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Recent content by shearlag

  1. shearlag

    buckling factor as low as 0.05

    Well trying to figure it out.....the modelling error... thanks
  2. shearlag

    buckling factor as low as 0.05

    hi everyone, I carried out a linear buckling analysis of a skin panel using nastran solver 105. The loads were applied as enforced displacement form a global model. surprisingly first mode buckling factor was 0.06365. Iam quite sure that the panel will not buckle at the applied load times the...
  3. shearlag

    Development of program

    Thanks all for your valuable suggestions. Yes I have heard of qbasic recently.Most of you are suggesting Excel in association with VBA. Probabaly I need to use Excel in a more efficient way .
  4. shearlag

    Development of program

    I do not know whether I am posting my concerns in the right forum or not. I am a aircraft structural engineer. I always encounter new or updated loads on wings from aerodynamics.I generally use excel and convert these loads into FE nodal loads.Now I want to write a generalised program for nodal...
  5. shearlag

    Average shear stress

    Yes I tried bruhn, but got low net stress. Moreover in my problem its 2mm thick machined rib web with 5 mm thick doubler. I think the graphs are valid for lightly loaded shear webs, ( ribs formed from sheet metal). I shall try with averaging the element shear flows across the web section. Thank...
  6. shearlag

    Average shear stress

    Dear all, I do have a general model of nose box. The spar web has a cutout. But FE model does not have it. The web has around 18 CSHELL elements between two stiffeners. The shear flow values vary from 30 N/mm to 150 N/mm. My doubt: Should I take max shear flow or average shear flow or…(no idea)...
  7. shearlag

    pressure distribution to nodal loads

    yes rb..thanks, Its basically how we map CFD results to the FE mesh.Knowing Cp, dynamic pressure and elemental area, load can be calculated at the cg of the element. But as you say, one case has to be done and rest is easy.
  8. shearlag

    pressure distribution to nodal loads

    Dear all, conversion of Pressure distribution to FE nodal loads is a huge work and to do it manually is time consuming ,if it involves lot number of load cases. Is there any program available to convert pressure distribution to FE nodal loads.Kindly can anyone refer. Thank you in advance. shearlag
  9. shearlag

    criteria for choosing high strength carbon tapes

    dear RPstress, Thanks for the quite a good bit of information.Yes BMI's are on higher side from price consideration.Yes i have heard, Epsilon2/Epsilon1 is of importance for compression after impact. But i have not read in any technical articles. Regarding VKU material, my boss only told me it...
  10. shearlag

    criteria for choosing high strength carbon tapes

    Yes RPStress, M65 is a Hexcel BMI resin and VKU from source looks to be German material.But no much information is available.In fact I was referring to Epsilon2/Epsilon1 (not poission's ratio) similar to E22/E11 ratio.I beg an apology for not saying things correctly..Some UD tapes will have...
  11. shearlag

    criteria for choosing high strength carbon tapes

    Dear all, Is the ratio (longitudinal extension strain)/(transverse contraction strain) is a very useful criteria for choosing high strength Uni Directional carbon Tapes (like T800 or VKU-27 or M65) ?. If so , why ? thanks in advance with regards shearlag
  12. shearlag

    sandwich panel

    JJ22mW, yes my concern was from your last line that "local core compression".If i take freebody forces at any section to do a local check for core compression, i should'nt end up with increasing the core thickness or going for a high density core to cater for those forces which are results from...
  13. shearlag

    sandwich panel

    Dear all, Can any of you kindly help me in successfully executing a Nastran program for sandwich panel? Since the problem is of sandwich wing skin, the upper and lower wing skin is represented using CQUAD4 using SHELL topology. The top facing and the bottom facing ( 15 layup of 0.13 mm each) is...
  14. shearlag

    wing load distribution

    Thanks RB
  15. shearlag

    wing load distribution

    Yes rb1957, you got it right. i have few data points which i need to distribute on a fine grid.So you mean to say it can be done in a iterative way to match the shear force, bending moment & torque diagram.But various assumed distribution can give same max shear force, max bending moment & max...
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