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Background <p>Micro-laser powder bed fusion (μ-LPBF) enables the precise fabrication of meso- to micro-scale lattice structures for various engineering applications. </p> Objective <p>Investigating the mechanical behaviour of μ-LPBF-fabricated lattices is crucial for advancing lattice-based metamaterials. </p> Methods <p>To elucidate how internal defects affect deformation mechanisms, a miniature in situ testing rig was developed and integrated with a time-lapse synchrotron X-ray system. This setup facilitated real-time mechanical testing under compression, allowing detailed analysis of deformation modes, energy absorption, and failure mechanisms in both truss- and shell-lattice structures. </p> Results <p>Printing fidelity analysis revealed significant geometric deviations due to unmelted powder, while defect analysis identified spherical pores (ranging from 0.8 to 1) with equivalent diameter between 5 and 20 μm in solid regions. Truss lattices had larger pores and fewer defects compared to shell lattices. Defect densities decreased with increasing compressive strain. </p> Conclusions <p>The study identified two critical failure modes: node-related failure in truss lattices and shear failure in shell lattices. Internal defects exhibited a stronger influence on nodal failure than on shear-driven failure. The study also highlited a transition from unstable to stable deformation. These defect-dependent failure mechanisms provide valuable insights for assessing structural integrity and optimising the design of mechanical metamaterials.</p>

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In situ X-Ray Tomography of the Critical Role of Internal Defects in μ-LPBF Lattice Structures During Large Deformation

  • 期刊论文

  • 发表日期：

    2025年12月5日

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  • Y. Liu,
  • S. Wu,
  • J. Ding,
  • Y. Yuan,
  • B. Song,
  • L. Jing,
  • T. Guo,
  • Q. Xie,
  • Y. Shi,
  • X. Song

摘要

Background

Micro-laser powder bed fusion (μ-LPBF) enables the precise fabrication of meso- to micro-scale lattice structures for various engineering applications.

Objective

Investigating the mechanical behaviour of μ-LPBF-fabricated lattices is crucial for advancing lattice-based metamaterials.

Methods

To elucidate how internal defects affect deformation mechanisms, a miniature in situ testing rig was developed and integrated with a time-lapse synchrotron X-ray system. This setup facilitated real-time mechanical testing under compression, allowing detailed analysis of deformation modes, energy absorption, and failure mechanisms in both truss- and shell-lattice structures.

Results

Printing fidelity analysis revealed significant geometric deviations due to unmelted powder, while defect analysis identified spherical pores (ranging from 0.8 to 1) with equivalent diameter between 5 and 20 μm in solid regions. Truss lattices had larger pores and fewer defects compared to shell lattices. Defect densities decreased with increasing compressive strain.

Conclusions

The study identified two critical failure modes: node-related failure in truss lattices and shear failure in shell lattices. Internal defects exhibited a stronger influence on nodal failure than on shear-driven failure. The study also highlited a transition from unstable to stable deformation. These defect-dependent failure mechanisms provide valuable insights for assessing structural integrity and optimising the design of mechanical metamaterials.