Workshop Thirteen
Plasticity Postprocessing
Socket Connector (part 2)
REFERENCE:
Training Manual
Basic Plasticity (6-76)
13. Plasticity Postprocessing
Socket Connector (part 2)
Workshop Supplement
• Demonstrate common post processing features used for
plasticity analyses
Goal
• Post process a previously completed plasticity analysis
utilizing various results contours and graphs
Model Description
• 2D socket connector
• Applied displacement
STRAIN
STRESS
0.000625
10,000
0.0025
15,000
0.005
21,000
0.010
29,000
0.015
32,600
0.020
34,700
0.040
36,250
0.100
39,000
• Multilinear stress-strain curve
0.025 inches applied
displacement
Basic Structural Nonlinearities 6.0
Purpose
E = 16E6 PSI
Poisson’s ratio = 0.33
October 15, 2001
Inventory # 001566
W13-2
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
1.
Start an ANSYS Interactive session in the working directory specified by the instructor
using “connector2” as the jobname
2.
Resume the CONNECTOR (part 2) database
–
Utility Menu > File > Resume from
•
–
Select “connector.db2”
• [OK]
OR enter the following command:
RESUME, connector, db2
3.
Enter the General Postprocessor
and Specify the results file
–
Main Menu > General Postproc > Data & File Opts
•
–
Select “connector.rst2”
• [OK]
OR enter the following commands:
/POST1
FILE, connector, rst2
NOTE: The connector.db2 database contains the
completed geometry, material, boundary condition,
and loading definitions for this finite element model.
Basic Structural Nonlinearities 6.0
STEPS TO FOLLOW:
NOTE: The connector.rst2 file contains
the results from a successful completion
of workshop 12.
October 15, 2001
Inventory # 001566
W13-3
13. Plasticity Postprocessing
…Socket Connector (part 2)
Read the results set for the last substep of loadstep #2
–
–
Main Menu > General Postproc > By Load Step
•
Load step number = 2
•
Substep number = LAST
• [OK]
OR enter the following command:
SET, 2, LAST
5.
Plot the equivalent elastic strain
–
–
Main Menu > General Postproc > Plot Results
> Nodal Solu
•
Strain-elastic
•
von Mises EPELEQV
•
Def + undef edge
Or enter the following commands:
PLNSOL, EPEL, EQV, 2
NOTE: In Release 6.0, it is no longer
necessary to specify an effective Poisson’s
Ratio via the AVPRIN command.
ANSYS automatically calculates equivalent
elastic strain using the value specified by the
user with MP,PRXY,1,
In this example, n = 0.33.
Basic Structural Nonlinearities 6.0
4.
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-4
13. Plasticity Postprocessing
…Socket Connector (part 2)
Plot the equivalent plastic strain
–
–
Main Menu > General Postproc > Plot Results > Nodal Solu
•
Strain-plastic
•
von Mises EPPLEQV
•
Def shape only
• [OK]
OR enter the following commands:
PLNSOL, EPPL, EQV
NOTE: As with equivalent elastic strain, in
Release 6.0, it is no longer necessary to
specify an effective Poisson’s Ratio via the
AVPRIN command.
ANSYS will automatically calculate
equivalent plastic strain using n= 0.50
Basic Structural Nonlinearities 6.0
6.
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-5
13. Plasticity Postprocessing
…Socket Connector (part 2)
Plot the accumulated equivalent plastic strain
–
–
Main Menu > General Postproc > Plot Results > Nodal Solu
•
Strain-plastic
•
Eqv plastic EPEQ
• [OK]
OR enter the following command:
PLNSOL, NL, EPEQ
Basic Structural Nonlinearities 6.0
7.
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-6
13. Plasticity Postprocessing
…Socket Connector (part 2)
Plot the von Mises stress
–
–
Main Menu > General Postproc > Plot Results > Nodal Solu
•
Stress
•
von Mises SEQV
• [OK]
OR enter the following command:
PLNSOL, S, EQV
Basic Structural Nonlinearities 6.0
8.
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-7
13. Plasticity Postprocessing
…Socket Connector (part 2)
Plot the hydrostatic pressure stress
–
–
Main Menu > General Postproc > Plot Results > Element Solu
•
Stress
•
HydrostPres HPRE
• [OK]
OR enter the following command:
PLESOL, NL, HPRES
NOTE: A “checkerboard” pattern of the
hydrostatic pressure stress (HPRES) values
would have indicated volumetric locking.
