Phase 1: Reference Design Synthesis (Freesize Optimization)
In this phase the optimization setup is defined in the concept design phase to identify the stiffest design for the given fraction of the material.
In freesize optimization, the thickness of each designable element is defined as a design variable. Applying this concept to the design of composites implies that the design variables are the thickness of each 'Superply' (total designable thickness of a ply orientation) per element.
 Objective
 Minimize the compliance of the load case.
 Constraints
 Volume fraction < 0.3
 Design Variables
 Element thicknesses of each ply orientation.
 Manufacturing Constraints
 Ply percentage for the 0s no more than 80% exist.
Set Up the Optimization
Create Freesize Optimization Design Variables
Create Optimization Responses
 From the Analysis page, click optimization.
 Click Responses.

Create the volume fraction response.
 In the responses= field, enter Volfrac.
 Below response type, select volumefrac.
 Set regional selection to total and no regionid.
 Click create.

Create the compliance response.
 In the response= field, enter compliance.
 Below response type, select compliance.
 Set regional selection to total and no regionid.
 Click create.
 Click return to go back to the Optimization panel.
Create Design Constraints
 Click the dconstraints panel.
 In the constraint= field, enter volfrac.
 Click response = and select volfrac.
 Check the box next to upper bound, then enter 0.3.
 Click create.
 Click return to go back to the Optimization panel.
Define the Objective Function
 Click the objective panel.
 Verify that min is selected.
 Click response= and select compliance.
 Using the loadsteps selector, select nx_step.
 Click create.
 Click return twice to exit the Optimization panel.
Create Output Requests
Save the Database
 From the menu bar, click .
 In the Save As dialog, enter oht_opti_ph1.hm for the file name and save it to your working directory.
Run the Optimization
 oht_opti_ph1.out
 OptiStruct output file containing specific information on the file setup, the setup of the optimization problem, estimates for the amount of RAM and disk space required for the run, information for all optimization iterations, and compute time information. Review this file for warnings and errors that are flagged from processing the oht_opti_ph1.fem file.
 oht_opti_ph1_des.h3d
 HyperView binary results file that contain optimization results.
 oht_opti_ph1_s#.h3d
 HyperView binary results file that contains from linear static analysis, and so on.
 oht_opti_ph1_sizing.*.fem
 A plybased sizing optimization input file generated during freesizing phase. This resulting deck contains PCOMPP, STACK, PLY, and SET cards describing the plybased composite model, as well as DCOMP, DESVAR, and DVPREL cards defining the optimization data. The * sign represents the final iteration number.
 oht_opti_ph1_sizing.*.inc
 An ASCII include file contains the same plybased modeling and optimization data as in the input deck. The * sign represents the final iteration number.
View the Results
View the Element Thickness Results
View the Ply Thickness Results
View the Ply Bundles
Apply Ply Smoothing using OSSmooth
 From the Post page, click the OSSmooth panel.
 In the Select model field, select oht_opti_ph1_sizing.35.fem.
 Change the mode from Geometry to PLY Shape.
 In the output file field, select the original location with the name of oht_opti_ph1_sizing.35.smoothed.fem.
 In the smooth iterations field, enter 20.
 Under small region, clear the split disconnected and create geometry checkboxes.
 In the area ratio field, enter 0.010.
 Click OSSmooth to run the analysis to smooth the model.