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This paper describes a class of lattice metamaterials with tunable mechanical properties controlled by the material modulus and structural parameters of the cellular units. The deformation shapes can also be changed by external control. We have developed 3D printed quadrilateral cellular TPU units with specially shaped edge walls. A simplified mechanical model of the different cell deformation processes is established and verified by numerical simulations and experiments. On this basis, by tessellating and matching these transformations together, we create assembly grids with adjustable stiffness and deformation shapes controlled by thermal and displacement constraints. [ABSTRACT FROM AUTHOR]

Fault tolerance refers to the ability of a system to continue functioning even if some of its components fail. This concept is fundamental in several domains because reliability and continuous operation are essential in carrying out their functions. Graph embedding means mapping a graph into some other structure that preserves some of the properties or relations held by the original graph. Applications in machine learning, data mining, and network analysis make fault-tolerant embedding of graphs a crucial topic. In this paper, fault-tolerant embeddings are proposed in Archimedean tessellations. The path in the embeddings does not intersect or overlap. [ABSTRACT FROM AUTHOR]

Aluminum alloy lattice structures have important application prospects in modern engineering, construction, and lightweight manufacturing of key industrial components. The current "dot-by-dot" manufacturing method, using Wire Arc Additive Manufacturing (WAAM) with Cold Metal Transfer (CMT) as the heat source is an important way to achieve integrated manufacturing of large-sized and complex aluminum alloy lattice structure. In this paper, a detailed study is conducted on the design and prototype manufacturing of aluminum alloy dot-by-dot deposition process. Single strut design, "X lattice unit" design and geometric parameter design are explored through characterization of both microstructural and mechanical properties. The porosity, microstructure, and mechanical properties of the lattice strut in different areas were studied. The majority of pores were present between each layer deposition and accumulated in the line bridge area. A detailed discussion was then conducted on the formation mechanism of pores in aluminum alloy struts and the deposition strategy of the so-called X lattice unit. Finally, the manufacturing of a circular lattice structure composed of X lattice unit was achieved through deposition strategies control. [ABSTRACT FROM AUTHOR]

Lightweight lattice structure is of great significance in the fields of aerospace thermal protection and energy absorption. In this study, compressive properties and energy‐absorbing characteristics of additively manufactured body‐centered cubic (BCC) lattice structures of a high‐temperature titanium matrix composite (TMC) are investigated systematically. It is found that compressive strength increases monotonically as either lattice strut diameter or temperature increases. With lattice strut diameter increasing from 1.0 to 1.5 and 2.0 mm, strength increases from 78 to 94 and 108 MPa at room temperature (RT) and from 71 to 104 and 123 MPa at 650 °C. Unexpectedly, specific energy absorption (SEA) capability increases as strut diameter decreases, although also increases as temperature increases. BCC lattice structure with a strut diameter of 1.0 mm presents the highest SEA being up to 13.7 MJ m−3 at RT and 142 MJ m−3 at 650 °C. And sphericizing the lattice nodes is found incapable of enhancing strength and SEA. Besides, numerical simulation is used to demonstrate the compressive stress and strain fields, in order to explain the fracture modes and SEA capability of individual BCC lattice structures. This study provides deep insights into the mechanical properties and energy absorption behavior of additively manufactured lattice structures of TMCs. [ABSTRACT FROM AUTHOR]

Node reinforcement represents an effective strategy for enhancing the mechanical properties of lattice structures. Herein, four types of body‐centered‐cubic with Z‐strut (BCCZ) lattice structures with different node arrangements are fabricated using laser powder bed fusion (LPBF) technology. The surface morphology of four node‐reinforced BCCZ lattice structures fabricated by LPBF is examined using scanning electron microscopy. Quasistatic compression tests are conducted on these four types of node‐reinforced lattice structures. The experimental results show that the mechanical properties of all samples with node‐reinforced BCCZ lattice structures are superior to those of the traditional BCCZ lattice structure. Furthermore, the mechanical properties of the lattice structure improve in proportion to the density of the reinforced node sphere arrangement. Concurrently, an analysis of the deformation behavior of the BCCZ lattice structure with node reinforcement reveals that the TFB‐3 exhibits shear band formation at a strain level of 6.2%, which is the highest strain among all the tested structures. The results indicate that the diagonal reinforcement strategy can significantly minimize the formation of shear bands and enhance the mechanical properties of BCCZ lattice structure. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM) technology offers remarkable flexibility in fabricating products with intricate geometries, presenting unprecedented advantages in material efficiency and speed. The process planning of AM plays a pivotal role in ensuring overall quality and time-efficiency of printed products. This drives engineers and researchers to explore various approaches to achieve optimal AM process solutions. However, numerous challenges persist, particularly in logical relationship reasoning and information representation for complex manufacturing tasks and design requirements. In this study, a novel AM process reasoning method based on relation mining is proposed, leveraging knowledge graph representation and graph neural networks (GNN). An AM knowledge graph is constructed comprising essential process information, followed by implementing RED-GNN to accomplish graph reasoning tasks for parameter recommendation. We then focus on the process planning scenario of lattice structures, a common geometry used for designing products with weight-relief requirements and high sensitivity to process parameters. A series of lattice structure parts are designed and tested using our proposed method, demonstrating strong performance and unveiling new potentials and opportunities in advancing knowledge-based engineering and intelligent manufacturing. [ABSTRACT FROM AUTHOR]

