Editorial for the Special Issue “Additive Manufacturing-Enabled Architected Materials”

Abstract

Additive manufacturing (AM) has redefined the landscape of materials engineering, enabling the design and realization of architected materials with tailored mechanical and functional properties unimaginable with traditional approaches. This Special Issue of Advanced Engineering Materials captures the latest advancements in AM-enabled architected materials, spotlighting innovations that combine structural efficiency, multifunctionality, and sustainable design. Techniques such as Digital Light Processing (DLP), Direct Ink Writing (DIW), and Laser Powder Bed Fusion (LPBF) are enabling the fabrication of complex multiscale architectures, catalysing advances across bioengineering, aerospace, automotive, and energy sectors.

This issue brings together 15 contributions that reflect both the current state and future potential of architected materials. Key themes include multifunctionality, innovative material design, and the development of computational and experimental tools for enhancing performance. Topics range from bio-inspired architectures and topology optimization to inelastic behaviour, energy absorption, crashworthiness, phase heterogeneity, and multifunctional properties such as thermal/electrical conductivity, piezoresistivity, and stress shielding. These works collectively demonstrate the transformative potential of AM, offering unprecedented control over material properties and enabling applications previously deemed unattainable. Collectively, these contributions highlight AMs potential to create high-performance materials for a wide range of industries.

1. Bioinspired Design of Isotropic Lattices with Tuneable and Controllable Anisotropy (Boda et al. 2401881)

This paper presents novel bio-inspired isotropic lattices with tuneable anisotropy, mimicking architectures found in cortical bone and golden spirals. By introducing nested lattice structures with adjustable nesting orders and orientations, the study explores the transition from shear-dominant to tensile-compression-dominant behaviours and their effect on the mechanical properties of these lattices, identifying the design space for isotropic lattices.

2. Conceptual Design and Parametric Optimization of a New Multileveled Horsetail Structure for Bicycle Helmets (Leng et al. 2300884)

Inspired by nature, this study introduces a bioinspired horsetail structure for helmet liners that mitigates both linear and rotational acceleration, providing a promising route to mitigate brain injury risks in cycling accidents.

3. Enhanced Flexural Performance of Diamond Latticed Triply Periodic Minimal Surface Sandwich Panels (Mahapatra et al. 2300813)

This research explores bioinspired TPMS diamond lattices for aerospace applications, investigating how unit cell geometry and density influence the flexural strength and energy absorption of sandwich panels under bending conditions.

4. Elasticity of Diametrically Compressed Microfabricated Woodpile Lattices (Shalchy & Bhaskar, 2301158)

This study addresses modulus–porosity relationships in microfabricated woodpile lattices, providing insights into how the elastic behaviour of these lattices can be optimized for material design.

5. A Variational Beam Model for Failure of Architected and Truss-Based Architected Materials (Karapiperis et al. 2300947)

A new variational beam model is proposed for predicting the inelastic behaviour of architected materials, including damage and viscoplasticity, providing an efficient tool for the design of architected materials in engineering applications.

6. Bending Performance and Crashworthiness Characteristics of Sandwich Beams with New Auxetic Core (Chikkanna et al. 2300710)

The study evaluates the performance of newly developed re-entrant diamond auxetic metamaterials, revealing significant improvements in energy absorption and crashworthiness, crucial for reducing structural weight in the transportation sector.

7. Architected Lattices with a Topological Transition (Agarwal & Jin, 2301192)

This paper explores topological metamaterials that undergo multistep deformation, offering highly tuneable stress–strain responses and a new approach for the design of multifunctional lattice structures.

8. Exploiting Geometric Frustration in Coupled von Mises Trusses to Program Multifunctional Mechanical Metamaterials (Liétard et al. 2402006)

This study introduces a mechanical metamaterial based on bistable von Mises trusses coupled to induce geometric frustration, leading to programmable mechanical properties. The design enables reversible transitions between stable states, altering the material's stiffness in compression. Experimental validation with 3D-printed metamaterials demonstrates the practical applications of this approach, including tuneable sandwich panels with adjustable compressive and bending stiffness.

9. Topology Optimization of Lattice Support Structure for Cantilever Beams Fabricated via Laser Powder Bed Fusion (Hu et al. 2300976)

The paper presents a framework for designing optimized lattice supports to minimize thermal distortion in LPBF-fabricated components, offering a solution for improving the precision of 3D printed metal parts.

10. Multifunctional Design of Triply Periodic Minimal Surface Structures for Temporary Paediatric Fixation Devices (Ebrahimzadeh Dehaghani et al. 2400518)

This study investigates the use of 3D-printed TPMS structures for paediatric fracture fixation devices, addressing the challenge of stress shielding in traditional metallic implants. Several TPMS designs in Ti–6Al–4V are analysed using finite-element modeling and experimental testing to match cortical bone stiffness while ensuring osteointegration and manufacturability. The Primitive unit cell TPMS design outperforms others in strength/stiffness ratio and manufacturability, offering a promising approach for temporary paediatric implants.

