Skip to main content
`Ctrl`+`K`

# Sierra/SD parameters for file transfer with Sierra/SM

# 2.2. Sierra/SD parameters for file transfer with Sierra/SM

The parameters typically needed are stress and displacement.

    BEGIN RESULTS OUTPUT from_adagio
      Database Name = stage1.e
      Database Type = Exodus
      At Step 0, Increment = 1
      nodal Variables = displacement as displ
      element Variables = stress
    END

    BEGIN RESULTS OUTPUT from_adagio
      Database Name = stage1.e
      Database Type = exodus
      At Step 0, Increment = 1
      component separator character = ""
      nodal Variables = displacement as displ
      element variables = cord_modulus as fibermod
      element variables = memb_stress as memb_stress
      element Variables = stress
      element Variables = density as fiberdensity
      element Variables = element_thickness as fiberthickness
      element variables = cord_ax as ax
      element variables = cord_ay as ay
      global Variables = timestep as timestep
    END RESULTS OUTPUT_ADAGIO

Next, we consider a typical Sierra/SD text input shown below.

    SOLUTION
     case one
       receive_sierra_data
         scale=no
         lumped
     case two
       eigen
       nmodes 10
       solver=gdsw
    END

    FILE
        geometry_file   'mesh.g'
    END

    Boundary
        sideset 21
          fixed
        sideset 22
          fixed
        sideset 11
          fixed
        sideset 20
          fixed
    end

    LOADS
    END

    OUTPUTS
        disp
    END

    ECHO
      INPUT
    END

    BLOCK 11
      QuadM
        layer 1
          material ply
          thickness = from_transfer
          fiber orientation = from_transfer
    END

    BLOCK 1
            material 2
    END

    BLOCK 2
            material 2
    END

    BLOCK 6
            material 2
    END

    BLOCK 5
            material 2
    END

    MATERIAL 2
      name "steel"
      E 30.0e6
      nu 0.0
      density 2.61e-4
    END

    MATERIAL ply
      name "ply"
      density  = from_transfer
      orthotropic_layer
      E1 = from_transfer
      E2 = from_transfer
      nu12 = from_transfer
      G12 = from_transfer
      percent_continuum 0.005
    END

    Tied Data
      surface 2 1
      search tolerance 0.2
      edge tolerance 1.0e-8
      method = inconsistent
    END

There are several sections of interest in this input deck. The syntax involved in a Sierra/SD input is documented in the Users’s Manual. Here, we assemble an example that collects the inputs in different sections, and highlight those areas that are different due to the SM coupling.

    SOLUTION
      case xfer
        receive_sierra_data
        load 1
          lumped
      case two
        eigen
        nmodes 10
        solver=gdsw
    END

    LOAD 1
    END

    BLOCK 11
      QuadM
      layer 1
      material ply
      thickness = from_transfer
      fiber orientation = from_transfer
    END

    MATERIAL ply
      name "ply"
      density  = from_transfer
      orthotropic_layer
      E1 = from_transfer
      E2 = from_transfer
      nu12 = from_transfer
      G12 = from_transfer
      percent_continuum 0.005
    END

The `solution` section contains two cases. Case `one` uses the `receive_sierra_data` solution procedure to receive the necessary data from Sierra/SM. All data transfer occurs here, including data such as stresses, displacements, and analysis time. The second case instructs Sierra/SD to compute eigenvalues of the linearization of the state received from Sierra/SM. In this case, 10 modes are requested. Also, the GDSW solver is requested in this case. This solver is usually needed in problems with large numbers of constraint equations that are generated with tied data pairs.

The `boundary` section specifies nodesets and sidesets that are to be fixed. The four edges of the plate, which are denoted by sidesets 21, 22, 11, and 20, are fixed. These boundary conditions diff from those used in the Sierra/SM analysis. The boundary conditions in the Sierra/SD modal analysis may be the same or differ from those used in the Sierra/SM analysis, depending on the goals of the analysis. Only one Boundary section is applied in the Sierra/SD input, and it applies to the entire SD analysis.

An empty `load` section is present to avoid a warning.

In this example, Block 11 is a block of membrane elements. These elements are currently setup as layered elements in Sierra/SD, even though there is only one layer. Thus, the `layer 1` specification is needed. Following this, the material name, layer thickness and fiber orientation are needed. In this case, the latter two come in as data from the Sierra transfer, and `from_transfer` is used in lieu of a numerical value. If this were an uncoupled analysis, numeric values would be used instead. The remaining four blocks are hex elements, and thus the only required input syntax is the specification of the material identifier.

For the ‘orthotropic_layer’ material many element attributes may be specified as `from_transfer`. Table 2.1 summarizes some fields that `read_sierra_data` can input using the `from_transfer` option for the ‘orthotropic_layer’ material.

Table 2.1 Orthotropic_layer Quantities Available for FROM_TRANSFER Exchange in Read_Sierra_Data.
Quantity | Descriptor
--- | ---
element attribute | Nearly any element attribute that can be stored in the Exodus file may also be exchanged using `from_transfer`.
fiber orientation | 2D fiber orientation in a layer
thickness | 2D shell layer thickness
E1 | material modulus
E2 | material modulus
nu12 | material modulus
G12 | material modulus
density | material density

Next, the two material blocks are specified. Material 2 is specified to be an isotropic elastic material, with Young’s modulus, Poisson ratio, and material density. These values can differ from those used in the Sierra/SM analysis, and in fact they typically are.

For example, if the two-stage approach is employed, then the stiffer dynamic properties of the rubber would be used here, in place of the softer properties used in the inflate-deflect analysis in Sierra/SM.

Material ‘ply’ corresponds to the membranes. Here, there are several parameters that are required to fully specify the orthotropic material properties, and density. However, all of these properties are transferred from Sierra/SM, and thus the `from_transfer` option is used in lieu of numerical values.

Next, we consider the Tied Data block. As mentioned earlier, the parameters in this section are documented in the Users’s Manual. Here, we only focus on the special considerations needed for coupled Sierra/SM-Sierra/SD analysis. In particular, the search tolerance parameter is used by Sierra/SD to determine which nodes are in contact. We recommend using a very small search tolerance in Sierra/SD, since at the end of the Sierra/SM analysis the surfaces will already be in close contact.

Finally, although the previous example did not involve pressure forces, we note that when pressure loads are used in the Sierra/SM preload analysis, a follower stiffness term needs to be activated in Sierra/SD. For example, if a pressure of \(0.2\) was applied to sideset 1 in the Sierra/SM input deck, then the following block would be needed in the Sierra/SD input deck

    LOAD 1
      sideset 1
        pressure = 0.2
        follower = y
    END

Although no error will be reported if this block is left out, the results may be inaccurate.