A gradient elasticity approach to the indentation size effect at very small depths

Over the past two decades, the indentation size effect (ISE) has been studied extensively by several authors. A common point among all these studies has been the premise that during the indentation process sufficient plastic deformation is developed so that a gradient plasticity framework can be employed in order to capture this effect. However, recent studies have shown that a more detailed analysis of the deformation mechanism during nanoindentation reveals often situations that vary significantly from commonly held beliefs, i.e., configurations where plastic deformation is almost absent, yet an ISE is still observed. This paper deals with such situations and proposes an alternative approach based on a gradient elasticity framework that is capable of capturing the ISE in nanoindentations of small depth, where traditional macroscopic plasticity approaches may not be adopted