BEAM188单元中文说明

Release 10.0 Documentation for ANSYS

BEAM188

3-D Linear Finite Strain Beam 三维线性有限应变梁单元

BEAM188 Element Description BEAM188单元描述

BEAM188 is suitable for analyzing slender to moderately stubby/thick beam structures. This element is based on Timoshenko beam theory. Shear deformation effects are included.

Beam188 单元适合于分析从细长到中等粗短的梁结构，该单元基于铁木辛哥梁结构理论，并考虑了剪切变形的影响。

BEAM188 is a linear (2-node) or a quadratic beam element in 3-D. BEAM188 has six or seven degrees of freedom at each node, with the number of degrees of freedom depending on the value of KEYOPT(1). When KEYOPT(1) = 0 (the default), six degrees of freedom occur at each node. These include translations in the x, y, and z directions and rotations about the x, y, and z directions. When KEYOPT(1) = 1, a seventh degree of freedom (warping magnitude) is also considered. This element is well-suited for linear, large rotation, and/or large strain nonlinear applications.

Beam188 是三维线性（2 节点）或者二次梁单元。每个节点有六个或者七个自由度，自由度的个数取决于KEYOPT(1)的值。当KEYOPT(1)＝0（缺省）时，每个节点有六个自由度；包括节点坐标系的x、y、z 方向的平动和绕x、y、z 轴的转动。当KEYOPT(1)=1 时，每个节点有七个自由度，这时引入了第七个自由度（横截面的翘曲）。这个单元非常适合线性、大角度转动以及大应变等非线性问题。

BEAM188 includes stress stiffness terms, by default, in any analysis with

NLGEOM,ON. The provided stress stiffness terms enable the elements to analyze flexural, lateral, and torsional stability problems (using eigenvalue buckling or collapse studies with arc length methods).

当NLGEOM 选项打开的时候，beam188 的应力刚化，在任何分析中都是缺省项。应力刚化选项使本单元能分析弯曲、横向及扭转稳定问题（用弧长法分析特征值屈曲和塌陷）。

BEAM188 can be used with any beam cross-section defined via SECTYPE, SECDATA, SECOFFSET, SECWRITE, and SECREAD. The cross-section associated with the beam may be linearly tapered. Elasticity, creep, and plasticity models are supported (irrespective of cross-section subtype). A cross-section

associated with this element type can be a built-up section referencing more than one material.

Beam188可以采用sectype、secdata、secoffset、secwrite 及secread 命令定义横截面。本单元支持弹性、蠕变及塑性模型（不考虑横截面子模型）。这种单元类型的截面可以由不同材料组成。

BEAM188 ignores any real constant data beginning with Release 6.0. See the SECCONTROLS command for defining the transverse shear stiffness, and added mass.

Beam188 从6.0 版本开始忽略任何实常数，参考seccontrols 命令来定义横向剪切刚度和附加质量。

For BEAM188, the element coordinate system (/PSYMB,ESYS) is not relevant.

单元坐标系统（/psymb，esys）与beam188 单元无关。

Figure 188.1: BEAM188 Geometry 图188.1：Beam188 单元几何示意图

BEAM188 Input Data

BEAM188 输入数据

The geometry, node locations, and coordinate system for this element are shown in Figure 188.1: \. BEAM188 is defined by nodes I and J in the global coordinate system.

该单元的几何形状、节点位置、坐标体系如图188.1 “Beam188 单元几何示意图”所示，beam188 由整体坐标系的节点I 和J 定义。

Node K is a preferred way to define the orientation of the element. For information about orientation nodes and beam meshing, see Generating a Beam Mesh With Orientation Nodes in the ANSYS Modeling and Meshing Guide. See the LMESH and LATT command descriptions for details on generating the K node automatically.

节点K 是定义单元方向的首选方式，有关方向节点和梁的网格划分的信息可以参见ANSYS Modeling and Meshing Guide中的Generating a Beam Mesh With Orientation Nodes。参考LMESH和LATT命令描述可以得到k 节点自动生成的详细资料。

BEAM188 may also be defined without the orientation node. In this case, the element x-axis is oriented from node I (end 1) toward node J (end 2). For the two-node option, the default orientation of the element y-axis is automatically calculated to be parallel to the global X-Y plane. 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 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) is used only to initially orient the element.

Beam188 也以在没有方向节点的情况下被定义。在这种情况下，单元的x 轴方向为I 节点指向J节点。对于两节点的情况，默认的y 轴方向按平行x－y 平面自动计算。对于单元平行与z 轴的情况（或者斜度在0.01％以内），单元的y 轴的方向平行与整体坐标的y 轴（如图188.1）。用第三个节点的选项，用户可以定义单元的x 轴方向。如果两者都定义了，那么第三节点的选项优先考虑。第三个节点（K）如果采用的话，将和I、J 节点一起定义包含单元x 轴和z 轴的平面(如图188.1)。如果该单元采用大变形分析，需要注意这个第三号节点仅仅在定义初始单元方向的时候有效。

The beam elements are one-dimensional line elements in space. The cross-section details are provided separately using the SECTYPE and SECDATA commands (see Beam Analysis and Cross Sections in the ANSYS Structural Analysis Guide for

details). A section is associated with the beam elements by specifying the section ID number (SECNUM). A section number is an independent element attribute. In addition to a constant cross-section, you can also define a tapered cross-section by using the TAPER option on the SECTYPE command (see Defining a Tapered Beam).

