Studies of the Effect of Microstructure on the Dynamic Behavior of Granular and Particulate Media (First Year Report)
Annual rept. Mar 1993-Feb 1994
RHODE ISLAND UNIV KINGSTON DEPT OF MECHANICAL ENGINEERING AND APPLIED MECHANICS
Pagination or Media Count:
A combined experimental-numerical investigation is being conducted to study dynamic load transfer in particulate materials due to explosive loadings. The primary emphasis in the study is to relate the microstructural features of the particulate media tot he load transfer process. The experimental techniques of dynamic photoelasticity is used to investigate the effect of cementation and of the particle shape on the local contact stress fields. The stiffness of the cement relative to that of the particle controls the location of the peak contact stresses. Strong cementation increases the load transfer velocity and also promotes fracture of the particles. The particle shapes as presently studied in this research program seem to have little influence on the load transfer process. The applicability of the fiber optic sensors and the speckle techniques to contact stress measurements is evaluated. Fiber optic sensors show promise of future applications to three dimensional problems. Discrete element numerical wave simulation has been conducted for saturated granular materials through the introduction of a new contact law using elastohydrodynamic theory. Pore fluid acts to decrease the wave speed and increase the attenuation. Future numerical studies will focus on additional changes of the interparticle contact response through cementation and particle shape effects.