**Preface to "Fracture Mechanics and Fatigue Damage of Materials and Structures"**

One of the most important aspects of the engineering assessment of the technical condition of structures and materials is the ability to assess the fatigue behavior of materials and structures. In addition, another important topic is the design of materials or structures that can resist fatigue and fracture. Modern science provides us with an increasing number of new materials, from superalloys of metals manufactured conventionally as well as via additive manufacturing to functionally advanced composites. Against this background, fundamental knowledge of the fatigue behavior and fracture mechanics of different material groups provides a convenient platform for communication between different interested groups and fields, from material science, numerical engineering and mathematical modeling to hybrid methods for fatigue life prediction.

This Special Issue presents the latest research findings on crack growth and fatigue damage in metallic materials. The latest achievements in experimental research and the modeling of static and cyclic loads are presented. Fundamental research insights as well as practical predictions are presented, including the influence of microstructure, defect assessment, damage analysis, mathematical modelling, numerical simulation and S-N curve parameters. For this Special Issue, 16 submissions were received and 14 papers were published, attracting submissions from 10 countries around the world.

We would also like to express our most profound appreciation to the MDPI Book staff; the editorial team of the *Materials* journal, especially Mr. Felix Guo; the Assistant Editor of this Special Issue; the talented authors; and the hardworking and professional reviewers.

> **Grzegorz Lesiuk and Dariusz Rozumek** *Editors*
