MTS Model Application to Materials Not Starting in the Annealed Condition

Area of Science:

• Materials Science
• Mechanical Engineering
• Computational Materials Science

Background:

• The Mechanical Threshold Stress (MTS) constitutive model is widely used for predicting material behavior.
• Its application is typically straightforward for annealed materials with low initial dislocation densities.
• Pre-existing work (warm or cold) complicates MTS model application by altering internal state variables and strain hardening analysis.

Purpose of the Study:

• To investigate the challenges in applying the MTS model to materials with existing work.
• To present strategies for adapting the MTS model for materials with non-annealed conditions.
• To demonstrate these challenges and solutions using molybdenum and a hypothetical Body-Centered Cubic (BCC) alloy.

Main Methods:

• Analysis of the impact of pre-existing dislocations on MTS model parameters.
• Development of modified approaches for evaluating internal state variables.
• Simulation and comparison of model predictions for annealed versus worked material states.

Main Results:

• Existing work significantly affects the accuracy of standard MTS model predictions.
• Modified methods for state variable evaluation and activation energy specification are proposed.
• The study provides a framework for applying MTS to materials with complex initial conditions.

Conclusions:

• The MTS model requires adjustments when applied to materials with prior mechanical work.
• The presented strategies offer viable pathways for accurate material modeling in non-ideal conditions.
• Further research can refine these methods for broader material applications.