| 摘要 |
The invention provides structural elements comprising an elongated internal member and an elongated external member enclosing said internal member, in which a mid-portion enveloping the internal member and being in tight association with the external surface of the internal member, defines, jointly with said internal member, a first, core- envelope sub-structure, while two flanking portions extending from and integral with the mid-portion and facing and contacting one another to jointly define a second, layered sub-structure. The invention further provides methods for manufacturing such structural elements. |
