Study on Generation of Macro-pores of Bionic Bone Scaffold Based on Knapsack Problem Model

An algorithm to generate macro-pores of bionic bone scaffold is proposed based on knapsack problem model in the paper. That is to construct the negative model of macro-pore structure of bionic bone scaffold according to the structure of knapsack problem model, with the ellipsoid as the basic unit, and the three-dimensional boundary of scaffold as the constrained space. Then, the model of bionic bone scaffold with macro-pores is generated by Boolean operation between the negative model and the model without macro-pores. In the algorithm, the unit model is constructed according to parameter information on major axis of ellipsoid, scale factor of major axis and minor axis, its geometric center coordinate, and its spatial attitude. Float encoding method based on two-dimensional array is adopted to organize the individual gene. The individual fitness is calculated according to the constraint of porosity and connectivity. New individuals are constantly generated to increase the diversity of population by the selection, crossover and mutation operation of individuals. The disturbing operator is adopted to improve the global searching efficiency of algorithm, and avoid algorithm to fall into the local extremum. The validity and feasibility of algorithm are validated by generating a model of bionic bone scaffold with macro-pores.