Depth-dependent hysteresis in adhesive elastic contacts at large surface roughness

Area of Science:

• Materials Science
• Mechanics of Materials
• Surface Science

Background:

• Contact experiments with compliant materials like polymers and gels exhibit depth-dependent hysteresis (DDH).
• Classical contact mechanics theories fail to explain DDH, attributing it to factors like viscoelasticity, plasticity, and surface interactions.
• Previous models for DDH were limited to small surface roughness regimes.

Purpose of the Study:

• To develop a new mechanics model for explaining depth-dependent hysteresis (DDH) in compliant materials.
• To account for the observed decrease in energy loss with increasing surface roughness in the large roughness regime.
• To capture the experimentally observed dependencies of energy loss on indentation depth, material, and surface properties.

Main Methods:

• Development of a novel mechanics model based on the Maugis-Dugdale theory of adhesive elastic contacts.
• Integration of Nayak's theory of rough surfaces into the adhesive contact model.
• Theoretical analysis of contact force-indentation depth relationships for compliant materials with varying surface roughness.

Main Results:

• The new model successfully explains the trend of decreasing energy loss with increasing surface roughness.
• The model accurately captures the experimentally observed relationship between energy loss and maximum indentation depth.
• The model accounts for the influence of material and surface properties on depth-dependent hysteresis.

Conclusions:

• The developed mechanics model provides a comprehensive explanation for depth-dependent hysteresis in compliant materials across different roughness regimes.
• This model advances the understanding of energy dissipation mechanisms in adhesive elastic contacts involving rough surfaces.
• The findings have implications for predicting and controlling the mechanical behavior of polymers and gels in contact applications.