Papers by Author: Min Qiang Xu

Abstract: This article presents a SSDG---based intelligent fault diagnosis method. This method uses five signed threshold value modes to define nodes for carrying quantified information. This method establishes the SDGs of the system and its components, uses the based on rules method to diagnosis, then expands the diagnosing rule bank with logical operators to construct the diagnosing rule bank of the system. Applying in satellite battery system, this method can diagnosis the multiple fault, and batter explain, reworked and faster diagnosis.

Abstract: In order to investigate material behavior at the stage of early fatigue damage and critical fatigue fracture, a new nondestructive testing called metal magnetic memory (MMM) technology, has been introduced in this paper. The fatigue experiments are carried out on the PQ1-6 rotary bending fatigue machine. The MMM fatigue characteristics are presented and analyzed. It has been found that Hp(x) is increasing up to the peak value while the fatigue crack is initiating and growing. After that peak, Hp(x) decreases gradually with the fatigue crack deepening and stress releasing. The gradual increasing Hp(x) is the sign of the early fatigue damage and the Hp(x) peak predicts the critical fracture state. The validity of MMM results has been certified by microscopic metallographic examination. Furthermore, the MMM fatigue behavior is deduced theoretically based on the dislocation mechanics and fracture mechanics.

Abstract: Metal magnetic memory (MMM) method, based on the magneto-elasticity and mechanical effect theory, is a new nondestructive testing technology. This paper aims at the material property and failure analysis for steam turbine blade with MMM method. The failure blade and its fracture face are tested with MMM technology at workshop. It has been found that the MMM signal variation gradient of the crack transition zone in the fracture face is minimal, that of the crack initiation zone is in the middle, and that of the tear fracture zone is maximal. MMM testing results reflect material behavior degradation of the failure blade. In order to proof the MMM results, the dynamic stress of the steam turbine blade under the operation loading is calculated by WESTHOMES software and analyzed theoretically. It has proved the validity of the MMM method applied on material property evaluation and failure analysis for steam turbine blade.