KnowledgeBase

The following script increases the helix angle of a cylindrical gear by 1° in each step, runs a system calculation including gear mesh excitation, and outputs the maximum transmission error to the Scripting Monitor.

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Running the script in the FVA-Workbench

1var gearUnitID = 1;
2var stageID = getCompByType("cylindrical_mesh")[0];
3var gearID = getCompByType("cylindrical_gear")[0];

4setAttr("gta_switch_deactivate_all_calculations", gearUnitID, true, EDAT);
5setAttr("gta_switch_3d_load_distribution_analytical", gearUnitID, true, EDAT);
6setAttr("gta_switch_3d_force_excitation", gearUnitID, true, EDAT);

7for(angle = 0; angle <= 20; angle++){
8    setAttr("helix angle reference diameter", gearID, angle, EDAT);
9    runCalcMethod("001_SYSTEM_CALCULATION", gearUnitID);
10    var trans_error_max = getAttr("result_transmission_error_maximum", stageID, RDAT);
11    println("Transmission Error at "+angle+"°: "+trans_error_max+" µm");
     }

The following script reads the height, width coordinates and the modification matrix from an Excel file and writes these values into the corresponding attributes of a modification component in the FVA-Workbench model. The Excel script functions getValuesRow(), getValueColumn() and getValuesMatrix() are used to write the arrays and matrix from the Excel file to script variables.

let excelfile = "C:\\folder\\modification_matrix.xlsx";
let workbook = workbookFactory.createWorkbook(excelfile);

let modificationID = 1399;
let width_coords = workbook.getValuesRow("B1", 5);
let height_coords = workbook.getValuesColumn("A2", 6);
let mod_matrix = workbook.getValuesMatrix("B2", 6, 5);

println(width_coords);
println(height_coords);
println(mod_matrix);

setAttr("sekor_matrixk_enabled", modificationID, true, EDAT);
setAttr("width_coordinates", modificationID, width_coords, EDAT);
setAttr("height_coordinates", modificationID, height_coords, EDAT);
setAttr("modification_matrix", modificationID, mod_matrix, EDAT);

The following script determines the optimum amount for a helix angle modification so that the face load factor KH_Beta is minimized.

In the FVA-Workbench, modifications are separate components that can be added. Multiple types of modifications (e.g., width and depth crowning) can be activated and configured for the modification component. In this case, the helix angle modification is activated. There is a checkbox for "consider helix angle modification" under the modification component in the FVA-Workbench. To activate this switch via scripting, the attribute "sekor_CHB_enabled" must be set to true.

Furthermore, the attribute "form of helix angle modification" is set to "at beginning of the face width (smaller u-coordinate)." To make this selection via scripting, the attribute "sekor_hcb_form" is set to the value "3."

For more information on "setting attribute values" see Data types

In order to run, this script requires a model that contains at least one cylindrical gear stage with a modification component added to at least one of the gears.

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Part 1: Determine the direction of the modification

In the first step, the direction of the modification must be determined. Since "beginning of the face width" is selected as the form of the helix angle modification, the direction of the modification refers to Point A in the figure. In this case, the modification direction is left, and material will be removed from the left side. If the modification direction is right, material will be removed from the right side (Point B). If the direction is right, a positive value is specified for the modification. Correspondingly, if the modification direction is left, a negative value is specified.

Example of modification with material being removed from the left side, e.g., +15µm starting from Point A, the beginning of the face width.

So that the following script can be used on any model, the component IDs are not specified as variables, but rather queried from the user while the script is running using the prompt() function.

