Biaxial tensile testing machines are used to improve accuracy of yield loci and constitutive model for sheet materials. The frame of these machines is the main load-bearing structure significantly affecting the machine accuracy. However, the available loading frames are too heavy to be practical for popularization and application. To reduce both the total weight of the frame and install consumption, this study develops a design method of stepwise multi-stage topology optimization based on the solid isotropic microstructures with penalization (SIMP) method. First, the validity of the finite element model during the optimization is verified by experiments. Next, the design method of stepwise multi-stage topology optimization is proposed based on the results of conventional topology optimization and the influence law of key parameters. This method is then applied to the topological optimization design of frames for a biaxial tensile testing machine. Finally, the optimized frame is manufactured, and biaxial tensile tests are conducted on the designed machine. The measurement of frame deformations shows that the frame weight is decreased by 19.5% compared with that of the initial design and that the frame stiffness meets design requirements. These results prove the effectiveness of the proposed method.

使用双轴拉伸试验机来提高板材的屈服点和本构模型的准确性。这些机器的机架是主要的承重结构，对机器的精度有很大影响。但是，可用的加载框架太重，无法推广和应用。为了减少框架的总重量和安装消耗，本研究开发了一种基于惩罚性的固体各向同性微结构的逐步多阶段拓扑优化设计方法。首先，通过实验验证了优化过程中有限元模型的有效性。接下来，根据常规拓扑优化的结果和关键参数的影响规律，提出了逐步多阶段拓扑优化的设计方法。然后将该方法应用于双轴拉伸试验机框架的拓扑优化设计。最后，制造出优化的机架，并在设计的机器上进行双轴拉伸测试。框架变形的测量结果表明，与初始设计相比，框架重量减轻了19.5％，并且框架刚度符合设计要求。这些结果证明了该方法的有效性。与初始设计相比降低了5％，并且框架刚度符合设计要求。这些结果证明了该方法的有效性。与初始设计相比降低了5％，并且框架刚度符合设计要求。这些结果证明了该方法的有效性。