| Recently some advanced technologies for acoustic emission (AE) test system have been caused much more attentions. The key technologies and design method of wireless AE systm are studied. The wireless AE sensor node are designed and constructed. The design and implementation of a monitoring and evaluating soft system based on virtual instrument (VI) techniques are discussed and tested in the laboratory.The theory, types and componets of tranditonal AE system are discussed in the paper. Considering the whole performance monitoring of civil engineering structures and disadvantages of the traditional AE test system, a new wireless AE system is proposed after studying the sensor technology, signal processing technology and the wireless communication technology well. The wireless AE system is divided into four main functional modules: analog signal input, data aquisiton, data communication (composed of two submodules: wireless sending and receiving) and signal analysis. Related electronic components are compared, analyzed and selected to develop the system. Software of wireless AE sensor node, which is composed of analog signal input molule, data aquisiton module and wireless sending submodule, is investigated based on ZigBee protocol. The performance of the node is investigated: Sampling frequency reaches to 300kHz, data precision reaches to 12bit, and the active time in idle mode reaches to 468 days. A software system for signal analysis based on VI is designed and developed, which is composed of several function modules, including data acquisition, data communication, signal analysis, sound alarm, etc. And the whole wireless AE system is tested in the laboratory. It is proved that the system possesses strong conveniently and more precisely in practical use. |
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