梁单元是一维空间线单元。横截面资料用sectype和secdata 命令分别提供，参见ANSYS Structural Analysis Guide 的Beam Analysis and Cross Sections 看详细资料。截面与单元用截面ID 号（SECNUM）来关联，截面号是独立的单元属性。除了等截面，还可以用sectype 命令中的锥形选项来定义楔形截面（参考Defining a Tapered Beam）。

The beam elements are based on Timoshenko beam theory, which is a first order

shear deformation theory: transverse shear strain is constant through the cross-section; that is, cross-sections remain plane and undistorted after deformation. BEAM188 is a first order Timoshenko beam element which uses one point of integration along the length with default KEYOPT(3) setting. Therefore, when SMISC quantities are

requested at nodes I and J, the centroidal values are reported for both end nodes. With KEYOPT(3) set to 2, two points of integration are used resulting in linear variation along the length.

单元基于铁木辛哥梁理论，这个理论是一阶剪切变形理论；横向剪切应力在横截面是不变的，也就是说变形后横截面保持平面不发生扭曲。Beam188 是一阶铁木辛哥梁单元，沿着长度用了一个积分点，用默认的KEYOPT(3)设置。因此，在I 和J 节点要求SMISC 数值的时候，中间数值在两端节点均输出。当KEYOPT（1） 设置为2，两个积分点作为延长的线性变量被运用。

BEAM188 lements can be used for slender or stout beams. Due to the limitations of first order shear deformation theory, only moderately \The slenderness ratio of a beam structure (GAL2/(EI)) may be used in judging the applicability of the element, where:

Beam188单元可以用在细长或者短粗的梁。由于一阶剪切变形的限制，只有适度的“粗”梁可以分析。梁的长细比（GAL2/(EI))可以用来判定单元的适用性，式中：

G

Shear modulus 剪切模量 A

Area of the cross section 截面积 L

Length of the member 构件长度

EI

Flexural rigidity 抗弯刚度

It is important to note that this ratio should be calculated using some global distance measures, and not based on individual element dimensions. The following graphic provides an estimate of transverse shear deformation in a cantilever beam subjected to a tip load. Although the results cannot be extrapolated to any other application, the example serves well as a general guideline. We recommend that the slenderness ratio should be greater than 30.

需要注意的是这个比例的计算需要用一些全局距离尺寸，不是基于独立的单元尺度。下面这个图提供了受端部集中荷载的悬臂梁的横向剪切变形的例子，这个例子可以作为一个很好的大致的指导。我们推荐长细比要大于30。

Figure 188.2: Transverse-Shear Deformation Estimation

图188.2：横向剪切变形的评估示意

Slenderness Ratio (GAL2/(EI)) 长细比 25 50 100 1000 δ Timoshenko / δ Euler-Bernoulli 位移：铁木辛哥/欧拉－伯努力 1.120 1.060 1.030 1.003 These elements support an elastic relationship between transverse shear forces and transverse shear strains. You can override default values of transverse shear stiffnesses using the SECCONTROLS command.

这些单元支持横向剪切力和横向剪切变应力的弹性关系。你可以用seccontrols 命令重新定义默认的横向剪切刚度值。

The St. Venant warping functions for torsional behavior are determined in the undeformed state, and are used to define shear strain even after yielding. ANSYS does not provide options to recalculate in deformed configuration the torsional shear distribution on cross-sections during the analysis and possible partial plastic yielding

of cross-sections. As such, large inelastic deformation due to torsional loading should be treated and verified with caution. Under such circumstances, alternative modeling using solid or shell elements is recommended.

无形变的状态决定了扭转作用引起的圣维南翘曲变形，可以用来定义屈服后的剪应力。Ansys 没有提供选项使不成型的结构重新计算，这种结构是由分析过程中的扭转剪切对横截面的作用以及部分截面塑性屈服引起的。正因为此，由扭转作用引起的非弹性大变形需要小心的来处理和校核。在这样的情况下，推荐使用solid 或者shell 单元来替换。

BEAM188 elements support “restrained warping” analysis by making available a seventh degree of freedom at each beam node. By default, BEAM188 elements assume that the warping of a cross-section is small enough that it may be neglected (KEYOPT(1) = 0). You can activate the warping degree of freedom by using

KEYOPT(1) = 1. With the warping degree of freedom activated, each node has seven degrees of freedom: UX, UY, UZ, ROTX, ROTY, ROTZ, and WARP. With KEYOPT(1) = 1, bimoment and bicurvature are output.

Beam188单元支持“约束扭转”分析，通过定义梁节点的第七个自由度来实现。Beam188 单元默认的假设是截面的扭转是足够小的以至于可以忽略（KEYOPT（1）＝0）。你可以激活它的扭转自由度通过定义KEYOPT（1）＝1。当激活节点的扭转自由度的时候，每个节点有七个自由度：UX，UY，UZ，ROTX, ROTY, ROTZ, 和WARP。当KEYOPT(1) = 1，双力矩和双弧线将被输出。

In practice, when two elements with “restrained warping” come together at a sharp angle, you need to couple the displacements and rotations, but leave the out-of-plane warping decoupled. This is normally accomplished by having two nodes at a physical location and using appropriate constraints. This process is made easier (or automated) by the ENDRELEASE command, which decouples the out-of plane warping for any adjacent elements with cross-sections intersecting at an angle greater than 20 degrees.