Lattice structures, characterized by their repetitive, interlocking patterns, provide an efficient balance of strength, flexibility, and reduced weight, making them essential in fields such as aerospace and automotive engineering. These structures use minimal material while effectively distributing stress, providing high resilience, energy absorption, and impact resistance. Composed of unit cells, lattice structures are highly customizable, from simple 2D honeycomb designs to complex 3D TPMS forms, and they adapt well to additive manufacturing, which minimizes material waste and production costs. In compression tests, lattice structures maintain stiffness even when filled with powder, suggesting minimal effect from the filler material. This paper shows the principles of creating finite element simulations with 3D-printed specimens and with usage of the lattice structure. The comparing of simulation and real testing is also shown in this research. The efficiency in material and energy use underscores the ecological and economic benefits of lattice-based designs, positioning them as a sustainable choice across multiple industries. This research analyzes three selected structures—solid material, pure latices structure, and boxed lattice structure with internal powder. The experimental findings reveal that the simulation error is less than 8% compared to the real measurement. This error is caused by the simplified material model, which is considering the isotropic behavior of the used material PA12GB (not the anisotropic model). The used and analyzed production method was multi jet fusion. [ABSTRACT FROM AUTHOR]

In the current study, a new type of novel lattice structures with the concept of bio-mimicking three different nature-inspired designs from the honeycomb patterns, the overlapping phenomenon of the scales present on fish dermal layers, and scutes pattern observed from the top skin layers present on crocodile species are developed. These lattice structures are designed within a cubic volume of 30 mm. The design of lattice unit cells is made with two different geometrical sizes of 4 and 6 mm with different overlapping areas of 20, 30, 40, and 50% calculated from each cell area. All the unit cells' walls are maintained at 0.4 and 0.6 mm only. The specimens are modeled and manufactured through the VAT photopolymerization process, one of the significant additive manufacturing principles for great dimensional accuracy with negligible defects in 3D printing (3DP). The research approach used to develop lightweight bio-inspired structures has been laid out, starting with observing design that served as inspiration. The cured 3D-printed specimens are examined under quasi-static compressive loading carried out on all specimens as per ASTM 1621 standards to measure the crashworthiness response of designed specimens. The energy ingestion capacity of all the specimens is assessed. A good correlation is observed between the experimental and numerical results for better validation. The best design parameters among all 16 specimens are identified for applying energy absorption applications in the automobile and aviation fields in real-time. [ABSTRACT FROM AUTHOR]

This study investigates the design of additive manufacturing for controlled crack propagation using process parameters and lattice structures. We examine two lattice types—octet-truss (OT) and diamond (DM)—fabricated via powder bed fusion with Ti-6Al-4V. Lattice structures are designed with varying densities (10%, 30%, and 50%) and process using two different laser energies. Using additive-manufactured specimens, Charpy impact tests are conducted to evaluate the fracture behavior and impact energy levels of the specimens. Results show that the type of the lattice structures, the density of the lattice structures, and laser energy significantly influence crack propagation patterns and impact energy. OT exhibits straighter crack paths, while DM demonstrates more random fracture patterns. Higher-density lattices and increased laser energy generally improve the impact energy. DM consistently outperformed OT in the impact energy for angle specimens, while OT showed superior performance in stair specimens. Finally, a case study demonstrates the potential for combining OT and DM structures to guide crack propagation along predetermined paths, offering a novel approach to protect critical components during product failure. [ABSTRACT FROM AUTHOR]

Multi-material lattice structures demonstrate superior mechanical advantages and lightweight potential, enabling it preferable in many engineering fields, especially with the rise of additive manufacturing. However, employing multi-scale topology optimization inherently involves computational complexities of designing the macromaterial distribution and microlattice geometric size simultaneously. In this paper, a modified relative density mapping (MRDM) method is proposed, which generates a multi-material lattice structure by projecting the continuum multi-material topology optimization results. The proposed method extends the standard relative density mapping (RDM) method to multi-material problem and improves the performance. To achieve such purpose, a new mapping relation considering multi-material density and stress information is introduced to generate mapping weight of materials, which is the most novel contribution. Second, to avoid intersection of different materials, two types of material mapping strategies, namely continuous mapping strategy, and discrete mapping strategy, are introduced to generate multi-material lattice structure using the mapping weight of materials. Several numerical examples are exhibited, which demonstrate that the proposed method is capable of generating a multi-material lattice structure with clear material interface and good performance. [ABSTRACT FROM AUTHOR]

