This study investigates the tensile response of body-centered cubic (BCC) lattice structures with tapered struts manufactured from Ti6Al4V powder using a laser-beam powder bed fusion (PBF-LB) process. It quantifies how the end diameter \((d_\textrm{end}\) ), mid-span diameter \((d_\textrm{mid}\) ), and joint-node height \((h)\) affect Young’s modulus \((E\) ), 0.2% proof stress \((R_\mathrm{p0.2}\) ), and ultimate tensile strength \((R_\textrm{m}\) ). Experimental tensile tests performed on lattice specimens were combined with simulations based on the finite element method (FEM). A parametric dataset was created using results from finite element simulations and used to develop response surface regression models. The elastic and early plastic responses estimated numerically showed high agreement with experimentally observed responses, whereas the post-peak regime exhibited larger discrepancies associated with progressive failure and fabrication-induced variability. Increases in \(d_\textrm{mid}\) and \(d_\textrm{end}\) led to higher E, \(R_\mathrm{p0.2}\) , and \(R_\textrm{m}\) , with the largest gains observed when both diameters increased simultaneously. This indicates a strong geometric interaction. Joint-node height showed a secondary and geometry-dependent influence. All developed regression models explained more than 99% of the variability in FEM-estimated \(E\) , \(R_\mathrm{p0.2}\) , and \(R_\textrm{m}\) , capturing nonlinear diameter effects and their interaction. When compared with experimentally determined \(E\) , \(R_\mathrm{p0.2}\) , and \(R_\textrm{m}\) , the models explained 85%, 90%, and 88% of the variability in experimentally determined mechanical properties, respectively. Overall, the proposed framework and the developed regression models may serve as useful tools for early-stage unit-cell geometry screening in lattice structures with tapered struts within the investigated design space, while broader experimental validation remains necessary.
