Spatiotemporal variations and control strategies for buckling deformation during laser powder bed fusion thin-walled structures

Buckling deformation has been a pervasive challenge in laser powder bed fusion (LPBF) of thin-walled structures, severely degrading dimensional fidelity and constraining the fabrication of complex components. Despite its prevalence, the spatial distribution, temporal evolution, and effective mitigation of buckling have remained poorly understood. In this study, we systematically investigated the spatiotemporal characteristics and underlying mechanisms of buckling deformation in LPBF-fabricated thin-walled structures covering a broad range of length-to-thickness ratios, geometries, and build heights. We found that buckling deformation exhibited pronounced periodicity along both circumferential and axial directions. Its evolution proceeded through three distinct stages: thermal shrinkage, initiation of circumferential buckling associated with a concave-to-convex transition (CCT), and subsequent axial propagation. Notably, a hysteretic buckling behavior was identified, which caused false-negative signals in camera-based in-situ monitoring. By combining X-ray diffraction measurements with numerical modeling, we demonstrated that buckling was co-driven by thermally induced compressive stress and critical buckling conditions. Guided by these mechanistic insights, we developed practical control strategies, including auxiliary infrared heating and the introduction of infill lattice structures, which reduced the buckling amplitude from 0.96 mm to 0.045 mm. A buckling sensitivity map integrating process energy density and structural dimensions was further established to guide the design of thin-walled structures. The novel findings advance the fundamental understanding of buckling in LPBF of thin-walled structures, and deliver robust frameworks to mitigate buckling in the manufacture of complex thin-walled structures.