BACKGROUND: Cartilage tissue engineering repair is an important method to repair cartilage defects. Silk fibroin/type II collagen scaffolds are viscoelastic materials that have excellent biocompatibility and exhibit solid and liquid characteristics, but the micro-mechanical properties between different layers are still a problem worthy of attention.

OBJECTIVE: To obtain the relationship between macro-loading force of scaffold and micro-force between layers, so as to obtain the macro-force under the micro-force of optimal cell proliferation.

METHODS: The compression stress relaxation experiment of the blank scaffold was designed, and the finite element model of the scaffold was constructed after fitting viscoelastic constitutive equation with experimental data. The stress relaxation of the model was simulated to obtain the mechanical state between the scaffold layers.

RESULTS AND DISCUSSION: The force of each layer of the scaffold was distributed at 1.185-3.305 N, and the stress of each layer gradually decreased with time until it converged. The total displacement of the scaffold increased with the number of layers. The strain values between the layers of the scaffold ranged from 1.82x10^-2 to 4.47x10^-2. This value indicates that this is the best state for culturing cells. The finite element analysis results show that when 10% strain occurred macroscopically in the scaffold, the strain value of each layer was distributed in the numerical range of 2%-7%. When the macro strain of the stent was 5%, the strain value of each layer was distributed between 1% and 2%. When 20% strain occurred on the scaffold macroscopically, the strain value of each layer was distributed between 8% and 18%. Comparison results revealed the optimal strain value for cell proliferation was 4%-7%.