This paper compares the results of a theoretical approach, finite element analysis (FEA) and mechanical tests of monolithic TA6V Dode-Thin lattice core sandwich structures manufactured by powder bed laser beam melting process. An analytical approach to evaluate the mechanical properties of one Dode-Thin strut is briefly presented. The strut is then replaced by an equivalent beam whose cross-section is a solid circle. Various finite element (FE) models are used to calculate the effective mechanical properties of a defect-free structure and compared to the analytical results of beam theory. Besides the calculations, different experimental tests and measurements are carried out to measure the stiffness of the sandwich beams. These experiments show that both theoretical and numerical predictions significantly overestimate the stiffnesses. The discrepancies between the models and the as-built components are mainly due to geometrical imperfections and internal defects (porosity) caused by the AM process. Optical observations and X-ray computed tomography (CT) are then performed to determine the actual cross-sectional properties of the struts. Finally, this study provides the engineer with a simple method to replace a Dode-Thin strut with an equivalent beam of solid circular cross-section, and to define the equivalent 3D-orthotropic material with homogenized mechanical properties. Another contribution of this work is the insight into the as-built physical parameters to improve the correlation between models and experimental data. [ABSTRACT FROM AUTHOR]

Multicell design and lattice structure as filling material are two effective methods for enhancing the energy absorption performance of thin‐walled tubes. This study combines these two approaches to present a multicell tube with a novel lattice structure and investigates the energy absorption performances of these hybrid multicell tubes under axial (0°) and oblique (10°, 20°, and 30°) impact loading conditions. As filling structure, β‐Ti3Au lattice geometry with varying lattice strut diameters and the number of lattice unit cells are used, while the single and multicell thin‐walled tubes with different tube thicknesses are employed as main absorbing element. In this context, the effects of numbers of lattice unit cells, lattice strut diameter, cell numbers of the tube, and tube thickness on energy absorption performance of hybrid tubes are examined using validated nonlinear finite element models. This investigation unveils that the synergistic interplay between the multicell tubes and lattice structure during deformation significantly elevates the energy absorption performance of the hybrid structure. Notably, the findings demonstrate that multicell hybrid tubes exhibit a remarkable capacity to absorb up to 30.36% more impact energy compared to the aggregate absorption of individual components in hybrid tubes. [ABSTRACT FROM AUTHOR]

The objective of this research is to explore the scale effect on the mechanical properties of sheet‐based triply periodic minimal surface (TPMS) uniform lattice structures fabricated with PLA (polylactic acid) under quasi‐static loading conditions. The scale dependency was evaluated by two additional breakdown categories, namely, wall thickness effect and unit cell size effect. Deformation mechanisms and failure modes as well as mechanical properties including stiffness, yield strength, first peak stress, and energy absorption based on the categories of wall thickness, unit cell size, and scale were evaluated experimentally. The assessment of the scale effect involved considering the combined influence of wall thickness and unit cell size. In addition, numerical analysis was also performed to investigate the stress distributions and compare with the experimental results for certain geometries. Ultimately, the relation between the normalized mechanical properties and relative density is evaluated and categorized, which can be used as an indication for future design practices. Highlights: Scale, wall thickness, and unit cell size effect of lattice structures were studied.Relative density played a significant role in determining mechanical properties.Unit cell size to wall thickness ratio is critical for different failure mechanisms.Normalized mechanical properties were evaluated for the future design. [ABSTRACT FROM AUTHOR]

3D Kagome lattice sandwich structure is recognized as the most excellent lattice configuration. However, the preparation method of 3D Kagome is complicated and the raw materials for its preparation are limited to materials with high plasticity. In this study, we developed a wood-based 3D Kagome lattice structure that combines discrete rods into a continuous core using reinforcement. Orthogonal tests, theoretical analysis, and finite element simulations were performed to investigate the correlation between the dimensional parameters, the mechanical properties, and the energy absorption capacity. The damage modes were found to be mainly bending fracture, core shear, and panel rupture, with the use of reinforcement affecting the damage modes. Compressive properties of the 3D Kagome lattice structure are increased by increasing core diameter and inclination degree, decreasing core in-cut diameter, and using high-strength reinforcements. Finite element simulations further confirm that the use of high-strength reinforcements changes the stress distribution of the lattice structure. The 3D Kagome lattice structure with an inclination degree of 65°, a core diameter of 10 mm, a reinforcement wall thickness of 2 mm, and a core in-cut diameter of 2 mm has the optimal compression performance and energy absorption capacity. [ABSTRACT FROM AUTHOR]

Lattice structures show advantages in mechanical properties and energy absorption efficiency owing to their lightweight, high strength and adjustable geometry. This article reviews lattice structure classification, design and applications, especially those based on additive manufacturing (AM) technology. This article first introduces the basic concepts and classification of lattice structures, including the classification based on topological shapes, such as strut, surface, shell, hollow-strut, and so on, and the classification based on the deformation mechanism. Then, the design methods of lattice structure are analyzed in detail, including the design based on basic unit, mathematical algorithm and gradient structure. Next, the effects of different lattice elements, relative density, material system, load direction and fabrication methods on the mechanical performance of AM-produced lattice structures are discussed. Finally, the advantages of lattice structures in energy absorption performance are summarized, aiming at providing theoretical guidance for further optimizing and expanding the engineering application potential of lattices. [ABSTRACT FROM AUTHOR]

