The length of the lower of the Indominus rex is 1.2470052 m.
1.2470052/(213/209)=1.2236 meters
1.2236*(630/228)=3.381 m
1.2236*(552/228)=2.9624 m
2.9624*3.381=10.016 m^2
Now for the thickness
2.9624/(1067/55)=0.152701031 m
0.152701031/(85/16)=0.028744 m
(10.016*0.028744)*10^6=287899.904 cm^3
It's stated in the Evolution of Claire novel that its made up of a plastic polymer, though not made of glass, it should be comparable to ballistic glass as it withstand being hit by a Pteranodon. The fragmentation value of ballistic glass is 32.41 joules/cm^3.
32.41*287899.904=9330835.88864 joules
9330835.88864/1000000=9.33084 megajoules (9-B, Wall level)