Basic Structural Nonlinearities 6.0
9.
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-8
13. Plasticity Postprocessing
…Socket Connector (part 2)
–
–
Main Menu > General Postproc > Plot Results > Nodal Solu
•
Stress
•
StressRatio SRAT
• [OK]
OR enter the following command:
PLNSOL, NL, SRAT
11. Read the last results set
–
–
Main Menu > General Postproc > Last Set
OR enter the following command:
SET, LAST
NOTE: If the stress ratio (SRAT) value is
greater than or equal to 1 then the node is
currently undergoing active plastic straining.
Basic Structural Nonlinearities 6.0
10. Plot the stress ratio
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-9
13. Plasticity Postprocessing
…Socket Connector (part 2)
–
–
Main Menu > General Postproc > Plot Results > Nodal Solu
•
DOF solution
•
UY
•
Def + undef edge
• [OK]
OR enter the following command:
PLNSOL, U, Y, 2
NOTE: This plot represents the residual
vertical displacements after “spring-back”.
Basic Structural Nonlinearities 6.0
12. Plot the vertical displacement
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-10
13. Plasticity Postprocessing
…Socket Connector (part 2)
–
–
Main Menu > General Postproc > Plot Results > Nodal Solu
•
Stress
•
von Mises SEQV
•
Def + undef edge
• [OK]
OR enter the following command:
PLNSOL, S, EQV, 2
NOTE: This plot represents the residual
von Mises stresses after “spring-back”.
Basic Structural Nonlinearities 6.0
13. Plot the von Mises stress
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-11
13. Plasticity Postprocessing
…Socket Connector (part 2)
–
Main Menu > TimeHist Postpro > Variable Viewer…
•Open Results
•Select “connector.rst2”
•[OK]
–OR enter the following command:
/POST26
FILE,'connector','rst2'
Basic Structural Nonlinearities 6.0
14. Enter Time/History Postprocessor to plot results data
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-12
13. Plasticity Postprocessing
…Socket Connector (part 2)
–
Add the Y component of Displacement and assign it the variable name “DISPLACEMENT”
–
–
[OK]
OR enter the following command:
NSOL, 2, 1, U, Y, DISP
Basic Structural Nonlinearities 6.0
15. Define deflection as a variable
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-13
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
•
Select node #1 on the screen or enter node “1” in the input window
•
[OK]
Pick node number 1
Basic Structural Nonlinearities 6.0
16. Define the Deflection Variable
October 15, 2001
Inventory # 001566
W13-14
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
•
Add the Y- component of force at node #1 associated with element 548 and accept the
default variable name FY_3
•
Total Force
•
[OK]
Basic Structural Nonlinearities 6.0
17. Define Nodal Force Variable
October 15, 2001
Inventory # 001566
W13-15
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
–
•
Select element number 548
•
[OK]
•
Pick node number 1
• [OK]
OR enter the following command:
ESOL, 3, 548, 1, F, Y
Pick node
number 1
Pick element
number 548
Basic Structural Nonlinearities 6.0
18. Define a nodal force variable
October 15, 2001
Inventory # 001566
W13-16
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
–
•
Add the Y component of force for node #1 associated with element 549 (using same
procedure as FY_3) and accept the default variable name FY_4
•
Select Element 549
•
[OK]
•
Pick node number 1
• [OK]
OR enter the following command:
ESOL, 4, 549, 1, F, Y
Pick element
number 549
Basic Structural Nonlinearities 6.0
19. Define a nodal force variable
October 15, 2001
Inventory # 001566
W13-17
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
•Use the variable viewer calculator to sum up FY_3 and FY_4, to obtain the total FY force
at node #1.
