###### Abstract  
This Special Issue presents the latest advances in the field of fatigue and fracture performances of additively manufactured mechanical components, including components made of traditional materials (metals, sintered steels, etc.) but undergoing complex loading conditions (multiaxial fatigue and mixed mode fracture). This Special Issue is composed of seven papers covering new insights in structural and material engineering. The advent of additive manufacturing (AM) processes applied to the fabrication of structural components creates the need for design methodologies and structural optimization approaches that take into account the specific characteristics of the process. While AM processes give unprecedented geometrical design freedom, which can result in significant reductions of component weight (e.g., through part count reduction), they have implications in the fatigue and fracture strength due to residual stresses and microstructural features. This is due to stress concentration effects and anisotropy that still need research. The papers of this Special Issue report on numerical simulation and experimental work, or a combination of both. The application of damage and fracture mechanics concepts, the appraisal of stress concentration effects, and the consideration of residual stresses and anisotropic behaviour are tackled for a range of structural applications from biomedical engineering to aerospace components. fatigue; fracture; additive manufacturing; finite element method (FEM) 20202  
The understanding of the mechanical behaviour and its incorporation into design practice is made through structural analysis, and this subject is also of interest for this Special Issue. Computational mechanics progressed from the traditional finite element method (FEM) and dual boundary element method (DBEM) approaches to combined/hybrid and multiscale analyses that may accurately model and predict crack paths and damage within controlled computational effort. The purpose of this Special Issue is to draw the attention of the scientific community to recent advances in modelling and optimizing the structural behaviour of advanced materials and their possible applications, while also considering non-destructive testing and evaluation. Theoretical, numerical, and experimental contributions describing original research results and innovative concepts on materials and structures were collected. This Special Issue includes several high-quality papers written by leading and emerging specialists in the field. Among the articles collected, a number of high-quality papers existed, which led to seven published articles. A very short description of the addressed topics, in the order of themes cited below, is presented. When studying the performance of additively manufactured components, an important issue is related to the correct design of the specimen in fatigue testing. In the property characterization of additive manufacturing materials, mini specimens are preferred due to the specimen preparation and manufacturing cost, but mini specimens demonstrate higher fatigue strength than standard specimens due to the lower probability of material defects resulting in fatigue. In Reference [1], a novel adaptive displacement-controlled test set-up was developed for fatigue testing using mini specimens. In this study, a dual gauge section Krouse type mini specimen was designed to conduct fatigue tests on additively manufactured materials. A fully reversed bending (R = -1) fatigue test was performed on simply supported specimens. The fatigue performance of the wrought 304 and additively manufactured 304L stainless steel was compared applying a control signal monitoring (CSM) method. The test results and analyses were useful to validate the design of the specimen and the effective implementation of the test bench in the fatigue testing of additively manufactured materials. It was proven that surface integrity alteration induced by the machining process or AM has a profound influence on the performance of a component.