On the Morphological Deviation in Additive Manufacturing of Porous Ti6Al4V Scaffold: A Design Consideration

Designing porous titanium scaffolds for bone replacement requires precise control over morphology and mechanical properties. Prior research has shown that triply periodic minimal surface (TPMS) structures like diamond and gyroid geometries influence scaffold performance. It was already known that diamond structures offer high stiffness while gyroid structures enhance osseointegration. However, no prior work had resolved how additive manufacturing processes affect the deviation between as-designed and as-built scaffold morphologies. This gap motivated a closer examination of how manufacturing impacts scaffold geometry. Existing studies focus on mechanical performance but lack detailed analysis of dimensional deviations. The uncertainty about how orientation and geometry affect printed dimensions has limited design accuracy. Understanding these deviations is essential for optimizing scaffold performance in vivo.

This study aimed to investigate the morphological deviations between as-designed and as-built Ti6Al4V scaffolds with diamond and gyroid structures. The specific problem addressed is the lack of data on how additive manufacturing alters scaffold dimensions. The motivation stems from the need to improve design accuracy for biomedical applications. Researchers propose examining both macro- and microscale properties of these scaffolds. The study focuses on strut thickness, pore size, and mechanical properties. The goal is to quantify deviations and identify patterns based on scaffold orientation. This approach allows for better design compensation before fabrication. The findings could help reduce the gap between intended and actual scaffold performance.

The study used triply periodic minimal surface (TPMS) scaffolds with diamond and gyroid geometries. These scaffolds were fabricated using additive manufacturing techniques. Researchers examined scaffold properties at both macro and microscales. They measured strut thickness, pore size, and compressive properties. The global compression method was used to calculate Young's modulus and yield strength. Microhardness and phase-specific Young's modulus were analyzed from α and β phases of Ti6Al4V. The study compared vertical and horizontal strut orientations. Data collection included both dimensional and mechanical assessments.

The study found that printed strut thickness exceeded the designed target value. For diamond scaffolds, vertical struts showed a 2.5% excess while horizontal struts had a 35.1% excess. Gyroid scaffolds showed even greater deviations, with horizontal struts reaching 66.2% excess. Mean pore size was less than the designed value for both geometries. Diamonds had a -8.4% deviation in horizontal struts while gyroids reached -21.1%. Compressive Young's modulus was highest in bulk samples at 35.8 GPa. Gyroid and diamond scaffolds had 6.81 GPa and 7.59 GPa, respectively. Yield strength measurements were 1012 MPa for bulk samples, 108 MPa for gyroids, and 134 MPa for diamonds. Microhardness and Young's modulus from α and β phases were 4.1 GPa and 131 GPa, respectively.

The authors propose that morphological deviations in additive manufacturing affect scaffold performance. They suggest that design compensation strategies could reduce these deviations before fabrication. The findings highlight the importance of considering orientation and geometry in scaffold design. The study demonstrates that horizontal struts experience greater deviations than vertical ones. The researchers propose that these deviations influence mechanical properties like Young's modulus and yield strength. They suggest that understanding these deviations could improve scaffold design accuracy. The data supports the need for further investigation into design optimization techniques. The authors conclude that their findings could help refine scaffold fabrication processes.