Mechanical properties and deformation behavior of porous titanium alloy structures with different femoral inclination angle

In the anatomical structure of the natural femur, there is typically a characteristic inclination angle relative to the vertical direction. However, the influence of this inclination angle on mechanical performance remains unclear. Therefore, in this study, the N-type porous structure with 7 degrees inclination angle and the U-type porous structure without inclination angle were designed by topology optimization technology. They were fabricated by selective laser melting (SLM) technology, and their mechanical properties, deformation behavior and energy absorption were studied by quasi-static compression test and simulation. The stress-strain curve of porous structure has elastic stage, plateau stage and densification stage. The elastic modulus and yield strength of the N-type porous structure are 25.39-35.7 GPa and 127.76-295.60 MPa, respectively. The elastic modulus and yield strength of the U-type porous structure are 25.15-49.44 GPa and 128.86-434.21 MPa, respectively. The Young's modulus and yield strength are found to be within the range of bones in the N-type porous structure when the pore sizes are 0.7, 0.8, and 0.9 mm. However, only the pore sizes with 0.8 and 0.9 mm in the U-type porous structure meet the demands of human bones. The deformation behavior of N-type porous structure is dominated by 45 degrees shear fracture. The U-type porous structure shears after stacking layer by layer. The stress concentration of the N-type porous structure is evenly distributed in the strut, while the stress concentration of the U-type porous structure is dispersed on both sides. In addition, the displacement distribution of the U-type porous structure has shifted to the left, while the displacement distribution of the N-type porous structure is more uniform. When the pore size are 0.6 and 0.7 mm, the energy absorption efficiency of the N-type porous structure is lower than that of the Utype porous structure, while when the pore size are 0.8 and 0.9 mm, the results are opposite. Therefore, the Ntype porous structure can reduce the stress shielding effect and has a more uniform stress distribution, which better meets the implant requirements.