A Novel Methodology for Calculating Crack Opening Stress under Tension-Compression Cyclic Load

Figure 5

Opening stress curve. With the same amplitude of maximum load, the opening stress decreases with the increase of compressive load (i.e., the increase of negative stress ratio). The decrease of opening stress can be described by quadratic polynomial of stress ratio, as shown by five types of dashed line. When the maximum load is greater than 160 MPa, the opening stress will be negative with the increase of compressive load. It means that the crack opens during the unloading stage of compressive load. It means that the crack opens during the unloading stage of compressive load.