Constitutive equation of friction based on the subloading-surface concept

Area of Science:

• Tribology
• Materials Science
• Mechanical Engineering

Background:

• The subloading-friction model effectively describes static friction and transitions to kinetic friction.
• Existing models often exhibit negative rate sensitivity, where friction decreases with increasing velocity.
• Modeling friction across a wide range of sliding velocities, including impact, remains a challenge.

Purpose of the Study:

• To develop a generalized subloading-friction model that incorporates overstress for viscoplastic sliding velocity.
• To enable the model to describe both negative and positive friction rate sensitivity.
• To validate the model's performance from quasi-static to impact sliding conditions.

Main Methods:

• Incorporation of the overstress concept into the existing subloading-friction model.
• Formulation of a generalized model to account for viscoplastic effects.
• Numerical experiments and comparison with experimental data from lubricated steel specimens.

Main Results:

• The generalized model successfully describes static and kinetic friction transitions.
• The model accurately predicts both negative and positive rate sensitivity across diverse sliding velocities.
• Numerical simulations align well with experimental friction test data.

Conclusions:

• The generalized subloading-friction model provides a comprehensive framework for friction analysis.
• This enhanced model offers improved accuracy for predicting friction behavior under varying velocity conditions.
• The findings contribute to a better understanding of tribological phenomena in engineering applications.