Mechanics of Particulate and Porous Materials

Professor Nicolaie D. Cristescu
Department of Aerospace Engineering,
Mechanics & Engineering Science
University of Florida
Gainesville, FL   32611-6250

Sponsored by Center for Materials Research and Analysis and the Dept. of Engineering Mechanics through a a grant provided by Professor Emeritus C. Wayne Martin

Date: Tuesday, February 20, 2001
Time: 3:30 p.m.
Place: W128 Nebraska Hall


Experimental data for dry and saturated powders subjected to triaxial testing will be presented. Compressibility and dilatancy behavior will be discussed. Experimental procedures and methods to determine constitutive functions and coefficients will be presented and examples will be given. The influence of the particle size, initial density, loading rate, loading history, will be discussed, as well as the flow initiation and internal loss of stability. The formulation of constitutive equations of non-associated viscoplastic type or viscoelastic type, able to describe both compressibility and dilatancy as well as creep flow, will be presented.

For porous materials (rock like) the experimental data are showing specific properties under hydrostatic pressure and/or shearing stress. The concept of compressibility/dilatancy boundary is first introduced and it is shown how it is related to porosity change, to permeability change, and to acoustic emission. Methods to determine the elastic parameters are given and their variation under loading is discussed. A schematic of the procedure to be used to determine a general constitutive equation of non-associated elastic/viscoplastic type will be presented. Examples of evolutive damage will be presented as well.