Optimization Of Process Parameters And Structural Optimization Of Bio-inspired Hyperboloid Lattice Structure Based On Selective Laser Melting

Development of additive manufacturing technology effectively extends the design and application of novel lattice structures.In this paper,a novel lattice structure,inspired from the beetle's front wing,was designed.The unit lattice was fabricated by selective laser melting(SLM)to investigate the effects of processing parameters on densification behavior and mechanical properties.The SLM-processed lattice structures were sandblasted at different sandblasting pressures.The surface roughness,surface morphology and strut diameters of SLM lattice structure were compared before and after sandblasting.The influence of sandblasting pressures on residual stress and compression performance of SLM-processed lattice structure were studied.Multi-cell lattice structures with different numbers of unit cells were prepared,and the effects of the number of unit cells on the compression mechanical behavior and fracture mode of the multi-cell lattice structure were studied.Bio-inspired lattice structures were fabricated by SLM technology with Al Si10Mg powder at different process parameters.The lattice structure exhibited high densification(>97%)at the optimized processing parameters.As the laser power increased,the transformation from the cellular dendritic to the columnar dendritic was observed,simultaneously accompanying the grain coarsening.The load-displacement curves of all lattice structures exhibited three characteristic deformation stages:elastic deformation;inhomogeneous plastic deformation;failure.During the compressive process,the successive transfer of stress concentration from the intersections of the horizontal struts to the intersections of the diagonal struts occurred.At the optimized processing parameter(P=375 W,v=3500 mm/s),the lattice structure exhibited excellent energy absorption capability(3.45 J)with high bearing force(2.95 k N)and large displacement(1.18 mm).Sand blasting could effectively improve the surface roughness of SLM-processed lattice structures.When the sandblasting pressure was 0.3 MPa,the surface roughness of the lattice structure was 33.90?m,and the unmelted metal particles and surface bulged on the surface reduce.The shape of strut became regular cylinder,and the surface appears micro pitted formed by quartz sand impacting the lattice structure,at this time,the strut diameter of the lattice structure was close to the designed value(0.988 mm).When the sandblasting pressure was 0.3MPa,the maximum force F_max(2.99 k N)of the lattice structure was the largest,and the lattice structure showed excellent energy absorption capacity,with a value of 2.93 J.The number of unit cells mainly affected the maximum force F_max,energy absorption behavior and failure behavior,instead of failure displacement.With the increase of the number of unit cells,the maximum force F_max,energy absorption(EA)and specific energy absorption(SEA)of multi-cell lattice structure increased,and the damage degree of lattice structure decreased.The maximum bearing capacity F_max of six cell lattice structure was 11.02k N,and the values of EA and SEA were19.97 J and 2.44 J/g respectively.