The prestress is much larger than its elastic stress limit, which means if I add this stress to the material, the material will endure plastic strain immediately.
Should I only input the elastic stress and change its shape or input all stress?
In Abaqus, you can indeed use inelastic (or plastic) prestress. Defining prestress that exceeds the elastic limit implies that the material is already in a plastically deformed state before the analysis begins. This can be modelled in Abaqus by defining appropriate material properties and initial conditions.
Here's a general approach to model inelastic prestress:
Define Material Properties:Define the elastic and plastic behaviour of the material using the appropriate material models in Abaqus. This could include defining the elastic modulus, Poisson's ratio, yield stress, and the plastic hardening behaviour.
Define Initial Conditions:You can define initial conditions for the inelastic prestress analysis. This may include defining an initial plastic strain distribution corresponding to the given prestress state.
Use Step-Dependent Procedures: You might consider using a step-dependent procedure to capture the inelastic prestress properly. Start with an initial step where the prestress is applied, possibly using a user subroutine like PREDEF to define the necessary initial conditions. For example, if the prestress is applied via a thermal expansion analogy, you might define an initial temperature step that leads to the desired prestress state, followed by subsequent analysis steps.
Verify and Validate: Verifying and validating your model will be vital because modelling inelastic prestress can be complex. If available, consider using simple benchmark problems to test the model and compare the results with analytical solutions or experimental data.
Consult Abaqus Documentation:The specific details for implementing inelastic prestress can depend on the exact nature of the problem you are solving. It may be helpful to consult the Abaqus documentation and any relevant technical support resources for guidance tailored to your particular situation.
Remember that modelling inelastic prestress is a complex task, and the details can vary depending on the specific materials, geometry, loading conditions, and analysis objectives. Careful consideration of the problem's physics and validation against known solutions or experimental data is crucial for building confidence in your model's predictions.