Figure 5.

Twelve samples were impacted at 6 different deflections of the internal spring. (A) Representative photographs and binary images of the 6 mm diameter surface for low (below damage threshold) and high impact (above damage threshold) samples after application of India ink. (B-F) Correlations between surface cracking and mechanical aspects of impact were determined from closed circle data points, which included all data points with >1% cracking and the highest point that did not reveal cracking. Only stress (B) and stress rate (D) provided significant correlations with surface cracking (P < 0.05).