Research On Dynamic Stress Data Acquisition And Fatigue Analysis System

With the acceleration of urbanization and the development of the economy, Traffic congestion has become a growing problem. Especially in urban rail transit subway system is one of the most important solutions, has been widely used, its operating safety are bound to get more and more attention. Bogie as a core component of the rail vehicle, in the actual operating environment will be long and complex alternating stress, leading to fatigue damage and even fatigue failure on the key parts of the bearing, seriously affecting the safe operation of the vehicle.In general, we do test dynamic stress test in the actual operation to obtain the stress state data of the bogie key positions, then do the data processing to obtain fatigue strength assessment and fatigue life prediction.For the principles and characteristics of dynamic stress testing and fatigue analysis, we designed a dynamic stress data acquisition and fatigue analysis system, which can complete all the work from dynamic stress data acquisition to the fatigue analysis.For data acquisition part, we take full account of the characteristic of using environment, performance, cost and other requirements,then proposed ARM + CPLD double control core architecture.Programmable logic device CPLD is responsible for analog acquisition and conversion, including the timing control of multi-channel selector switch, AD converter chip, FIFO memory chips and other devices; STM32F407 is responsible for the overall system control and communication with the host computer using ethernet, via FSMC bus communication with CPLD, read staging converted data from the FIFO and upload it to PC with Ethernet.For fatigue analysis, we write analysis software with Matlab and Delphi,.and play to their respective advantages. We complete the design of human-computer interaction and the overall framework of analysis software on the Delphi environment, and use Matlab to write the actual handler. Software is divided into two modules, including data pre-processing and data analysis,In the data analysis module, we realized the rain flow counting and preparation of stress spectrum, using Goodman diagram and equivalent stress amplitude to evaluate the fatigue strength, fatigue life estimation based on two theories includingCorten-Dolan and Miner theory.,and other functions. Furthermore, verify the function of each module with the actual test data, and complete the fatigue strength assessment and life estimation of the test bogie fatigue.