实际上，当两个“约束扭转”的单元以一个锐角组合在一起的时候，你需要耦合他们的唯一合转角，使它们平面外的自由度解藕。一般通过用两个节点在物理位置和运用合适的约束可以实现。这个过程通过ENDRELEASE命令很容易的（自动的）实现，命令将两个临近横截面相交角度大于20度的单元的平面外扭转解耦。

BEAM188 allows change in cross-sectional inertia properties as a function of axial elongation. By default, the cross-sectional area changes such that the volume of the element is preserved after deformation. The default is suitable for elastoplastic applications. By using KEYOPT(2), you can choose to keep the cross-section constant or rigid. Scaling is not an option for nonlinear general beam sections (SECTYPE,,GENB).

Beam188 允许改变横截面惯性属性来实现轴向伸长的功能。默认的，截面面积改变而使得单元的体积变形后不变化。这种默认的值对于弹塑性应用是适用的。通过运用KEYOPT（2）选项,你可以选择横截面是恒定的或者刚性的。Scaling命令不适用于一般的非线性梁截面。

Element output is available at element integration stations and at section integration points.

单元的输出在单元积分位置和截面的积分点可以使用。

Integration stations (Gauss points) along the length of the beam are shown in Figure 188.3: \.

沿着梁长度的积分点（高斯点）如图Figure 188.3所示：

Figure 188.3 BEAM188 Element Integration Stations

图188.3：Beam188单元积分点

The section strains and forces (including bending moments) may be obtained at these integration stations. The element supports output options to extrapolate such quantities to the nodes of the element.

截面的应变和力（包括弯距）可以在这些积分点上得到。单元支持输出选项来外推这些数值到单元的节点。

BEAM188 can be associated with either of these cross section types:

Beam188可以设置各种截面形式：

? ? ?

Generalized beam cross sections (SECTYPE,,GENB), where the relationships of generalized stresses to generalized strains are input directly.

可直接输入材料广义应力应变关系生成广义梁截面(SECTYPE,,GENB)。

Standard library section types or user meshes which define the geometry of the beam cross section (SECTYPE,,BEAM). The material of the beam is defined either as an element attribute (MAT), or as part of section buildup (for multi-material cross sections).

可生成既有的或者用户指定的截面形式(SECTYPE,,BEAM)，梁元材料可以由MAT命令生成，也可以由多种材料的截面形式组成。

?

Generalized Beam Cross Sections 广义的梁横截面

When using nonlinear general beam sections, neither the geometric properties nor the material is explicitly specified. Generalized stress implies the axial force, bending moments, torque, and transverse shear forces. Similarly, generalized strain implies the axial strain, bending curvatures, twisting curvature, and transverse shear strains. (For more information, see Using Nonlinear General Beam Sections.) This is an

abstract method for representing cross section behavior; therefore, input often consists of experimental data or the results of other analyses.

当使用非线性梁截面时，几何特征和材料属性均明确指定。广义应力包括轴力，弯矩，扭矩以及横向切应力。同样，广义应变包括轴向应变，弯曲应变，扭转应变以及横向剪切应变（更多信息详见Using Nonlinear General Beam Sections.）这是一个抽象方法反映截面的行为，因此输入的数据常常由试验或者其他分析构成。

The BEAM188 elements, in general, support an elastic relationship between

transverse shear forces and transverse shear strains. You can override default values of transverse shear stiffnesses via the SECCONTROLS command.

Beam188一般支持横向切应力和横向切应变之间的弹性关系，可通过SECCONTROLS 命令改写默认的应力应变关系。

When the beam element is associated with a generalized beam (SECTYPE,,GENB) cross section type, the relationship of transverse shear force to the transverse shear strain can be nonlinear elastic or plastic, an especially useful capability when flexible spot welds are modeled. In such a case, the SECCONTROLS command does not apply.

当梁单元采用广义梁截面时，横向切应力和横向切应变之间的关系为非弹性或者塑性，会生成一个可用的屈服点。这种情况下，SECCONTROLS命令不再适用。

Standard Library Sections 标准截面形式：

BEAM188 are provided with section-relevant quantities (area of integration, position, Poisson function, function derivatives, etc.) automatically at a number of section points using SECTYPE and SECDATA. Each section is assumed to be an assembly of a predetermined number of 9-node cells. The following graphic illustrates models using the rectangular section subtype and the channel section subtype. Each cross-section cell has 4 integration points and each may be associated with an independent material type.

Beam188提供了截面相关参数（面积，位置，分布函数，导数等等）可以通过SECTYPE and SECDATA命令使用于定义截面。每个截面假定由预定的9个节点单位组成。下图列举了通过矩形子项和通道子项建立模型，每个截面单元有4个积分点，每个积分点可设置独立的材料属性。

Figure 188.4 Cross-Section Cells 图188.4：Beam188截面单元格

BEAM188 provide options for output at the section integration points and/or section nodes. You can request output only on the exterior boundary of the cross-section. (PRSSOL prints the section nodal and section integration point results. Stresses and strains are printed at section nodes, and plastic strains, plastic work, and creep strains are printed at section integration points.)

