For each of the following cases, plot the load (P) versus the crack opening displacement (8) curve for a metallic material subjected to loading and unloading phases in zero-tension-zero fatigue:
(a) Plastic deformation at crack tip; no change in crack configuration (i.e. crack opening and crack length); loading phase.
(b) Gradual opening of the crack during the loading phase and plastic deformation at crack tip.
(c) Elastic behavior at constant crack configuration during the loading phase.
(d) Effect of plastic behavior = effect of configuration change on the P-δ plot during the unloading phase.
(e) Effect of plastic behavior > effect of configuration change on the P-δ plot during the unloading phase.
(f) Effect of plastic behavior < effect="" of="" configuration="" change="" on="" the="" p-="" δ="" plot="" during="" the="" unloading="" phase.="">
(g) Configuration change during the unloading, with negligible plastic deformation at crack tip.