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Testing sheet metals and stamping dies costs the automotive industry tons of cash, and it's all wrong, wrong, wrong

Sheet metal isn't high-tech stuff, but a lot of work goes into getting it right when it comes to things like the automotive industry. The surface of a stamped piece of metal is an indicator to the amount of stress it can handle and how, when and where it may fail. The standard method of measurement for surface profiling is being called into question for its accuracy after findings from a group of NIST researchers.

Traditionally, the measurements in question were done with an instrument called a profilometer. The simple device, similar to a phonograph needle, is drawn in a line over the surface of a material to measure the often microscopic terrain. After repeated tests, the data from the instrument is averaged to make a "roughness" measurement.

Unfortunately, as the NIST research shows, this method may be terribly inaccurate due to uncertainties and statistical errors when the measurements are extrapolated into a three-dimensional surface.

Rather than using a two-dimensional technique like the profilometer, Mark Stoudt, Joseph Hubbard and Stanley Janet of NIST use an instrument called a scanning laser confocal microscope to make a point-by-point image of a surface. The measured area from one image is roughly 1000 x 800 micrometers long and wide by 20 micrometers deep. The data from each point is then analyzed simultaneously using mathematical techniques to give a more accurate measurement than could be obtained by two-dimensional methods.

One discovery already made on aluminum alloy used in the study is that the generally accepted linear relationship between surface roughness and material deformation for the alloy is wrong. Data from the research suggests a more complicated relationship was hidden by the uncertainties of linear profilometers.

This and the rest of their findings have been published in a paper titled "Using Matrix Methods to Characterize Evolution of Deformation Induced Surface Roughness in Aluminum Sheet" in the journal Materials Science and Technology.

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RE: Like the title
By Ringold on 1/21/2008 2:55:54 AM , Rating: 2
I've met several politicians, I think that general theory of them is wrong. I think they're generally smart people, have to have some degree of intelligence in order to have cut a sufficient number of throats to even get elected.

Take for example, the current "stimulus package" deal. Democrats and Republican's, united for the first time in almost a decade with the goal of giving away money that isn't theirs to the masses; much like a Roman general returning to Rome with gifts for the people so that they would honor him with a triumph; this time, they just want votes in November. I bet you, though, that both parties are aware that it's ultimate impact will be virtually nil, that no one knows how to "fix" a business cycle, and that, besides, the root of the problem is in the financial markets anyway. That doesn't stop Republican's from trying to get in business depreciation benefits in, nor Democrats from trying to sneak in extra welfare money (though Bernanke did say the business benefits have more bang-for-the-buck, dont tell the left that, they dont care -- it wont get them elected!) Similar story in Europe; politicians know how to fix Europe's economic woes (Reaganomics, Ireland-style), just, as they often say, not how to get re-elected after they do it. Both of those being economic issues, I partly blame government educations that barely teach one how to balance a check book, much less look at marcoeconomic issues, but still.

Thats what it comes back to, though, the people and elections.Therefore.. I think the electorate are the idiots, not politicians. I don't care how miserable the weather was in Michigan, anybody note how low that turnout was for the primary? The politicians are slaves to the structure that we, the people, at least the fraction of us that vote, haphazardly create for them.

That said, they're not experts in many particular fields, but then again what does a scientist working at a biotech firm know about tax policy or defense anyway. Two of the worst presidents in United States history happened to be engineers; Hoover and Carter.

"Nowadays, security guys break the Mac every single day. Every single day, they come out with a total exploit, your machine can be taken over totally. I dare anybody to do that once a month on the Windows machine." -- Bill Gates

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