Deformation mechanism and mechanical properties of diamond-like lattice materials

The lattice material is a lightweight, multi-functional periodic porous material. Compared with traditional materials, lattice materials have high specific strength, high specific stiffness, excellent energy absorption and impact resistance, and are widely used in aerospace, transportation, lightweight design of mechanical parts and other fields. In this paper, according to the order distribution of carbon atoms in the diamond lattice, two kinds of diamond-like unit cell configuration lattice materials (Cube nested Slanted Cube, C-SC; Cube nested Regular Octahedron, C-RO) were constructed, and C-SC (20.6%, 27.8%, 35.4%) and C-RO (22.3%, 30.1%, 38.2%) lattice materials with three relative densities were prepared by selective laser melting (SLM) technology. The method of combining experimental and numerical simulation was adopted. The mechanical properties of the new lattice materials with different relative densities were studied, including size effects, deformation modes, tensile and compressive asymmetry, and specific mechanical properties. The experimental data and numerical simulation results show that there is a size effect on C-SC and C-RO specimens under uniaxial loading conditions, and the overall mechanical properties of C-SC and C-RO specimens tend to be stable when the number of lattices in the side length direction is greater than to 4. Within the scope of the study, the specific stiffness of the newly designed C-RO and C-SC lattice materials is higher than that of the existing lattice materials, such as Face Centered Cube (FCC), Vertex Cube (VC), Edge Centered Cube (ECC), Body Centered Cubic (BCC), Body Centered Cubic added with bar in Z direction (BCCZ) and Face Centered Body Centered Cube (F₂BCC) by 709%, 520.7%, 393.1%, 300%, 163.4%, 535.3% and 809.8%, 616.1%, 490.4%, 397.8%, 200%, 655.1%, respectively. Compared with BCC and F₂BCC, the specific strength of C-SC is increased by 43.2% and 34.9% at most, which is basically the same as that of FCC. The specific strength of C-RO is increased by 42.1% and 36.4% compared with BCC and F₂BCC, and 3.8% higher than that of FCC.