Behavior Of Lattice Structures Research Articles

Micro-macro analysis of Hyperelastic auxetic lattice structures under finite-strain regime

This paper addresses the intricate analysis of lattice structures, pivotal components in engineering applications, confronted by challenges arising from their diverse unit cells (UCs) and complex behavior across micromechanical and macro-scale dimensions. The present study deals with a comprehensive analysis of lattice structure with honeycomb and re-entrant auxetic unit cells under large deformation via both a robust finite element analysis (FEA) and experimental tests. The proposed FEA is developed based on the hyperelastic Mooney–Rivlin strain energy function and the novel exact motion field that can fully describe the projection of cross-section. The results demonstrate that mechanical parameters such as Young's modulus, Poisson's ratio, and shear modulus have significant nonlinear behaviors with respect to UC geometrical parameters that are crucial for optimization across varied operational conditions. Additionally, the lattices made of TPU material and fabricated by Fused Deposition Modeling are tested under three-point bending and compression considering contact interaction. The results reveal highly nonlinear responses due to instabilities in some links and material nonlinearity. Furthermore, the behavior of lattice structures is exceedingly dependent on the orientations and types of UCs. It also can be found that both of the proposed FEA and constitutive model are in good agreement with experimental data.

Finite element modelling of lattice angle steel structures exposed to wildland fires

Essential civil infrastructure such as transmission line supporting towers and communication base towers that are traditionally formed from lattice angle steel structures are critical global assets, since their development promotes the establishment of electric power supply systems and modern telecommunication networks. Because this infrastructure is commonly located in rural and urban wildland areas, such towers may be prone to wildland fire attack, particularly in the current climate of severe heatwaves and droughts. Accordingly, a comprehensive study of the behaviour and response of lattice angle steel structures under fire loading is needed to assist in structural design to resist fire loading. In this paper, a finite element (FE) model of lattice angle steel structures is constructed using ABAQUS software. Several aspects that include material and geometric non-linearities, load eccentricities on component members, bolted joint slippage, and the use of the explicit dynamic analysis technique for a quasi-static loading procedure, are considered and applied in the FE model. The accuracy and reliability of the FE representation are validated by comparing its predictions with relevant existing experimental results. By incorporating the codified temperature-dependent material properties of structural steel as well as a calibrated load-slip relationship for bolted connections at elevated temperatures, the FE model is extended for performing structural fire analysis. The variations of the steelwork temperatures in wildland fires can be calculated based on representative temperature-time wildland fire curves and is adopted in the fire analysis. By invoking the FE model, an example of lattice angle steel structures is contrived to elucidate the fundamental behaviour of these structures in wildland fires, through both steady and transient state fire analyses. Parametric studies are also undertaken to evaluate the effects of the changes in the wind load direction, bolt pretension and the protection of critical panel sections on the behaviour of lattice structures when exposed to wildland fires.

Dynamic compression and impact analyses of the lattice structures for battery safety

In this study, a battery pack consisting of 18650-lithium-ion cells and battery housing was designed considering lattice structures instead of the plain sheet to improve crashworthiness. The behavior of lattice structures, including a novel design, cross semicircle, semicircle lattices, and topology-optimized model, in total seven different lattice models in dynamic compression and impact loading were examined. Displacement, energy absorption, and specific energy absorption values were compared with the 1.5 mm thick plain sheet model, which is common in the market. In the dynamic compression loading, honeycomb, and plain sheet models absorb more energy with the value of 97.34, and 88.67 J, respectively. Specific energy absorption is best for the plain sheet with the value of 3122.05 J/g, but honeycomb and cross semicircle lattices still have an impressive result of 2923.04, and 2158.30 J/g respectively. On the other hand, in the impact loading, the plain sheet is causing the jellyroll deformation with the highest value of 141.65 MPa, while the best protective structure is 3D kagome with a value of 4.85 MPa. However, the cross-semicircle keeps an average safety performance for both loading conditions.

Nonlinear static and dynamic modeling of energy absorption lattice structures behavior

Belonging to cellular solids subclasses, lattice structures have recently obtained much interest in the lightweight engineering sector thanks to the potential of their specific structural properties. This investigation explores the mechanical properties of lattice cells selected for their energy absorption capacity while considering strut orientation angle, vertical reinforcement, combination of cells and aspect ratio as geometrical and topological parameters. Truss lattices are examined given their excellent results from the point of view of energy absorption behavior. While non-linear static analyses are used to determine both volumetric and specific energy absorption, dynamic calculations are employed to identify the densification point and assess on the crashing load efficiency of the considered cells. This contribution aims at providing a deeper understanding of the mechanical behavior of lattice structures in order to provide construction guidelines that can be employed in rapid prototyping and design of lightweight structures.

The Static and Fatigue Behavior of AlSiMg Alloy Plain, Notched, and Diamond Lattice Specimens Fabricated by Laser Powder Bed Fusion

The fabrication of engineered lattice structures has recently gained momentum due to the development of novel additive manufacturing techniques. Interest in lattice structures resides not only in the possibility of obtaining efficient lightweight materials, but also in the functionality of pre-designed architectured structures for specific applications, such as biomimetic implants, chemical catalyzers, and heat transfer devices. The mechanical behaviour of lattice structures depends not only the composition of the base material, but also on the type and size of the unit cells, as well as on the material microstructure resulting from a specific fabrication procedure. The present work focuses on the static and fatigue behavior of diamond cell lattice structures fabricated from an AlSiMg alloy by laser powder bed fusion technology. In particular, the specimens were fabricated with three different orientations of lattice cells—[001], [011], [111]—and subjected to static tensile testing and force-controlled pull–pull fatigue testing up to 1 × 107 cycles. In parallel, the mechanical behavior of dense tensile plain and notched specimens was also studied and compared to that of their lattice counterparts. Results showed a significant effect of the cell orientation on the fatigue lives: specimens oriented at [001] were ~30% more fatigue-resistant than specimens oriented at [011] and [111].

Indirect determination of the mechanical properties of stochastic lattices

Determination of the mechanical behaviour of lattice structures has become a necessity to successfully implement lightweight concepts in various applications. Due to the large surface to volume ratio of these structures, the computational effort required for the FE simulation of models incorporating lattices is significantly increased mainly because of the large finite elements number which are necessary to accurately describe the complex input geometry. In this work a simple solution is employed in order to calculate the stress – strain properties, using a bilinear material law and equivalent bulk geometry. The verification of the FE model is fulfilled through the comparison of the lattice deformation and compressive force between experimental data and FE calculated results. After the verification of the FE model, it was possible to determine the mechanical behaviour of stochastic lattices, for an extended range of the investigated parameters, using only computational tools.