The direction of the modification is determined as follows:

1. Calculation of KH_Beta without modification

2. Calculation of KH_Beta with a modification amount of +1µm

3. Calculation of KH_Beta with a modification amount of -1µm

4. If the value of KH_Beta with +1µm is greater than with -1µm the modification direction is right, otherwise it is left

1var stageID = prompt("Enter Cylindrical Stage ID");
2var gearID = prompt("Enter Cylindrical Gear ID");
3var modificationID = getSubComponents(gearID, "gear_correction")[0];
4var gearUnitID = 1;

5setAttr("sekor_CHB_enabled", modificationID, true, EDAT);
6setAttr("sekor_hcb_form", modificationID, "3", EDAT);

7setAttr("sekor_chb_bet", modificationID, 0, EDAT);
8runCalcMethod("001_SYSTEM_CALCULATION", gearUnitID);
9var khBetaNoMod = getAttr("gta_result_face_load_factor_flank", stageID, RDAT);
10println("KH_Beta unkorrigiert: " + khBetaNoMod);

11setAttr("sekor_chb_bet", modificationID, 1, EDAT);
12runCalcMethod("001_SYSTEM_CALCULATION", gearUnitID);
13var khBetaPosMod = getAttr("gta_result_face_load_factor_flank", stageID, RDAT);

14setAttr("sekor_chb_bet", modificationID, -1, EDAT);
15runCalcMethod("001_SYSTEM_CALCULATION", gearUnitID);
16khBetaNegMod = getAttr("gta_result_face_load_factor_flank", stageID, RDAT);

17if (khBetaPosMod > khBetaNegMod){
18    var direction = "right";
19}else {var direction = "left";} //kleine u-Koordinate

20println("Direction of modification: "+direction);

1	Writes the user-provided stage ID to the stageID variable.
2	Writes the user-provided gear ID to the gearID variable.
3	getSubComponents() queries all modification components on a cylindrical gear. [0] is used to write the ID of only the first modification to modificationID.
4	Assigns the ID of the gear unit to the gearUnitID variable.
5	Sets the attribute "consider helix angle modification" for the modification component to true.
6	Sets the value for the "form of helix angle modification" attribute to "3."
7	Sets the input value (EDAT) of the "amount of helix angle modification" attribute to 0 (µm).
8	Runs a system calculation.
9	Writes the result value (RDAT) of the "calculated flank face load factor" attribute of the cylindrical gear stage to khBetaNoMod.
10	Outputs the value for KHBeta (unmodified) to the Scripting Monitor.
11	Sets the input value (EDAT) of the "amount of helix angle modification" attribute to 1 (µm).
12	Runs a system calculation.
13	Writes the result value (RDAT) of the "calculated flank face load factor" attribute of the cylindrical gear stage to khBetaPosMod.
14	Sets the input value (EDAT) of the "amount of helix angle modification" attribute to -1 (µm).
15	Runs a system calculation
16	Writes the result value (RDAT) of the "calculated flank face load factor" attribute of the cylindrical stage to khBetaNegMod.
17	If khBetaPosMod is less than khBetaNegMod:
18	Assigns the string "right" to the direction variable.
19	Otherwise, assigns the string "left" to the direction variable.
20	Outputs the modification direction to the Scripting Monitor.

Part 2: Iterative determination of the optimum correction amount

One result of the system calculation is a 2D proposed modification for uniform load distribution. The modification amounts for multiple supporting points across the face width are saved in an array attribute (correction_proposal_system_calculation). The goal of the optimization in this script is that the difference between the first (1) and last (2) points in the array should be less than 1.

The procedure is as follows:

1. The current modification value is saved to a variable.

2. The difference between the first and last points of the array is determined.

3. The difference is added or subtracted from the current modification amount, depending on the direction of the modification

4. A system calculation is performed with the new modification value.

5. The difference is determined once again. If the difference is less than 1, the script is terminated.

The proposed modification calculation result can be queried via the attribute correction_proposal_system_calculation.

