Ductile damage and fragmentation of highly porous gamma-alumina under multi-point crushing

Abstract : Mechanical behavior of highly porous alumina catalytic supports is investigated through a non-conventional approach consisting in a multi-point crushing of individual cylindrical extrudates. A ductile behavior characterized by irreversible deformation and fragmentation phenomena is observed and pointed out by experimental load-displacement curves. SEM fractographies of the fragments collected after the tests confirm the presence of dense micro-cracking and of local deformations under contact zones. A Finite Element analysis of the test shows that a Drucker-Prager strength criterion associated with a perfectly plastic flow rule mimics the global damageable behavior of the specimen under the multi-point crushing test. A correlation is proposed between the evolution of the mass of fine fragments and the plastic energy dissipation.