**Preface to "Mechanics of Corrugated and Composite Materials"**

One of the challenges in research by modern engineers is the acquisition of new materials for the creation of various constructions in order to improve their properties, including mechanical ones. One possible way to achieve this goal is through composite materials. Moreover, the use of such materials in various real constructions leads to material, cost, energy and environmental savings, e.g. by reducing the weight of the products, significant reductions in fuel consumption, exhaust emissions and costs during transport can be achieved. Therefore, composite materials are of great practical importance, as seen in various applications in the automotive and aerospace industries, building construction and many other fields.

Composite materials are inhomogeneous materials consisting of at least two various materials of different properties. Considering the construction of the composites, one can distinguish some typical examples, e.g., fibrous composites, when one component of the composite is made of fibers and the other is called a matrix. Another kinds of composite materials are sandwich or layered plates, in which their components are arranged in layers. Both of them have a wide range of applications in various engineering fields. On the other hand, there are multiple methods for analyzing the mechanical properties of these composites, including experimental, analytical or numerical studies. Corrugated cardboard, commonly used in the packaging industry, is a special type of corrugated material. In the case of corrugated cardboard boxes, the key is to obtain a durable and stable structure with a relatively low weight.

Another important issue is the modeling of structures made of composite or corrugated materials. Their specific design and heterogeneity make it very expensive to build a complete model while maintaining all the details and is thus also very time-consuming. Therefore, both the material of individual components (layers) and the cross-sectional geometry are usually a priori homogenized to simplify and speed up the calculations. The simplification should not, however, distort the results that would be obtained using the full model. Therefore, the selection of an appropriate homogenization method is often a key issue when analyzing structures made of corrugated or composite materials.

This Special Issue is devoted to the mechanics of composite materials, particularly corrugated materials, e.g., corrugated cardboard or multilayer boards with a soft core. In addition, the articles published in this Special Issue of *Materials* present different approaches to the research and application of various computational methods and the homogenization of selected composite materials.

Finally, we take this opportunity to express our most profound appreciation to the MDPI Book staff; the editorial team of *Materials*, especially Ms. Daisy Liu, the managing editor of this Special Issue; all of the authors; and all of the professional reviewers.

## **Tomasz Garbowski, Tomasz Gajewski, and Jakub Krzysztof Grabski** *Editors*
