使用SFBEAM怎么控制力的方向？

cyh3278

使用SFBEAM时怎么控制力的方向，如图：所施加的压力有时沿X轴方向，有时又会沿Z轴方向，我要使力只沿X轴方向，怎么来控制，命令流又是怎么样的？

zzzxxxx

SFBEAM, ELEM, LKEY, Lab, VALI, VALJ, VAL2I, VAL2J, IOFFST, JOFFST
中的LKEY用来标示方向
LKEY：
Load key associated with surface load (defaults to 1). Load keys (1, 2, 3, etc.) are listed under "Surface Loads" in the input table for each element type in the ANSYS Elements Reference. For beam elements, the load key defines the load orientation.

标示由单元参考查得：
Surface Loads
Pressure --
face 1 (I-J) (-z normal direction),
face 2 (I-J) (-y normal direction),
face 3 (I-J) (+x tangential direction),
face 4 (J) (+x axial direction),
face 5 (I) (-x direction).
(use a negative value for loading in the opposite direction)
I and J denote the end nodes.
具体根据你用的单元查得。

cyh3278

我用的是beam4，beam4下面的信息我不怎么明白：
表面荷载：

压力-（括号内为压力正值作用方向）

face 1 (I-J) (-Z法线方向)

face 2 (I-J) (－Y法线方向)

face 3 (I－J) (+X 轴切线方向)

face 4 (I) (+X 轴向)

face 5 (J) (-X 轴向)
如图：我每个单元的LKEY都是1，压力各个方向不一样，压力方向怎么确定的呢，上面的信息（红色部分）怎么理解？

zzzxxxx

你首先要弄明白梁单元是怎么定向的，beam4里面说得很清楚啊！
The element x-axis is oriented from node I toward node J. For the two-node option, the default (θ = 0°) orientation of the element y-axis is automatically calculated to be parallel to the global X-Y plane. Several orientations are shown in Figure 4.1: "BEAM4 Geometry". For the case where the element is parallel to the global Z axis (or within a 0.01 percent slope of it), the element y axis is oriented parallel to the global Y axis (as shown). For user control of the element orientation about the element x-axis, use the θ angle (THETA) or the third node option. If both are defined, the third node option takes precedence. The third node (K), if used, defines a plane (with I and J) containing the element x and z axes (as shown). If this element is used in a large deflection analysis, it should be noted that the location of the third node (K), or the angle (THETA), is used only to initially orient the element.
这需要看你是否使用定向节点，两者的单元定向过程是不一样的。
要想使所有梁单元定向一致，可以将定向节点的坐标取得非常大，大几个数量级，这样各个定位的坐标就近视一致了，加载也比较容易些。具体看你怎么建的模型了。如果是没有使用定向节点，就得一个一个思考他的方向了。

cyh3278

我仔细看了beam4的说明，终于看懂了，谢谢你的指点！

玉在水心

谢谢啊  呵呵