Thermodynamically consistent relations involving plasticity, internal energy and thermal effects

Area of Science:

• Thermodynamics
• Materials Science
• Continuum Mechanics

Background:

• Experimental plastic deformation shows temperatures lower than predicted by plastic work dissipation.
• A constant 'beta' is often used to reconcile theoretical and experimental results.
• Existing models do not fully capture the thermodynamic behavior during plastic deformation.

Purpose of the Study:

• To propose an alternative thermodynamic framework for plastic deformation.
• To introduce an internal energy component linked to dislocation accumulation.
• To derive a variable 'beta' based on material properties and plastic strain.

Main Methods:

• Developed a thermodynamic framework incorporating internal energy from dislocation density.
• Utilized experimental data relating flow stress to dislocation density and plastic strain.
• Formulated expressions for 'beta' and temperature as functions of effective plastic strain.

Main Results:

• The derived internal energy provides a better correlation between theory and experiment.
• 'Beta' is shown to be a function of effective plastic strain, not a constant.
• Representative results for 'beta' and temperature are presented for uncoupled and coupled thermoplastic theories.

Conclusions:

• The proposed thermodynamic model offers a more accurate representation of thermoplastic behavior.
• The variability of 'beta' is explained by internal energy associated with dislocations.
• The formulation serves as a foundation for advanced theories in large deformation and complex internal energy scenarios.