workshop 4 minimizing the weight of a composite...
TRANSCRIPT
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 1
WORKSHOP 4
Minimizing the Weight of a Composite Wing
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 2
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 3
• Workshop Objective
– Become familiar with the steps to set up a composite optimization analysis
• Software Version
– Patran 2011
– MD Nastran 2011.1
• Required File:
– composite_wing_opt.db
• Problem Description:
– Preliminary stress analysis from workshop 1 showed the margins of safety are
high for the 8-ply carbon/epoxy quasi-isotropic layup
– Determine optimal ply thicknesses to minimize weight while maintaining a
positive strength margin of safety
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 4
b
c
a
Step 1. Open an existing Patran Database
Start Patran and open a database
containing a wing model:
a. Click File Open in the Defaults
group.
b. Select
composite_wing_opt.db as
the File name.
c. Click OK.
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 5
Step 2. Create Design Variables
Create design variables for the
thicknesses of the carbon-epoxy plies:
a.Pull down Tools > Design Study >
Pre-Process.
b.Select Design Variable for Object.
c.Select Material for Type.
d.Select Composite, Thickness, and
Local Ply for Category.
e.Click the Select Material Set(s) icon.
f.Click and hold down on bs1 and drag
down to select all 17 properties.
g.Click the Select Material Property
icon.
h.Click and hold down on 1 and drag
down to select all 4 plies.
i.Enter 0.005 for Lower bound and 0.25
for Upper bound.
j.Click Apply.
This step creates 68 ply thickness
variables.
a
f
e
d
c
b
g
i
j
h
0.0054
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 6
Step 3. Create the Design Objective
Create a Design Objective to minimize
the overall weight.
a.Select Objective for Object.
b.Select Global for Solution.
c.Select Weight for Response.
d.Enter mass for Objective Name.
e.Select minimize for MinMax.
f.Click Apply.
a
b
f
e
d
c
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 7
Step 4. Create Constraints on Composite Failure
Create constraints on composite
failure index:
a.Select Constraint for Object.
b.Select Linear Static for Solution.
c.Select Composite Failure for
Response .
d.Enter FI_Ply1 for Constraint Name.
e.Select PSET.
f.Click the Select Property Set(s)
icon.
g.Click Select All.
h.Click Apply.
i.Select Ply for Index.
j.Enter 1 for Ply Number.
k.Enter 1.0 for Upper Bound.
l.Click Apply.
Repeat steps d, j, k, l for Constraint
Names FI_Ply2 thru FI_Ply8. Enter
2 thru 8 for Ply Number, respectively.
a
b
g
f e
d
c
h
i
j
k
l
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 8
Step 5. Create Design Study Create a design study consisting of all the design
variables, responses, and constraints.
a.Select Design Study for Object.
b.Enter wing_ply_thickness for Design Study
Name.
c.Click Select Design Variables.
d.Review the design variables and click Cancel.
e.Click Select Objectives.
f.Select mass.
g.Click Select Constraints.
h.Click Select All.
i.Click Apply.
j.Click Apply.
k.Click Close.
f
g
c
b
a
e
g
h
i j k d
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 9
Step 6. Set up Optimization Analysis
Set up the optimization analysis:
a.Click the Analysis tab.
b.Set Action to Optimize.
c.Enter comp_wing_thickness_opt
for Job Name.
d.Click Design Study Select.
e.Select wing_ply_thickness.
f.Click Global Obj./Constr. Select.
g.Select mass.
h.Click OK
b
c
d
e
g
a
f
h
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 10
Step 6. Set up Optimization Analysis (Cont.)
Set up the optimization analysis (cont.):
a.Click Optimization Parameters.
b.Enter 20 for Standard Cycles
(DESMAX).
c.Click OK.
c
b
a
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 11
Step 6. Set up Optimization Analysis (Cont.)
Set up the optimization analysis (cont.):
a.Click Subcases…
b.Select wing up bending.
c.Click Constraints/Objective...
d.Select all 8 constraints.
e.Click OK.
f.Click Apply.
g.Click Yes to the prompt to create a
new subcase.
h.Click Cancel.
c
b
a
d
e
f
g
h
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 12
Step 6. Set up Optimization Analysis (Cont.)
Set up the optimization analysis (cont.):
a.Click Subcase Select…
b.Select wing up bending.
c.Click OK.
d.Click Apply to run the analysis.
You’ve just submitted the Nastran
optimization analysis. It will take about
a minute to run the analysis.
a
b
c
d
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 13
Step 7. Access Results
Access analysis results:
a.Select Access Results for Action.
b.Select Read Output2 for Object.
c.Click Select Results File.
d.Select
comp_wing_thickness_opt.op2
e.Click OK.
f.Click Apply.
d
c
b
e
a
f
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 14
Step 8. Plot Displacements and Failure Index
Create a deformed shape and
failure indices plot of the initial
design:
a. Click the Results tab.
b. Select the first result case to
view the results of the initial
design.
c. Under Select Fringe Result,
select Failure Indices,
Maximum Indices.
d. Under Select Deformation
Result, select Displacements,
Translational.
e. Click Apply.
a
e
b
c
d
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 15
Step 8. Plot Displacements and Failure Index
Plot failure indices for the final
design:
a. Select the last result case to
view the results of the final
design.
b. Click Apply.
a
b
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 16
Step 9. View Optimization History Plots
View Design Variable History to
review the ply thickness
optimizaton history:
a. Click Post in XY Plots group.
b. Select Design Variable History
under Post/Unpost XY
Windows.
c. Click Apply.
a
c
b
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 17
Step 9. View Optimization History Plots (cont.)
View Maximum Constraint History
to review the failure index
constraint optimization history:
a. Select
MaximumConstraintHistory
under Post/Unpost XY
Windows.
b. Click Apply.
a
b
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 18
Step 9. View Optimization History Plots
View Objective Function History to
review the wing total weight
optimization history:
a. Select
ObjectiveFunctionHistory
under Post/Unpost XY
Windows.
b. Click Apply.
a
b
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 19
Analysis Summary
• The total weight of the wing has been reduced substantially.
• Possible next steps:
– Add ply orientation angle variables to optimize the fiber orientations.
– A balanced layup is often desirable. Use DLINK entries to link the +45
and -45 ply thickness variables to enforce equal thickness.
– Create discrete values for ply thicknesses using the DDVAL entry to
make the final optimized thickness results possible to manufacture.
– Account for local panel buckling by adding buckling constraints
Composites Technology Day, February 2012
Copyright 2012 MSC.Software Corporation WS4 - 20
End of Workshop 4
File/Quit to exit Patran.