The increasing application of additively manufactured (AM) materials in engineering and biomedical fields highlights the necessity of understanding their mechanical behavior, particularly with complex lattice structures. Polylactic acid (PLA), a popular biopolymer in additive manufacturing, exhibits mechanical characteristics highly dependent on its structural design. This research investigates the quasi‐static puncture failure analysis and mechanical characteristics of additively manufactured (AM) polylactic acid (PLA) materials with various lattice structures. The mechanical behavior, including tensile strength, flexural properties, interlaminar shear strength (ILSS), Izod impact resistance, and quasi‐static punch shear strength (QS‐PSS), was investigated following the respective ASTM protocols. Results indicate a 6% increase in tensile strength, to ca. 28 MPa, for the triangular PLA lattice structure compared with plain lattice structures. In the flexural test, the hexagonal structure showed a 13% increase in bending strength, to ca. 45 MPa, compared with the plain structure. Additionally, the hexagonal PLA lattice structure exhibited a 24% increase in shear strength, to approximately 8 MPa, over the plain lattice structure in the interlaminar shear strength analysis. In the Izod impact analysis, the plain lattice structure demonstrated a 17% increase in impact strength, to ca. 278 J/m, compared with the circular structure. A stainless‐steel hemispherical indenter was employed to investigate the quasi‐static punch shear behavior (QS‐PSS) of different lattice structures. The triangular structure displayed increased total energy absorption capacity and specific energy absorption of ca. 19 J and 0.529 J/g, respectively, compared with other lattice structures. These results are important for the creation of additively manufactured PLA lattice structures, improving the puncture resistance of advanced composites. Highlights: Polylactic acid (PLA) lattice structures were fabricated.Plain, circular, triangular, and hexagonal lattice structures were investigated.Lattice structures were used as reinforcements.The triangular structure demonstrated improved strength.The triangular structure reduced crack formation and propagation. [ABSTRACT FROM AUTHOR]

Additive manufacturing provides new possibilities in product design compared to traditional manufacturing processes. Particularly additive material extrusion offers the freedom to combine multiple materials in a single component without additional steps. However, combining multiple materials often leads to reduced adhesion, which can hinder the creation of high-strength designs. This issue can be largely mitigated using the geometric freedom of additive manufacturing to produce interlocking structures. This publication investigates the use of lattice structures as interlocking bonds in multi-material applications. The aim is to aid the design of suitable lattice structures by collecting geometric freedoms of lattices, application requirements, and manufacturing constraints, for this information to be used in suitable designs in the future. Initially, the general design freedoms of lattice structures are compiled and explained. Subsequently, these design freedoms are narrowed down based on the specific requirements for interlocking bonds and the limitations imposed by geometry and material combinations during manufacturing. The publication concludes with design recommendations that can be used as the basis for interlock bonds. Suitable lattice designs should aim for high interconnectivity, interconnected porosity, and a high number of similar strut structures, all the while maintaining low dimensions in the interface direction. [ABSTRACT FROM AUTHOR]

The application of two-dimensional lattice structures is increasingly prevalent due to their significant potential in various multifunctional applications such as energy absorption, heat dissipation, and sound insulation. Similar to phononic crystals, lattice structures exhibit periodicity, and being composed of lightweight rods, they are sensitive to vibrations. Incorporating the concept of acoustic metamaterials into lattice structures can facilitate the design of lattices with vibration isolation properties. However, the low-frequency bandgaps generated by local resonances in lattice structures tend to be narrow. To widen the frequency range of these low-frequency bandgaps, several studies have emerged. This study focuses on rapidly optimizing the phononic bandgaps of two-dimensional lattice structures, aiming to efficiently and accurately determine the optimal geometry of each truss unit, thereby exhibiting outstanding vibration (elastic wave) isolation within a specific frequency range (bandgap). The proposed approach employs an Extended Multiscale Finite Element Method (EMsFEM) to achieve equivalence in the mechanical performance of truss structures, enabling the rapid computation of bandgap optimization for lattice structures with large-scale truss units. The results illustrate the effectiveness and feasibility of this method, which can attain broadband low-frequency bandgaps without compromising computational efficiency. [ABSTRACT FROM AUTHOR]

