Biomechanical interaction of additively manufactured Ti6Al4V metamaterial inserts with vascular tissue: Effects of surface topography on tissue damage and residual stress distribution

This study evaluates the biomechanical response of vascular tissue subjected to compression by mechanical metamaterial-based inserts fabricated from Ti6Al4V alloy using additive manufacturing. The inserts featured varying surface topographies: smooth, moderately notched, and deeply notched; and internal void geometries: circular, elliptical, triangular. Ring-shaped porcine aorta samples were compressed under controlled conditions for 10 minutes in a simulated physiological environment. Digital microscopy and histological analysis revealed tissue delamination and a reduction in vessel wall thickness, with delamination observed in up to 90% of the reference samples and wall thickness ranging from ∼1.2 mm for the reference to ∼2.4–3.0 mm for the modified configurations. While tissue alterations were observed, no visible deformation of the metallic inserts was detected post-testing, confirming their structural integrity and the precision of the 3D printing process. Therefore, the material's response to pressure on a blood vessel was examined in terms of structural deformation, i.e., changes in the interplanar distance manifested in the form of residual stresses. The stress distribution was measured by X-ray diffraction tomography. X-ray diffraction measurements indicated the presence of high-magnitude compressive residual stresses, especially in samples with deeper surface structuring. These compressive stresses-confined within individual grains – are associated with enhanced resistance to crack initiation and improved fatigue performance. Finite element modeling supported experimental observations, showing increased stress with greater surface complexity. Overall, the results demonstrate that surface morphology in mechanical metamaterial inserts critically influences both tissue interaction and residual stress distribution, offering guidance for the design of durable and tissue-safe surgical tools. • Surface topography of Ti6Al4V inserts governs stress transfer to vascular tissue • Deep surface structuring increases tissue damage and compressive residual stresses • Additively manufactured metamaterials show high structural stability under loading • XRD reveals depth-dependent compressive residual stresses after vessel compression • Moderate surface structuring reduces vascular trauma while preserving durability