Nondestructive evaluation and analysis of particle modulus of granular composites based on indentation energy

This study examines the mechanical behaviour of particle-reinforced composite materials (PRCMs) under micro and nano-indentation using FEM simulations. Particular attention is given to deep indentation, where the contact between the indenter and reinforcing particles plays a more prominent role. To address this, a new approach is introduced to estimate the elastic modulus of individual particles based on energy decomposition combined with a segmented fitting strategy, allowing local mechanical properties to be evaluated without causing damage. FEM simulations, together with experimental validation, are used to analyse how particle distribution, matrix properties, and residual stresses influence the indentation response. The results show that, unlike homogeneous materials, PRCMs exhibit more complex indentation behaviour due to the significant effect of particles on local stiffness and hardness. Even under complex loading conditions, the proposed method provides reliable modulus extraction, offering practical guidance for the mechanical characterisation and design optimisation of composite materials.