The modern additive manufacturing process enables the fabrication of innovative structural designs of lattice structures with enhanced mechanical properties. Characterizing the designability of lattice geometries and the corresponding mechanical performance, particularly the compressive strength is vital to commercializing lattice structures for lightweight components. In this paper, a Novel hybrid type of lattice structure was developed inspired by the overlapping pattern of scales on dermal layers of the species like fish and circular patterns observed from the bamboo tree structure. This research designed the lattice cell with 20%,30%,40%, and 50% overlapping areas based on the proposed circular area. The unit cell wall thickness varies between 0.4 mm and 0.6 mm. The designed structures with a constant volume of 40x40x40 mm, varied circular diameters, overlapping areas, and unit wall thickness are modeled in Fusion 360 software. 3D-printed lattice structures were fabricated using the vat polymerization type three-dimensional printing machine using the principle of stereolithography (SLA) technique. Then, the 3D-printed specimens are tested for quasi-static compressive response in a universal testing machine (UTM) by following ASTM standards. The test results are evaluated and compared with the simulation results. Finally, the best lattice structure is selected for energy absorption application in the aerospace and defense sectors. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Computer-Aided Design & Computer Graphics / Jisuanji Fuzhu Sheji Yu Tuxingxue Xuebao is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel 3D centrosymmetric lattice that exhibits a large twist angle during compression is proposed by tailoring the twist buckling mode of a body-centered cubic lattice and a simple cubic truss to the first. The imperfections of offset and multimaterial systems are introduced to control the twist direction. Effects of geometrical parameters and material properties on twist behavior are studied. Results suggest that the buckling-driven lattice configuration can twist at an angle of 100° and an average angle per unit axial strain of 6.7°/%. The novel configurations can be used as force switches, safety devices, and temperature-controlled transmission devices. [ABSTRACT FROM AUTHOR]

This paper presents novel configurations for additively manufactured lattice structures, including helical and elliptic designs, in addition to the pyramid base model. Functionally graded versions of the pyramid and elliptic lattice structures are developed by considering desirable relative densities in each layer. The lattice structures were manufactured using Ti-6Al-4V powder in a three-dimensional selective laser melting printer. The averaged porosities are 0.86, 0.91, 0.916, 0.93 and 0.74 for pyramid, functionally graded pyramid, elliptic, functionally graded elliptic and helical, respectively. The mechanical behavior of the lattice structures was characterized through compression tests using a universal testing machine and computationally analyzed using finite element code. The results indicate that the elliptic and functionally graded elliptic lattices have elastic moduli of 0.76 and 0.67 GPa, while the yield strengths are 41.32 and 32.24 MPa, respectively, in comparison to cancellous bone. Moreover, pyramid, functionally graded pyramid, and helical lattices show relatively lower elastic moduli of 0.57, 0.65 and 0.41 GPa and higher yield strengths of 54.1, 52.15 and 61.02 MPa, respectively. This could be an indication that they are fit for cortical bones. All samples have low elastic moduli coupled with high yield strengths. This could reduce or eliminate stress shielding, making them suitable for some load-bearing bio-inspired applications. A comparative study utilizing experimental and numerical models was conducted to evaluate the performance of the proposed designs. [ABSTRACT FROM AUTHOR]

In the present work, the influence of defects on the compressive response of octet‐truss AlSi10Mg lattice structure specimens produced with a selective laser melting process is investigated. The defect population in one cell, in two cells, and cubic specimens composed of 27 cells has been assessed with micro‐computed tomography (micro‐CT) analyses. The statistical distributions of the characteristic defect sizes, i.e., the equivalent diameter, the volume, and the surface, assessed in the lattice structure specimens and in volumes randomly extracted from a rectangular bar have been compared. Finally, the compressive behavior of lattice structure specimens has been simulated with a simplified damage‐tolerant finite element model accounting for the influence of defects and compared with experimental results. The analyses have proven that the defect population in volumes extracted from a rectangular bar can provide reliable simulated results, even if micro‐CT inspections of a unit cell or specimens made of several cells are suggested. Highlights: Manufacturing defects strongly influence the structural integrity of lattice structures.Defect volume, surface, and equivalent diameter are reliable characteristic defect sizes.The defect population should be assessed on multiple cells for damage‐tolerant design.Finite element analyses should model the influence of defect size. [ABSTRACT FROM AUTHOR]

Phononic crystals based on lattice structures provide important wave dispersion characteristics as band structures, showing excellent compatibility with additive manufacturing. Although the lattice structures have shown the potential for vibration suppression, a design guideline to control the frequency range of the bandgap has not been well established. This paper studies the dispersion characteristics of plane wave propagation in lattice-based mechanical metamaterials to realize effective vibration suppression for potential aerospace applications. Triangular and hexagonal periodic lattice structures are mainly studied in this paper. The influence of different geometric parameters on the bandgap characteristics is investigated. A finite element approach with Floquet–Bloch's principles is implemented to effectively evaluate the dispersion characteristics of waves in lattice structures, which is validated numerically and experimentally with a 3D-printed lattice plate. Based on numerical studies with the developed analysis framework, the influences of the geometric parameters of lattice plate structures on dispersion characteristics can mainly be categorized into three patterns: change in specific branches related to in-plane or out-of-plane vibrations, upward/downward shift in frequency range, and drastic change in dispersion characteristics. The results obtained from the study provide insight into the design of band structures to realize vibration suppression at specific frequencies for engineering applications. [ABSTRACT FROM AUTHOR]

