Measure the starting length of your material. Clamp the material into the universal testing machine. Attach the extensometer according to the operating procedures for your machine.
Enter the load range for your material. This varies depending on what you are testing. Start with a conservatively low load number if you're working with a new material.
Start the tensile test. Go slowly and take note of the load applied by the machine and the length of the material. Use the calipers to measure the material rather than trying to fit the ruler into the machine. Some testing machines record all information on the computer for you; for other machines you will need to take measurements manually.
Stop the test as soon as the material breaks. This is the strain-to-fracture point.
Remove the material from the machine. Fit the material end-to-end and measure its final length. This is the maximum point of elongation. The change in the material's length is the strain. The amount of load applied is how much stress the material can handle before fracture.