Stress Rupture Testing
Creep Test Capabilities Too
Stress rupture testing applies a constant load to a test sample at a specified temperature until failure to determine the tendencies of materials that may break under an overload. A creep test helps determine how material deforms at temperatures that are generally elevated and under a constant load over time.
Fully Qualified for Reliable Results
At Laboratory Testing Inc., the stress rupture test and creep test are Nadcap accredited and comply with ASTM standards. The Lab, near Philadelphia, PA (USA), is equipped with fully-automated machines that provide:
- Testing at temperatures up to 1800°F
- Calibrated thermocouples attached to the test specimens to provide the required temperature control
- Automatic load at various time intervals for reliability and efficiency
GE Aviation has approved LTI for stress rupture testing and Pratt & Whitney (P&W) has qualified LTI as a commercial laboratory for performing Reference MCL Manual Section Appendix 56: Code 3 stress rupture testing. The stress rupture and creep testing systems used at LTI also meet with ISO 9000 and ASTM compliance.
- ASTM E139
- ASTM E292
The Test Processes
Stress rupture and creep testing are generally performed at elevated temperatures which may be as high as nearly a few thousand degrees Fahrenheit. Stress rupture and creep test machines are designed to apply a static stress to a test specimen at a specific temperature for an extended period of time. During the test, data is plotted showing stress versus time. This information can then be used to extrapolate time-to-failure for longer times.
Stress Rupture Test
During the stress rupture test, material is subjected to constant load at a constant temperature while the time to rupture is measured. The reported results are very useful in the selection of materials where dimensional tolerances are not critical, but rupture cannot be allowed.
The creep test is conducted using a specimen to which a constant stress is applied. The test is important for determining the speed at which a component or part will deform at a given load and temperature, if components are to be safely designed for high temperature service. The elongation or deformation of the specimen is measured by an extensometer, thereby calculating how a component or part will change in shape during service. This is of particular importance where dimensional control is crucial.
Test Specimens Machined at LTI
The test specimen is machined from a sample of the material in question, according to specific guidelines usually published in a specification. The variety of test specimens required for stress rupture testing and creep testing can be machined at LTI including:
- Combination smooth & notched
- Temperatures – up to 1800°F
- Standards – comply with ASTM standards E139, E292, and NASM-1312-10
- Nadcap accredited – stress rupture and creep testing
- GE Aviation
- P&W qualified as a commercial laboratory for Reference MCL Manual Section Appendix 56: Code 3 stress rupture testing
- Test Specimens – LTI’s Machine Shop can provide smooth, notched, combination smooth & notched and flat stress rupture test and creep test specimens