Hi,
I've always been under the impression that for single shear details that aren't stabilized by some other feature (loading causes rotation of the joint) the shear allowable of the fastener is reduced from the standard, "1/2 of the double-shear strength value". For instance, this is reflected...
I've been told that there are some standard charts that exist to size simply supported panels so you don't run into panel flutter problems. The airflow for the particular problem I'm looking at is only on one side of this panel (OML panel). Has anyone seen something like this? I'm looking for...
Hi,
I'm trying to track down an allowable for a Nitronic (21-6-9) orbital weld. I've been told that 32% is the appropriate knockdown to apply but I'd like to find a reference that supports this. Does anyone know of anything?
Thanks much...
Hi,
I'm looking for a good tutorial on performing low frequency acoustic response analysis via Nastran (structural vibroacoustic response of panels to acoustic loading, etc). Does anyone know of any good tutorials or textbooks that go over this topic? I'm looking for something that will have...
Hi,
I'm looking to purchase a textbook on the topic of crack growth. Sort of a Bruhn or Niu equivalent in the crack growth field. Does anyone have any recommendations?
thanks much
Hi,
I have a problem in which I have a metallic liner (AL6061-T4) in a pressure vessel which is designed to yield biaxially during pressurization. My question is, what would be the ultimate failure criteria for this condition? That is, what combined stress state would be the most appropriate...
Hello,
I have a question about interlaminar shear failure of composites, specifically pertaining to finding an appropriate interlaminar shear stress using Nastran.
I'm analyzing a carbon fiber overwrapped pressure vessel (COPV). In the region I'm looking at I have modeled two plies; one 17 deg...
hi,
so I'm looking at some steels that I can't find published bearing allowables for (Fbru for A500, A36, etc). does anyone know any rules of thumb for establishing a bearing allowable as a function of Ftu, Fsu, etc? For instance, I know that for steels Fsu ~ 0.6Ftu. Does such a rule of thumb...
Hello folks,
So, we all know about the basic design practice of using stiffeners at all locations where point loads are introduced into beams, right? For instance, if you have an I-beam that is loaded in the middle you'd put a stiffener where the point load is introduced to stabilize the web...
Hi,
I'm looking at my copy of Bruhn, pg. C7.2, equation C7.6. This equation is missing the "g" term (which are present in C7.4 and C7.6) and I'm guessing that this must be an error. Is anyone familiar with this?
Thanks much.
Does anyone know of any rules of thumb for estimating fatigue limits for various metallics (steel/aluminum) as a function of Ftu or Fty? Just looking for something for quick and dirty checks.
Seems like I've heard of rules of thumb in the past (infinite fatigue life at Ftu/3 or something of...
Hello everyone,
I'm curious about your thoughts in performing linear buckling analysis on webs (via a FEM). I have some webs that have multiple holes in them at various locations so I can't just perform a Bruhn type calc for plate buckling. These webs are stability critical (buckle before...
Hello,
I'm looking at my copy of Niu, 2nd Ed., pg 456 which gives the methodology to calculate a plastic reduction factor for plate buckling. There is a factor for plates loaded in compression as well as plates loaded in shear. For the sake of this discussion I'm considering a plate loaded in...
hi,
does anyone have recommendations on the latest/best ways to estimate shock response spectra due to pyrotechnic events. What I'm aware of is:
- NASA Vol VI document: This is some old Martin-Marietta document that give source levels and how to attenuate as a function of distance and...
Hello,
During my time at Boeing I recall that there was some issue with how a fastener was installed relative to the grain (say of a machined AL part). That is, installing a fastener in the ST vs. LT vs. L directions. I can't remember if this was a strength issue or fatigue issue. Can anyone...
Back in my Boeing days I remember that in their Boeing Design Manual (BDM) as well as corresponding IAS tool they had a Johnson-Euler buckling tool. You could select how many "supported edges" the given cross-section had (1 for a "tee" and 2 for a "zee", for example). If you selected "1...
Hi, I have a question regarding fastener thread shear failure. I know that often when analyzing fastener threads its common to assume that all of the load reacts on the first two or three threads. I was wondering if its appropriate, when dealing with ultimate loads, to just claim however many...
I have a question regarding fastener failure modes. I was reading through my "Spacecraft Structures and Mechanisms" textbook the other day and read the following:
"In tension, a threaded fastener with a suitable head will fail first in the threaded section, usually at the thread nearest the...
Hello,
I have a pretty simple question - I know that its common to call out "break sharp edges" on machined parts. I'm curious, what tool do they generally use to do this?
Or for instance, on a machined aluminum I-beam, what would be the most common way to remove the sharp edges from the...
Hi,
I'm in the aircraft/aerospace business and was wondering if anyone knows of an online card/printout that gives the fastener hole size for various fit types (transition fit, shifted transition, etc).
Thanks much,
Dan
