Dynamic Strain Measurement Instrument Based On Virtual Instrument Technology

Strain measurement, which has been concerned by many theoretical and experimental mechanical workers, is an important analysis method of measuring stress and strain of components in mechanical engineering. Resistance strain measurement method is a method used the most widely in experimental stress analysis. Through the introduction of advanced virtual instrument technology, we can better solve the problems of traditional resistance strain instruments. The traditional virtual instruments need a piece of data acquisition card used for test data collection. Commercial data acquisition cards with greater commonality, high sampling rate and high sampling accuracy etc, but because of its high prices, make some instrument function in some specific application scope appear not quite practical. But ordinary sound cards can achieve data acquisition needs in particular application asituations, it is mainly because of its 16 quantization accuracy and 44.1khz data acquisition frequency. In addition, the sound card itself has an A/D and D/A transformation device, low cost, and the standard configurations as computer soundcards, its standards are the same. Therefore the design based on virtual strain tester sound card has stronger generalization, lower cost and acceptable accuracy, and has a strong practical significance. Therefore, with quick speed developing high-performance strain measurements is completely needed.This paper firstly introduces the developing overview of strain measurement instruments. Then introduces the concept,composition and characteristics of virtual instruments, and analyses research status and developing trend of virtual instruments at home and abroad. Virtual instruments are compared with traditional instruments highlighting the superiority of virtual instruments. Subsequently introduces the theoretical basis of strain measurement techniques, including the characteristics,work principle of strain measurement and the type of strain measurement instruments. Then describes a software development platform—C++Builder and digital signal processing technology. Finally introduces the hardware and software of dynamic strain measurement system based on virtual instrument technology, and develops the virtual dynamic strain measurement.The virtual dynamic measurement using the normal sound card as the dynamic data collection card at C++Builder development platform in the Borland company, has many functions, such as filtering, labeling, data storing, wave displaying, frequency domain analyzing. Users can easily observe, analyse and deal with experiment results. The measurement instrument is a good choice for the more precision and medium-low frequency dynamic strain measurement.