2019 Scholarship Winner Feature – Preethi Ravula

University of Maryland Doctoral Student Receives Philadelphia STLE Scholarship

L to R: Scholarship Committee Member Rick Nachenberg, Scholarship Awardee Preethi Ravula, Professor B. Balachandran

The Philadelphia Section of the STLE is pleased to award a scholarship to Preethi Ravula, a doctoral student in Mechanical Engineering at the University of Maryland.

Preethi is studying granular media interactions with different legged robots using numerical and experimental methods. Granular media exhibit complex behavior because of its transition between solid, liquid and gaseous states. A dense and/or cohesion-less material can flow, thereby exhibiting a fluid-like behavior and whereas under certain conditions, the material acts as a solid by supporting shear loads. To numerically simulate the granular media interactions with legged robots, Preethi uses a discrete element method (DEM).

In the use of DEM, the granular media is represented as finite number of particles and the dynamics of the particles is governed by contact forces arising from collision with other particles. The contact forces between the particles include spring force, damping force and frictional forces. Friction plays an important role in the dynamics of granular media. In DEM, the frictional contact between the particles is modelled using Coulomb’s law of friction.

DEM can also be used to model wet or lubricated granular media. Due to interactions, energy within the granular media propagates through force networks and eventually dissipates. With experimental studies, force chains and networks in granular media are studied by Preethi using high speed imaging of photo-elastic particles during interaction with different robotic legs.