Dear all mechanicians,

I modeled a disk with outer diameter of 48 mm and inner diameter of 24 mm. The material is defined as isotropic; in this case, it's glass-ceramics (E = 90GPa, v = 0.24). The inner diameter is constrained to transverse directions, while it is subjected to half-sine wave impulse of 500G (G = 9.81 m/s^2) within 2 ms. The disk moved up under this loading, and I extracted the vertical displacement at the tip with respect to time (time-history analysis). The time step was 1e-6 second, and the duration was 4 ms. The disk was made of 8-node hexahedron element, with one element in the thickness. Three formulations were tested: (1) reduced integration [RI], (2) selectively-reduced integration [SRI] and (3) full integration [FI].