Multi-material compliant mechanisms design enables potential design possibilities by exploiting the advantages of different materials. To satisfy mechanical/thermal impedance matching requirements, a method for multi-material topology optimization of large-displacement compliant mechanisms considering material-dependent boundary condition is presented in this study. In the optimization model, the element stacking method is employed to describe the material distribution and handle material-dependent boundary condition. The maximization of the output displacement of the compliant mechanism is developed as the objective function and the structural volume of each material is the constraint. Fictitious domain approach is applied to circumvent the numerical instabilities in topology optimization problem with geometrical nonlinearities. The method of moving asymptotes is applied to solve the optimization problem. Several numerical examples are presented to demonstrate the validity of the proposed method. The optimal topologies of the compliant mechanisms obtained by the proposed method can satisfy the specified material-dependent boundary condition.

多材料兼容机制设计通过利用不同材料的优势实现潜在的设计可能性。为了满足机械/热阻抗匹配要求，本研究提出了一种考虑材料相关边界条件的大位移柔顺机构的多材料拓扑优化方法。在优化模型中，采用元素堆叠方法来描述材料分布并处理与材料相关的边界条件。以柔顺机构输出位移的最大化为目标函数，以每种材料的结构体积为约束条件。虚拟域方法用于规避具有几何非线性的拓扑优化问题中的数值不稳定性。应用移动渐近线的方法来解决优化问题。给出了几个数值例子来证明所提出方法的有效性。通过所提出的方法获得的柔顺机构的最佳拓扑结构可以满足指定的材料相关边界条件。