一种圆环形构件，其直径远大于其他任一方向的尺寸。圆环的横截面可以是任意形状（如圆形、五边形等）。
另见 — 圆盘 圆棒 薄壁管
A circular ring-shaped member whose diameter is much larger than any of its other dimensions. The ring's cross-section can have any shape (e.g., circular, pentagon, etc.).
Also see — Disk Rod Thin-walled tube