Open research questions in Cellular and Composite Structures

What the literature leaves open

• The effects of unit cell size on the manufacturing quality, mechanical behavior, and energy absorption of LPBF-fabricated Ti6Al4V TPMS structures are not well understood. There is a need to investigate the topology-dependent stress distribution and failure mechanisms of TPMS structures.

  Unit Cell Size Effects on LPBF-Manufactured Ti6Al4V TPMS Structures: Manufacturing Quality, Mechanical Behavior, and Energy Absorption · 2026 · DOI

• The high cost and long duration of experimental testing for bird strike phenomena. The limitations of conventional homogeneous bird models in capturing localized impact damage. The need for a more accurate assessment of hollow fan blade damage mechanisms under bird strike.

  Structural Integrity and Dynamic Failure Mechanisms of Wide-Chord Hollow Fan Blades Under Soft Tissue–Skeleton Coupled Bird Impact · 2026 · DOI

• Conventional homogeneous bird models have limitations in capturing localized impact damage. The internal structural design of hollow fan blades strongly affects their impact response under bird strike, but this is not well-represented in existing simulations.

  Structural Integrity and Dynamic Failure Mechanisms of Wide-Chord Hollow Fan Blades Under Soft Tissue–Skeleton Coupled Bird Impact · 2026 · DOI

• However, their manufacturability using PBF-LB/M remains underexplored, especially for demanding applications in process engineering that require structural integrity under extreme conditions.

  Design guidelines for laser powder bed fusion of triply periodic minimal surface structures for applications in smart reactors · 2026 · DOI

• These findings establish specimen sizing as a critical, yet previously underexplored, factor in achieving reliable Mode I characterization of sandwich structures.

  Impact of Intact Length and Initial Debond on the Mode I Fracture Toughness of Sandwich Structures · 2025 · DOI

• However, the influence of SCB geometry in determining the accuracy of Mode I characterization remains underexplored.

  Impact of Intact Length and Initial Debond on the Mode I Fracture Toughness of Sandwich Structures · 2025 · DOI

• However, limited studies pay attention to the mechanical behavior of hybrid sandwich beams with various ALF densities.

  Effect of core densities on quasi‐static and low‐velocity impact behaviors of AFRP ‐aluminum foam hybrid sandwich beams · 2024 · DOI

• The extreme cooling rates inherent to Selective Laser Melting typically induce a martensitic phase transformation, resulting in an acicular microstructure that is prohibitively brittle in its as-built state, - Surface roughness and lack-of-fusion porosity substantially degrade fatigue resistance and specific energy absorption

  TRIPLY PERIODIC MINIMAL SURFACES STRUCTURES IN ENERGY ABSORPTION: A REVIEW OF GEOMETRIC TOPOLOGIES, MANUFACTURING CONSTRAINTS, AND FUTURE SMART MATERIALS · 2026 · DOI

• The convergence of smart materials and 4D Printing heralds a new era of adaptive, stimulus-responsive TPMS structures, - Future directions toward multifunctional applications and AI-assisted inverse design are outlined

  TRIPLY PERIODIC MINIMAL SURFACES STRUCTURES IN ENERGY ABSORPTION: A REVIEW OF GEOMETRIC TOPOLOGIES, MANUFACTURING CONSTRAINTS, AND FUTURE SMART MATERIALS · 2026 · DOI

• For its repairing, this study develops a Ti6Al4V (TC4) gradient porous filled scaffold, and the corresponding mechanical behavior needs to be studied.

  STUDY ON THE FATIGUE MECHANICAL BEHAVIOR OF SELECTIVE-LASER-MELTED TI6AL4V GRADIENT POROUS SCAFFOLD FOR REPAIRING TIBIAL BONE DEFECT · 2026 · DOI

• The study does not provide a comprehensive comparison with other bone implant materials. The sample size is limited to three samples per configuration. The study focuses on compression tests and does not explore other loading modes.

  Functional Graded PEEK Cellular Lattice as a Bone Implant · 2026 · DOI

• Exploring other loading modes and their effects on the mechanical properties of PEEK-based lattices. Investigating the biocompatibility and osseointegration of PEEK-based lattices. Developing new gradation strategies to improve the mechanical properties of PEEK-based lattices.

  Functional Graded PEEK Cellular Lattice as a Bone Implant · 2026 · DOI

• The optimal cell density for a honeycomb structure depends on the specific application and performance requirements. There is a need to investigate the influence of relative density and material on the compressive response of 3D-printed honeycomb structures.

  Influence of Relative Density and Material on the Compressive Response of 3D-Printed Honeycomb Structures for Crashworthiness · 2026 · DOI

• The limitation of negative Poisson's ratio honeycomb structures under dynamic loading. The need for novel reinforced configurations to improve load-bearing capacity and energy absorption performance.

  In-plane dynamics crushing behavior of reinforced auxetic star-shaped honeycombs · 2026 · DOI

• The need for improved energy absorption characteristics in structural members. The lack of investigation on the effect of design parameters on the energy absorption characteristics of modular structures.

  Experimental investigation of energy absorption characteristics of a novel modular structure · 2026 · DOI

• At present, the core-to-face sheet interaction in conventional sandwich structures subjected to impact loads has not been fully elucidated, and the quantitative characterization of damage is insufficient, so this paper aims to optimize the lightweight impact-resistant structure by exploring the synergistic energy dissipation mechanism between the high-strength core material and the steel plate.

  Study on Impact Resistance of Sandwich-Structured Battery Protection Panels · 2026 · DOI

• The conventional inner concave hexagonal honeycomb has limitations in terms of deformation stability and energy dissipation efficiency. There is a need for novel honeycomb structures that can enhance crashworthiness and energy absorption capacity.

