CBAR

Bulk Data Entry Defines a simple beam element (BAR) of the structural model.

Attention: Valid for Implicit and Explicit Analysis

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CBAR EID PID GA GB X1/G0 X2 X3 OFFT
PA PB W1A W2A W3A W1B W2B W3B

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CBAR 2 39 7 3 13
513

Definitions

Field Contents SI Unit Example
EID Unique element identification number.

No default (Integer > 0)
PID PBAR or PBARL property entry identification number or string.
Integer
Specifies an identification number for this property.
<String>
Specifies a user-defined string label for this property. 7

Default = EID (Integer > 0 or <String>)
GA,GB Grid point identification numbers of connection points.

No default (Integer > 0 or <PartName.number>; GA ≠ GB). 6
X1,X2,X3 Components of vector v, at end A, measured at end A, parallel to the components of the displacement coordinate system for GA, or the basic coordinate system, to determine (with the vector from end A to end B) the orientation of the element coordinate system for the BAR element. 4

No default (Real)
G0 Grid point identification number to optionally supply X1, X2, X3. Direction of orientation vector is GA to G0.

No default (Integer > 0 or <PartName.number>). 6
OFFT Character string specifying the interpretation of the offset vector specification. 5

Default = GGG (Character or blank)
PA, PB Pin flags for bar ends A and B, respectively. Used to remove connections between the grid point and selected degrees-of-freedom of the bar. The degrees-of-freedom are defined in the element's coordinate system. The bar must have stiffness associated with the PA and PB degrees-of-freedom to be released by the pin flags. For example, if PA=4 is specified, the PBAR entry must have a value for J, the torsion stiffness. 1

No default (Integer > 0; up to 5 of the unique digits 1-6 with no embedded blanks)
W1A,W2A,W3A W1B,W2B,W3B Components of offset vectors wa and wb in displacement coordinate systems at points GA and GB, respectively, or in the element coordinate system. 4

Default = blank (Real or blank)
Figure 1. Bar Element Coordinate System (for CBAR element)


Figure 2. Moments and Internal Forces in the x-y Plane (for a CBAR element)


Figure 3. Moments and Internal Forces in the x-z Plane (for a CBAR element)


Comments

  1. If there are no pin flags or offsets, the continuation may be omitted.
  2. G0 cannot be located at GA or GB.
  3. If X1/G0 is a positive integer and X2 and X3 are blank, then G0 is used to orient the element, otherwise X1, X2, X3 is used.
  4. The OFFT character string specifies how the offset and orientation vector components are computed. By default, the offset vectors are specified in the global (local displacement) coordinate system of both grid A and B, and the orientation vector is specified in the global coordinate system of grid A. With the codes below, the offset vector can be specified in the offset coordinate system and the orientation vector can be specified in the basic coordinate system. The valid character strings and their meanings are listed below.
    OFFT Orientation Vector End A Offset End B Offset
    GGG Global Global Global
    BGG Basic Global Global
    GGO Global Global Offset
    BGO Basic Global Offset
    GOG Global Offset Global
    BOG Basic Offset Global
    GOO Global Offset Offset
    BOO Basic Offset Offset
    The offset system x-axis is defined from GA to GB. The orientation vector and the offset system x-axis are then used to define the z and y axes of the offset system. A vector is formed from the cross product of a vector going from grid A to grid B and the orientation vector to create the offset coordinate z-direction.
  5. Offset vectors are treated like rigid elements. The length of the offset vectors is not affected by thermal loads.
  6. Supported local entries in specific parts can be referenced by the use of "fully-qualified references" on CBAR entries in the model. A fully-qualified reference ("PartName.number") is similar to the format of a numeric reference. "PartName" is the name of the part that contains the referenced local entry (part names are defined on the BEGIN Bulk Data Entry in the model). "number" is the identification number of a referenced local entry in the part "PartName". Refer to Parts and Instances in the User Guide for detailed information on the use of fully-qualified references.
  7. String based labels allow for easier visual identification of properties, when being referenced by the elements cards. For more details, refer to String Label Based Input File in the Bulk Data Input File.
  8. In the ASCII .force file below, the SHEAR-1 and BENDING-1 values are associated with Plane-1, while SHEAR-2 and BENDING-2 values are associated with Plane-2 in Figure 1.
    ITER     0     1
        1        1 LOAD:      2 (LOAD) Transverse_Load
   BAR #-END  AXIAL     SHEAR-1     SHEAR-2     TORQUE    BENDING-1   BENDING-2
       1-A  0.000E+00  0.000E+00  -2.5000E+02  0.000E+00  0.000E+00  -2.5000E+04
       1-B  0.000E+00  0.000E+00  -2.5000E+02  0.000E+00  0.000E+00   1.4552E-11
  9. This card is represented as a bar2 element in HyperMesh.