A non-associated constitutive model incorporating measurable plastic strain-increments for anisotropic thin-walled metals

The constitutive model used to analyze the plastic deformation characteristics of anisotropic materials should have the most important ability to predict plastic strain accurately. However, traditional constitutive models are mainly developed to improve the accuracy of predicting stress parameters, and the accuracy of predicting plastic strain-increment parameters cannot be directly controlled through using the experimental plastic strain parameter. To overcome these limitations, a new constitutive model is proposed that incorporates a plastic strain-increment function, but does not take into account the Bauschinger effect. The main purpose is to achieve direct applications of the experimental strain parameters to control the constitutive model for predicting plastic strain-increments. This new anisotropic constitutive model is developed to fulfil comprehensive prediction accuracy for both stress and strain parameters. The model was validated by a considerable amount of experimental data involving simple and complex loading states, including materials with different anisotropic properties. Comparing the application of different theories, the new theoretical model can improve the accuracy of predicting plastic strain parameters by 9.73% for uniaxial tensile test data, and by 16.5% for complex loading state test data on average.