Stress relaxation testing to assess the behavior of materials involves stretching specimens, by applying a load ramp, to a pre-determined value, using a device at elevated temperature. The device is then switched to strain control (or stroke control, using the position of the machine crosshead) to hold the specimen at a constant strain/elongation. The temporal drop of the stress is then monitored for the required duration fo the test. The characteristic value obtained from the test is called the relaxation stress.
![Example of actual stress-relaxation data](https://smart-swansea.com/wp-content/uploads/2019/10/stress-relaxation-graph.jpg)
SMaRT routinely conduct stress relaxation testing in compliance with the following international and industry standards (working to other standards are available upon request):
- ASTM E328-13 Standard Test Methods for Stres Relaxation for materials and Structures