## How to determine material limits from test data

## How to determine material limits from test data

(OP)

Hi

I've received uniaxial tension test data for a range of materials. Each material test was repeated either three or five times. I'd like to establish an appropriate UTS limit for each material. At the moment I'm taking the minimum stress at failure from the range of test data -10%. I was wondering if someone could point me in the direction of a suitable standard which details a more robust method.

Thanks in advance.

I've received uniaxial tension test data for a range of materials. Each material test was repeated either three or five times. I'd like to establish an appropriate UTS limit for each material. At the moment I'm taking the minimum stress at failure from the range of test data -10%. I was wondering if someone could point me in the direction of a suitable standard which details a more robust method.

Thanks in advance.

## RE: How to determine material limits from test data

## RE: How to determine material limits from test data

In aerospace they require 10 separate tests form each of three different lots (or heats) as a minimum.

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P.E. Metallurgy, Plymouth Tube

## RE: How to determine material limits from test data

## RE: How to determine material limits from test data

israelkkhas inferred, the use of statistical methods will only be valid if the specimens were obtained from truly random samples. This is unlikely to be the case. Depending on the material and form, it can difficult to obtain a random sample.For example, if the tests were performed to verify the properties met the minimum requirements of their respective specifications, it is likely that they were chosen to represent the minimum properties of the lot to help insure the entire lot met the minimum requirements. In such cases, the distribution of test results is more descriptive of process control than the range of properties one could expect.

Of course, this does not help the OP at all. Perhaps the best way for the OP to get the information he wants is to ask the producer of the materials in question. They will have a much better idea than anyone else. They may not want to share all of their information, but they may be able to help answer the question posed by the OP.

## RE: How to determine material limits from test data

Thanks for the advise, very useful. The test is to determine the properties of the materials. I've used a t-distribution to account for the low sample count and calculated the 99% confidence interval. I've taken the lower limit as my UTS.

## RE: How to determine material limits from test data

## RE: How to determine material limits from test data

## RE: How to determine material limits from test data

## RE: How to determine material limits from test data

.## RE: How to determine material limits from test data