Combination of Shell and Beam Elements
Problem Statement:
Consider a plate welded to two beams as shown below. Determine the . . .
a. deflection of the structure b. x‐component of stress acting on the model c. y‐component of stress acting on the model d. z‐component of stress acting on the model
X
96 in
48 in
Y
X
Z
Pressure acting on the plate: 50 psi
1 in
4 in
2 in Front view
Y
ANSYS procedure:
1. Preprocessor >Element type > Add/Edit/Delete > (Add) > (Shell) > (8 node 93) > Apply > (Add) > Beam > (3 node 189)
2. Preprocessor > Real constants > Add/Edit/Delete > (Add) > Type 1 (Shell 93) > OK > Shell thickness at node I = 1 > OK
3. Preprocessor > Material properties > Material models > Structural > Linear > Elastic > Isotropic Enter EX = 29 6 and PRXY = 0.3
4. Preprocessor >Modeling > Create > Key points > In active CS
Key point X coordinate Y coordinate Z coordinate 1 0 0 0 2 48 0 0 3 48 0 96 4 0 0 96 5 0 40 48 6 48 40 48
Keypoints 5 and 6 are orientation keypoints that will be used for the BEAM189 elements.
5. PlotCtrls > PanZoomRotate > Iso 6. Preprocessor > Modeling > Create > Lines >Lines > Straight lines (Click on the key points
1,2,2,3,3,4,4,1 to create the boundary of rectangle ) 7. Preprocessor > Modeling > Create > Areas > Arbitrary > By lines > Pick the four lines, starting
with 1 and ending with 4, to make a rectangular area. The order that the lines are entered can influence the surface normal and the direction that the pressure loading acts (up or down).
8. Preprocessor > Meshing > Mesh tool > Element attributes > Areas > Set > Pick area > OK > TYPE = Shell 93 > OK
9. Preprocessor > Meshing > Mesh tool > Size cntrls > Areas > Set > Pick area > OK > SIZE = 4
10. Preprocessor > Meshing > Mesh
tool > Mesh > Areas > Free > Mesh > Pick area > OK
11. Preprocessor > Meshing > Mesh tool > Element attributes > Lines > Set > Pick line 2 (the one between keypoints 2 and 3) > OK > TYPE = Beam 189 > Orientation key points = Yes > OK > Pick key point 5 >OK
12. Preprocessor > Meshing > Mesh tool > Element attributes > Lines > Set > Pick line 4 (the one between keypoints 3 and 4) > OK > TYPE = Beam 189 > Orientation key points = Yes > OK > Pick key point 6 >OK
Line 1
Line 2
13. Preprocessor > Meshing > Mesh tool > Mesh > Lines > Mesh > Pick lines 2 and 4 > OK 14. Utility menu > Plot ctrls > Style > Size and shape > /ESHAPE = on > OK 15. Preprocessor > Sections > Beam > Common sections >
Front view
Since the SAME lines were used to define beam elements AND the area from which the shell elements were meshed, the shell and beam elements share the same degrees of freedom along the long edges of the plate. Also note that since quadratic elements (3 nodes on a side) were used for the shell and beam elements, there is no chance for unwanted gaps developing between the two element types.
16. Utility menu > Plot > Replot
Applying loads: 17. Solution > Define loads >
Apply > Structural > Displacement > On keypoints
Key point DOF 1 Ux,Uy,Uz = 0 2 Uy,Uz = 0 3 Uy = 0 4 Ux,Uy = 0
The beams are simply supported, and the plate is supported by the beams. 18. Solution > Define loads >
Apply > Structural > Pressure > On areas > Pick area > OK > VALUE =50
19. Solution > Solve > Current LS
Post processing:
20. General Postproc > Plot results > Deformed Shape > Def + Undef edge
23. General Postproc > Plot results > Contour plot > Element solution > Stress > Y‐component of stress > OK
21. General Postproc > Plot results > Contour plot > Element solution > Stress > von Mises stress > OK
22. General Postproc > Plot results > Contour plot > Element solution > Stress > X‐component of stress > OK
24. General Postproc > Plot results >
Contour plot > Element solution > Stress > Z component of stress > OK
Summary of results:
a. Maximum deflection : 2.202 in b. Maximum X‐component of stress : 111668 psi (tensile on bottom of plate) c. Maximum Y‐component of stress : ‐ 50 psi (traction on surface = applied pressure, as expected) d. Maximum Z‐component of stress : 27250 psi e. Maximum von Mises stress : 111835 psi
This tutorial was developed by David Hall and Sai Ravi Kanth Tummala © 2008