Beam188提供在积分点和界面节点输出的选项。你可以要求仅在截面的外表面输出。（PRSSOL 打印截面节点和截面积分点结果。应力和应变在截面的截面打印，塑性应变，塑性作用，蠕变应力在截面的积分点输出）。

When the material associated with the elements has inelastic behavior or when the temperature varies across the section, constitutive calculations are performed at the section integration points. For more common elastic applications, the element uses precalculated properties of the section at the element integration points. However, the stresses and strains are calculated in the output pass at the section integration points.

当与单元相关的材料有非弹性的行为或者当截面的温度有变化，基本计算在截面的积分点上运行。对于更多的常见的弹性的运用，单元运用预先计算好的单元积分点上的截面属性。无论如何，应力和应变通过截面的积分点输出来计算。

If the section is assigned the subtype ASEC, only the generalized stresses and strains (axial force, bending moments, transverse shears, curvatures, and shear strains) are

available for output. 3-D contour plots and deformed shapes are not available. The ASEC subtype can be displayed only as a thin rectangle to verify beam orientation.

如果截面指定为ASEC 子项，仅仅广义的应力和应变（轴力、弯距、横向剪切、弯曲、剪应力）能够输出。3－D 轮廓线和变形形状不能输出。ASEC 子项仅仅可以作为薄矩形来认定梁的方向。

BEAM188 allow for the analysis of built-up beams, (i.e., those fabricated of two or more pieces of material joined together to form a single, solid beam). The pieces are assumed to be perfectly bonded together. Therefore, the beam behaves as a single member.

Beam188 能够对组合梁进行分析，（例如，那些由两种或者两个以上材料复合而成的简单的实体梁）。这些组件被假设为完全固接在一起的。因此，该梁表现为单一的构件。

The multi-material cross-section capability is applicable only where the assumptions of a beam behavior (Timoshenko or Bernoulli-Euler beam theory) holds.

多材料截面能力仅仅在梁的行为假定（铁木辛哥或者伯努力欧拉梁理论）成立的时候能运用。

In other words, what is supported is a simple extension of a conventional Timoshenko beam theory. It may be used in applications such as:

换言之，支持简单的传统铁木辛哥梁理论的扩展。可应用于以下方面：

? ? ? ? ? ?

bimetallic strips 双层金属带

beams with metallic reinforcement 带金属加固的梁

sensors where layers of a different material has been deposited 位于不同材料组成的层上的传感器

BEAM188 do not account for coupling of bending and twisting at the section stiffness level. The transverse shears are also treated in an uncoupled manner. This may have a significant effect on layered composite and sandwich beams if the layup is unbalanced.

Beam188不会计算在截面刚度水平上的弯距和扭距的耦合。横向的剪切也作为一个独立的量来计算。这对于分层的组合物和夹层量可能会有很大的影响，如果接头处不平衡。

BEAM188 do not use higher order theories to account for variation in distribution of shear stresses. Use ANSYS solid elements if such effects must be considered.

Beam188没有用高阶理论来计算剪切应力的变化，如果这些作用必须考虑的话，就需要运用ANSYS 实体单元。

Always validate the application of BEAM188 for particular applications, either with experiments or other numerical analysis. Use the restrained warping option with built-up sections after due verification.

要使beam188用于特殊的应用，做试验或者其他的数值分析，合适验证后使用组合截面的约束扭曲的选项。

For the mass matrix and evaluation of consistent load vectors, a higher order

integration rule than that used for stiffness matrix is employed. The elements support both consistent and lumped mass matrices. Use LUMPM,ON to activate lumped mass matrix. Consistent mass matrix is used by default. An added mass per unit length may be input with the ADDMAS section controls. See \Summary\.

对于质量矩阵和一致荷载向量的赋值，将使用到比刚度矩阵使用的规则更高阶的积分规则。单元支持一致质量矩阵和集中质量矩阵。用LUMPM，ON 命令来激活集中质量矩阵。一致质量矩阵是默认使用的。每单位长度的附加质量将用ADDMAS 截面控制来输入，详见\。

Forces are applied at the nodes (which also define the element x-axis). If the

centroidal axis is not colinear with the element x-axis, applied axial forces will cause bending. Applied shear forces will cause torsional strains and moment if the centroid and shear center of the cross-section are different. The nodes should therefore be located at the desired points where you want to apply the forces. Use the OFFSETY and OFFSETZ arguments of the SECOFFSET command appropriately. By default, ANSYS uses the centroid as the reference axis for the beam elements.

在节点（这些截面定义了单元的x 轴）上施加力，如果重心轴和单元的x 轴不是共线的，施加的轴力将产生弯距。如果质心和剪切中心不是重合的，施加的剪切力将导致扭转应力和弯曲。因而需要在那些你需要施加力的位置设置节点，可以使用secoffset 命令中的offsety 和offsetz 自变量。默认的，ansys 会使用梁单元的质心作为参考轴。

Element loads are described in Node and Element Loads. Pressures may be input as surface loads on the element faces as shown by the circled numbers on Figure 188.1: \. Positive normal pressures act into the element. Lateral pressures are input as force per unit length. End \

单元荷载在Node and Element Loads 被描述。压力可能被作为单元表面力被输入，就像图188.1中带圈的数字所示。正的压力指向单元内部。水平压力作为单元长度的力来输入。端部的压力作为力输入。

When KEYOPT(3) = 0 (default), BEAM188 is based on linear polynomials, unlike other Hermitian polynomial-based elements (for example, BEAM4). Refinement of the mesh is recommended in general.

