Thermal shakedown in granular materials with irregular particle shapes

Area of Science:

• Geotechnical Engineering
• Materials Science
• Thermodynamics

Background:

• Granular materials experience diverse temperature fluctuations in natural and engineered settings.
• The mechanical response of granular materials to cyclic temperature variations is not well understood.
• Key factors like particle shape, stress, density, and temperature amplitude are under-explored.

Purpose of the Study:

• To investigate the impact of cyclic temperature variations on the mechanics of granular materials, specifically sands.
• To quantify the influence of particle shape, stress level, relative density, and temperature amplitude on this response.

Main Methods:

• Advanced laboratory experiments were conducted on granular materials, focusing on sands.
• Cyclic temperature variations were applied to samples under controlled conditions.
• Deformations and microstructural changes were monitored.

Main Results:

• Cyclic temperature variations induce 'thermal shakedown' in sands, causing irreversible bulk deformations.
• These deformations result from microstructural rearrangements due to particle thermal expansion and contraction.
• The extent of deformation is dependent on particle shape, stress, density, and temperature amplitude.

Conclusions:

• Thermal shakedown leads to significant cumulative compaction in sands and other granular materials over multiple cycles.
• This phenomenon can have substantial implications for the performance of natural and engineered systems.
• Understanding thermal shakedown is crucial for predicting the long-term behavior of granular materials under thermal cycling.