A THEORETICAL-ANALYSIS OF STRESS-CONCENTRATIONS IN GELS CONTAINING SPHERICAL FILLERS

Stress conditions in a model biocomposite system undergoing uniaxial c ompression have been theoretically analyzed. The composite structure c onsidered was that of an incompressible isotropic gel system containin g a dilute dispersion of spherical filler particles. The analysis was based on the theory of elasticity and the assumption that particle-par ticle interactions were negligible. The stress concentration in the vi cinity of the filler was calculated for adhesive and nonadhesive inter faces between the filler and the medium. The analysis indicates that l ocalized stress concentrations are induced in the medium within two ra dii from the filler particle. The level of stress concentration depend s upon the condition of the interface and the ratio of the shear modul i of the two materials. The stress concentration factor may be as high as 3 at the interface in the case where rigid filler particles are lo osely embedded in a soft gel. The minimum stress concentration occurs at a bonded interface when the two materials have similar elastic modu li.