Micromechanisms of fracture and fatigue. In a multiscale context
The book presents a modern view on micromechanisms of fracture and fatigue of metallic materials and alloys. The book consists of three basic chapters and a concluding chapter covering the main results of the book. Three sections of Chapter 1 are devoted to the mechanical behavior of perfect crystals. The first section discusses the application of ab initio methods to calculations of elastic stress-strain response and defines ideal strength under various loading conditions developing two-scale models based on electronic and atomic structures. The authors describe a difference between intrinsic lattice properties and those induced by defects and secondary phases of materials and composites. The second section presents the brittle/ductile behavior of perfect crystals based on the three-scale approaches dealing with electronic, atomic and crystallographic structures of crystals. The authors also consider here the multiscale models coupling atomistic, crystallographic and fracture mechanics methods. The third section models nanoindentation tests with regard to the physical interpretation of pop-ins observed at the end of the elastic part in the force-indentation depth diagram. This model couples numerical methods and results covering all spatial scales from nano to macro. Chapter 2 studies damage and fracture mechanisms operating under monotonically increasing forces applied to metallic and ceramic materials (in particular, brittle, quasi-brittle and ductile fracture). First, the micromechanisms of crack shielding and amplification induced by crack trajectory and interaction with particles and microcracks are present by using theoretical background and practical examples. Then, a statistical approach to geometrical shielding effects occurring in multi-phase materials is outlined based on two-level concept giving quantitative interpretation of results obtained for fracture toughness and the absorbed impact energy (notch toughness) of some metallic materials. In order to quantify the quasi-brittle fracture, the shielding effect is related to the ratio of a characteristic microstructure dimension and to the crack-tip plastic zone size in a two-scale analytical model based on quantitative fractography and fracture mechanics. Finally, analytical three-scale models of ductile fracture processes based on dislocation dynamics, microvoid formation kinetics and fracture mechanics are developed which are able to predict the fracture strain in the tensile testing of ductile materials and the corresponding fracture micromechanisms. Four sections of Chapter 3 are devoted to fatigue fracture of metallic materials. The first section studies morphological patterns reflecting all crack growth stages on the fracture surface by using topological methods utilized in fatigue investigations and the quantitative fractography. The second section considers the propagation of fatigue cracks under remote mode I. Moreover, it is considered a local mixed mode I+II developing at the next stages of the fracture. The third section refers to shear-mode and mixed-mode crack growth. The theoretical models and test results concerning the crack growth under pure-shear and torsion loading are reported. Moreover, the results of study of the combined cyclic bending-torsion loading are discussed. The fourth section presents an application of quantitative fractography to failure analysis. In particular, it is shown how the knowledge of fracture micromechanisms can help to identify the reasons for fracture of structural components in service. In total, this book presents an interesting attempt to review the modern multiscale view on fracture and fatigue of metallic materials and alloys, and to couple different levels (from nano to macro) of fracture processes with estimation of crack shielding or amplification mechanisms. The book could be recommended to students studying the fracture mechanics due to clear physical ideas and sufficiently strict mathematical representation of the results. The teachers can also obtain important additional information to modernize the corresponding lectures and practical lessons.
scientific article; zbMATH DE number 5763811