Stress Rupture Testing

Stress rupture testing is used to measure the ultimate load-carrying ability of a material as a function of time. This test determines the time necessary to result in breakage or failure of material under an overload. Results of stress rupture testing are extremely beneficial in material selection when dimensional tolerances are not critical, but rupture cannot be tolerated.

Test Specimens

Stress rupture machines are designed to apply a static stress to a test specimen at a specific temperature for an extended period of time. The test specimen is machined from a sample of the material in question, according to specific guidelines usually published in a specification. Smooth, notched, combination smooth & notched and flat test specimens can all be used for stress rupture testing.

Stress Rupture Test Data

Stress rupture testing is generally performed at elevated temperatures which may be as high as a few thousand degrees Fahrenheit. During this type of testing, data is plotted showing stress versus time. A straight line is usually obtained at each temperature. This information can then be used to extrapolate time-to-failure for longer times. Changes in slope of the stress rupture line are due to structural changes in the material. It is important to be aware of these changes in material behavior when extrapolating the data, because they could result in errors.

Tagged as: stress rupture, stress rupture testing, test specimen

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