Chapter 2: Fracture Mechanics Theory
2.3 Modes of Induced Stress
There are three types of stress that a body can be subjected to. Figures 2.3.1, 2.3.2 and 2.3.3 illustrate the three regimes.
2.3.1 Axial
Figure 2.3.1 Axial Stress
With this type of stress regime the orientation of the applied stress is in one plane only. A test method that conforms to this type of behaviour would be a direct tensile pull test.
2.3.2 Biaxial
Figure 2.3.2 Biaxial Stress
Stress is applied in two orientations, perpendicular to one another. The ‘Brazilian’ test method is one that exhibits this type of behaviour as it is loaded in compression but fails in tension.
2.3.3 Triaxial
Figure 2.3.3 Triaxial Stress
As illustrated, the body is subjected to stresses in the X, Y and Z planes. An example of a test that creates these types of stress fields is a hydraulic liquid compression test.