaxial loading at different temperatures is investigated. A modified yield criterion based on the hypothesis that the yield of materials is determined by total strain energy density, is proposed to derive the biaxial yield surface of isotropic cellular materials at different temperatures. The core advantage of this model is that the multi-axial yield behavior can be predicted by uniaxial tests instead of taking multi-axial tests. Temperature is taken into consideration by adding the thermal stress term into the model, which influences the hydrostatic pressure in the yield criterion. Then the effect on the yield surface caused by the temperature is discussed. Afterwards, the yield surfaces of Ti-6Al-4V lattice at elevated temperatures are predicted by the modified model. In order to verify the analytical framework, numerical approach is used by coupling the thermal and mechanical analysis to simulate the biaxial loading process at different temperatures. The numerical results match well with the prediction of the modified model.