Computational systems for special structural...

VSB – TECHNICAL UNIVERSITY OF OSTRAVA

FACULTY OF CIVIL ENGINEERING

Computational systems for specialstructural problemsMaterial for practice: ANSYS

Petr Konečný, Jiří Brožovský

Office: LP H407/3Phone: 597 321 384

E-mail: petr.konecny@vsb.czhttp://www.fast.vsb.cz/konecny

Credit conditions

• sufficient presence

• preparation of project

• presentation and defence of prepared project

2

Outline of class

• progressive procedures when using software (automation

of work, user macros etc.)

• nonlinear tasks: plasticity, large deformations, contact pro-

blems

• other special tasks

3

ANSYS system (1)

• commercial general multi purpose finite element system (no

codes etc.)

• software and documentation in English

• large number of finite element types for various tasks

• the mesh and its type may be directly controlled

• contact tasks

• static, dynamic, heat conduction,...

• linear and nonlinear tasks

• own command language (allows for macros preparation, sup-

portive codes)

4

ANSYS system (2)

• help: help,něco (note.: in instalation at FAST is something not

working)

• use comma decimal separator

• dialog window invokes commands

• commands: n„5.3,6.3,7.7 (parameter delimiter is comma. . . )

• empty fields will be filled with zero (if parameter is real number)

or closest empty value (if parameter is index or ordinal number)

• parametrs of commands as well as input fields in dialogues

accepts mathematic expressions (FORTRAN language): 5 ∗

∗2 = 25 or 1+ 3 ∗ 2/3 = 3 etc.

5

ANSYS system (3)

Recommended finite element types:Task Type Numberplannar truss LINK1 13D truss LINK8 8plannar frame BEAM3 33D frame BEAM4 3, 188, 189planar problem PLANE42 42, 182slab SHELL63,. . . 63, 93, 181slab on Winkler’s subsoil SHELL63 63volumes SOLID45,. . . 45, 95, 185volumes from concrete SOLID65,. . . 65

For the parameters of elements, allowable analysis types and

results type: help,number6

Commands ANSYS 1:selected objects

Object Letter Examplekey point k k„1,1,2 kdel,p klistline l l,1,2 l,p ldel,allarea a a,1,2,3,4 a,p adel,pvolume v v,p vdel,all vlistnode n n„0,0,7.7 nlist ndel,allelement e e,1,7 e,p edel,allnode support d d,p dlist ddel,pnodal force f f,p flist fdel,p

7

Commands ANSYS 2:selected operations

Operation Abreviation Examplescreation k„1,1,2 l,1,2 a,1,2,3,4creation with mouse ,p l,p a,p v,p e,p d,pdeletion del ldel,3 ldel,p ldel,alllisting list alist nlist elistplotting plot aplot nplot eplot gplot

8

Commands ANSYS 3:selected operations

Operation Commandpreprocessor initiation /prep7solver initiation /solusolution solvepostprocessor initiation /post1saving of project saveresuming project resu

9

Commands ANSYS 4:selected operationsSaving and reading a data in the form of command file database

– might demand larger disk space however, it is better transferable

between ANSYS versions.

Operation Commandsaving of data cdwrite,DB,soubor,cdbreading of data cdread,DB,soubor,cdb

Where „file“ is the name of the file and „cdb“ is its extension (např.

mymodel.cdb)10

Example 1: Planar truss (1)

10kN 10kN

5 kN

2m

3m

2m 2m

Properties: E = 20 GPa,A = 0.01 m2.

11

Example 1: Planar truss (2)

Properties: E = 20 GPa,A = 0.01 m2. We will assign 1 type

of finite element, 1 type of material and 1 set of real constants:

• Preprocessor initiation: /prep7

• Element selection (LINK1): et,1,LINK1

• Youngus modulus assignment E = 20 GPa: mp,EX,1,20e9

• Cross-sectional area assignment A = 0.01 m2: r,1,0.01

Notes: material properties use stadndardized identifiers (EX, EY, EZ. . . for moduli of elasti-

city, PRXY. . . coefficient of lateral contraction, DENS. . . density), sequence and meaning of real

constants are specific for specific element type (see help).

12

Example 1: Planar truss (3)

Numbering of nodes (red) and elements (blue):

10kN 10kN

5 kN

2m

3m

2m 2m

5 6

21 431

2 3

4

5

6

7

8

9

13

Example 1: Planar truss (4)

Modeling of nodes:

10kN 10kN

5 kN

2m

3m

2m 2m

5 6

21 431

2 3

4

5

6

7

8

9

n„0,0

n„2,0

n„4,0

n„6,0

n„2,3

n„4,3

14

Example 1: Planar truss (5)

Modeling of elements:

10kN 10kN

5 kN

2m

3m

2m 2m

5 6

21 431

2 3

4

5

6

7

8

9

Easygoing: e,p and clicking the nodes.

e,1,2

e,1,5

e,2,5

e,2,3

e,2,6

e,5,6

e,3,6

e,3,4

e,4,6

15

Example 1: Planar truss (6)

Modeling of supports:

10kN 10kN

5 kN

2m

3m

2m 2m

5 6

21 431

2 3

4

5

6

7

8

9

Easygoing: d,p and clicking the nodes.

d,1,ux

d,1,uy

d,4,uy

16

Example 1: Planar truss (7)

Modeling of loading:

10kN 10kN

5 kN

2m

3m

2m 2m

5 6

21 431

2 3

4

5

6

7

8

9

Easygoing: f,p and clicking the nodes.

f,5,fy,-10e3

f,6,fy,-10e3

f,6,fx,-5e3

17

Example 1: Planar truss (8)

18

Example 1: Planar truss (9)

Solution:

• Preprocessor exit: fini

• Solver initiation: /solu

• Solution: solve

19

Example 1: Planar truss (10)

Postprocessing results:

• Solution exit: fini

• Postprocessor initiation: /post1

• Total deformation plot: plns,u,sum,1Note to plns:

• 1 et the end means „draw nondeformed elements“; value 2 would means „draw onlyoutline of the structure“.

• instead of sum (total deformation) might be specified direction (x, y, z) – selectioninfluences the colors and values, not the shape of deformation.

20

Example 1: Planar truss (11)

21

Example 1: Planar truss (12)

Internal forces using Element Table:

• Parameter definition NX: etable,nx,smisc,1

• Plotting NX by elements: plls,NX,NX

• Total deformation plotting : plns,u,sum,1

22

Example 1: Planar truss (13)

23

Example 1: Planar truss (14)

List of results:

• Reactions: prrs

• Deformations: prns,ux

• Internal forces list: pretab,NX

24

Commands: how to invoke, whereto find• File name.mac in working folder of ANSYS.

• It can be called by name and the commands contained in the

file will be executed.

• Command history: jobname.log in ANSYS working folder.

• Warning: circa from version 9 cannot be this file used directly

(<CTRL>C, <Ctrl>V), it needs to be modified (there is P51X

instead of list of selected elements etc.).

25