Simplified indentation mechanics to connect nanoindentation and low-energy impact of structural composites and polymers

Nanoindentation (nanometer scale, extremely small) and impact (microsecond scale, extremely fast) experiments are two important techniques for characterizing modern material systems. However, these two experiments were often studied individually. In this pilot study, a multiscale indentation mechanics approach is proposed to correlate these two very different mechanics events acting on the same target materials using a spherical indenter and a projectile. The contact stiffness of nanoindentation of a target material is fitted using Hertz’s contact law, and then the contact stiffness of impact is obtained using a simplified multiscale relation. Therefore, the maximum impact force of a projectile impact can be predicted by inputting the impact energy and the contact stiffness of impact. The above new approach was validated by drop-weight impact experiments of polymers and structural composite materials subjected to low-energy impact. Results show that only a few minutes are needed to predict the maximum impact force.