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In view of the large difference between the elastic modulus of human bone structure and metal materials and the difficulty of control, the goal is to reduce or eliminate the “stress shielding” effect in a wide span, introduce a negative Poisson’s ratio metamaterial with an unconventional deformation mechanism, carry out the design and experimental research of porous microstructure with wide span and low elastic modulus. Based on the negative Poisson’s ratio auxetic structure unit, the three-dimensional cellular porous microstructures with different control parameters and porosity were designed.Experimental samples were prepared by selective laser melting. The variation rules between mechanical properties and structural parameters such as strength and elastic modulus were revealed through compression tests, and the matching degree of negative Poisson’s ratio microstructure and human bone was evaluated. The experimental results show that the auxetic structure has good manufacturability, and the forming quality is correlated with the concave angle and porosity.The mechanical properties of negative Poisson’s ratio auxetic structure are highly dependent on the geometric structure and porosity of the cell.Compared with the positive Poisson’s ratio structure, the auxetic structure with negative Poisson’s ratio has lower elastic modulus and similar yield strength under the same porosity, and can control the 316 L stainless steel bone material with wide span elastic modulus by 0.47 GPa～1.75 GPa.Therefore, the negative Poisson’s ratio auxetic microstructure has potential advantages in the application of human bone structure.

There are increasingly high performance requirements of energy-absorbing systems in aerospace, defense and military, transportation and other fields, especially in the field of emergency protection where the study of self-locking characteristics is of great significance. In this paper, an energy absorption system is designed by snap-fit thin-walled tubes, which can be edited, easy to assemble quickly and spatial omnidirectional self-locking, and the spatial self-locking characteristic of the system was verified by numerical simulation under the uniform/concentrated impact loadings. The results show that the energy-absorbing system can withstand the uniform/concentrated impact loadings in all directions in space. Furthermore, the good comprehensive performance of the loading condition in direction 3 (α = 90 deg, β = 0 deg) was verified by the quantitative analysis of the complex proportional assessment (COPRAS) method and the qualitative analysis of Radar Diagram method. [ABSTRACT FROM AUTHOR]

Gradient Ti6Al4V porous scaffolds were designed based on triply periodic minimal surfaces (TPMS) and were fabricated by SLM technology. The effects of edge porosity Pout, center porosity Pin and average porosity P on mechanics properties and energy absorption were analyzed. The results show that elastic modulus, compressive strength and total absorbed energy per unit volume VV of gradient porous scaffolds with the same P all decrease with the increase of Pout and increase with the increase of Pin. The elastic modulus, compressive strength and Wv of gradient porous scaffolds with the different P all decrease with the increase of P. P has greater influence on elastic modulus, compressive strength and Wv than Pin and Pout. The printed gradient porous scaffolds meet the requirements of elastic modulus and compressive strength of femur and tibia. The mechanics property model established may provide a reference for the applications of porous scaffolds in orthopedics. [ABSTRACT FROM AUTHOR]