Method and apparatus for measuring fatigue of vibration member

PURPOSE: To indicate the accumulated fatigue of apparatus on-line by detecting the displacement caused by an accumulated force, calculating the amplitude and instantaneous frequency of the force, and determining an accumulated damage based on the calculation results. CONSTITUTION: A sensor group 23 comprising sensors 16-22 arranged oppositely to the outer blade of a turbine blade 12 generates a signal indicative of displacement caused by vibration of the turbine blade 12. The displacement signal is delivered to a signal conditioning circuit 24 where noise is from the signal. The signal is then introduced to a digitizer 26 and subjected to analog/digital conversion before being inputted to a data processing unit 28. The data processing unit 28 calculates the fatigue using data and formula stored in a data storage unit 30 and then calculates the fatigue age based on the displacement signal. The displacement signal is recorded in the data storage unit 30 and outputted, as a message 32, to an operator. COPYRIGHT: (C)1989,JPO