Using ANSYS Simple Truss Problem Truss1
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Transcript of Using ANSYS Simple Truss Problem Truss1
Using ANSYS Simple truss problem Truss1
http://mae.uta.edu/~lawrence/ansys/trussfreq/trussfreq.htm[02/08/2014 17:53:54]
Using ANSYS - Natural Frequencies of a Simple Truss
Objective: To prepare a text file defining the ANSYS FEM model for the elementary truss problem shown below and use ANSYS to solve for natural frequencies and modes.
1. Prepare a text file containing the following information. The 1000 lbf load is not needed.
/FILNAM,truss/title, Simple Truss
/prep7
n, 1, 25.0, 0.0, 0.0 ! Node 1 is located at (25.0, 0.0, 0.0)n, 2, 0.0, 18.0, 0.0n, 3, 0.0, 0.0, 0.0
et, 1, link1 ! Element type; no.1 is link1
!Beginning with ANSYS Release 13 link1 has been replaced with link180
mp, ex, 1, 3.e7 ! Material Properties, E for material no. 1 mp, prxy, 1, 0.3 ! poisson's ratio for material no.1mp, dens, 1, 0.736e-3 ! mass density for material no. 1
r, 1, 0.5 ! 'Real Constant' number 1 is 0.5
! (Cross sectional area)en, 1, 3, 1 ! Element Number 1 connects nodes 1& 2
en, 2, 2, 1
d, 3, ux, 0. ! Displacement at node 3 in x-dir is zerod, 3, uy, 0. ! Displacement at node 3 in y-dir is zerod, 2, ux, 0.d, 2, uy, 0.
2. Start ANSYS and select 'Run Interactive' Select the Working Directory
3. Select File > Read Input From (locate and select the file truss.txt that you prepared)
4. Solution > Analysis Type > New Analysis > Modal > OK
5. Analysis Options > Block Lanczos No. of Modes to Extract 2 Expand mode shapes yes NMODE No. modes to expand 2
Using ANSYS Simple truss problem Truss1
http://mae.uta.edu/~lawrence/ansys/trussfreq/trussfreq.htm[02/08/2014 17:53:54]
OK
FREQB 0 FREQE 0
Normalize mode shapes To mass matrix
OK
6. Solve > Current LS > OK
7. General Postprocessor > Results Summary (Shows frequencies calculated.)
8. Read Results > First Set
9. Plot Results > Deformed Shape > Def. + Undef.
The first mode of vibration is shown in the figure below.
(Use PlotCtrls > CaptureImage to print or save your plots. Can also use Animate to visualize motion.)
To list the nodal deformation values for the mode use
Using ANSYS Simple truss problem Truss1
http://mae.uta.edu/~lawrence/ansys/trussfreq/trussfreq.htm[02/08/2014 17:53:54]
List Results > Nodal Solution > DOF solution > All DOFs DOF
10. For the next mode: Read Results > Next Set
11. Plot Results > Deformed Shape > Def. + Undef. etc.
Last update 5-2-03
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