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Recent content by kilbchoi

  1. kilbchoi

    Shell neutral axis offset consideration in NASTRAN

    Hi! Is there anyone who knows about the consideration of shell neutral axis offset in NASTRAN ? Especially when modeling honeycomb panel to the frame(beam) with laminated element, there is a offset for neutral axis with respect to the reference curve. I saw the dummy element with very weak...
  2. kilbchoi

    Attachment factor of 1.33 to the seating system

    Hi guys, Is there anybody who has a clear idea on the attachment factor of 1.33 in the seat design ? According to FAR, the factor is required to the attachment of - seat to the structure - belt/harness the the seat or the structure Therefore I understand for example, - It doesn't have to be...
  3. kilbchoi

    Crippling Strength in bending and Plastic Bending Theory

    Hi Ed, Thank you for your help. Could you please send it to my email address, Gilbert.Choi@eurocopter.ca Thanks, Kilb
  4. kilbchoi

    Crippling Strength in bending and Plastic Bending Theory

    Hi, Regarding the compressive failure mode in the bending member such as circular tube, rectangular tube, or hat section, What is the relationship between the plastic bending theory and the crippling strength ? If I consider the crippling stregnth as the compressive strength (Fcc < Fcy), it's...
  5. kilbchoi

    Criteria regarding Resin Content

    Hi guys, I am choosing the suitable Glass Fabric product. I am wondering if there is any criteria regarding the resin content. As far as I know, roughly 40% is quite standard. What about 30%? Obviously it can provide better mechanical properties for stfinness and strength. As far as I know...
  6. kilbchoi

    Bearing strength failure mode in the bolted joint

    Hi ! I am looking at the bearing strength of FRP material in the bolted joint. I am wondering what is the main failure mode for the bearing strength. In metal, it is obviously contact compress stress at the contact area. In my analysis model using NASTRAN, in-plane shear stress is more...
  7. kilbchoi

    Modelling of rivets in thin plate

    Hi Gary, I would like to share my experience. <1> I alwas roughly model it as rigid element. Obviously it provides higher data than the real one due to the assumption of rigidity. <2> If there is a too high load exceeding its allowable, I remodel it as BAR element. Normally I ended here since...
  8. kilbchoi

    RBE3 Element in NASTRAN

    Hi guys, I am happy to get comments from the top ranking persons in this forum regarding my case. Hi vonlueke, I want to confirm one of your recommendations, the number (1). <1> At first it is not artificial high load in the perpendicular axis to the loading axis, in my case, &quot;X&quot...
  9. kilbchoi

    RBE3 Element in NASTRAN

    Hi pj, I've already tried your suggestion just before you replied to me. (1) It looks much more resonable than direct RBE2 application. However it still has quite high &quot;Y&quot; constraint force. (2) In this particular torsion problem, I concluded that the additional &quot;Y&quot; and...
  10. kilbchoi

    RBE3 Element in NASTRAN

    Hi pj, Thank you for your quick and great answer. The reason why I think RBE2 is too conservative is, (Input Model) (1) Let's suppose, &quot;y&quot; axis is beam axis, &quot;x&quot; axis is perpendicular to &quot;y&quot; in the same plane. (2) Beam length is relatively short, 300 mm length...
  11. kilbchoi

    RBE3 Element in NASTRAN

    Hi ! I have a question of rigid element usage of applying load. Let's suppose I put the rigid cylinder weight onto the wide cantilever beam end, and I applied the side load at the CG causing the torsion on the beam. I have four or eight bolts to fasten the cylinder. Most of people might use a...
  12. kilbchoi

    Bolt bending formula in single shear joint

    Hi ! In single shear joint, I normally pick up the bending moment arm with the half of assembled length. I've checked all references, but I couldn't find a formula of the subject. I blieve that moment arm is conservative. I need less conservative but more practical formula especially for...
  13. kilbchoi

    Bolt Hole Clearance

    Hi, Anybody who let me know hole clearance to allow all bolts transfer shear load? For instance regarding M6 (in metric). Thanks, K. Choi
  14. kilbchoi

    Regarding Single Shear Lug Joint

    Hi Visitior 2002, Thank you for your reply. In the formula which I introduced, Fa is the selected minimum load from a set of strength based on net tension, shear bearing, ..., you mentioned. My exact question is for futher reduction of lug strength of single shear joints based on double shear...
  15. kilbchoi

    Regarding Single Shear Lug Joint

    Hellow! I have a question about single shear lug joint strength. If assuming I get the nominal axial strength of a lug, Fa, then one of my references, German design hand book, says that Fa* = Ka x Fa x (Sbr / Stu) where, Fa* = final lug strength of sigle shear lug joint Ka =...
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