Interface Arguments (interface_args.json)

This file stores all configurations and arguments that will be used in the interface script. All arguments can be roughly divided to three groups: general, cross-sectional analysis and post-processing.

General

To control the screen output of preVABS and VABS, use the keyword scrnout:

"scrnout": false,

To control the level of logging message output, use the following keywords. log_level_cmd sets the output level to the screen. log_level_file sets the output level to the log file. The level can be one of the following: debug, info, warning, error, critical, with logging level increasing from the first to the last. log_file_name sets the log file name.

"log_level_cmd": "critical",
"log_level_file": "info",
"log_file_name": "eval.log",

data_process_functions_file sets the script file name (without file extension) storing data processing functions.

"data_process_functions_file": "data_proc_funcs",

This file will be imported into the analysis script, see moduel loading in Section: Step 1: Initialization.

Cross-sectional analysis

Corresponding to the cross-sectional analysis step in the interface script (Section: Step 2: Cross-sectional analysis), some arguments need to be configured here.

First, names of pre-processing functions are given in a list after the keyword cs_pre_process. The order indicates the sequence the functions will be executed.

"cs_pre_process": [
  "materialId2Name",
  "calcEmbeddedPoint"
],

Then, some execution-related settings are provided. Use the keywords prevabs_cmd_win and prevabs_cmd_linux to set the executable name of preVABS on Windows and Linux, respectively.

"prevabs_cmd_win": "prevabs.exe",
"prevabs_cmd_linux": "prevabs",

Use the keyword solver to set the executable name of VABS.

"solver": "VABS",

The keyword analysis sets what analysis will be carried out by VABS. In this example, use h to indicate the cross-sectional analysis (homogenization).

"analysis": "h",

The keyword timeout is used to prevent the preVABS from stucking in an infinite loop and kill the process when the time is expired.

"timeout": 10,

The keyword cross-section_design_template sets the cross-section template file name corresponding to a unique cross-section name.

"cross-section_design_template": {
  "uh60a_section": "uh60a_section.xml.tmp"
},

The keyword beam_properties indicates the beam properties that will be needed for calculating objective and constraints. In this example, the properties listed in Table 11 will be needed.

"beam_properties": ["mu", "gj", "ei22", "ei33", "sc2", "mc2"],

Post-processing

The last part specifies how to calculate the interim and final outputs. Since the post-processing functions are mainly scripted by the user, the data structure of this part can be highly flexible and customizable. In other words, this part of the arguments only provides a place to conveniently make some changes for other similar optimization cases. User can also put these data in data_proc_funcs.py completely.

This tutorial only serves as an example.

The keyword is post_process and all outputs are placed in a list. Each item in the list specifies one output and how to calculate it. The inputs for each item are arranged as:

[output_label, function, arguments, type]

output_label should be the same as those in the Dakota input file if this is a ‘final’ output. function can be two types. If it is self, this means that the value of the arguments will be directly copied to output_label. Otherwise, this should be a function defined in the file data_proc_funcs.py. In this case, arguments will be passed to the function. The last entry type indicates that this output is a final or interim one.

For example, mass per unit length is a constraint and used directly. This is specified as:

["mpl", "self", "mu"]

The difference between the calculated and target torsional stiffnesses is needed to compute the overall difference (diff). The function used is called calcRelDiff and coded in the file data_proc_funcs.py. Arguments to this function are the beam property gj and the target value 24.31e6. This difference will be stored as an interim output. Hence, the above setting can be specified as:

["gj_diff", "calcRelDiff", ["gj", 24.31e6], "interim"]

Complete file

Listing 4 interface_args.json

{

  "scrnout": false,
  "log_level_cmd": "critical",
  "log_level_file": "info",
  "log_file_name": "eval.log",

  "prevabs_cmd_win": "prevabs.exe",
  "prevabs_cmd_linux": "prevabs",
  "solver": "VABS",
  "analysis": "h",
  "timeout": 10,


  "cross-section_design_template": {
    "uh60a_section": "uh60a_section.xml.tmp"
  },
  "beam_properties": ["mu", "gj", "ei22", "ei33", "sc2", "mc2"],


  "data_process_functions_file": "data_proc_funcs",

  "cs_pre_process": [
    "materialId2Name",
    "calcEmbeddedPoint"
  ],

  "post_process": [
    ["mpl", "self", "mu"],
    ["gj_diff", "calcRelDiff", ["gj", 24.31e6], "interim"],
    ["eiflap_diff", "calcRelDiff", ["ei22", 22.2e6], "interim"],
    ["eilag_diff", "calcRelDiff", ["ei33", 835e6], "interim"],
    ["sc2_le_diff", "calcRelDiff", ["sc2", -5.19], "interim"],
    ["mc2_le_diff", "calcRelDiff", ["mc2", -0.822, -5.19], "interim"],
    ["gj", "self", "gj", "interim"],
    ["eif", "self", "ei22", "interim"],
    ["eic", "self", "ei33", "interim"],
    ["sc2", "self", "sc2", "interim"],
    ["mc2", "self", "mc2", "interim"]
  ]

}