1 / 21

Section Tool v5.3

Section Tool v5.3. Section properties of shell/beam structures. Larry Pearce. June 5, 2006. Disclaimer. Although useful, this tool is provided As-Is and should be reviewed carefully by the user for accuracy and appropriateness. What does this tool do?.

arich
Download Presentation

Section Tool v5.3

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Section Tool v5.3 Section properties of shell/beam structures Larry Pearce June 5, 2006

  2. Disclaimer • Although useful, this tool is provided As-Is and should be reviewed carefully by the user for accuracy and appropriateness.

  3. What does this tool do? • Calculates section properties of an airframe finite element model • Calculated quantities include: • Section “cut” area • Centroid • Inertia • Ixx, Iyy, Ixy • I11, I22, q • Jp=Ixx+Iyy • Material weighted inertia • EIxx, EIyy, EIxy, GJp • For closed sections (or cells) • Cell/enclosed area • Cell perimeter distance • J • GJ • Supports 1 or 2 cells

  4. Section Definition • Sections are analogous to “cuts” through the fuselage or wing • All section cuts are defined normal to a section plane Section cutting planes “Behind” the cutting plane

  5. Section Definition • The section plane is defined by selecting a coordinate frame axis that is normal to this plane • Individual section cut locations are defined via • Offset locations from the origin of the reference coordinate frame • Point/node locations • Plane locations (not orientation) Reference coordinate frame In this example all section planes will be parallel to the yz- plane Section normal axis

  6. Calculation Options • Calculations are based on only rod, bar, beam and shell/shear elements • Each element type can be included/excluded via toggles • Supported bar/beam section data • Explicitly entered (PBAR, PBEAM) • Standard section (PBARL, PBEAML) • Arbitrary section • Tapered beams are supported • Linear variation between beam nodes is assumed • Offsets can be included or excluded • Shell elements include • Plate/shell • Bending only • Membrane • Shear panels • Offsets can either be included or excluded

  7. Calculation Options • Rods contribute to • Cut area & centroid • Inertia, weighted inertia via Parallel Axis theorem Ad2 term • Rod “J” ignored, contributes to Jp via Ad2 term, i.e., Jp = Ixx + Iyy • Bar/beams contribute to • Cut area and centroid • Inertia, weighted inertia • Bar/beam “J” ignored, contributes to Jp via Jp = Ixx + Iyy • Plate/shell/shear contribute to • Cut area and centroid • Inertia, weighted inertia • Cell area, J, GJ • Data defined by fields is supported, i.e., rod area,shell thickness, etc.

  8. Calculation Options • Material weighted inertia calculations • EA, EIxx, EIyy, and GJp • GJ is also calculated if Calculate Cell/Enclosed Area is selected • Supported materials • Isotropic • 2D Orthotropic (MAT8) • 2D Anisotropic (MAT2) • Laminates • Effective E and G are used for orthotropic materials and laminates • All supported element types contribute to weighted inertia calculations • Rods contribute via Parallel Axis theorem Ad2 term ü

  9. Calculation Options • Echo material data • Only available if weighted inertia requested • Echoes material property data used in calculations, i.e., E, G, n, E11, E22, G12, n12, etc. • Create axis @ NA • Creates a coordinate frame at the neutral axis • Coordinate frame axes are aligned with the reference coordinate frame • Create principal axis @ NA • Creates a coordinate frame at the neutral axis with axes aligned with the principal system ü ü ü

  10. Calculation Options • Dump detailed data • Dumps element-by-element information to a file, SectionData.out • Geometric tolerance • Used to determine if the section plane cuts an element • Essentially, this tolerance is used to determine if element nodes lie in the section plane • If all element nodes lie in the section plane, the element is not included in calculations Elm: 16, Elm Type: Shell Area: 0.075000003 Elm Ixx:6.2500E-5 Iyy:3.5156E-3 Ixy:0.0000E+0 Ref Ixx:9.8438E-2 Iyy:7.5063E-2 Ixy:-8.4375E-2 NA Ixx:5.6250E-2 Iyy:7.5063E-2 Ixy:-8.4375E-2 E(elm): 10000000. G(elm): 3846154. ü ü

  11. Calculation Options • Calculate cell/enclosed area • The cell or enclosed area represents the area enclosed by the plate/shell/shear element edges that are cut by the section plane • Thus, the enclosed area can only be calculated if plate/shell/shear elements are included in the calculations and selected • Bars, beams, and rods are not included in calculations • No cell/enclosed area is calculated for open sections • 1 or 2 cells are supported ü Open section Single cell Single cell Double cell

  12. Calculation Options • Calculate cell/enclosed area • J and GJ are only calculated for the closed portion of the section • GJ is calculated if Material Weighted Inertia is also selected • J and GJ are calculated per Airframe Stress Analysis and Sizing, 2nd edition, Michael C. Y. Niu Cell area only calculated for the enclosed area Not included in J or GJ calculations because does not form a closed section ü N_cells n J = S [ 4Ai2 / S bj/tj ] Ai = cell area bj = cut shell element width tj = cut shell element thickness n = number of shell elements N_cells = number of enclosed cells i=1 j=1 N_cells GJ = S [ 4Ai2 / S bj/(Gjtj) ] n i=1 j=1

  13. Selected Elements • Elements to Include • This list of elements will be searched to determine which elements are cut by the section planes • Elements not in the include list will not be used in calculations even though they may be cut by section planes • The primary purpose of the include list is to improve performance of the PCL by reducing the number of elements to consider • That is, it is prudent to only select elements in the area of the cut planes. Generally speaking, you should not select the entire model.

