NICOP - Theoretical, numerical and experimental analysis of elastic and
Abstract
We are interested to investigate the mechanical behaviour of an aggregate of elastic particles in a saturated conditions. The goal of our activity can be summarized in two main points:1) understand ripple formation in absence of mean shearing on saturated sand bed;2) micro-mechanical analysis on the waves propagation in a saturated aggregate of particles.The first goal regards an experimental, numerical and theoretical analysis about ripple formation over a saturated sand bed. We think this as a simple example of fluidization. The experiment is carried out by an oscillating plate above the bed of saturated sand which induces pressure fluctuations and generates fluidization.The relative theoretical analysis is based upon a fluid-particle mixture model. Weconsider the fluid and particle momentum balances, a constitutive relation, and mass balance that leads to a parabolic partial differential equation for the excess pore pressure. We investigate the possibility that the gradient of the excess pore pressure induces fluidization over the bed.In the second project we extend a micro-mechanical model from the dry to the saturated case. We predict the response of a saturated aggregate of compressed particles when contact particles interaction is given by a visco-elastic term. That is, particle interaction is characterized by a viscous contribution because of the fluid between particles and an elastic contribution due to particle deformation. We work in a micro-mechanical context where we consider a kinematic between contacting particles based upon a non-affine deformation. Next we employ force and moment equilibrium at particle level. An average stress can be derived through a suitable statistical description of the aggregate. Our activity will be based upon both a theoretical model above described and a Distinct Element Method numerical simulation. The numerical code is modified to include the viscous part contribution for the particle interaction.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 03, 2017
- Source ID
- N629091712048
Entities
People
- Luigi La Ragoine
Organizations
- Office of Naval Research
- Polytechnic University of Bari
- United States Navy