Abstract: The front and middle shield was an important part of shield machines. Because of the large structural size and complex service environment， it was very important to carry out lightweight design on the premise of ensuring structural strength. Aiming at the front and middle shield of a slurry balance shield， a lightweight design method was proposed herein based on topology optimization and size optimization. Firstly， topology optimization was used in the front and middle shield structural design， and secondary design was carried out based on the topology optimization results. Then， the size optimization model of the front and middle shields was built after the secondary design， where the structural parameters that had great impacts on the mass， maximum deformation and maximum stress of the front and middle shields were selected as design variables by orthogonal experiment and analysis of variance. The optimal Latin hypercube design and finite element analysis method were used to obtain 45 groups of sample points， thereby a Kriging agent model with design variables-performance responses implicit relation were constructed. Finally， the size optimization model of the front and middle shields was solved by the sequential quadratic programming（SQP） algorithm， and the optimal size parameter groups were obtained. The verification results show that， the mass of the front and middle shields decreases by 30 t（with a drop of 3.1%）after topology optimization and size optimization. 

Key words: front and middle shield, finite element analysis, topology optimization, size optimization, Kriging model

摘要： 前中盾是盾构机的重要部件，其结构尺寸大、服役环境复杂，因此，在保证结构强度的前提下进行轻量化设计至关重要。针对某型号泥水平衡盾构机的前中盾，通过拓扑优化和尺寸优化实现轻量化。对现有前中盾结构进行拓扑优化设计，并根据拓扑优化结果进行二次设计；针对二次设计后的前中盾结构，构建尺寸优化模型，利用正交试验和方差分析筛选出对性能响应（前中盾质量、最大变形和最大应力）影响较大的结构参数作为设计变量，并通过最优拉丁超立方采样和有限元分析获得45组样本点，由此构建设计变量-性能响应隐式关系的Kriging代理模型；通过序列二次规划算法对前中盾尺寸优化模型进行求解获得最优的尺寸参数组合。验证结果表明，前中盾经过拓扑优化和尺寸优化后，质量减小约30 t，降幅达3.1%。

关键词: 前中盾, 有限元分析, 拓扑优化, 尺寸优化, Kriging模型