Multiscale force networks in highly polydisperse granular media

Area of Science:

• Granular physics
• Materials science
• Computational mechanics

Background:

• Understanding granular material behavior under shear is crucial.
• The influence of particle size polydispersity on granular texture and force chains remains an open question.
• The impact of these factors on shear strength needs further investigation.

Purpose of the Study:

• To investigate highly polydisperse granular packings under simple shear.
• To determine the dependence of granular texture and force chains on size polydispersity.
• To assess the influence of polydispersity on shear strength.

Main Methods:

• Contact dynamics simulations were employed.
• Statistical representation of particle size classes was ensured for numerical treatment.
• Analysis focused on force chain stability and internal friction angle.

Main Results:

• The internal friction angle was found to be independent of polydispersity.
• Two mechanisms were identified for force chain stability: large particles carrying strong forces, and smaller particles equilibrating these forces.
• Coulomb cohesion increases with polydispersity in the presence of adhesion due to enhanced force anisotropy.

Conclusions:

• Granular material shear strength is surprisingly robust against changes in size polydispersity.
• The interplay between large and small particles stabilizes force chains.
• Adhesion effects amplify with polydispersity, increasing cohesion.