The properties of each lattice structure are a function of four basic lattice factors, namely the morphology of the unit cell, its tessellation, relative density, and the material properties. The recent advancements in additive manufacturing (AM) have facilitated the easy manipulation of these factors to obtain desired functionalities. This review attempts to expound on several such strategies to manipulate these lattice factors. Several design-based grading strategies, such as functional grading, with respect to size and density manipulation, multi-morphology, and spatial arrangement strategies, have been discussed and their link to the natural occurrences are highlighted. Furthermore, special emphasis is given to the recently designed tessellation strategies to deliver multi-functional lattice responses. Each tessellation on its own acts as a novel material, thereby tuning the required properties. The subsequent section explores various material processing techniques with respect to multi-material AM to achieve multi-functional properties. The sequential combination of multiple materials generates novel properties that a single material cannot achieve. The last section explores the scope for combining the design and process strategies to obtain unique lattice structures capable of catering to advanced requirements. In addition, the future role of artificial intelligence and machine learning in developing function-specific lattice properties is highlighted. [ABSTRACT FROM AUTHOR]

Heat exchangers make it possible to utilize energy efficiently, reducing the cost of energy production or consumption. For example, they can be used to improve the efficiency of gas turbines. Improving the efficiency of a heat exchanger directly affects the efficiency of the device for which it is used. One of the most effective ways to intensify heat exchange in a heat exchanger without a significant increase in mass-dimensional characteristics and changes in the input parameters of the flows is the introduction of turbulators into the heat exchangers. This article investigates the increase in efficiency of heat exchanger apparatuses by introducing turbulent lattice structures manufactured with the use of additive technologies into their design. The study is carried out by numerical modeling of the heat transfer process for two sections of the heat exchanger: with and without the lattice structure inside. It was found that lattice structures intensify the heat exchange by creating vortex flow structures, as well as by increasing the heat exchange area. Thus, the ratio of convection in thermal conductivity increases to 3.03 times. Also in the article, a comparative analysis of the results obtained with the results of heat transfer intensification using classical flow turbulators is carried out. According to the results of the analysis, it was determined that the investigated turbulators are more effective than classical ones, however, the pressure losses in the investigated turbulators are much higher. [ABSTRACT FROM AUTHOR]

In this work, dynamic mode decomposition (DMD) was applied as an algorithm for determining the natural frequency and damping ratio of viscoelastic lattice structures. The algorithm has been developed based on the Hankel alternative view of Koopman (HAVOK) and DMD. In general, the Hankel matrix is based on time-delay embedding, which is meant for the hidden variable in a time-series data. Vibration properties of a system could be then estimated from the eigenvalues of the approximated Koopman operator. Results of the proposed algorithm were firstly validated with those of the traditional discrete Fourier transform (DFT) approach and half-power bandwidth (HPBW) by using an analytical dataset of multi-modal spring-mass-damper system. Afterward, the algorithm was further used to analyze dynamic responses of viscoelastic lattice structures, in which data from both experimental and numerical finite element (FE) model were considered. It was found that the DMD-based algorithm could accurately estimate the natural frequencies and damping ratios of the examined structures. In particular, it is beneficial to any dataset with limited amounts of data, whereby experiments or data gathering processes are expensive. [ABSTRACT FROM AUTHOR]

Towards a sustainable future in construction, worldwide efforts aim to reduce cement use as a binder core material in concrete, addressing production costs, environmental concerns, and circular economy criteria. In the last decade, numerous studies have explored cement substitutes (e.g., fly ash, silica fume, clay-based materials, etc.) and methods to mimic the mechanical performance of cement by integrating polymeric meshes into their matrix. In this study, a systemic approach incorporating computer aid and biomimetics is utilized for the development of 3D-printed clay-based composite mortar reinforced with advanced polymeric bioinspired lattice structures, such as honeycombs and Voronoi patterns. These natural lattices were designed and integrated into the 3D-printed clay-based prisms. Then, these configurations were numerically examined as bioinspired lattice applications under three-point bending and realistic loading conditions, and proper Finite Element Models (FEMs) were developed. The extracted mechanical responses were observed, and a conceptual redesign of the bioinspired lattice structures was conducted to mitigate high-stress concentration regions and optimize the structures' overall mechanical performance. The optimized bioinspired lattice structures were also examined under the same conditions to verify their mechanical superiority. The results showed that the clay-based prism with honeycomb reinforcement revealed superior mechanical performance compared to the other and is a suitable candidate for further research. The outcomes of this study intend to further research into non-cementitious materials suitable for industrial and civil applications. [ABSTRACT FROM AUTHOR]

The design representations of lattice structures are fundamental to the development of computational design approaches. Current applications of lattice structures are characterized by ever-growing demand on computational resources to solve difficult optimization problems or generate large datasets, opting for the development of efficient design representations which offer a high range of possible design variants, while at the same time generating design spaces with attributes suitable for computational methods to explore. In response, the focus of this work is to propose a parametric design representation based on crystallographic symmetries and investigate its implications for the computational design of lattice structures. The work defines design rules to support the design of functionally graded structures using crystallographic symmetries such that the connectivity between individual members in a structure with varying geometry is guaranteed and investigates how to use the parametrization in the context of optimization. The results show that the proposed parametrization achieves a compact design representation to benefit the computational design process by employing a small number of design variables to control a broad range of complex geometries. The results also show that the design spaces based on the proposed parametrization can be successfully explored using a direct search-based method. [ABSTRACT FROM AUTHOR]

