Cyclic perturbations facilitate athermal creep in yield-stress materials

Area of Science:

• Physics
• Geophysics
• Materials Science

Background:

• Yield stress materials deform irreversibly only when stress exceeds a critical threshold (sigma-c).
• Sub-critical conditions (stress < sigma-c) typically prevent persistent deformation, barring transient or thermal effects.

Purpose of the Study:

• To characterize irreversible deformation in materials under sub-critical athermal conditions induced by cyclic parameter variations.
• To investigate the role of a novel critical stress (sigma-0) in this phenomenon.

Main Methods:

• Utilized established models from yielding and depinning transition physics.
• Analyzed deformation behavior as critical stress thresholds were approached from above and below.

Main Results:

• Deformation per cycle increases as sigma-c is approached from below.
• Deformation decreases and vanishes at a new critical stress, sigma-0 (< sigma-c), when approached from above.
• Sigma-0 functions analogously to the fatigue limit in damage propagation.

Conclusions:

• Cyclic environmental or system parameter fluctuations can drive persistent irreversible deformation in materials below their yield stress.
• Findings suggest potential applications in understanding sub-critical landform evolution and soil creep mechanisms influenced by environmental cycles.