  Research on the failure mechanism and enhanced energy-absorbing capacity for a novel concave octagonal NPR honeycomb structure · 2026 · DOI

• The combined effects of TPMS type, layer thickness, and volume fraction on mechanical and energy absorption behavior are not well understood.

  The effect of design parameters on the mechanical performance and energy absorption behavior of additively fabricated triply periodic minimal surface structures · 2026 · DOI

• The study is based on a numerical framework and does not include experimental validation. The study only considers a single type of carbon-fibre-reinforced polymer (CFRP) composite. The study uses a limited number of sampled configurations, with six data points. A separate material-parameter sensitivity analysis is beyond the scope of the study.

  Effect of Curvature Height on the Low-Velocity Impact Behaviour of Unidirectional T300/5208 CFRP Laminated Shell Panels: A Comparative Numerical Parametric Analysis of Intralaminar + Interlaminar and Intralaminar-Only Models · 2026 · DOI

• Experimental validation of the numerical models is needed to confirm the findings. Further research on the effect of different material parameters on the impact response is required. Investigation of the impact response of other types of CFRP composites is necessary.

  Effect of Curvature Height on the Low-Velocity Impact Behaviour of Unidirectional T300/5208 CFRP Laminated Shell Panels: A Comparative Numerical Parametric Analysis of Intralaminar + Interlaminar and Intralaminar-Only Models · 2026 · DOI

• The study only considers a limited number of uncertain parameters, - The study uses a simulation-based approach, - The results may not be directly applicable to all honeycomb sandwich panels

  Influence of Structural and Material Uncertain Parameters on Honeycomb Sandwich Panels Based on Neural Networks · 2026 · DOI

• Further studies can be conducted to investigate the influence of defects on the mechanical properties of auxetic cellular materials under different loading conditions. The results of this study can be used to design and optimize auxetic cellular materials for various applications.

  Study on defect influence on elastic stifnesses and strength of auxetic cellular materials · 2026 · DOI

• The relationship between void geometry and crash performance remains insufficiently explored. There is a need for a systematic evaluation of the influence of void shape and aspect ratio on crashworthiness.

  Modeling and simulation of the influence of void shape and aspect ratio on the crashworthiness of closed-cell aluminum foam · 2026 · DOI

• The study involves simulation-only analysis. The analysis is limited to two materials, Aluminium 6061-T6 and Automotive HSS 590 Steel.

  Finite Element Analysis of Automobile Bumper Impact Resistant Under Repeated and Oblique Collisions · 2026 · DOI

• Further studies can be conducted to investigate the crashworthiness performance of bumper systems under different material properties and collision scenarios. The development of more efficient and safer bumper systems can be explored.

  Finite Element Analysis of Automobile Bumper Impact Resistant Under Repeated and Oblique Collisions · 2026 · DOI

Most-cited papers in Cellular and Composite Structures

• Lightweight hybrid materials and structures for energy absorption: A state-of-the-art review and outlook · Thin-Walled Structures · 2022 · 388 citations
• Manufacturing, characteristics and applications of auxetic foams: A state-of-the-art review · Composites Part B Engineering · 2022 · 273 citations
• Compressive performance and energy absorption of additively manufactured metallic hybrid lattice structures · International Journal of Mechanical Sciences · 2022 · 227 citations
• Quasi-static compression and dynamic crushing behaviors of novel hybrid re-entrant auxetic metamaterials with enhanced energy-absorption · Composite Structures · 2022 · 208 citations
• A novel auxetic metamaterial with enhanced mechanical properties and tunable auxeticity · Thin-Walled Structures · 2022 · 205 citations
• Auxetic materials — A review · Materials Science-Poland · 2013 · 197 citations
• Mechanical properties and energy absorption of bio-inspired hierarchical circular honeycomb · Composites Part B Engineering · 2022 · 193 citations
• Nanograin–glass dual-phasic, elasto-flexible, fatigue-tolerant, and heat-insulating ceramic sponges at large scales · Materials Today · 2022 · 177 citations
• Mechanical metamaterials with negative Poisson’s ratio: A review · Engineering Structures · 2025 · 169 citations
• Experimental investigation on 3D printed lightweight sandwich structures for energy absorption aerospace applications · Aerospace Science and Technology · 2023 · 164 citations

Most recent work

• Programmable multifunctional auxetic metamaterials via concave rib architecture · Engineering Structures · 2026
• Metallic lattice structures via additive manufacturing: Applications, challenges and opportunities in aerospace and defence · Journal of Manufacturing Processes · 2026
• Octagonal hierarchical honeycomb with enhanced crashworthiness: Design, optimization, and performance under axial compression · Structures · 2026
• Mechanical behaviour and energy absorption performance of modified anti-tri chiral novel auxetic structures through experimental and numerical analysis subjected to surrogate metamodeling · Results in Engineering · 2026
• Design and crashworthiness of a modular discrete re-entrant auxetic honeycomb · Engineering Structures · 2026
• Research progress on osseointegration performance of porous structure-modified titanium alloy implants · Frontiers in Bioengineering and Biotechnology · 2026
• Research on in-plane energy absorption capacity of novel hybrid star-shape honeycombs · Structures · 2026
• Integrating microstructural defect mapping into geometric refinement of LPBF lattices for enhanced mechanical performance · Journal of Manufacturing Processes · 2026
• Low-velocity impact behaviour of sandwich structures: a comprehensive review · Progress in Additive Manufacturing · 2026
• Thermal expansion matching design for integrated thermal protection systems based on a novel tunable CTE metamaterial · Aerospace Science and Technology · 2026

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