当keyopt（3）＝0 的时候（默认），beam188 基于线性多项式，和其他的基于厄密多项式的单元（例如beam4）不同，一般来说要求网格划分要细化。

When KEYOPT(3) = 2, ANSYS adds an internal node in the interpolation scheme, effectively making this a Timoshenko beam element based on quadratic shape functions. This option is highly recommended unless this element is used as a stiffener and you must maintain compatibility with a first order shell element.

Linearly varying bending moments are represented exactly. The quadratic option is similar to BEAM189, with the following differences:

当keyopt（3）＝2，ansys 增加了一个中间积分点在内插值图标，有效的使得单元成为基于二次型功能的铁木辛哥梁。强烈推荐此选项除非这个单元作为刚体使用，而且必须维持和一阶shell 单元的兼容性。可精确的表现弯距线性变化。二次选项和beam189 相似，有如下的不同：

The initial geometry is always a straight line with BEAM188 with or without the quadratic option.

? 不论是否使用二次选项，beam188 单元最初始的几何总是直线。

? You cannot access the internal node; and thus boundary conditions/loading cannot be specified on those nodes.

? 你不能读取中间节点，所以边界条件/荷载不能在那些节点被指定。

?

Offsets in specification of distributed loads are not allowed. Non-nodal concentrated forces are not supported. Use the quadratic option (KEYOPT(3) = 2) when the element is associated with tapered cross-sections.

均布荷载是不允许指定偏移的。不支持非节点的集中力。当单元和契型截面相关应使用二次选项（keyopt （3）＝2）。

Temperatures may be input as element body loads at three locations at each end node of the beam. At each end, the element temperatures are input at the element x-axis (T(0,0)), at one unit from the x-axis in the element y-direction (T(1,0)), and at one unit from the x-axis in the element z-direction (T(0,1)). The first coordinate temperature T(0,0) defaults to TUNIF. If all temperatures after the first are

unspecified, they default to the first. If all temperatures at node I are input, and all temperatures at node J are unspecified, the node J temperatures default to the corresponding node I temperatures. For any other input pattern, unspecified temperatures default to TUNIF.

温度可以作为单元的体力在梁的每个端部节点的三个位置输入，单元的温度在单元的x 轴被输入（T（0，0）,和在离开x 轴一个单元长度的y 轴（T（1，0））， 和在离开x 轴一个单元长度的z 方向（T（0，1））。第一坐标温度T（0，0） 默认是TUNIF。如果所有的温度在第一次以后是没有被指定，那么它们默认的就为第一次输入的温度。如果所有i 节点的温度均输入了，j 节点的都没有指明，那么j 节点的温度默认的是等于i 节点的温度。对于其他的输入模式，没有指明的温度默认的是TUNIF。

You can apply an initial stress state to this element through the ISTRESS or ISFILE command. For more information, see Initial Stress Loading in the ANSYS Basic Analysis Guide. Alternately, you can set KEYOPT(10) = 1 to read initial stresses from the user subroutine USTRESS. For details on user subroutines, see the Guide to ANSYS User Programmable Features.

你可以对该单元通过istress 和isfile 命令来定义初始应力状态。要获取更多的信息，可以参考ANSYS Basic Analysis Guide的Initial Stress Loading。可以替换的，你可以设置keyopt（10）＝1 来从用户的子程序ustress 来读取出初始应力。关于用户子程序的详细资料，参见ANSYS User Programmable Features 的指南。

The effects of pressure load stiffness are automatically included for this element. If an unsymmetric matrix is needed for pressure load stiffness effects, use NROPT,UNSYM.

应力刚化作用在单元中没有自动计算，如果对应力刚化作用需要非对称矩阵，使用nropt，unsym。 A summary of the element input is given in \.

\给出了单元的输入总结。

BEAM188 Input Summary BEAM188 输入数据摘要

Nodes 节点

I, J, K (K, the orientation node, is optional but recommended)

K，方向点，可选择但是推荐主动输入

Degrees of Freedom 自由度

UX, UY, UZ, ROTX, ROTY, ROTZ if KEYOPT(1) = 0 UX, UY, UZ, ROTX, ROTY, ROTZ, WARP if KEYOPT(1) = 1 Section Controls 截面控制

TXZ, TXY, ADDMAS (See SECCONTROLS) (TXZ and TXY default to A*GXZ and A*GXY, respectively, where A = cross-sectional area) Material Properties 材料属性

EX, (PRXY or NUXY), ALPX, DENS, GXY, GYZ, GXZ, DAMP Surface Loads 表面力

Pressure -- 压力

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)

(用负数表示作用方向相反)

I and J denote the end nodes.

