Chapter 2: Fracture Mechanics Theory
2.4 Modes of Load Application
There are a number of ways in which to apply a force to a body depending on the geometry of a test piece. Test pieces can range from irregular lumps to highly machined complex geometric shapes. The loading implements can take the form of a number of different designs, from points to flat surfaces. There are two main ways in which to induce stress during mechanical testing of a cylindrical test piece. Figures 2.4.1 and 2.4.2 illustrate the two methods.
2.4.1 Axial Loading
Figure 2.4.1 Axial Loading
This configuration of loading can utilise both point and flat plate loading depending on the specifics of the test method.
2.4.2 Diametral Loading
This form of load application involves changing the orientation of the cylinder. The possible loading methods include both point and line.
Figure 2.4.2 Diametral Loading
Figure 2.4.2 illustrates diametral point loading. If line loading, is required, as in the ‘Brazilian’ test the surface of the cylinder needs to have a good surface finish to avoid an uneven stress build up.