基于谐响应分析和应力圆的定义，探索一种对汽车车轮动态弯曲疲劳试验机输出弯矩的空间不均性进行分析的通用方法。对试验机在工作时所承受的力的情况进行分析与计算，并将计算结果导入有限元分析软件中，得到试验机规定位置的应力数据并绘制应力圆曲线，将在仿真环境中绘制的应力圆与试验机实际工作时所测绘出的应力圆曲线进行图形与参数的对比，明确了试验机工作时的受力情况：离心力是试验机的主要影响力；陀螺力矩是由于转子转动和加载臂横向摆动产生；非线性油膜力是润滑油在不平衡转子旋转下产生。对比上述三种作用力共同施加时的仿真结果与试验机实际工作测绘得到的应力圆曲线，其在形状和参数指标上都符合很好，证明了这种以应力圆来分析试验机工作性能的方法是可行的。

Based on the harmonic response analysis and the define of plane stress circle, a new method about the spatial non-uniformity analysis of the moment output for the car wheel dynamic bending fatigue testing machine is provided. The forces applied on the testing machine are analyzed and computed. Then, the forces are applied into the finite element model. The stress dates of the assigned positions are obtained and the curve of plane stress circle is plot. The simulation date and the measured results were compared by the plane stress circle curve graph and parameters. The analysis showed the three main influence forces of the testing machine: the effect of the centrifugal force is dominant for the performance of the testing machine; the gyroscopic moment comes from the coupling between the rotation of rotor and its lateral swinging; and the nonlinear oil film forces are caused by the lubricating oil and the unbalanced rotor rotation. Compared the plane stress circles between the measured results and the simulations when all the three kinds of dynamic load were applied on the testing machine, by the graphic and parameters, the data fit well. It proved that this method is appropriate for the analysis and design of the testing machine.