1do {
2   runCalcMethod("001_SYSTEM_CALCULATION", gearUnitID);
3   var helixAngleModAmount = getAttr("sekor_chb_bet", modificationID, RDAT);
4   var correctionProposal = getAttr("correction_proposal_system_calculation", stageID, RDAT);

5   var delta = correctionProposal[0] - correctionProposal[correctionProposal.length-1];
6   if (direction == "left"){
7       var newHelixAngleModAmount = helixAngleModAmount + delta;
8   }else{  newHelixAngleModAmount = helixAngleModAmount - delta;}

9   setAttr("sekor_chb_bet", modificationID, newHelixAngleModAmount, EDAT);
10   println("Modification Amount: "+newHelixAngleModAmount+" mym"+" -> delta: "+ delta);
11}while(delta < 1);

12runCalcMethod("001_SYSTEM_CALCULATION", gearUnitID);
13var finalKhBeta = getAttr("gta_result_face_load_factor_flank", stageID, RDAT);
14println("Final KH_Beta: "+finalKhBeta);

1	Starts the do-while loop.
2	Starts a system calculation.
3	Writes the result value (RDAT) of the "helix angle modification amount" attribute to the helixAngleModAmount variable.
4	Writes the result value of the "proposed modification from system calculation" array attribute to the correctionProposal variable.
5	Subtracts the last value in the correctionProposal array from the first value and writes it to the delta variable.
6	If the modification direction is left:
7	Adds the difference to the helixAngleModAmount variable and writes the value to newHelixAngleModAmount.
8	Otherwise: subtracts the difference from the helixAngleModAmount variable and writes the value to newHelixAngleModAmount.
9	Sets the input value (EDAT) of the "amount of helix angle modification" attribute to newHelixAngleModAmount.
10	Outputs the new modification amount + difference to the Scripting Monitor.
11	Repeats the do-while loop until the difference is less than 1.
12	Performs a system calculation with the final modification amount after the loop is completed.
13	Outputs the final KHBeta value to the Scripting Monitor.

The following script creates a text file that includes the formatted name, symbol, value, and unit for multiple attributes. The format() function is used for the formatting. The writeToFile()function is used to output to the file.

Output file of the script

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1function formatAttr(attributeID, compID, DAT) { 
2   let name = getAttrProperty(attributeID, compID , 'NAME');
3   let symbol = getAttrProperty(attributeID, compID , 'SYMBOL');
4   let value = getAttr(attributeID, compID, DAT)+0.0;
5   let unit = getAttrProperty(attributeID, compID , 'UNIT_NAME'); 
    
6   let format_name   = format("%-35s", name);
7   let format_symbol = format("%-10s",  symbol);
8   let format_value;
9   let valueType = typeof value;
  
10  if(valueType == "number" && value %1 == 0){
11	 valueType = "int";
       }
12  switch (valueType) {
13     case "number": format_value = format("%-12.3f", value); break;
14     case "int":    format_value = format("%-12.0f", value); break; 
15     case "string": format_value = format("%-12s", value); break;
16     default:       format_value = format("%-12s", "Error"); break;
       }
17  let format_unit = format("%-3s", unit);
18  let resultstring = format_name + format_symbol + format_value + format_unit +"\n";
19  return resultstring;
}

1let filepath = "C:\\geometry.txt";
2let stageID = 3;
3let gearID = 8;

4writeToFile(filepath, "---------------------- Geometry ---------------------------\n", "c", "UTF-8");
5writeToFile(filepath, formatAttr("normal module", gearID, EDAT), "a", "UTF-8");
6writeToFile(filepath, formatAttr("face width", gearID), "a", "UTF-8", EDAT);
7writeToFile(filepath, formatAttr("center_distance_editor", stageID, RDAT), "a", "UTF-8");
8writeToFile(filepath, formatAttr("helix angle reference diameter", gearID, EDAT), "a", "UTF-8");
9writeToFile(filepath, formatAttr("addendum modification coefficient", gearID, EDAT), "a", "UTF-8");
10writeToFile(filepath, formatAttr("minimum_tip_clearance_factor", gearID, EDAT), "a", "UTF-8");

The following script queries the maximum tooth root stress for each individual mesh in a planetary stage and outputs the results in a tree structure on the Scripting Monitor.

