Abstract Drag brake experiments using hexagonal, pentagonal, and circular friction blocks are conducted using a self-designed small-scale brake dynamometer to investigate the influence of the friction block shape on the tribological and dynamical behaviours of high-speed train brakes. A four-degree-of-freedom model that considers the interface contact behaviour is established to investigate the influence of the contact stiffness at the friction interface on the stability and vibration characteristics of the braking system. The experimental results show that the surface of the hexagonal friction block is slightly worn, and the contact plateaus is relatively uniform in size, whereas the pentagonal and circular friction blocks show visible ploughing and exfoliation and a significant proportion of large contact plateaus. Accordingly, the hexagonal friction block produces considerably less friction-induced vibration and noise than the pentagonal block and the circular block. Moreover, analysis of the vibration characteristics of the friction system indicates that the interface of the hexagonal friction block is mainly subjected to normal impact, whereas the interfaces of the other two blocks exhibit significantly more ploughing and shearing action in the tangential direction. In general, higher contact stiffness results in stronger friction-induced vibration, thereby enhancing the instability of the friction system. In this work, it is found that the friction block shape has a significant effect on the contact pressure distribution. The hexagonal friction block exhibits a more uniform distribution of contact pressure than the pentagonal and circular friction blocks, resulting in the lowest contact stiffness, as well as the least wear, vibration, and noise.

中文翻译：

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摩擦块形状对高速列车制动器摩擦学和动力学行为的影响

摘要 使用自行设计的小型制动测功机进行六边形、五边形和圆形摩擦块的阻力制动实验，研究摩擦块形状对高速列车制动器摩擦学和动力学行为的影响。建立考虑界面接触行为的四自由度模型，研究摩擦界面处的接触刚度对制动系统稳定性和振动特性的影响。实验结果表明，六边形摩擦块表面有轻微磨损，接触平台尺寸相对均匀，而五边形和圆形摩擦块则出现明显的翻耕剥落现象，大接触平台比例较大。因此，六边形摩擦块产生的摩擦引起的振动和噪音比五边形块和圆形块少得多。此外，对摩擦系统振动特性的分析表明，六边形摩擦块的界面主要受到法向冲击，而其他两个块的界面在切向方向上表现出明显更多的犁切作用。一般来说，较高的接触刚度会导致更强的摩擦引起的振动，从而增强摩擦系统的不稳定性。在这项工作中，发现摩擦块形状对接触压力分布有显着影响。六边形摩擦块比五边形和圆形摩擦块表现出更均匀的接触压力分布，