ABSTRACT
Abstract Strength and fracture experiments are often conveniently planned and profitably executed in the laboratory as scale model experiments. Unfortunately, geometrically homothetical samples of the same material often show mechanical characteristics that are not constant, but a function of the specimen size. This size-scale effect leads to the concept of a Representative Volume Element RVE for the considered property. All the significant quantities must be scaled such that the resulting system can be studied as a valid substitute for the original case. Several laboratory testing devices have been proposed in order to describe the failure mechanisms including fracture, strength and the evolution of damage. Dilatancy characteristics occurring under shear loading have been analysed for non cohesive and cohesive materials. They generate softening behaviour on the stress-strain curves and are usually responsible for unavoidable sizescale effects. The representativeness of strength testing results has been analysed in the framework of similarity scaling laws. Keywords: Dilatancy properties, laboratory testing, modelling of models, representative volume element, scaling laws, size-scale effects, strength testing.