11. Digital Light Processing of 2D Lattice Composites for Tuneable Self-Sensing and Mechanical Performance (Saadi et al. 2300473)

This work demonstrates how DLP-printed CNT-based 2D lattices exhibit tuneable piezoresistivity and mechanical performance, offering a pathway toward lightweight, self-sensing structures.

12. Additive Manufacturing of Self-Sensing Carbon Fiber Composites (Xu et al. 2301249)

Focusing on the integration of self-sensing functionality in carbon fibre-reinforced composites, this study demonstrates the potential of AM to enhance the performance of advanced composite materials in various industrial applications.

13. Geometry-Assisted Phase Selection: Interplay of Phase Heterogeneity and Geometry in Gyroid Shell Metamaterials Printed with 17-4 PH Stainless Steel (Pürstl et al. 2402309)

This work explores the role of geometry in phase evolution within gyroid shell metamaterials fabricated from 17-4 PH stainless steel using laser powder bed fusion. The study reveals how geometric complexity influences local phase changes, enhancing the material's properties through phase heterogeneity. The findings suggest that controlling geometry can significantly improve part performance, enabling the design of functionally graded metamaterials with tailored microstructures.

14. Flexural Behaviour of Bidirectionally Graded Lattice (Rodrigo et al. 2300915)

This work investigates the flexural properties of bidirectionally graded lattice beams, fabricated from stainless steel using electron beam melting, and explores how density gradients can enhance energy absorption and flexural strength.

15. Creep Characterization of Inconel 718 Lattice Metamaterials Manufactured by Laser Powder Bed Fusion (Bhuwal et al. 2300643)

Investigating the creep behaviour of LPBF-printed Inconel 718 lattices, this contribution provides valuable insights into the high-temperature performance of metallic lattice materials and identifies key microstructural factors that influence their mechanical properties.

These contributions provide critical insights into the state-of-the-art advancements in AM-enabled architected materials, which now enable us to discuss broader implications for design strategies and multiscale approaches to the sustainable applications of these innovative materials.

Building on the diverse contributions featured in this issue, we highlight a paradigm shift in architected material design—from the traditional structure–processing–property framework toward a more forward-looking properties–architecture–fabrication approach.^{[1, 2]} Historically, material properties were primarily governed by composition, internal structure, and processing conditions. However, recent advances in data-driven modeling, along with multiscale fabrication and characterization techniques, have enabled the direct design of materials with tailored functionalities by precisely controlling their architecture.^[3] While inverse design has traditionally relied on physics-based modeling and optimization, data-driven approaches have dramatically expanded the design landscape. These methods allow rapid exploration of high-dimensional, multiphysics-informed design spaces and facilitate direct mapping from target properties to architectural features and fabrication parameters. This integrated approach empowers the properties–architecture–fabrication paradigm, accelerating the discovery and realization of advanced architected materials with highly customized mechanical, thermal, electrical, biological, and other multifunctional attributes.

Central to this paradigm shift is the capability to engineer material properties across nanoscale to macroscale dimensions. At the nanoscale, AM unlocks enhancements in both mechanical and functional properties—enabling materials with superior strength, strain tolerance, electrical conductivity, and thermal resistance.^[4] Such control has led to the development of lightweight, multifunctional materials previously unattainable by conventional means. For example, nanoscale plate lattices approach theoretical limits of stiffness and strength,^[5] while nanoscale ceramic metamaterials, fabricated via two-photon lithography (TPL), demonstrate over 50% reversible strain tolerance.^[6]

In parallel, multiscale strategies that integrate design across micro, meso, and macro scales further elevate material performance. These approaches not only enable hierarchical tuning of properties but also incorporate predictive models that account for AM-induced imperfections—offering tools for failure mitigation and reliability enhancement.^[7] Advanced multiscale simulations are now combining phase-field models (e.g., for grain evolution in 316 L stainless steel) with machine learning surrogates to link process parameters—such as laser power and cooling rates—to resultant mechanical performance.^[8] This integrated predictive framework bridges atomic to continuum scales, enabling the design of architected materials with tailored, application-specific properties.

By harnessing both nanoscale effects and multiscale design principles, the field is now positioned to create adaptive, multifunctional systems capable of responding dynamically to external stimuli. These advances are catalysing a transition from conventional periodic structures toward more complex, chiral, and aperiodic designs—ushering in a new era of architected materials.