The utilization of lattice structure in engineering components by additive manufacturing (AM) is gaining attention due to its lightweight design, high strength-to-weight ratio, and effective material utilization. Producing holes in additively manufactured lattice structures with dimensional accuracy is challenging. In the current study, we fabricate near circular through-holes on deterministic lattice structured components fabricated by laser powder bed fusion by utilizing electric discharge machining (EDM). In the additively manufactured Inconel 718 (IN718) lattice structure, nodes are connected by strut leaving voids/pores amongst different nodal points. Due to EDM, the nodes at the boundary of the hole experience concentration plasma interaction, heating, and rapid cooling, which causes a substantial change in the microstructure. The selective removal of material from different nodal positions causes uncharacteristic recast layers, partial damages, and uncontrolled cracking of the struts. In the present study, we investigated and characterized the differential behaviour and mechanism of various surface integrity issues associated with the selective material removal of LPBF IN718 lattice structures and their elements (nodes and struts). [ABSTRACT FROM AUTHOR]

The advancement in additive manufacturing has significantly expanded the use of lattice structures in many engineering fields. Titanium diamond lattice structures, produced by a direct metal laser sintering process, were experimentally investigated. Two cell sizes were selected at five different relative densities. Morphological analysis was conducted by digital microscopy. The compressive tests and digital image correlation technique allowed the evaluation of elastic moduli to be used in the Gibson–Ashby model. Failure mechanisms of the structures have been analysed by digital image correlation, which represents a promising technique for strain evaluation of such structures. A non-linear finite element model of the lattice structures was developed and validated using the experimental data. The analysis of the results highlights the good mechanical properties of the Ti6Al4V alloy lattice structures. [ABSTRACT FROM AUTHOR]

Lattice structures are a prime candidate for applications in the medical implant industry due to their versatile mechanical behaviour, which can be tailored to meet specific patient needs and reduce stress shielding, while enabling the natural flow of body fluids. In this work, the mechanical properties of metallic lattices made of five different unit cell types, Cubic (C), Truncated Octahedron (TO), Truncated Cubic (TC), Rhombicuboctahedron (RCO), and Rhombitruncated Cuboctahedron (RTCO), were evaluated under uniaxial compression at three different relative densities, 5%, 15%, and 45%. The evaluation was experimental, and it was compared with previous and new finite element simulations. Specimens for the experimental tests were fabricated in stainless steel 316L by laser powder bed fusion, and stress–strain curves were obtained for the different lattices. The combination of the test results with a critical interpretation of the deformation mechanisms allowed us to confirm that two unit cell types, TO and RTCO, are stable for the whole range of relative densities evaluated. The other three unit cells exhibit more unpredictable behaviour, either due to manufacturing defects or limitations, or because their unstable compression behaviour leads to bucking. For these reasons, TO and RTCO unit cell types are mechanically more adequate for applications in the medical implant industry. [ABSTRACT FROM AUTHOR]

This study investigates the microstructure and compressive behaviour of PLA/PHA-wood lattice structures manufactured using fused filament fabrication (FFF). The primary objective is to evaluate the effects of defects, such as porosity and surface roughness, on the mechanical properties of these lattice structures. X-ray micro-tomography (XRT) and finite element analysis are employed to compare CAD models with real lattice structures, offering insights into defect-induced performance deviations. The novel approach integrates experimental and numerical methods to better understand damage accumulation in porous structures. The methodology includes uniaxial compression testing and image processing for microstructural characterization. Results reveal significant differences in relative density and stress concentration due to manufacturing defects. In particular, 3D printed lattice structures display typical cellular material behaviour with a primary bending deformation mechanism. X-ray tomography reveals that process-induced porosity generate stress heterogeneity, which is not captured from CAD-based model resulting in an overestimation of the stiffness. The study concludes that accounting for these defects can be quantified by shifting the target relative density to compensate lack of performance in 3D-printed lattice materials.

Additive manufacturing of architected materials, particularly lattice or porous structures, has garnered significant interest in recent years due to its ability to enhance weight-to-strength performance, load-bearing capabilities, and superior energy absorption. Integrating these structures with shape memory alloys (SMAs) introduces unique functionality, enabling them to revert to their original shape after unloading. This paper offers a comprehensive review of the capabilities and challenges associated with additively manufactured architected SMAs. Several examples are presented to illustrate the functional and thermomechanical performance of these structures. Additionally, potential applications are examined, and future trends in this innovative field are explored.

