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<p>Lattice structures are favorable engineering architectures because they enable the tailoring of stiffness, strength, and energy-absorption performance through controlled geometric design. Material Extrusion is a particularly relevant additive manufacturing route for such structures due to its accessibility, geometric flexibility, and suitability for cost-effective polymer lattice fabrication. The current study experimentally investigates the effect of unit-cell aspect ratio on the compressive response and failure behavior of Material Extrusion fabricated PLA lattice structures. Five topologies were examined, namely Body-Centered Cubic, Diamond, Face-Centered Cubi, Fluorite, and Truncated Octahedron, while aspect ratio was varied from 1 to 2.5 at a constant relative density of 20%. Uniaxial compression tests and full-field digital image correlation were used to evaluate stiffness, strength, energy absorption, and collapse evolution. Increasing aspect ratio produced a monotonic increase in compressive Young’s modulus for all topologies, with values ranging from 33.29&#xa0;MPa for Body-Centered Cubic at aspect ratio = 1 to 280.91&#xa0;MPa for Face-Center Cubic at aspect ratio = 2.5. The compressive yield strength increased from 0.97 to 4.99&#xa0;MPa across the investigated design space, while the ultimate compressive strength increased from 1.21 to 5.46&#xa0;MPa. However, this strengthening trend did not result in uniformly improved crushing performance. At high aspect ratios, total absorbed energy decreased markedly, reaching 616&#xa0;kJ·m⁻³ for Body-Centered Cubic, 544&#xa0;kJ·m⁻³ for Diamond, 770&#xa0;kJ·m⁻³ for Face-Centered Cubic, 740&#xa0;kJ·m⁻³ for Fluorite, and 460&#xa0;kJ·m⁻³ for Truncated Octahedron at aspect ratio 2.5. Similarly, the energy-absorption efficiency decreased with increasing aspect ratio, with the lowest value observed for Truncated Octahedron at aspect ratio = 2.5. The deformation analysis revealed a topology-dependent transition from distributed progressive collapse at low aspect ratio to more localized and unstable failure at high aspect ratio. Overall, aspect ratio is shown to be a critical but non-monotonic design parameter that should be selected according to the targeted balance between stiffness, strength, and energy-absorption performance.</p>

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Effect of unit-cell aspect ratio on the compressive behavior and collapse mechanisms of MEX lattice structures

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月14日

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  • Kacper Rydzoń,
  • Emmanouil L. Papazoglou,
  • Panagiotis Karmiris-Obratański

摘要

Lattice structures are favorable engineering architectures because they enable the tailoring of stiffness, strength, and energy-absorption performance through controlled geometric design. Material Extrusion is a particularly relevant additive manufacturing route for such structures due to its accessibility, geometric flexibility, and suitability for cost-effective polymer lattice fabrication. The current study experimentally investigates the effect of unit-cell aspect ratio on the compressive response and failure behavior of Material Extrusion fabricated PLA lattice structures. Five topologies were examined, namely Body-Centered Cubic, Diamond, Face-Centered Cubi, Fluorite, and Truncated Octahedron, while aspect ratio was varied from 1 to 2.5 at a constant relative density of 20%. Uniaxial compression tests and full-field digital image correlation were used to evaluate stiffness, strength, energy absorption, and collapse evolution. Increasing aspect ratio produced a monotonic increase in compressive Young’s modulus for all topologies, with values ranging from 33.29 MPa for Body-Centered Cubic at aspect ratio = 1 to 280.91 MPa for Face-Center Cubic at aspect ratio = 2.5. The compressive yield strength increased from 0.97 to 4.99 MPa across the investigated design space, while the ultimate compressive strength increased from 1.21 to 5.46 MPa. However, this strengthening trend did not result in uniformly improved crushing performance. At high aspect ratios, total absorbed energy decreased markedly, reaching 616 kJ·m⁻³ for Body-Centered Cubic, 544 kJ·m⁻³ for Diamond, 770 kJ·m⁻³ for Face-Centered Cubic, 740 kJ·m⁻³ for Fluorite, and 460 kJ·m⁻³ for Truncated Octahedron at aspect ratio 2.5. Similarly, the energy-absorption efficiency decreased with increasing aspect ratio, with the lowest value observed for Truncated Octahedron at aspect ratio = 2.5. The deformation analysis revealed a topology-dependent transition from distributed progressive collapse at low aspect ratio to more localized and unstable failure at high aspect ratio. Overall, aspect ratio is shown to be a critical but non-monotonic design parameter that should be selected according to the targeted balance between stiffness, strength, and energy-absorption performance.