I 和j 是端节点

Body Loads 体力

Temperatures -- 温度

T(0,0), T(1,0), T(0,1) at each end node 温度坐标在每个节点端部 Special Features 特殊特征

Plasticity塑性

Viscoelasticity粘弹性 Viscoplasticity粘弹性 Creep蠕变

Stress stiffening应力刚化 Large deflection大挠曲 Large strain大应变

Initial stress import初始应力导入

Birth and death (requires KEYOPT(11) = 1)单元生死，需要KEYOPT(11) = 1 Automatic selection of element technology自动选择单元技术

Supports the following types of data tables associated with the TB command: 支持下列用TB 命令相关的数据表种类

BISO, MISO, NLISO, BKIN, MKIN, KINH, CHABOCHE, HILL, RATE, CREEP, PRONY, SHIFT, PLASTIC, and USER.

Generalized cross section (nonlinear elastic, elasto-plastic,

temperature-dependent)广义横截面（非线性弹性，弹塑性，温度决定）

Note

See the ANSYS, Inc. Theory Reference for details of the material models.

对于材料模型细节可以参见ANSYS, Inc. Theory Reference

See Automatic Selection of Element Technologies and ETCONTROL for more information on selection of element technologies.

对于更多的关许单元技术选择的信息可以参见Automatic Selection of Element Technologies 和ETCONTROL

KEYOPT(1)

Warping degree of freedom:扭转自由度 0 --

Default; six DOF, unrestrained warping默认6个自由度，不限制扭转 1 --

Seven DOF (including warping). Bimoment and bicurvature are output.

7 个自由度（包括扭转）， 输出双力矩和双曲线

KEYOPT(2)

Cross-section scaling, applies only if NLGEOM,ON has been invoked:

截面缩放比例，当大变形开关打开的时候被调用。

0 --

Default; cross-section is scaled as a function of axial stretch

默认；截面因为轴线拉伸效应被缩放；

1 --

Section is assumed to be rigid (classical beam theory)

截面被认为是刚性的（经典梁理论）

KEYOPT(3)

Interpolation scheme:插值数据 0 --

Default; linear polynomial. Mesh refinement is recommended.

默认；线性多项式。要求划分细致。

2 --

Quadratic shape functions (effectively a Timoshenko beam element); uses an internal node (inaccessible to users) to enhance element accuracy, allowing exact representation of linearly varying bending moments

瞬态分析的命令。要观察模态分析和特征值屈曲分析的3－D 模态形状，必须用激活单元结果扩展模态（MXPAND 命令Elcalc＝YES 的选项）

Linearized Stress

线性应力

It is customary in beam design to employ components of axial stress that contribute to axial loads and bending in each direction separately. Therefore, BEAM188 provides a linearized stress output as part of its SMISC output record, as indicated in the following definitions:

对于梁设计很常规的轴力由轴向荷载和在各个端点的弯曲独立提供。因此，beam188 提供线性的应力输出作为它的SMISC 输出命令的一部分，由下面的定义来指示：

SDIR is the stress component due to axial load.

SDIR 是轴力引起的应力分量。

SDIR = FX/A, where FX is the axial load (SMISC quantities 1 and 14) and A is the area of the cross section.

SDIR＝FX/A，FX 是轴力（SMISC 的数值为1 和14），A 表示截面面积。

SBYT and SBYB are bending stress components.

SBYT 和SBYB 是弯曲应力分量。

SBYT = -MZ * ymax / Izz SBYB = -MZ * ymin / Izz SBZT = MY * zmax / Iyy SBZB = MY * zmin / Iyy

where MY, MZ are bending moments (SMISC quantities 2,15,3,16). Coordinates ymax, ymin, zmax, and zmin are the maximum and minimum y, z coordinates in the cross

section measured from the centroid. Values Iyy and Izz are moments of inertia of the cross section. Except for the ASEC type of beam cross section, ANSYS uses the maximum and minimum cross section dimensions. For the ASEC type of cross section, the maximum and minimum in each of Y and Z direction is assumed to be +0.5 to -0.5, respectively.

这里MY、MZ 是弯距（SMISC 数值是2、15、3、16）。坐标ymax, ymin, zmax, 和 zmin 是y 和z 坐标的最大和最小值。Iyy 和Izz 是截面惯性距。对于ASEC 梁截面，ANSYS 用最大和最小截面尺度，对于ASEC 种类的截面，最大最小的Y 和Z 方向直接分别假定在+0.5 到-0.5。

Corresponding definitions for the component strains are:

单元应力的相应定义

EPELDIR = EX EPELBYT = -KZ * ymax EPELBYB = -KZ * ymin EPELBZT = KY * zmax EPELBZB = KY * zmin

where EX, KY, and KZ are generalized strains and curvatures (SMISC quantities 7,8,9, 20,21 and 22).

这里EX、KY 和KZ 是总应力和曲率（SMISC 数值是7,8,9, 20,21 和22）

The reported stresses are strictly valid only for elastic behavior of members.

BEAM188 always employs combined stresses in order to support nonlinear material behavior. When the elements are associated with nonlinear materials, the component stresses may at best be regarded as linearized approximations and should be interpreted with caution.

