The aim of this paper was to investigate the compression properties of several trabecular structures produced by additive laser manufacturing of a Ti6Al4V, having different densities and unit cells. Filling space structures were investigated, with different unit cells characterized by both bending-dominated and stretching-dominated behaviour. The stiffness and yield strength were correlated to relative density according to the Gibson and Ashby model. For a constant porosity, the stiffness and the yield strength varied between two extremes represented by the cubic structure (stretching-dominated deformation) and the cross structure (bending-dominated deformation). The properties of the deformed structures did not differ substantially from those of the regular structures. Only in the cubic structure did distortion enhance the contribution of bending to deformation and both stiffness and strength decreased. Cross structures displayed the highest strength at constant stiffness than the others, since they are characterized by the most favourable orientation of the struts.

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A fast and simple method for the determination of the residual deformation for a class of welding problems, ring-stiffened pipes, is proposed. The method can predictradial as well as angular distortion of the thin-walled pipe-ring-stiffener/flange assembly. The pipe and stiffener material is elasto-plastic. In particular, the accumulation of deformation in multipass welding is incorporated in the model. Each weld pass is treated separately. This facilitates the assessment of the influence of the sequence in which the weld passes are deposited on the residual deformation state. The method will be included in a conversational knowledge-based “expert” system for the production of a welded ring-stiffened pipe.

The compression Young's modulus and strength of lattice structures with porosity between 47.8% and 82.6% produced by Selective Laser Melting (SLM) of a Ti6Al4V powder were investigated. The Young's modulus and yield strength range from 1 GPa to 20 GPa and from 10 MPa to 250 MPa, respectively. On increasing porosity, both stiffness and strength decrease. When porosity increases above 60-65%, the strength shows an accentuated decrease compared to the stiffness decrease. The absence of struts parallel to the loading direction in the lattice structure allows to achieve higher yield strength than other structures having the same Young's modulus.