[mitchntx]

Just wondering what kind of technical/practical background we all have.

I work at a Nuke Power Plant in a Overview organization. It's more than just your average QA/QC organization. I produce video and multi-media presentations for employee training and information Been doing this for 22 years.

[lateapex]

Boeing Engineer.  Right now I'm a Stress Analyst for the Fuselage of the 747 but people are moving around a lot here these days....

Jon,

I attended an interesting seminar last month put on by Vishay. It presented their new, inexpensive package (less than $10,000) for PhotoStress analysis, that now provides measurements with hard numbers. Volunteers were allowed to do the PhotoStress measurements while the Vishay personnel did the strain gage control measurement. The results tracked within 5-6%. Of course, it was a controlled experiment designed to demonstrate the new capability of the photo technology, but it worked for me. And we were not measuring at the edge of the part, which would be much simpler.

They showed a lot of video of PhotoStress analysis (visual analysis, not hard numbers) done by Airbus. It seemed to me that that is still the strong suit of photo analysis, but what a great tool! Airbus found a problem with an internal spar for a rudder that they had failed to uncover with many strain gage attempts. I didn’t think that so many strain gages could be located on one piece of metal. But that analysis kept saying that the part should hold up, when it continued to fail in testing. The photo analysis not only identified the problem area, but found some “zero” stress areas where they ended up cutting holes to lighten the part! I couldn’t believe they made additional edges in a part that was already failing. I guess that if that area sees no stress, that you aren’t creating a stress riser. I would fear that if some other part fails and a load is applied to this part in a different plane (not airplane), that the part under discussion might then fail because of the new holes. It was all very interesting.

I most enjoyed seeing the stress distribution in an automobile steering knuckle. Wow. But they did tend to downplay the difficulty of making the molds for the stress coating. When I pressed one presenter on the time it took to make one series of complex molds and coatings, he admitted that it was 3 weeks from the start till they were ready to test. I would also be concerned that the picture you see does not represent the entire stress picture if you don’t apply the forces in all of the axes that will occur in the real application, which could be the most difficult part.

I imagine that you have a VERY interesting job.

Me, I have never picked one career. I jump back and forth between being a fry cook, a brain surgeon, and a double-naught spy.

Bob