轨枕路基疲劳试验机加载反力架设计与优化

Design and optimization of the counterforce frame for sleeper and roadbed fatigue testing machine

针对目前动力加载反力框架刚度过小、结构形式不合理和材料用量过大等不足,系统地进行反力架的设计与优化。通过SOLIDWORKS建立4种不同结构形式加载反力框架的三维模型,使用ANSYS和ABAQUS静力分析了不同结构反力框架的刚度、强度大小及分布范围,并对比用钢量、力学性能指标,选出鱼腹梁结构形式进行优化设计。针对鱼腹梁反力架,通过ANSYS的模态分析得到其固有频率及振型,发生第一次垂向振动的频率为25.6 Hz,满足10 Hz作动器加载不引起共振的要求。通过瞬态分析模拟了10 Hz作动器试验时,反力框架的振动响应情况,最大位移为1.128 mm,但5 s后逐渐稳定在0.720 mm,满足动载荷精度和刚度要求。研究表明,相比于其他3种结构形式,鱼腹梁结构刚度最大、最经济,既满足动载荷刚度要求也节省了钢材。

The counterforce frame was systematically designed and optimized, aiming to improve its current disadvanta ges of small stiffness, unreasonable structures, and excessive material consumption, etc. By adopting SOLIDWORKS, the 3D models of four different kinds of counterforce frame structures were established, upon which static analysis were then conducted by ANSYS and ABAQUS. The magnitude and distribution of their stiffnesses and strengths were ob tained, and after comparing the steel consumptions and mechanical properties, the style of fish-bell sill was chosen to be further optimized. As for the fish-belly sill counterforce frame, its inherent frequency and vibration modes were ob tained through the modal analysis in ANSYS. The first vertical vibration took place at the frequency of 25.6 Hz, satisfy ing the requirement that the 10Hz actuator loading could not trigger resonance. Afterwards, the transient analysis could provide the vibration response of this specific counterforce frame, when tested with the 10 Hz actuator. The displace ment peaked at 1. 128 mm, and then stabilized at 0. 72 mm after 5 seconds, which met the requirements of both dynamic loading accuracy and counterforce frame stiffness. In sum, the results showed that the fish-belly sill structure could offer the most stiffness compared with the other three, which was large enough to meet the dynamic loading stiffness require ment, and in the meantime was the most economical with the least steel consumption.