The Columbia failed due to an impact of foam on RCC panel 8 or 9. The foam was traveling at 500-600 MPH. Currently the number being evaluated is 545 MPH. This speed was the result of a drop in velocity of the foam due to aerodynamic drag forces. (rather large in shape but, light like a...
DET,
My experience is that you don't have much choice here. The problem is that there is no closed form solution for plastic deformation. I would suggest that you perform a finite element analysis with elastic perfectly plastic material properties. If the strains do not exceed 5% then the...
Prex,
I am not an ANSYS user so I cannot really say much about the program in general. I have, however, compared the linearization routine output from anysy solutions and found that they match the Patran results. I agree with you about the max-min comment, but I supposed that Holaproto was...
HolaPronto,
If I understood your description of the Pro/Mechanica output, it appears that the output is not directly comparable to the ASME code limits as are the outputs by Ansys and Patran. The ASME code does not use principal stress or von Mises stress as comparables. It uses Stress...
hello K,
For thermal problems you must look to expansion and contraction of elements of your design which have differing thermal expansion coefficients. These could cause structural stresses which which could for example cause solder connections to fatigue and fail.
For vibration it is best...
more information please. I would simply comment that integration is an averaging procedure and we should not expect anything too precise from an average.
Helloooo Guys,
I fear something is missing here in this thread. The missing multiplier is in the turning of rotating mass. I will not provide the calculations because it is late and I am lazy. I leave that to those who will come after.
Imagine if you will; you are holding a static wheel...
Hello roger roll,
I generally agree with the responses you have gotten. I have been using finite element software for 20 years now and it is my preferred method of solving problems like this one. However, if I were you, with a limited budget, and limited knowlege, and wanting to get just a...
Hello tj,
Buckling of curved plates has on occasion been termed buckling of the barrel vaulted roof. A google search on this term will produce many hits. However, your thin film has no bending stiffness, and if wrinkling is involved, you will probably need to use finite element analysis to...
Very funny guys :) Steve, I hate to admit I chuckled at the cut and paste comment. I'd just like to add this one thread directed to the younger engineers. Todays struggle with this beastly code is tomorrows job security. It takes a while, so be patient. The gray hairs come quickly.
CAB
Matteo,
First let me agree wholeheartedly with cb4. You should be doing a hand calculation to check your fea. For instance, you can look at the radial stress and check that it equals the internal pressure at the inner wall.
Also, you can check your hoop stress and axial stress away from any...
Mark,
The reason for the 3X limit is not to protect against yielding. The yield limits are for primary (global) membrane and bending stresses. The code allows for localized plastic straining and applies this 3X limit to these areas. What the limit actually does is guarentee that shakedown of...
Hello folks,
Seems this thread is catching fire, so I thought I would throw some kindling on it. First, I'd like to tip my engineering hat to everyone for asking and answering good questions(not that I haven't been anymore confused than others). Secondly, I would like to boldy predict that the...
Dave, the 1.5 factor comes from the plastic hinge (see Z factor in steel manual for rectangular beam) calculation for a rectangular beam in bending. The intent is to insure that a primary load does not cause a plastic collapse failure. The 3.0 factor is an entirely different failure mode. In...
Help,
I have been explaining to my colleagues that the primary membrane + bending stress calculation found in APPX 4, section VII, is designed to prevent collapse due to plastic hinge and that it is the highest value found at the reference section (see para 4-133). I have finished a linear FEA...