The inherent manufacturing defects in laser powder bed fusion (LPBF)-processed samples leads to deviations from results of finite element analysis (FEA) using the designed model. To systematically evaluate process-induced defects and elucidate their effect, a novel methodology, combining statistical analysis, precision computed tomography (CT) characterisation techniques, mechanical properties assessments and FEA, has been developed. Compared to designed models, CT reconstructed models consider defects, which may affect mechanical properties evaluation, especially along the building direction. FEA based on the CT reconstructed model can more accurately display the stress distribution and the anisotropy of samples. Results indicate that mechanical properties correlate with geometric structure and building direction. Anisotropy becomes more pronounced at a strut diameter of 1.0 mm, the universal anisotropic index AU can reach to 6.31. Overall, this method improves predictive ability by elucidating structure–property relationships in LPBF-processed lattice structures, offering insights into the efficient design for LPBF-processed lattice structures with desirable mechanical properties.

Optimising the cell type and configuration is a key approach for overcoming stress concentration and irreversible deformation in lightweight lattice structures with high strength. In this work, the topology optimisation method was utilised to design force-direction-sensitive structures, including face-centre loaded (FCL), central-edge loaded (CEL), and hybrid-loaded (HL) structures, which were manufactured by laser powder bed fusion (LPBF) using Nitinol (NiTi) shape memory alloy. Results indicated that the HL lattice exhibited the highest initial peak force of 7.6 kN with higher specific compressive strength (41.74 MPa·cm3/g) and specific energy absorption (6.82 J/g), which was benefit from the layer-by-layer deformation mechanism. Furthermore, the HL lattice also exhibited the best damping properties and energy absorption capacity, while achieving a high shape recovery ratio of 85%. This work offers insights into a design strategy for functional structures with high strength and large deformation recovery capacity.

This study evaluates topologically optimized lattice structures for high strain rate loading, crucial for impact resistance. Using the BESO (Bidirectional Evolution Structural Optimisation) topology optimisation algorithm, CompIED and ShRIED topologies are developed for enhanced energy absorption and impact resistance. Micromechanical simulations reveal CompIED surpasses theoretical elasticity limits for isotropic cellular materials, while the hybrid design ShRComp achieves theoretical maximum across all relative densities. Compared to TPMS, truss, and plate lattices, the proposed structures exhibit higher uniaxial modulus. Manufactured via fused deposition modeling with ABS thermoplastic, their energy absorption capabilities are assessed through compression tests and impact simulations. The ShRComp lattice demonstrates superior energy absorption under compression compared to CompIED. Impact analyses of CompIED and ShRComp sandwich structures at varying velocities show exceptional resistance to perforation and higher impact absorption efficiency, outperforming other classes of sandwich structures at similar densities. These findings position these new and novel topologies as promising candidates for impact absorption applications.

ABSTRACTThe increasingly distressing problem of noise pollution prompts the rapid research and development of lattice-based acoustic materials for practical applications. These lattices boast excellent mechanical properties and unlimited design freedom made possible using additive manufacturing technologies. Currently, there is a lack of analytical mathematical models relating the lattice geometry to the acoustic models and the absence of software dedicated to the acoustic modelling of strut lattice-based sound absorbers. This work presents LattSAC, an acoustics calculator that takes in all the geometrical parameters of the lattice structure and outputs directly the sound absorption coefficients (SAC) and their statistics. Hidden within the code is the novel Multi-layered Micropore-Cavity (MMC) model with semi-empirical mathematical models well-trained using experimental data to output the SACs with excellent accuracies. This software aims to accelerate the research and development of lattice-based acoustic absorbers for actual applications. It also functions as a valuable tool for users looking to design sound-absorbing materials using lattice structures. The software installer may be downloaded for free from the following GitHub repository: https://github.com/JunWeiChua/LattSAC. If there are any suggestions or contributions, the user may write to zhaiweigroup@gmail.com.

ABSTRACT3D-printing enables fabricating insoles with locally variable mechanical properties that can better redistribute plantar pressure by altering the mechanical structure. However, current approaches have limitations in terms of speed, strand thickness, and gradual stiffness transitions. To address this, our research proposes utilising the 3D-printed Spacer technique. Our approach involves 3D-printing the insole on their lateral side, with gradual stiffness transitions achieved by modulating the feed speed and material extrusion, enabling strands thinner than the nozzle diameter, while eliminating travel movements. We present a workflow for customisation and fabrication of insole geometry utilising 3D foot scans and automatic g-code generation directly from our design tool. Additionally, we introduce a novel automated support removal process using a hot-wire cutter mounted on a 6-axis robotic arm. We evaluated the printed structures’ mechanical properties and durability through compression tests and assessed the insoles’ performance using a user wear test that included pressure distribution analysis.

3D lattice structures comprise a connected network of segments that allow positioning of the base material where needed while maintaining an open-cell characteristic. These structures represent an ideal lightweight core material for high-performance sandwich panels. This work presents, for the first time, the performance of lattice-based cores fabricated via indirect additive manufacturing using pultruded Carbon Fiber Reinforced Polymer (CFRP) rods. The CFRP sandwich panels were tested under out-of-plane compression, and their compressive properties and failure modes were predicted via analytical and FE analyses, later contrasted with mechanical testing. Finally, the study compares favorably with similar core materials found in the literature.