Study Of The Fatigue Crack Measuring System Based On The Virtual Instrument Technology

The mechanical component fatigue crack damage has become increasingly serious in industry, so studying the fatigue crack growth process is of great significance for engineering applications.Currently, there are varieties of fatigue test equipments, but lack of an ideal crack on-line measuring device to reduce the people’s work capacity, test time and improve test accuracy. In order to meet new national standards for fatigue and fracture performance testing requirements, it is very important to carry out the on-line fatigue crack measurement task. With the image processing technology and the virtual instrument technology as the basis, this paper presents a fatigue crack-length on-line measuring method which applied to the high frequency fatigue testing system and works very well. The detail studies are as follows:1. Supply the entire architecture of the dual cameras fatigue crack monitoring system based on the virtual instrument technology and the related technologies are discussed briefly;2. Consider the system accuracy, efficiency and economy requirements, the fatigue crack detection hardware system is analyzed, the core hardware components and the related matching parameters are identified3. According to the system analysis of function, the overall framework of the software system is proposed. Also, the related modules are designed in detail.4. A new fatigue crack-length measuring method based on the virtual instrument technology and image processing technology is given, as further study, the algorithms are carried out based on LabVIEW and IMAQ Vision toolkit.5. Based on the NI motion control card, the camera motion control method is studied and applied to the high frequency fatigue testing system to get a clear crack images during the crack image acquiring process.6. The related experimental results show that the measurement system with the fatigue crack detection method proposed in this paper can accurately and reliably detect the fatigue crack and crack-length measuring accuracy reaches 0.01mm.Under the design of modular concept in this paper, the system has good reliability, maintainability and scalability. At present, the proposed fatigue crack detection method has been applied to many domestic fatigue test devices and has important theoretical study and practical application values.