I also agree, AD rivets are not hard to be driven, and we have never heat treated them as well! This is dangerous and the repair should not be approved by the authority!
...well I thought floor beam would react the pressurization load, as a balloon expanding and creating mostly axial tensile loads on the beams. It is B737, with 20' beams pitch, so I assumed a area of A =20 x 40 = 800 in^2, delta p = 9 psi(assumed), P = 800 x 9 = 7,200 lbf. Beam cross section...
Hi All,
I am analyzing a floor beam modification and was wondering how can I incorporate fuselage pressurization load on top of 6g down load, no FEM model available? Conservatively stress within the floor beam due to pressurization load would be around 10 ksi, but I need to validate it. Your...
Yes, I was asked that question. I also think, the deflection is quite small and wouldn't be a problem. Last night I was plying with the natural and impulse frequencies showing that they are of different diapason. No history with that type of question unfortunately, thanks again rb1957!
...no, it's not a helicopter, and under 6g down flight load, due to that Mod, there is a -0.013" deflection, so from that deflection probably I could get the undamped natural period of vibration - I don't know, just still thinking in that direction. If won't work, yes FEA is the next.
Thanks rb1957
Hi All,
On a modified beam I have statically proved that is OK. However on the beefed portion of the beam, since the weight of the Post-Mod beam is bigger than the original Pre-Mod beam, I was wondering what would be the dynamical behavior of the beam. I am thinking of getting approach to...
...I am in Bruhn A17.6, hope it will help. Another thing, which a friend recommended me is, to look at it like a cable, and substantiate the end reactions, which might be a problem due to the high end magnitude of this reaction. Hope in Bruhn to find some answer, other than that a stiffeners, as...
...from all the information I was able to get - Timoshenko Large Deflection of Plates, Roarks, Effects of Large Deflection and Bending of Rectangular Plates with large Deflection Tech Note 846, all large deflection are limited to pb^4/Et^4 = 250 or 300. For my case, this value is 3169, not even...
Thank you JStephen - I quickly did it, so for 1" wide, 13" long beam, with a w = p*b = 29.61 x 1 = 29.61 lb/in, the bend moment is 626 in-# and stress f = 6*626/(0.071^2) = 745,090 psi, which is relatively close to my 585,184 psi. As rb1957 mentioned, probably my problem would be under "large...
...my panel thickness is 0.071' 2024-T3, and my deflection is 23.63". So looks like it is a large deflection problem - any hint where I could look at to solve my problem? Thank you rb1957!!!...I feel like standing in front of a big concrete wall with no way out...
Thank you rb1957,
so my stress is 585,184 psi and I have a failure. That's it! So, I guess, have to reduce the panel size, or applied load...(just for the record, for another panel configuration, I triple checked with Michael Niu (page 196), and the stress result from his graphic, I multiplied...
Hi All,
I am analyzing a rectangular plate under uniform liquid pressure in order to evaluate its max deflection and stress. My approach was using "Roark's Formulas...." and for my panel (25.0" x 13.0"), with p = 29.61 psi, I got a panel stress of f = 585,184 psi. I double checked with...
Most of the time, we have been using etch and alodine and after that epoxy primer and top coating (for external antenna doublers). Looks like it's faster and more economical than anodise, and its covered as per the A/C SRM.
