An engineering approach to suppress typical defects in additive manufacturing based on structure-manufacturing integration

Additive manufacturing (AM) technology, with advantage of achieving near-net-shape fabrication of complex structures through layer-by-layer material deposition, holds broad application prospects in the field of aero-engines. As additively manufactured fuel nozzles continue to be applied and verified in aero-engines, issues arising from manufacturing defects with various scales and types have become increasingly prominent. Examples include excessive porosity at the micro-scale, fluorescent linear indications caused by cracks at the meso-scale, and high-cycle fatigue cracking induced by surface roughness at the macro-scale. With systematic analysis of the AM process, it is found out that the formation of defects is closely related to the temperature field, stress field, and material flow field during the forming process. Optimization of AM process parameters should aim to reduce temperature gradients, alleviate stress concentrations, and constrain material movement to minimize defects. Analysis of multiple engineering cases involving defect suppression in additively manufactured fuel nozzles reveals that optimizing manufacturing parameters under a fixed part structure often yields limited results. In contrast, a design-led structure-manufacturing integration approach was identified as a critical engineering method to transfer AM parts from being “usable” to “highly reliable”. Therefore, considerations such as the evolution of the temperature field during additive manufacturing, influencing factors of the stress field, and driving sources of material movement should be incorporated into the structural design phase. Through methods such as optimizing structural details, defining structural windows for key post-processing requirements, and adjusting support strategies, the manufacturability of parts can be significantly enhanced, the defect occurrence rate can be substantially reduced, and the engineering applicability of additively manufactured components can be improved.