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Aiming at the problem of pressure uniformity optimization of hydrodynamic pressure suspension polishing flow field, the influence of process parameters on the dynamic pressure in processing area was studied. Computational fluid dynamics (CFD) and uniform design method were used to solve the pressure mean and pressure standard deviation of the processing area under different process parameters. The mathematical model of the fitting of process parameters and pressure mean or pressure standard deviation were established by multiple nonlinear regression method, the process parameters were optimized by genetic algorithm and through numerical model. The pressure distribution and processing effect before and after optimization were compared. The results indicate that there is a nonlinear regression relationship between the selected process parameters, the pressure mean and pressure standard deviation. The optimal process parameters are h = 285 μm, ω = 1 300 r/min, and φ = 0. 12. Under this parameter, the flow field pressure in the workpiece area is the largest and the pressure standard difference is the least, which helps to remove the material quickly and evenly. [ABSTRACT FROM AUTHOR]

Fe-based coatings are deposited by plasma spraying technique. The fatigue wear experiments of the coatings are on-line monitored to capture the dynamic information of the cracks by using acoustic emission (AE) technique. The typical signal model is summarized. The micro-damages on the coating surface are characterized by oil whiting test. The micro-damages on the coating surface are analyzed by FIB-SEM, and its failure mechanism is investigated. Results show that the AE signal model during the fatigue wear process is divided into 3 stages, namely run-in period, stable period, and mutation period. Penetrating test technique is introduced to confirm the micro-damages on the coating surface. The reliability of AE monitoring can also be proved. The results show that the fractures in the coating can be accurately captured by AE signals. The micro-defects are considered to be the origins of coating failure based on the results of FIB-SEM analysis. [ABSTRACT FROM AUTHOR]