elemno_layerid_theta1.dat file generating problem


    Hello, I have been troubled to use the PreVABS with ANSYS v15.

    I created the mold lines, segment layout successfully, glued the all sectional areas, and generated meshes without any problem.

    However, when I generated VABS input and executed VABS, the ‘ech’ file showed the following error message:
    “I/O error: read layer type and theta_1 for each element”

    Then, I generated input file individually and checked each file, and I found the error at the ‘VABSGen_7_elemno_layerid_theta1.dat’ file.

    My VABS model has and 3703 elements, and it was verified by ‘VABSGen_4_nnode_nelem_nmate.dat’ file. 'VABSGen_7_elemno_layerid_theta1.dat' file has only 3215 lines, even ‘VABSGen_6_elemno_nodeno.dat’ file has 3703 lines exactly. There are some missing elements information for layered and theta1, and overlapping elements also exist.

    Here, I attached the every VABS input files. Please let me know what I missed.

    Best regards,
    Seil Kim

  2. Fang Jiang

    Dear Seil,

    Thank you very much for your valuable feedback. The issue is due to that the link between the elements and the corresponding segment mold line is not successfully created. Please allow me to walk you through the steps of operating the GUI.

    Please make sure you perform the following steps, in that order:
    1.Header assignment: VABS control parameters
    2.Input material constants
    3.Import airfoil profiles and webs as mold lines
    Note: Do you have non-zero data into "Tilting Angle around Pitch Axis"?

    4.Store mold lines into memory
    Note: This step is critical and necessary. Since you have the theta_1 data, I assume you have done this.

    5.Assign layout: assign layout files onto mold lines
    6.Segment boundaries: choose boundary types 
    7.Segment Overview
    8.Repeat 5-7 for all segments
    When step block 5-8 is finished, there will be several big segment areas. 
    Some of them may also overlap each other, particularly in the leading and trailing edges. 
    Sometimes these overlapping areas are very small due to the nature of airfoil lines. 
    So please zoom in these locations to check the overlapping, especially the leading edge.
    Also, increasing the amount of sampling points shown on page 24 in example eg_Blade_Bell540.pd may improve the design

    9.Tailor sectional areas: leading edge, trailing edge, webs
    Here is usually where the problem is. 
    Firstly, make sure that you keep the mold lines unchanged and at least some lines on the inner boundary of the segment also kept.
    Secondly, based on the observation from step 8, you need to manually use the ANSYS booleans function to precisely make the new segment boundaries.
    The way to perform the tailoring is very flexible depending on airfoil design and also analyst's preference.
    Please refer pages 33-43 in example eg_Blade_Bell540.pdf
    Please also refer to video the tailoring begins at 08:30.

    10.Glue sectional areas 
    If step 9 is not done properly, this step will ignore some overlapping area and just glue the others which may cause the issue.
    Please refer page 44 in example eg_Blade_Bell540.pdf

    11.Laminates: cut each segment area into layer-wise areas
    Please refer pages 45-53 in example eg_Blade_Bell540.pdf
    Please also refer to video the lamination begins at 12:45.

    12.Foam filled sectional areas
    If you have foam filled sectional areas, please make sure that you do this step after step 11.
    Please refer to video the filling begins at 14:05.

    13.Assign layer-IDs to foam areas
    15.Generate VABS input file

    Sorry for the inconvenience... if possible, I could take a similar airfoil profile to go through this and profile it for you through email

    Please let me know if I can be any further assistance!

    Best Regards,
    Fang Jiang