输出的应力仅仅对于单元的弹性行为有效。Beam188 总是组合应力来支持非线性材料的行为。当单元和非线性材料相关的时候，组合应力最好作为线性近似来对待，应该谨慎的说明。

The Element Output Definitions table uses the following notation:

单元运用以下符号输出定义表格：

A colon (:) in the Name column indicates the item can be accessed by the Component Name method [ETABLE, ESOL]. The O column indicates the availability of the items in the file Jobname.OUT. The R column indicates the availability of the items in the results file.

name 列表示该项目可以通过构成名字的方法来获得[ETABLE, ESOL]。第O 列表示该项有效的说明在文件Jobname.OUT 中。R 列表示该项的结果显示在results 文件中。

In either the O or R columns, Y indicates that the item is always available, a number refers to a table footnote that describes when the item is conditionally available, and a - indicates that the item is not available.

无论在0 还是R 列中，Y 表示该项一直是可用的。数值表示描述哪里该项是选择性提供的脚注，－表示该项不提供。

Table 188.1 BEAM188 Element Output Definitions 表 188.1 BEAM188单元输出定义

Name EL NODES MAT C.G.:X, Y, Z AREA SF:Y, Z SE:Y, Z Element number Element connectivity Material number Center of gravity Area of cross-section Section shear forces Section shear strains Definition O R Y Y Y Y Y Y Y Y 1Y 1Y 1Y S:XX, XZ, XY Section point stresses E:XX, XZ, XY Section point strains MX KX KY, KZ EX FX MY, MZ BM BK SDIR SBYT SBYB SBZT SBZB EPELDIR EPELBYT EPELBYB EPELBZT EPELBZB TEMP Torsional moment Torsional strain Curvature Axial strain Axial force Bending moments Bimoment Bicurvature Axial direct stress Bending stress on the element +Y side of the beam Bending stress on the element -Y side of the beam Bending stress on the element +Z side of the beam Bending stress on the element -Z side of the beam Axial strain at the end Bending strain on the element +Y side of the beam. Bending strain on the element -Y side of the beam. Bending strain on the element +Z side of the beam. Bending strain on the element -Zside of the beam. Temperatures T0, T1(1,0), T2(0,1) 2Y 2Y Y Y Y Y Y Y Y Y Y Y Y Y 3333- 1- 1- 1- 1- 1- 1- 1- 1- 1- 1- 1Name Definition O R Note More output is described via the PRSSOL command in /POST1. 1. See KEYOPT(6) description.参照KEYOPT(6)功能说明。

2. See KEYOPT(7), KEYOPT(8), KEYOPT(9) descriptions. 参照KEYOPT(7)、

KEYOPT(8)、KEYOPT(9)功能说明。

3. See KEYOPT(1) description. 参照KEYOPT(1)功能说明。

Table 188.2: \ lists output available through ETABLE using the Sequence Number method. See Creating an Element Table in the ANSYS Basic Analysis Guide and The Item and Sequence Number Table in this

manual for more information. Table 188.2: \ uses the following notation:

表188.2: \列出了通过etable 命令用序列号方法提供的输出。参见ANSYS Basic Analysis Guide 中的Creating an Element Table 和The Item and Sequence Number Table 来获取更多的信息。

Name

output quantity as defined in the Table 188.1: \Definitions\

在表 188.1: \中定义的输出量

Item

predetermined Item label for ETABLE

etable 提前定义的项目标签

I,J

sequence number for data at nodes I and J

在i 和j 节点数据的序列号

Table 188.2 BEAM188 Item and Sequence Numbers 表188.2 BEAM188 结果输出项与节点编号 Output Quantity Name FX MY MZ MX SFZ SFY EX KY KZ KX SEZ SEY Area BM BK SDIR SBYT SBYB SBZT SBZB EPELDIR EPELBYT EPELBYB EPELBZT EPELBZB ETABLE and ESOL Command Input Item SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC SMISC 31 32 33 34 35 41 42 43 44 45 1 2 3 4 5 6 7 8 9 10 11 12 13 27 28 30 36 37 38 39 40 46 47 48 49 50 I 14 15 16 17 18 19 20 21 22 23 24 25 26 29 J

Output Quantity Name TEMP ETABLE and ESOL Command Input Item SMISC 51-53 I 54-56 J

Transverse Shear Stress Output 横向剪切应力的输出

BEAM188 formulation is based on three stress components:

Beam188 基于三应力成分的表述。

one axial单轴

? two shear stress components双向剪切组合

?

The shear stresses are caused by torsional and transverse loads. BEAM188 are based on first order shear deformation theory, also popularly known as Timoshenko Beam theory. The transverse shear strain is constant for the cross section, and hence the shear energy is based on a transverse shear force. This shear force is redistributed by predetermined shear stress distribution coefficients across the beam cross-section, and made available for output purposes. By default, ANSYS will only output the shear stresses caused by torsional loading. KEYOPT(4) of BEAM188 may be used to activate output of shear stresses caused by flexure or transverse loading.

剪切应力是由扭转和横向荷载引起。Beam188 基于一阶剪切变形理论，和众所周知的铁木辛哥梁理论。横向剪切应变对于截面是常数，因此剪切能量基于横向剪应力。建立通过提前确定的梁横截面剪应力分布系数重新分布，可以用于输出。默认的，ansys 将仅仅输出扭转荷载导致的剪应力，keyopt（4） 用来激活由屈曲和横向荷载引起的剪切应力的输出。

The accuracy of transverse shear distribution is directly proportional to the mesh density of cross-section modeling (for determination of warping, shear center and other section geometric properties). The traction free state at the edges of cross-section, is met only in a well-refined model of the cross-section.

