An on-line correction technique of random loading with a real-time signal processor for a laboratory fatigue test

The authors present an application of the Solartron 1200 Real Time Signal Processor to correcting the on-line random loading in a fatigue test system. By inputting a power spectrum described by a data die to a computer, its corresponding random process may be simulated. Since the processor is connected with a computer, results of signal processing done by the processor are sent to the computer periodically during the test. The computer performs pattern matching using the correlation coefficient value (CCV) between a loading spectrum and its predetermined target. If a CCV exceeds its threshold, the old data file will be replaced with a new one and the random loading exerted on a specimen will be updated. When the new data file is obtained based on optimal control strategy, the updated loading spectrum will approach its target. Therefore, an electrohydraulic fatigue test system equipped with a real-time signal processor can realize an on-line correction of a random loading based on the target spectrum desired. Since this updating does not change the original software package and hardware of the system, the performance of the system and testing quality are safely improved.