Design and analysis of energy absorbent bioinspired lattice structures

The increasing demand for energy absorbent structures, paired with the need for more efficient use of materials in a wide range of engineering fields, has led to an extensive range of designs in the porous forms of sandwiches, honeycomb, and foams. To achieve an even better performance, an ingenious solution is to learn how biological structures adjust their configurations to absorb energy without catastrophic failure. In this study, we have attempted to blend the shape freedom, offered by additive manufacturing techniques, with the biomimetic approach, to propose new lattice structures for energy absorbent applications. To this aim we have combined multiple bio-inspirational sources for the design of optimized configurations under compressive loads. Periodic lattice structures are fabricated based on the designed unit cell geometries and studied using experimental and computational strategies. The individual effect of each bio-inspired feature has been evaluated on the energy absorbance performance of the designed structure. Based on the design parameters of the lattices, a tuning between the strength and energy absorption could be obtained, paving the way for transition within a wide range of real-life applicative scenarios

Multiaxial fatigue of additively manufactured metallic components: a review of the failure mechanisms and fatigue life prediction methodologies

Additive manufacturing techniques offer significant advantages over conventional manufacturing methods. These include the possibility of realizing highly customized components in which not only can the geometry be defined with a high degree of freedom, but the material composition or geometrical properties can also be manipulated throughout the component by introducing lattice structure zones. Such variations cannot be realized using conventional manufacturing techniques. However, the application of additively manufactured parts at the industrial scale is still limited owing to the high variability in mechanical properties, which also makes it difficult to define feasible tools to assess their structural integrity and determine their expected fatigue life with a sufficient degree of reliability. In addition, real components often experience multiaxial stresses at critical locations owing to their geometry or service-loading conditions. Thus, a proper under-standing of the fatigue performance of additively manufactured components with complex ge-ometries cannot neglect the consideration of multiaxial stress states. This review presents an overview of multiaxial fatigue in additively manufactured metallic components, providing in-sights into crack initiation sites and growth orientations and relating them to the fatigue failure mechanisms in these components. The principal life prediction methodologies applied for the fatigue damage assessment of additively manufactured components under multiaxial fatigue loading are presented, with a particular focus on their accuracy in correlating fatigue data ob-tained for different loading conditions

The fatigue behavior of V-notches in presence of residual stresses: recent developments and future outcomes

Residual stresses, arising from welding processes or nonhomogeneous plastic deformations, broadly influence the high cycle fatigue behavior of mechanical components. The presence of V-notches leads to singular residual stresses ahead of the notch tip and the asymptotic stress field can be described by the notch stress intensity factor (NSIF). However, plastic effects induce redistribution of residual stresses during cyclic loading and this variation is accounted in several numerical models developed for the calculation of the residual NSIFs. Due to the development of these models, the fascinating issue of predicting the fatigue strength of pre-stressed notched components has gained widely attention by the researchers and new approaches were recently developed and some of them are here reviewe

Fatigue of additively manufactured 316L stainless steel : the influence of porosity and surface roughness

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Role of metal 3D printing to increase quality and resource-efficiency in the construction sector

Demand for the construction of new structures is increasing all over the world. Since the construction sector dominates the global carbon footprint, new construction methods are needed with reduced embodied carbon and high resource efficiency to realize a sustainable future. In this direction, Metal Additive Manufacturing, also known as 3D printing, can be an opportunity. Many studies are underway to answer open questions about printed metal products and processes for high-tech industries. The construction sector must join the metal 3D printing research more actively to enrich the knowledge and experience on this technology and correctly adapt the process parameters suitable to the construction sector requirements. This paper states the opinion of a research group composed of academics and practitioners from Europe, the US, Japan, and South Africa on how metal 3D printing can be a complementary tool/technology to conventional manufacturing to increase productivity rates and reduce the costs and CO2 emissions in the construction industry