•Assign this expression the variable name “FORCE” (= FY_3 + FY_4)
•[ENTER]
–OR enter the following command:
ADD, 5, 3, 4, , FORCE, , , 1, 1
Variable viewer
calculator input
window
Retrieve variables from
pull down window
Basic Structural Nonlinearities 6.0
20. Define a nodal force variable
October 15, 2001
Inventory # 001566
W13-18
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
–
OR enter the following command:
XVAR, 2
PLVAR, 5
3. Select
the graph
button
2. Highlight
the FORCE
variable
1. Specify
the DISPL
variable for
the X-axis
Basic Structural Nonlinearities 6.0
21. Graph the force vs deflection curve using the variable viewer
October 15, 2001
Inventory # 001566
W13-19
13. Plasticity Postprocessing
…Socket Connector (part 2)
Basic Structural Nonlinearities 6.0
…TO OBTAIN …
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-20
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
NOTE: The graph shows a stiffness change during the
unloading phase.
Is this realistic?
What could have caused this behavior?
HINT: When does the kinematic hardening model become
inappropriate due to the Bauschinger effect?
EXTRA CREDIT GRAPH SETTINGS
Basic Structural Nonlinearities 6.0
For EXTRA CREDIT, try modifying the graph
settings to improve the quality of the graph.
October 15, 2001
Inventory # 001566
W13-21
13. Plasticity Postprocessing
…Socket Connector (part 2)
•
[Add]
•
Element Solution
•
Stress
•
Von Mises Stress
•
Variable Name = STRESS
•
[OK]
Basic Structural Nonlinearities 6.0
22. Define the von Mises stress variable
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-22
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
–
•
Pick element number 1
•
[OK]
•
Pick node number 30
• [OK]
OR enter the following command:
ESOL, 6, 1, 30, S, EQV, STRESS
Pick node
number 30
Pick element
number 1
Basic Structural Nonlinearities 6.0
23. Define the von Mises stress variable
October 15, 2001
Inventory # 001566
W13-23
13. Plasticity Postprocessing
…Socket Connector (part 2)
•
[Add]
•
Element Solution
•
Plastic Strain
•
Equivalent Plastic Strain
•
Variable Name = EPEQ
•
[OK]
Basic Structural Nonlinearities 6.0
24. Define the accumulated equivalent plastic strain variable
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-24
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
–
•
Pick element number 1
•
[OK]
•
Pick node number 30
• [OK]
OR enter the following command:
ESOL, 7, 1, 30, NL, EPEQ
Pick node
number 30
Pick element
number 1
Basic Structural Nonlinearities 6.0
25. Define the accumulated equivalent plastic strain variable
October 15, 2001
Inventory # 001566
W13-25
13. Plasticity Postprocessing
…Socket Connector (part 2)
•
Enter expression in calculator
– STRAIN = {STRESS}/16E6+{EPEQ}
–
[OK]
OR enter the following command:
ADD, 8, 6, 7, , STRAIN, , , 1/16E6, 1
STRESS
STRAIN
SEQV
 tot  E  EPEQ
MODULUS
Basic Structural Nonlinearities 6.0
26. Calculate the equivalent total strain using the variable viewer calculator
Workshop Supplement
EQUIVALENT PLASTIC
STRAIN
October 15, 2001
Inventory # 001566
W13-26
13. Plasticity Postprocessing
…Socket Connector (part 2)
NOTE: Equivalent total strain calculation is
only valid for proportional, monotonic loading.
Basic Structural Nonlinearities 6.0
27. Graph the stress vs. strain curve
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-27
13. Plasticity Postprocessing
…Socket Connector (part 2)
–
–
Main Menu > TimeHist Postpro > Settings > Graph
•
Minimum time = 1
•
Maximum time = 2
• [OK]
OR enter the following command:
PLTIME, 1, 2
27. Plot the modified stress vs. strain graph
–
–
Utility Menu > Plot > Replot
OR enter the following command:
/REPLOT
Basic Structural Nonlinearities 6.0
26. Specify time range for stress-strain graph
Workshop Supplement
October 15, 2001
Inventory # 001566
W13-28
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
Basic Structural Nonlinearities 6.0
28. Compare the results to the input stress-strain curve:
For EXTRA CREDIT, try modifying the graph
settings to improve the quality of the graph.
EXTRA CREDIT GRAPH SETTINGS
October 15, 2001
Inventory # 001566
W13-29
13. Plasticity Postprocessing
…Socket Connector (part 2)
Workshop Supplement
Basic Structural Nonlinearities 6.0
October 15, 2001
Inventory # 001566
W13-30