Only two cylindrical gear stages are shown in the FVA-Workbench model tree for the planetary gear shown above: the planet-ring gear and planet-sun meshes. These 2 parent stages include all of the input data, it is not necessary to show all 6 gear meshes. However, the calculation results may differ for each of the individual gear meshes (1-6 in the figure above). Therefore, each of the 2 parent stages has 3 instance components for the individual stages. Access to the result attributes of these instance components is shown in the following script.

Output of the script on the Scripting Monitor.

let planetaryStageID = 9;
let stageIDs = getSubComponents(planetaryStageID, "general_stage");

for (let i = 0; i < stageIDs.length; i++){
    let stageInstanceIDs = getSubComponents(stageIDs[i], "planet_instance");
    let gearsInStageIDs =  getSubComponents(stageIDs[i], "general_gear");
	println(getCompProperty(stageIDs[i], "NAME"));
	
	for (let i = 0; i < stageInstanceIDs.length; i++){
		let planetAngle = getAttr("polar_angle_of_planet_instance", stageInstanceIDs[i], EDAT);
		println("\tIndividual tooth engagement ["+stageInstanceIDs[i]+"] @ "+planetAngle+"°");
		let stageGearDataID1 = getStageGearData(stageInstanceIDs[i], gearsInStageIDs[0]);
		let stageGearDataID2 = getStageGearData(stageInstanceIDs[i], gearsInStageIDs[1]);
		let toothRootStressGear1 = getAttr("result_tooth_root_stress_compression_maximum", stageGearDataID1, RDAT);
		let toothRootStressGear2 = getAttr("result_tooth_root_stress_compression_maximum", stageGearDataID2, RDAT);
	
		println("\t\tTooth root stress maximum "+getCompProperty(gearsInStageIDs[0], "NAME")+": "
		+toothRootStressGear1);
		println("\t\tTooth root stress maximum "+getCompProperty(gearsInStageIDs[1], "NAME")+": "
		+toothRootStressGear2);
	}
}

The following example shows how XML files can be read in, modified and written out.

For more information see: ECMAScript for XML (E4x) specification

Example XML file (people.xml)

<people>
   <person gender="male">
      <name>John Doe</name>
      <hair>Brown</hair>
      <eyes>Blue</eyes>
      <height measure="metric">176</height>
   </person>
   <person gender="female">
      <name>Jane Doe</name>
      <hair>Black</hair>
      <eyes>Grey</eyes>
      <height measure="imperial">5'7</height>
   </person>
</people>

Example script

1let xmlString =readFileAsString("C:/people.xml");
2xmlString = xmlString.replace(/<\?xml[^>]*\?>/, "");
3var xml = new XML(xmlString);

4println(xml.person[0].name);
5println(xml.person[0].@gender);

6xml.person[0].name = "Matthias";
7println(xml.person[0].name);

8xml.person[0]["nationality"] = "German";
9xml.person[0].@["title"] = "Mr";
10xml.person[1].@["title"] = "Mrs";

11writeToFile("C:/people.xml", xml, "c", "UTF-8");

The following example shows how JSON files can be read in, modified and written out.

Example JSON file (people.json)

[
  {
    "gender": "male",
    "name": "John Doe",
    "hair": "Brown",
    "eyes": "Blue",
    "height": {
      "measure": "metric",
      "value": "176"
    }
  },
  {
    "gender": "female",
    "name": "Jane Doe",
    "hair": "Black",
    "eyes": "Grey",
    "height": {
      "measure": "imperial",
      "value": "5'7"
    }
  }
]

Example script

1let jsonString =readFileAsString("C:/people.json");
2let json = JSON.parse(jsonString);

3println(json[0].name);
4println(json[0].gender);

5json[0].name = "Matthias";
6println(json[0].name);

7json[0]["nationality"] = "German";
8json[0]["title"] = "Mr";
9json[1]["title"] = "Mrs";
10let jsonStringifyed = JSON.stringify(json, null, 2);

11writeToFile("C:/people.json", jsonStringifyed, "c", "UTF-8");