An elastic-plastic transition criterion for the erosion of rocks and concrete materials by impinging liquid drops

Depending on loading regime and material type, mineralic materials behave either elastic or elastic-plastic if eroded by impinging water drops. A simple transition number that combines fracture toughness and compressive strength (respectively Vickers hardness), can be used to distinguish between both modes. Conventionally 'hard' materials, namely granite and feldspars, own low transition numbers (high hardness values) and respond elastic. Conventionally 'soft' materials, namely limestone, cement mortar and schist, are characterised by high transition numbers (low hardness values) and show an elastic-plastic response.