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This paper proposes a high-precision electrochemical micromachining (EMM) system. By applying nanosecond pulses, workpiece dissolution can be restricted to a very small area around the microelectrode. First, an EMM system that meets the requirements of the EMM process is built. Second, sets of comparative experiments are performed on pure nickel and superalloy plates to study the effects of main machining parameters, e.g., pulse on time, applied voltage, pulse period, and electrode diameters, on side gap. Finally, after the preliminary experiments, complex microshapes with characteristic size of several tens of micrometers are successfully fabricated on the nickel and superalloy plates, thereby demonstrating that EMM is a very promising microfabrication technology. [ABSTRACT FROM AUTHOR]

Electrochemical discharge machining with high-speed micro-electrode is a micro-machining process based on the fundamental of electrochemical discharge principle. The process has been applied in metal for drilling micro-holes. Drilling of micro-holes in stainless steel is a challenge working. A few qualitative conclusions are obtained by drilling micro-holes in stainless steel by electrochemical discharge machining with high-speed electrode using pure water as electrolyte. An experimental setup was established. A micro-hole was drilled in stainless steel successfully. [ABSTRACT FROM PUBLISHER]

A kind of embedded acoustic emission (AE) sensor for the concrete health monitoring was fabricated by using the 1-3 polymer/cement-based piezoelectric composite. The frequency bandwidth, sensitivity, threshold value, and response of the sensor were investigated. The results show that the embedded acoustic emission sensor has broad frequency bandwidth and low threshold value, and is very sensitive to crack propagation of the cement mortar in the loading test. Moreover, there is a good relationship between AE signals and the damage process of the cement mortar. The embedded acoustic emission sensor can be used to detect and collect the AE signals in different fracture stages, and make accurate judgments on the damage condition of the cement mortar. So, the embedded acoustic emission sensor is suitable for the concrete health monitoring. [ABSTRACT FROM AUTHOR]