超高速电梯安全钳制动界面的率相关摩擦特性、机理及实验方法研究

High-speed safety gear is one of the key safety components for ultra-high speed elevators. A stable braking friction of safety gear is mandatory for the reliable operation of an ultra-high speed elevator. The experiments performed in the testing tower of some renowned elevator manufacturer show that the braking friction of high-speed safety gear is highly rate-dependent which cannot be explained with existing theory. Meanwhile, considering the extremely high cost of tests in the testing tower, an equivalent experimental methodology as well as lab testing facility are in urgent need of further investigation of characteristics and mechanism of rate-dependent braking friction for high-speed safety gear. In this project, an impact load is applied on the test sample in double shear configuration by free falling a platform with big dead mass so that it can achieve a large initial velocity of 25~30m/s. A spring as well as a hydraulic actuator is used to control the normal pressure on the test sample in a range of 20~50MPa. Combining with mechanical and optical measurement technology, a high-speed safety gear braking tester with the real-time friction and temperature recorded is developed. With this tester, the characteristics and the mechanism of the rate-dependent friction at the braking interface are experimentally investigated. This research is supposed to bring us some fundamental understanding on the rate-dependent interfacial friction, especially for high-speed safety gear application which is benefit to ultra-high speed elevators development in China.

高速安全钳是超高速电梯的核心安全部件之一。超高速电梯的安全可靠运行要求安全钳的制动具有稳定的摩擦。国内某知名电梯厂商的井道试验数据表明高速安全钳的制动摩擦具有现有理论尚无法解释的率相关效应。由于井道试验的高昂成本，迫切需要发展有效的地面试验方法和装置对高速安全钳制动摩擦的率相关特性及机理进行系统的研究。本项目拟利用大质量跌落平台对双剪构型的试样施加冲击载荷使得试样瞬间获得高达(25~30）m/s的初速度，通过弹性元件和液压装置控制试样的法向加载（20~50MPa），并结合现代光测力学方法，实现高速安全钳制动摩擦及其温升的实时测量,发展一套超高速电梯安全钳制动摩擦的实验研究方法和装置，为系统研究高速安全钳制动界面的率相关摩擦机理提供有效的技术手段。通过系统的实验研究，揭示超高速电梯安全钳制动摩擦的率相关特性和机理，建立相应的率相关摩擦模型，为我国自主研发超高速电梯提供础技术支撑。

本项目着重于研究高速安全钳制动摩擦的率相关效应，发展了一套能够有效测量超高速电梯安全钳制动摩擦的试验方法和装置。本试验方法以液压方式提供制动力从而保证不同工况下制动压力的稳定，实时测量了率相关摩擦系数及制动压力、制动初速度，制动界面温度。结合高速安全钳制动材料的物理特性及摩擦学性能，通过实试验验证并解释了高速安全钳制动摩擦的率相关效应，研究了率相关摩擦系数随制动压力及初速度的变化规律，揭示了高速安全钳制动界面的率相关摩擦机理并建立了相应的率相关摩擦模型。