While periodic lattices have long been the foundation of architected material design, moving beyond periodicity opens new opportunities for creating materials with complex geometries and unique properties. Aperiodic architectures, such as spinodal and Spinodoid morphologies, can exhibit stretching-dominated responses previously thought to be exclusive to periodic structures.^[1] These architectures offer enhanced defect tolerance, superior performance across a broad range of relative densities, and scalability, making them a compelling avenue for exploration.^[9] Non-periodic structures provide greater flexibility in tailoring the mechanical, thermal, and electrical behaviours of materials, making them suitable for applications ranging from lightweight structures to adaptive systems that respond to environmental changes.^[10] The ability to design materials with complex, non-periodic architectures enables the development of multifunctional materials capable of serving multiple purposes within a single structure. For example, materials with chiral or hierarchical designs can exhibit improved mechanical performance, such as increased resistance to crack propagation and enhanced load-bearing capabilities,^[11] while simultaneously offering functionalities such as sensing,^[12] actuation,^[13] energy storage,^[14] and optimal tissue support.^[15]

As the boundaries of architected material design continue to expand, scaling these innovations remains a significant challenge. Issues such as printer resolution, material consistency, and production costs must be addressed to enable the widespread adoption of AM-enabled architected materials in real-world applications. Strategies such as hybrid manufacturing, recycling of feedstocks, and advances in high-throughput AM techniques will play critical roles in scaling sustainable production while maintaining performance integrity. Scalable architected materials, spanning from nanometre to centimetre scales, are essential for translating nanoscale properties into application-ready systems, yet maintaining high-resolution features across these scales remains difficult.^[1] Significant progress has been made in overcoming these hurdles, with new printing technologies and material formulations enabling the fabrication of more complex, functionally graded structures with higher resolution. While nanoscale architectures offer exceptional properties, such as high stiffness and ductility at low weight, achieving large tessellations necessary for reliable macroscopic property evaluation has only recently been demonstrated.^[16] For example, recent advances in TPL, which utilize ultrafast laser projection for parallelized layer-by-layer fabrication, have addressed scalability challenges while maintaining sub-micron resolution.^[17] Although AM remains the primary method for fabricating architected materials, trade-offs between resolution, build size, and speed still limit scalability. Emerging hybrid approaches, which combine AM with self-assembly in conjunction with AI-driven design, show promise in overcoming these challenges and enabling the scalable production of complex structures.^[18]

Furthermore, the sustainability of AM technologies is becoming increasingly important. Fabricating materials with minimal waste, using sustainable feedstocks, and employing energy-efficient processes are critical to making AM a truly sustainable manufacturing method. Efforts are underway to incorporate renewable materials and reduce energy consumption during the manufacturing process, thus contributing to the decarbonization of industrial sectors.

Advances in the design, fabrication, and characterization of architected materials over the past two decades have led to early adoption across sectors such as sports, biomedical engineering, aerospace, automotive, packaging, and energy, though widespread commercialization remains nascent.^[15] These materials are being explored for enhancing mechanical performance, sustainability, and multifunctionality, often by integrating stimuli-responsive functionalities into tailored architectures. Emerging applications span robotics, bioengineering, energy harvesting, catalysis, and flexible electronics, offering opportunities for self-powered systems, adaptive implants, high-efficiency energy devices, and advanced sensors.^[19]

In the energy sector, architected and AM-enabled materials are enabling the development of lightweight, high-performance systems for more efficient energy storage, conversion, and transmission.^[20] Custom geometries fabricated by AM technologies optimize components for renewable energy systems, such as wind turbines and solar panels, enhancing performance and reducing costs. In aerospace, architected lattices and multifunctional structures reduce weight, fuel consumption, and improve safety, while in the automotive sector, lightweight architected components contribute to the development of more energy-efficient vehicles.^[12] Despite these successes, challenges remain, including managing multiphysical couplings, scaling up fabrication processes, and rigorously benchmarking architected devices against conventional technologies. Addressing these hurdles is critical for achieving cost-effective, scalable integration into mainstream engineering systems.

Looking ahead, the transformative potential of AM-enabled architected materials lies not only in their technical superiority but also in their ability to address some of the most pressing challenges of our time—such as energy efficiency, sustainability, and decarbonization. The contributions within this Special Issue demonstrate how, by integrating advanced manufacturing processes with novel material architectures, AM is opening the door to smarter, more sustainable technologies across industries. The ability to design complex lattice structures and hybrid composite systems with tailored properties holds immense promise, paving the way for next-generation solutions in bioengineering, aerospace, automotive, energy, and beyond. As AM continues to evolve, its role in driving innovations for a decarbonized, energy-efficient future becomes increasingly vital. Collectively, these advances affirm that AM, coupled with innovative architected material design strategies, is poised to revolutionize multiple industries. We hope that the contributions featured in this Special Issue inspire continued innovation in the design, fabrication, and deployment of AM-enabled architected materials across multiple sectors. As AM technologies advance and merge with data-driven design and multiscale engineering, the future promises architected materials that are not only stronger and lighter but also smarter and more sustainable.