CBAR, CROD Opti.

Use this utility to setup size optimization for multiple CBAR or CROD elements.

1. Click CROD, CBAR Opti.
   You are prompted to select 1D elements for topological optimization.
2. Select elements.
3. Select PBAR or PROD.
   A new PBAR or PROD property is created for each 1D element selected. These properties are called DPROP#. A size design variable is created for each 1D element selected.
4. Input the initial value and upper and lower limits for this variable.
   The design variables are called DV#. These design variables represent the cross-sectional area of each 1D element.

   A DVPREL1 card is created linking each of the DV#’s to the cross-sectional area of each DPROP# card. These are called DX#.

   For simplicity, assume the 1D elements have solid, circular cross-sections. Two equations are created to calculate the I and J values if the PBAR property type is chosen:

   a) Equation for Ix and Iy values : Y(X1) = 0.0796*X1**2

   b) Equation for J values: Y(X1) = 0.1592*X1**2

   A DVPREL2 card is created for the I1 value of each DPROP#, referencing equation (a) and the appropriate design variable. These are named DA#.

   A 2nd DVPREL2 card is created for the I2 value of each DPROP#, referencing equation (a) and the appropriate design variable. These are named DB#.

   A 3rd DVPERL2 card is created for the J value of each DPROP#, referencing equation (b) and the appropriate design variable. These are named DC#.

   A 3rd equation is created to calculate the regional volume fraction for all DPROP# properties:

   Y(X1,Xi,....,Xn) = (X1+Xi+....+Xn)/(X1o+Xio+...+Xno)

   where Xi is the value of DVi, and where Xio is initial value of Xi.

   A function response, called BVFRAC, is generated using this equation and referencing all design variables.