Lightweight design of the Front-Middle Shield Using Kriging Model and Improved Simulated Annealing Algorithm

Shield machines are large-scale tunnel boring equipments, which are widely used in urban subway, railway, and water conservancy projects. The front-middle shield is one of the most critical components of shield machines. Lightweight design of the front-middle shield is of great significance, which can reduce the material cost and operation energy consumption. In this study, to minimize the weight of the front-middle shield, a lightweight design method using improved simulated annealing (ISA) algorithm and Kriging model is proposed. The finite element simulation and analysis of variance are employed to select key structural parameters. And then Kriging models are constructed to approximate the implicit relationships between structural parameters and performance respnses (including stress, deformation and weight). Finally, the lightweight design model of the front-middle shield is established, which is solved by ISA to obtain the global optimum solution. Compared with the classic simulated annealing (SA) algorithm, improvements are made to the perturbation model, attenuation method of annealing temperature, and temperature variation strategy, thus the optimization efficiency is significantly improved. The optimization results indicate that, while satisfying constraints of the stress and deformation, the proposed method effectively reduces the weight of the front-middle shield, achieving a weight reduction of 5.13%.