Self-adaptive ultrasonic measurement method for thickness of lubricating film of thick-coating sliding bearing

The invention discloses a self-adaptive ultrasonic measurement method for the thickness of a lubricating film of a thick-coating sliding bearing. In practical engineering, when a traditional ultrasonic method is used for measuring the thickness of a bearing lubricating film, a journal and a bearing usually need to be disassembled in advance to obtain a reference signal, and the mode is difficult to implement in some occasions. The self-adaptive ultrasonic measurement method for the thickness of the lubricating film without the reference signal has obvious significance. The method is oriented to ultrasonic detection of the thickness of a lubricating film of a sliding bearing with a thick coating, and based on superposition of ultrasonic waves of a four-layer medium system, a function relational expression of a reflection signal of a steel-coating interface and a reflection signal of a coating-lubricating oil interface is deduced; and obtaining the amplitude and phase of the reflection coefficient of the lubric