横向剪应力的分布的精度和截面模型的单元划分精度直接成比例关系（为了定义翘曲、剪切重心和其他截面几何属性）。截面边缘的牵引自由状态仅仅在截面定义合适的模型适用。

By default, ANSYS uses a mesh density (for cross-section model) that provides accurate results for torsional rigidity, warping rigidity, inertia properties, and shear

center determination. The default mesh employed is also appropriate for nonlinear material calculations. However, more refined cross-section models may be necessary if the shear stress distribution due to transverse loads must be captured very accurately. Note that increasing cross-section mesh size, does not imply larger computational cost if the associated material is linear. SECTYPE and SECDATA command descriptions allow specification of cross-section mesh density.

默认的，ansys 运用划分网格的密度（对于截面模型）， 这个密度提供扭转刚化、翘曲刚化和惯性属性、剪切中心定义的精确结果。默认的网格划分运用对于非线性材料的计算也是合适的。然而，如果由横向力引起的剪应力分布如果要十分精确的表示的话需要更多的截面模型的定义。注意：增加截面网格划分的尺寸，并不是导致更大的计算量，如果相关的材料是线性的话。Sectype 和secdata 命令描述允许定义截面网格划分的密度。

The transverse shear distribution calculation neglects the effects of Poisson's ratio. The Poisson's ratio affects the shear correction factor and shear stress distribution slightly.

横向剪应力分布计算忽略了泊松比的效应。泊松比对剪切修正因子和剪切应力分布有轻微的影响。

BEAM188 Assumptions and Restrictions Beam188 的假定和约束：

? ? ? ? ?

The beam must not have zero length.

梁长度不能为0 。

By default (KEYOPT(1) = 0), the effect of warping restraint is assumed to be negligible.

默认的（keyopt（1）＝0）翘曲约束效应假定为忽略的。

Cross-section failure or folding is not accounted for. ? 截面失效和折叠不计算。

? Rotational degrees of freedom are not included in the lumped mass matrix if offsets are present.

? ?

转动自由度在集中质量矩阵时不计算，如果存在偏移的话。

It is a common practice in civil engineering to model the frame members of a typical multi-storied structure using a single element for each member.

Because of cubic interpolation of lateral displacement, BEAM4 and BEAM44 are well-suited for such an approach. However, if BEAM188 is used in that type of application, be sure to use several elements for each frame member. BEAM188 includes the effects of transverse shear.

对于土木工程建立框架模型和典型多层结构模型而言每个构件运用单一单元是常见的。由于横向位移的三次插值，beam4 和beam44 对于这样一种方法更合适。然而，如果beam188 用于这样的分析，确定对于每个构件运用几种单元。Beam188 包括

?

横向剪力的效应。

?

This element works best with the full Newton-Raphson solution scheme (that is, the default choice in solution control). For nonlinear problems that are dominated by large rotations, we recommend that you do not use PRED,ON. 单元采用全牛顿－拉夫森方法计算最好（那是默认的计算控制选项）。对于非线性问题，算法由大转动决定，我们推荐不要使用pred，on命令。 ? ?

Note that only moderately \\Input Data\ for more information. ? 注意仅仅可以分析适当厚度的梁。参考\来获取更多信息。 ? When a cross-section has multiple materials and you issue the /ESHAPE command (which displays elements with shapes determined from the real constants or section definition) to produce contour plots of stresses (and other quantities), the element averages the stresses across material boundaries. To limit this behavior, use small cross-section cells around the material boundaries. There are no input options to bypass this behavior.

?

当一种截面有复合材料的时候，/eshape 用来提取应力等值线（和其他数值）， 单元通过材料边缘显示平均应力。为了限制这样的行为，在材料周围运用小截面元。没有输入选项来通过这样的行为。

? ? ?

For this element, the /ESHAPE command supports visualization of stresses, but not of plastic strains.

BEAM188 可以通过使用/ESHAPE命令显示应力，但是不能显示塑性应变。

Stress stiffening is always included in geometrically nonlinear analyses (NLGEOM,ON). It is ignored in geometrically linear analyses

(NLGEOM,OFF) when specified by SSTIF,ON. Prestress effects can be activated by the PSTRES command.

应力刚化在几何非线性分析中（NLGEOM，ON） 适用。当用SSTIF,ON时，在几何线性分析中是忽略的(NLGEOM,OFF)。预应力可以通过pstres 命令激活。

? ?

When the element is associated with nonlinear general beam sections

(SECTYPE,,GENB), additional restrictions apply. For more information, see Considerations for Employing Nonlinear General Beam Sections.

当单元用于一般非线性梁截面时，会有其他一些限制。更多信息参考Considerations for Employing Nonlinear General Beam Sections。

?

BEAM188 Product Restrictions Beam188 产品的限制

When used in the product(s) listed below, the stated product-specific restrictions apply to this element in addition to the general assumptions and restrictions given in the previous section.

当beam188被使用的时候，除了以上章节所做出的产品说明外，还有以下限制。

ANSYS Professional.

The only special features allowed are stress stiffening and large deflections. ? 仅仅应力强化和大变形是被允许的特殊特征。

?

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