| 摘要 |
The plate comprises a first side and a second side opposite the first side, with the first side comprising a first smooth surface and a hub member projecting essentially normally from the first smooth surface for engageably supporting the core on. The hub member and the first smooth surface being adjoined by a grooved portion, and wherein the hub member includes a cavity portion projecting outwardly of the second side. The second side has a first energy attenuation region surrounding the cavity portion, with the first attenuation region being provided with device to flex in response to shock. The flex device comprises the grooved portion, a second smooth surface adjoining the grooved portion, and a first annular rib surrounding the second smooth surface. The second side further comprises a second energy attenuation region surrounding the first energy attenuation region, and a third energy attenuation region surrounding the second energy attenuation region. The first, second and third energy attenuation regions are successively arranged concentric to the hub member. |