  14. Calculation Results • Calculated quantities for all selected sections are displayed in a spreadsheet. Each row represents a section cut.

  15. Calculation Results • List elements used in calculations for each section • Highlight elements used in calculations for each section • Highlight section boundary Highlight section elements Save spreadsheet data to a file Highlight section boundary

  16. Calculation Results • Calculated quantities include: • Inertias • Calculated with respect to the reference coordinate frame axes about the centroid of the section • Ixx, Iyy, Ixy, Jp, I11, I22, and q • Cross section area of the cut • Sum of rod, bar/beam areas and plate/shell/shear b*h • Centroid location with respect to the selected reference coordinate frame • Weighted inertias • Calculated with respect to the reference coordinate frame axes about the centroid of the section • EA, EIxx, EIyy, EIxy, GJp • Cell/enclosed area, S(ds/dt)= S(b/t), perimeter distance, J, GJ

  17. Notes • The enclosed area is only calculated if the plate/shell/shear elements completely enclose an area. Only single and double cells are supported at this time. • Elements that completely lie in the cutting or section plate (i.e., all element nodes are in the plane) are not included in the calculations. • Only elements “behind the cutting plane” contribute to the calculations Single cell Open section Ignored for J Double cell Single cell

  18. Examples • Open section MSC.Patran data shells only theory arbitrary section Area 0.5 0.5 0.4999 Ixx 1.239168E-1 1.2414E-1 1.2414E-1 Iyy 3.669167E-1 3.6742E-1 3.6742E-1 Jp 4.908334E-1 J -NA- 1.6667E-3 1.6771E-3 1.5” Section tool Ixx & Iyy mismatch with theory due to shell element overlap at corners Jtheory = 1/3*S(biti3) 2” b = 0.05 h = 0.1 data shells+rods shells+bars shells+bars+offsets everything Area 0.5314 0.515 0.515 0.5464 Ixx 1.442381E-1 1.258343E-1 1.254323E-1 1.457156E-1 Iyy 3.983167E-1 3.769261E-1 3.769261E-1 4.08326E-1 Jp 5.425548E-1 5.027604E-1 5.023584E-1 5.540416E-1 J -NA- -NA- -NA- -NA- r = 0.05 t = 0.1 Rods contribute to Ixx, Iyy & Jp via Parallel Axis theorem Ad2 term E = 10e6 n = 0.3

  19. Examples • Closed section MSC.Patran data shells only theory arbitrary section Area 0.7 0.7 0.6999 Ixx 2.815833E-1 2.82333E-1 2.8233E-1 Iyy 4.335833E-1 4.34583E-1 4.3458E-1 Jp 7.151667E-1 J 5.142857E-1 5.142857E-1 5.3030E-1 1.5” Jtheory = 2*t*a2*b2/(a + b), per Airframe Stress Analysis & Sizing, p 173. data shells+rods shells+bars shells+bars+offsets everything Area 0.7314 0.72 0.72 0.7514 Ixx 2.992458E-1 2.872187E-1 2.858188E-1 3.034812E-1 Iyy 4.649833E-1 4.435938E-1 4.435938E-1 4.749937E-1 Jp 7.642291E-1 7.308125E-1 7.294126E-1 7.784749E-1 J 5.142857E-1 5.142857E-1 5.142857E-1 5.142857E-1 2” b = 0.05 h = 0.1 Note that neither rods nor bars/beams are assumed to contribute to J r = 0.05 shells + upper & MSC.Patran data lower offset bars arbitrary section Area 0.71 0.70999 Ixx 2.858167E-1 2.86566E-1 Iyy 4.335854E-1 4.34585E-1 J 5.142857E-1 5.31086E-1 t = 0.1 E = 10e6 n = 0.3

  20. Examples • A-shaped section MSC.Patran data shells only theory arbitrary section Area 1.00 0.98999 Ixx 8.10333E-1 8.10014E-1 Iyy 7.33833E-1 7.24825E-1 Jp 1.54417 J 5.142857E-1 5.152857E-1 5.32256E-1 1.5” Jtheory = 2*t*a2*b2/(a + b) + 1/3*S(biti3), per Airframe Stress Analysis & Sizing, p 173. data shells+rods shells+bars shells+bars+offsets everything Area 1.0471 1.03 1.03 1.0771 Ixx 8.850318E-1 8.310438E-1 8.296438E-1 9.043080E-1 Iyy 7.809334E-1 7.538521E-1 7.538521E-1 8.009521E-1 Jp 1.665965 1.584896 1.583496 1.705260 J 5.142857E-1 5.142857E-1 5.142857E-1 5.142857E-1 1.5” Legs are ignored for J calculations by Section Tool Note that neither rods nor bars/beams are assumed to contribute to J 2” b = 0.05 h = 0.1 E = 10e6 n = 0.3 r = 0.05 t = 0.1

  21. Examples • 2 cell section MSC.Patran data shells only arbitrary section Area 1.2 1.19 Ixx 1.3505 1.35199 Iyy 8.00500E-1 7.91992E-1 Jp 2.151 J 1.028571 1.476264 1.5” data shells+rods shells+bars shells+bars+offsets everything Area 1.2471 1.235 1.235 1.2821 Ixx 1.421150 1.384267 1.382867 1.453517 Iyy 8.476001E-1 8.205199E-1 8.205199E-1 8.676198E-1 Jp 2.268750 2.204787 2.203387 2.321137 J 1.028571 1.028571 1.028571 1.028571 1.5” Note that neither rods nor bars/beams are assumed to contribute to J 2” b = 0.05 h = 0.1 E = 10e6 n = 0.3 r = 0.05 t = 0.1

More Related