Energy to Break Apart a Weld
Energy to Break Apart a Weld
(OP)
I'm a structural engineer working for the department of defense. I am currently trying to predict the throw distance for pieces of a structure following an internal detonation of a munition.
We have a 3 sided box with a ceiling. The box is made of steel panels which are welded to a steel channel frame. We know from testing that when a detonation occurs the steel panels are torn off the frame and thrown away from the center of the blast. We have establlished methodology for determining the pressure and impulse on the panels from the blast. We can then take that pressure and impulse and approximate a conservative velocity that will be imparted on the panels. From there we can determine the initial kinetic energy and make some reasonable assumptions about the launch angle in order to use physics to determine the final location of the panels.
However, our inital KE is too conservative because of the energy disappated in breaking apart the weld.
My questions...
What energy is used up in breaking apart the weld and how do I determine that energy?
I can determine the maximum force resisted by the weld. Would it be reasonable to subtract the weld resistance from the total force imparted per linear inch then back-calculate a new (reduced) pressure to the plates?
Any other thoughts on additional methods?
We have a 3 sided box with a ceiling. The box is made of steel panels which are welded to a steel channel frame. We know from testing that when a detonation occurs the steel panels are torn off the frame and thrown away from the center of the blast. We have establlished methodology for determining the pressure and impulse on the panels from the blast. We can then take that pressure and impulse and approximate a conservative velocity that will be imparted on the panels. From there we can determine the initial kinetic energy and make some reasonable assumptions about the launch angle in order to use physics to determine the final location of the panels.
However, our inital KE is too conservative because of the energy disappated in breaking apart the weld.
My questions...
What energy is used up in breaking apart the weld and how do I determine that energy?
I can determine the maximum force resisted by the weld. Would it be reasonable to subtract the weld resistance from the total force imparted per linear inch then back-calculate a new (reduced) pressure to the plates?
Any other thoughts on additional methods?





RE: Energy to Break Apart a Weld
Well, as a first approximation based on very high strain rate conditions, I would look at obtaining Charpy V-notch impact data (ft-lbs) for the welds/base metal. The impact energy absorbed by the steel and weld needs to be taken into account.
Most likely this would be a small contribution because the weld strength may be matched or higher in comparison to the base metal. Try it and see what happens.
RE: Energy to Break Apart a Weld
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Energy to Break Apart a Weld
RE: Energy to Break Apart a Weld
The consideration of full penetration v-groove welds under your loading conditions would be a bear, probably two.
My personal experience with two defalcations that completely destroyed 2 vessels designed to ASME Sec Viii Div 1. In both cases all failures were the base metal tearing, there were no weld failures.
http:
http://www.shipstructure.org/pdf/81symp14.pdf
braimstoner,
Unzipping is a term quite often used in the description of weld failures especially Aluminum. There are several technical papers with unzipping in the title.
RE: Energy to Break Apart a Weld
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Energy to Break Apart a Weld
RE: Energy to Break Apart a Weld
I haven't tried to find this article online.
http://www
Old paper but may have some leads to others.
http://www.shipstructure.org/pdf/004.pdf
http
Here is the index to information that may be of value at ASTM.
ht
I read one report on the strength of welds during a catastrophic event in either the this FEMA Report or one of the parallel investigations.
http://www.fema.gov/rebuild/mat/wtcstudy.shtm
RE: Energy to Break Apart a Weld
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