ULTRASONIC MEASUREMENT OF INTERNAL CONTACT PRESSURE BETWEEN MATING PORTIONS OF SOLIDS SEPARATED WITH LIQUID FILM

摘要

PURPOSE: To measure a contact pressure by applying an acoustic pulse to a thin liquid film that forms one portion of an interface being compressed in an interface region between two solid surfaces and measuring the reflection coefficient or the transmission efficient of the interface region. CONSTITUTION: Thread compound is applied to the sealing surface of a screw and a pin 8/a box 7 and the pin 8 is screwed into the box 7 and a film between contact surfaces in the pipe connection 6 is compressed. On the other hand, a supersonic probe 2 is placed on a positioning jig 9 and is retained at an accurate position on the annular box 7. Water flows from a low-pressure supply water bath II to a support drum 10 of the jig 9, thus functioning as an acoustic coupler between the probe 2 and the coupling 6. A supersonic flow detector 3 is electrically connected to the probe 2 and a recorder 4 and the recorder 4 measures a voltage output corresponding to the linear gate control peak reader output of the detector 3. In this manner, by giving the receiver of the detector 3 outside a specimen and measuring the amplitude change of a transmission pulse when a contact pressure is given to a thin liquid film, an amount that indicates the contact pressure of the liquid film can be obtained.