Multi-channel Synchronous Data Acquisition And Data Processing System For Modal Analysis

In order to meet the requirement of mechanical design and mechanical fault diagnosis, and improve the maneuverability and efficiency of modal analysis system software, based on the research on data acquisition, data processing and modal analysis, from the view of engineering applications, a experiment modal analysis system is designed used for mechanical structure's modal analysis.The system's general planning is designed. Hardware platform and software requirements are confirmed. The software system has been divided into four function modules, which are project data management module, synchronous data acquisition module, data processing module and modal analysis module. After proposed the conception of engineering data management system, File structure and directory structure is worked out as this conception. After proposed the method about standard interface develop, acquisition controlling interface, file access interface and data display interface is worked out as this conception. Project data management module is realized based on these researches.A acquisition controlling mechanism which deal with wave showing task and data recording task separately and a method with a self-adapting sample frequency function which can choose different processing method automatically are worked out for real-timing and accuracy. The problem of the shortage of memory space for long-playing recording is solved by loop buffer method technology. At last, synchronous data acquisition module is realized following these methods.Through research on the theory of modal parameter identification, using frequency domain method to identify modal parameter is ascertained. Refer to software engineering conception, the data input method, the program data flow and the program controlling flow of data processing module is designed. Structure building, frequency response function's analysis, parameters identification and vibration mode etc, is designed and placed as a part of modal analysis module.A mechanical structural modal analysis system is designed which contains synchronous data acquisition, data processing and data analysis, etc. Experimental modal analysis, toward motorcycle frame and rectangle frame, has been done by this software system and compared the results with the software DSAP. The compared results show that the system has the same accuracy with the software DSAP.