Impact simulation for brittle materials

I’m using the Johnson-Holmquist (JH-2) material model for brittle materials in Abaqus/Explicit (as illustrated in image 1) to do an impact analysis. I’m hoping for a simulation that looks like image 2, where the particle bounced back after impact. Instead, I get something like image 3, which shows the particle penetrating the substrate. Do you have any idea why this is happening? In the JH-2 model, the only material parameter that changes is the strain rate coefficient (C), which is 1 in image 2 and 0.007 in image 3.
Any suggestions you have would be greatly appreciated.
Thank you very much.

Figure 1

Figure 2

Figure 3