**1. Introduction**

Additive Manufacturing (AM) has emerged as a game-changer in the field of aerospace engineering, providing new opportunities for the design and manufacture of complex structures and systems with improved thermo-mechanical properties [1–5]. Currently, one of the key challenges in aerospace engineering is the development of low power effective anti-ice systems, which are essential for ensuring safe and efficient operations in cold and icy conditions [6–8]. State-of-the-art anti-icing systems use hot air spilled from the turbine engine compressors [9]. These systems present low thermal efficiencies and high losses [10–13]. In recent years, lattice structures made of AlSi10Mg alloy have emerged as a promising candidate for the development of innovative anti-ice systems [14–16]. Lattice structures indeed present interesting thermal and mechanical properties for heat and structure components making them the ideal candidate for a novel anti-icing material to integrate into the leading edge structure (Figure 1). The emerging benefit could be a sensible reduction of the air spilled and therefore, a reduction of the fuel consumption. Unfortunately, lattice structures in the core of the sandwich panel are subjected to cyclic loads. Being able to predict the fatigue strength under cyclic loading is currently one of the greatest challenges [17,18]. A search of the literature revealed a few studies, which experimentally evaluated the fatigue curves of lattice structures made of AlSi10Mg fabricated by AM [19,20]. In order to fill the gap between the requirements for a safe design of a critical component and the available literature, an extensive analysis campaign has been developed. This paper presents results aimed at investigating the fatigue strength of lattice structures made of AlSi10Mg alloy fabricated by AM in order to provides insights into the design of innovative systems for aerospace applications [21].

**Citation:** Ferro, C.G.; Varetti, S.; Maggiore, P. Experimental Evaluation of Fatigue Strength of AlSi10Mg Lattice Structures Fabricated by AM. *Aerospace* **2023**, *10*, 400. https://doi.org/10.3390/ aerospace10050400

Academic Editor: Andrea Di Schino

Received: 8 March 2023 Revised: 28 March 2023 Accepted: 21 April 2023 Published: 25 April 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

**Figure 1.** Integrated Anti-Ice Panel. (**a**): Isometrical View of the proposed novel anti-ice panel (**b**): Cross Section of the patented solutions.

Fatigue strength is a crucial parameter in the design of aerospace components, especially those that are subjected to cyclic loading. Lattice structures, also known as cellular or honeycomb structures, are highly desirable due to their lightweight nature and high stiffness-to-weight ratio [22–24]. They have been used in various applications, including heat exchangers, sandwich panels, and energy absorption systems [25–28]. AlSi10Mg is an aluminum alloy that has been extensively used in AM due to its excellent mechanical properties and good weldability [29]. In the case of anti-ice systems, lattice structures made of AlSi10Mg have been proposed as a potential solution due to their ability to provide excellent anti-ice performance by allowing a continuous flow of hot air to pass through the structure, thus melting the ice on its surface [21,30]. However, the fatigue strength of these structures is not well understood, which poses a significant challenge in their design and optimization. The experimental study presented in this paper involved the testing of AlSi10Mg lattices fabricated by AM under cyclic loading to determine their fatigue limits. The results of this study will provide new insights into the behavior of these structures under cyclic loading and will help in understanding their failure mechanisms. The findings will also aid in the development of design guidelines for lattice structures and will enable the optimization of innovative anti-ice systems for aerospace applications [31]. In summary, the experimental evaluation of the fatigue strength of lattice structures is of strong significant interest to the aerospace industry.

## **2. Materials and Methods**
